1
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Martin CD, Bender AT, Sullivan BP, Lillis L, Boyle DS, Posner JD. SARS-CoV-2 recombinase polymerase amplification assay with lateral flow readout and duplexed full process internal control. Sens Diagn 2024; 3:421-430. [PMID: 38495597 PMCID: PMC10939122 DOI: 10.1039/d3sd00246b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/08/2024] [Indexed: 03/19/2024]
Abstract
Nucleic acid amplification tests for the detection of SARS-CoV-2 have been an important testing mechanism for the COVID-19 pandemic. While these traditional nucleic acid diagnostic methods are highly sensitive and selective, they are not suited to home or clinic-based uses. Comparatively, rapid antigen tests are cost-effective and user friendly but lack in sensitivity and specificity. Here we report on the development of a one-pot, duplexed reverse transcriptase recombinase polymerase amplification SARS-CoV-2 assay with MS2 bacteriophage as a full process control. Detection is carried out with either real-time fluorescence or lateral flow readout with an analytical sensitivity of 50 copies per reaction. Unlike previously published assays, the RNA-based MS2 bacteriophage control reports on successful operation of lysis, reverse transcription, and amplification. This SARS-CoV-2 assay features highly sensitive detection, visual readout through an LFA strip, results in less than 25 minutes, minimal instrumentation, and a useful process internal control to rule out false negative test results.
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Affiliation(s)
- Coleman D Martin
- Department of Chemical Engineering, University of Washington Seattle Washington USA
| | - Andrew T Bender
- Department of Mechanical Engineering, University of Washington Seattle Washington USA
| | - Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington Seattle Washington USA
| | | | | | - Jonathan D Posner
- Department of Chemical Engineering, University of Washington Seattle Washington USA
- Department of Mechanical Engineering, University of Washington Seattle Washington USA
- Department of Family Medicine, University of Washington Seattle Washington USA
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2
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Olanrewaju AO, Sullivan BP, Gim AH, Craig CA, Sevenler D, Bender AT, Drain PK, Posner JD. REverSe TRanscrIptase chain termination (RESTRICT) for selective measurement of nucleotide analogs used in HIV care and prevention. Bioeng Transl Med 2023; 8:e10369. [PMID: 36684094 PMCID: PMC9842053 DOI: 10.1002/btm2.10369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/16/2022] [Accepted: 06/20/2022] [Indexed: 01/25/2023] Open
Abstract
Sufficient drug concentrations are required for efficacy of antiretroviral drugs used in HIV care and prevention. Measurement of nucleotide analogs, included in most HIV medication regimens, enables monitoring of short- and long-term adherence and the risk of treatment failure. The REverSe TRanscrIptase Chain Termination (RESTRICT) assay rapidly infers the concentration of intracellular nucleotide analogs based on the inhibition of DNA synthesis by HIV reverse transcriptase enzyme. Here, we introduce a probabilistic model for RESTRICT and demonstrate selective measurement of multiple nucleotide analogs using DNA templates designed according to the chemical structure of each drug. We measure clinically relevant concentrations of tenofovir diphosphate, emtricitabine triphosphate, lamivudine triphosphate, and azidothymidine triphosphate with agreement between experiment and theory. RESTRICT represents a new class of activity-based assays for therapeutic drug monitoring in HIV care and could be extended to other diseases treated with nucleotide analogs.
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Affiliation(s)
- Ayokunle O. Olanrewaju
- Department of Mechanical EngineeringUniversity of WashingtonSeattleWashingtonUSA
- Department of BioengineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Benjamin P. Sullivan
- Department of Mechanical EngineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Alicia H. Gim
- Department of Chemical EngineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Cosette A. Craig
- Department of Mechanical EngineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Derin Sevenler
- Center for Engineering in Medicine and SurgeryMassachusetts General HospitalBostonMassachusettsUSA
| | - Andrew T. Bender
- Department of Mechanical EngineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Paul K. Drain
- Department of EpidemiologyUniversity of WashingtonSeattleWashingtonUSA
- Department of Global HealthUniversity of WashingtonSeattleWashingtonUSA
- Department of MedicineUniversity of WashingtonSeattleWashingtonUSA
| | - Jonathan D. Posner
- Department of Mechanical EngineeringUniversity of WashingtonSeattleWashingtonUSA
- Department of Chemical EngineeringUniversity of WashingtonSeattleWashingtonUSA
- Department of Family MedicineUniversity of WashingtonSeattleWashingtonUSA
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3
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Chia CT, Bender AT, Lillis L, Sullivan BP, Martin CD, Burke W, Landis C, Boyle DS, Posner JD. Rapid detection of hepatitis C virus using recombinase polymerase amplification. PLoS One 2022; 17:e0276582. [PMID: 36282844 PMCID: PMC9595512 DOI: 10.1371/journal.pone.0276582] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
Over 71 million people are infected with hepatitis C virus (HCV) worldwide, and approximately 400,000 global deaths result from complications of untreated chronic HCV. Pan-genomic direct-acting antivirals (DAAs) have recently become widely available and feature high cure rates in less than 12 weeks of treatment. The rollout of DAAs is reliant on diagnostic tests for HCV RNA to identify eligible patients with viremic HCV infections. Current PCR-based HCV RNA assays are restricted to well-resourced central laboratories, and there remains a prevailing clinical need for expanded access to decentralized HCV RNA testing to provide rapid chronic HCV diagnosis and linkage to DAAs in outpatient clinics. This paper reports a rapid, highly accurate, and minimally instrumented assay for HCV RNA detection using reverse transcription recombinase polymerase amplification (RT-RPA). The assay detects all HCV genotypes with a limit of detection of 25 copies per reaction for genotype 1, the most prevalent in the United States and worldwide. The clinical sensitivity and specificity of the RT-RPA assay were both 100% when evaluated using 78 diverse clinical serum specimens. The accuracy, short runtime, and low heating demands of RT-RPA may enable implementation in a point-of-care HCV test to expand global access to effective treatment via rapid chronic HCV diagnosis.
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Affiliation(s)
- Catherine T. Chia
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Andrew T. Bender
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | | | - Benjamin P. Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | - Coleman D. Martin
- Department of Chemical Engineering, University of Washington, Seattle, Washington, United States of America
| | - Wynn Burke
- Department of Medicine, Division of Gastroenterology, University of Washington, Seattle, Washington, United States of America
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Charles Landis
- Department of Medicine, Division of Gastroenterology, University of Washington, Seattle, Washington, United States of America
| | | | - Jonathan D. Posner
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
- Department of Chemical Engineering, University of Washington, Seattle, Washington, United States of America
- Family Medicine, School of Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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4
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Sullivan BP, Chou YS, Bender AT, Martin CD, Kaputa ZG, March H, Song M, Posner JD. Quantitative isothermal amplification on paper membranes using amplification nucleation site analysis. Lab Chip 2022; 22:2352-2363. [PMID: 35548880 PMCID: PMC9202034 DOI: 10.1039/d2lc00007e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Quantitative nucleic acid amplification tests (qNAATs) are critical in treating infectious diseases, such as in HIV viral load monitoring or SARS-CoV-2 testing, in which viral load indicates viral suppression or infectivity. Quantitative PCR is the gold standard tool for qNAATs; however, there is a need to develop point-of-care (POC) qNAATs to manage infectious diseases in outpatient clinics, low- and middle-income countries, and the home. Isothermal amplification methods are an emerging tool for POC NAATs as an alternative to traditional PCR-based workflows. Previous works have focused on relating isothermal amplification bulk fluorescence signals to input copies of target nucleic acids for sample quantification with limited success. In this work, we show that recombinase polymerase amplification (RPA) reactions on paper membranes exhibit discrete fluorescent amplification nucleation sites. We demonstrate that the number of nucleation sites can be used to quantify HIV-1 DNA and viral RNA in less than 20 minutes. An image-analysis algorithm quantifies nucleation sites and determines the input nucleic acid copies in the range of 67-3000 copies per reaction. We demonstrate a mobile phone-based system for image capture and onboard processing, illustrating that this method may be used at the point-of-care for qNAATs with minimal instrumentation.
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Affiliation(s)
- Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, Washington, USA.
| | - Yu-Shan Chou
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
| | - Andrew T Bender
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, Washington, USA.
| | - Coleman D Martin
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
| | - Zoe G Kaputa
- Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, Washington, USA
| | - Hugh March
- Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, Washington, USA
| | - Minyung Song
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, Washington, USA.
| | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, Washington, USA.
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
- Department of Family Medicine, University of Washington, Seattle, Washington, USA
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5
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Zhang JY, Zhang Y, Bender AT, Sullivan BP, Olanrewaju AO, Lillis L, Boyle D, Drain PK, Posner JD. HIV pre-exposure prophylaxis adherence test using reverse transcription isothermal amplification inhibition assay. Anal Methods 2022; 14:1361-1370. [PMID: 35297917 PMCID: PMC8991996 DOI: 10.1039/d2ay00008c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Current HIV antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) therapy adherence monitoring relies on either patient self-reported adherence or monitored drug dispensing, which are not reliable. We report a proof-of-concept adherence monitoring assay which directly measures nucleotide reverse transcriptase inhibitor (NRTI) concentration using a reverse transcription isothermal amplification inhibition assay. We measure the concentration of Tenofovir diphosphate (TFV-DP) - an NRTI that functions as a deoxyadenosine triphosphate (dATP) analog and long-term adherence marker for PrEP - by measuring the inhibition of the reverse transcription of an RNA template. The completion or inhibition of reverse transcription is evaluated by recombinase polymerase amplification (RPA), an isothermal nucleic acid amplification assay commonly used for point-of-care diagnostics. We present and validate a model that predicts the amplification probability as a function of dATP and TFV-DP concentrations, nucleotide insertion sites on the RNA template, and RNA template concentration. The model can be used to rationally design and optimize the assay to operate at clinically relevant TFV-DP concentrations. We provide statistical analysis that demonstrates how the assay may be used as a qualitative or semi-quantitative tool for measuring adherence to NRTI drugs and used to support patient compliance. Due to its simple instrumentation and short runtime (<1 hour), this assay has the potential for implementation in low-complexity laboratories or point-of-care settings, which may improve access to ART and PrEP adherence monitoring.
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Affiliation(s)
- Jane Y Zhang
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
| | - Yu Zhang
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
| | - Andrew T Bender
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
| | - Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
| | | | | | | | - Paul K Drain
- Department of Global Health, University of Washington, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
- Department of Epidemiology, University of Washington, Seattle, WA, USA
| | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
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6
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Sullivan BP, Chou YS, Bender AT, Martin CD, Kaputa ZG, March H, Song M, Posner JD. Quantitative Isothermal Amplification on Paper Membranes using Amplification Nucleation Site Analysis. bioRxiv 2022:2022.01.11.475898. [PMID: 35043115 PMCID: PMC8764744 DOI: 10.1101/2022.01.11.475898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantitative nucleic acid amplification tests (qNAATs) are critical in treating infectious diseases, such as in HIV viral load monitoring or SARS-CoV-2 testing, in which viral load indicates viral suppression or infectivity. Quantitative PCR is the gold standard tool for qNAATs; however, there is a need to develop point-of-care (POC) qNAATs to manage infectious diseases in outpatient clinics, low- and middle-income countries, and the home. Isothermal amplification methods are an emerging tool for POC NAATs as an alternative to traditional PCR-based workflows. Previous works have focused on relating isothermal amplification bulk fluorescence signals to input copies of target nucleic acids for sample quantification with limited success. In this work, we show that recombinase polymerase amplification (RPA) reactions on paper membranes exhibit discrete fluorescent amplification nucleation sites. We demonstrate that the number of nucleation sites can be used to quantify HIV-1 DNA and RNA in less than 20 minutes. An image-analysis algorithm quantifies nucleation sites and determines the input nucleic acid copies in the range of 67-3,000 copies per reaction. We demonstrate a mobile phone-based system for image capture and onboard processing, illustrating that this method may be used at the point-of-care for qNAATs with minimal instrumentation.
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7
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Rutherford JW, Larson T, Gould T, Seto E, Novosselov IV, Posner JD. Source Apportionment of Environmental Combustion Sources using Excitation Emission Matrix Fluorescence Spectroscopy and Machine Learning. Atmos Environ (1994) 2021; 259:118501. [PMID: 34321954 PMCID: PMC8312701 DOI: 10.1016/j.atmosenv.2021.118501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The link between particulate matter (PM) air pollution and negative health effects is well-established. Air pollution was estimated to cause 4.9 million deaths in 2017 and PM was responsible for 94% of these deaths. In order to inform effective mitigation strategies in the future, further study of PM and its health effects is important. Here, we present a method for identifying sources of combustion generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy and machine learning (ML) algorithms. PM samples were collected during a health effects exposure assessment panel study in Seattle. We use archived field samples from the exposure study and the associated positive matrix factorization (PMF) source apportionment based on X-ray fluorescence and light absorbing carbon measurements to train convolutional neural network and principal component regression algorithms. We show EEM spectra from cyclohexane extracts of the archived filter samples can be used to accurately apportion mobile and vegetative burning sources but were unable to detect crustal dust, Cl-rich, secondary sulfate and fuel oil sources. The use of this EEM-ML approach may be used to conduct PM exposure studies that include source apportionment of combustion sources.
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Affiliation(s)
- Jay W. Rutherford
- Department of Chemical Engineering, University of Washington, Seattle WA, United States
| | - Timothy Larson
- Department of Civil and Environmental Engineering, University of Washington, Seattle WA, United States
| | - Timothy Gould
- Department of Civil and Environmental Engineering, University of Washington, Seattle WA, United States
| | - Edmund Seto
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle WA, United States
| | - Igor V. Novosselov
- Department of Mechanical Engineering, University of Washington, Seattle WA, United States
| | - Jonathan D. Posner
- Department of Chemical Engineering, University of Washington, Seattle WA, United States
- Department of Mechanical Engineering, University of Washington, Seattle WA, United States
- Department of Family Medicine, University of Washington, Seattle WA, United States
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8
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Bender AT, Sullivan BP, Zhang JY, Juergens DC, Lillis L, Boyle DS, Posner JD. HIV detection from human serum with paper-based isotachophoretic RNA extraction and reverse transcription recombinase polymerase amplification. Analyst 2021; 146:2851-2861. [PMID: 33949378 PMCID: PMC9151496 DOI: 10.1039/d0an02483j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The number of people living with HIV continues to increase with the current total near 38 million, of which about 26 million are receiving antiretroviral therapy (ART). These treatment regimens are highly effective when properly managed, requiring routine viral load monitoring to assess successful viral suppression. Efforts to expand access by decentralizing HIV nucleic acid testing in low- and middle-income countries (LMICs) has been hampered by the cost and complexity of current tests. Sample preparation of blood samples has traditionally relied on cumbersome RNA extraction methods, and it continues to be a key bottleneck for developing low-cost POC nucleic acid tests. We present a microfluidic paper-based analytical device (μPAD) for extracting RNA and detecting HIV in serum, leveraging low-cost materials, simple buffers, and an electric field. We detect HIV virions and MS2 bacteriophage internal control in human serum using a novel lysis and RNase inactivation method, paper-based isotachophoresis (ITP) for RNA extraction, and duplexed reverse transcription recombinase polymerase amplification (RT-RPA) for nucleic acid amplification. We design a specialized ITP system to extract and concentrate RNA, while excluding harsh reagents used for lysis and RNase inactivation. We found the ITP μPAD can extract and purify 5000 HIV RNA copies per mL of serum. We then demonstrate detection of HIV virions and MS2 bacteriophage in human serum within 45-minutes.
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Affiliation(s)
- Andrew T Bender
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
| | - Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
| | - Jane Y Zhang
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
| | - David C Juergens
- Department of Chemical Engineering, University of Washington, Seattle, USA
| | | | | | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, USA. and Department of Chemical Engineering, University of Washington, Seattle, USA and Family Medicine, School of Medicine, University of Washington, Seattle, USA
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9
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Olanrewaju AO, Sullivan BP, Bardon AR, Lo TJ, Cressey TR, Posner JD, Drain PK. Pilot evaluation of an enzymatic assay for rapid measurement of antiretroviral drug concentrations. Virol J 2021; 18:77. [PMID: 33858461 PMCID: PMC8048217 DOI: 10.1186/s12985-021-01543-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 04/03/2021] [Indexed: 01/16/2023] Open
Abstract
Objective Maintaining adequate drug adherence is crucial to ensure the HIV prevention benefits of pre-exposure prophylaxis (PrEP). We developed an enzymatic assay for rapidly measuring tenofovir-diphosphate (TFV-DP) concentrations—a metabolite that indicates long-term PrEP adherence. Setting The study was conducted at the Madison HIV Clinic at Harborview Medical Center in Seattle. Methods We enrolled adults receiving standard oral PrEP, and individuals not receiving any antiretrovirals. We measured TFV-DP concentrations in diluted whole blood using our novel REverSe TRanscrIptase Chain Termination (RESTRICT) assay, based on inhibition of HIV reverse transcriptase (RT) enzyme. Blood samples were diluted in water, DNA templates, nucleotides, RT, and intercalating dye added, and results measured with a fluorescence reader—stronger fluorescence indicated higher RT activity. We compared RESTRICT assay results to TFV-DP concentrations from matched dried blood spot samples measured by liquid chromatography tandem mass spectrometry (LC–MS/MS) using ≥ 700 fmol/punch TFV-DP as a threshold for adequate adherence (≥ 4 doses/week). Results Among 18 adults enrolled, 4 of 7 participants receiving PrEP had TFV-DP levels ≥ 700 fmol/punch by LC–MS/MS. RESTRICT fluorescence correlated with LC–MS/MS measurements (r = − 0.845, p < 0.0001). Median fluorescence was 93.3 (95% confidence interval [CI] 90.9 to 114) for samples < 700 fmol/punch and 54.4 (CI 38.0 to 72.0) for samples ≥ 700 fmol/punch. When calibrated to an a priori defined threshold of 82.7, RESTRICT distinguished both groups with 100% sensitivity and 92.9% specificity. Conclusions This novel enzymatic assay for measuring HIV reverse transcriptase activity may be suitable for distinguishing TFV-DP concentrations in blood that correspond to protective PrEP adherence.
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Affiliation(s)
| | - Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - Ashley R Bardon
- Department of Global Health, Schools of Medicine and Public Health, University of Washington, Seattle, USA
| | - Tiffany J Lo
- Department of Materials Science and Engineering, University of Washington, Seattle, USA
| | - Tim R Cressey
- PHPT/IRD 174, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.,Harvard T.H. Chan School of Public Health, Harvard University, Boston, USA.,Department of Molecular and Clinical Pharmacology, University of Liverpool, Liverpool, UK
| | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, USA.,Department of Chemical Engineering, University of Washington, Seattle, USA.,Department of Family Medicine, University of Washington, Seattle, USA
| | - Paul K Drain
- Department of Global Health, Schools of Medicine and Public Health, University of Washington, Seattle, USA. .,Department of Medicine, School of Medicine, University of Washington, Seattle, USA. .,Department of Epidemiology, School of Public Health, University of Washington, Seattle, USA.
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10
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Zhang JY, Bender AT, Boyle DS, Drain PK, Posner JD. Current state of commercial point-of-care nucleic acid tests for infectious diseases. Analyst 2021; 146:2449-2462. [PMID: 33899053 DOI: 10.1039/d0an01988g] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The COVID-19 pandemic has put the spotlight on the urgent need for integrated nucleic acid tests (NATs) for infectious diseases, especially those that can be used near patient ("point-of-care", POC), with rapid results and low cost, but without sacrificing sensitivity or specificity of gold standard PCR tests. In the US, the Clinical Laboratory Improvement Amendments Certificate of Waiver (CLIA-waiver) is mandated by the Food and Drug Administration (FDA) and designated to any laboratory testing with high simplicity and low risk for error, suitable for application in the POC. Since the first issuance of CLIA-waiver to Abbot's ID NOW Influenza A&B in 2015, many more NAT systems have been developed, received the CLIA-waiver in the US or World Health Organization (WHO)'s pre-qualification, and deployed to the front line of infectious disease detection. This review highlights the regulatory process for FDA and WHO in evaluating these NATs and the technology innovation of existing CLIA-waived systems. Understanding the technical advancement and challenges, unmet needs, and the trends of commercialization facilitated through the regulatory processes will help pave the foundation for future development and technology transfer from research to the market place.
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Affiliation(s)
- Jane Y Zhang
- Department of Mechanical Engineering, University of Washington, USA.
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11
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Moran JL, Wheat PM, Marine NA, Posner JD. Chemokinesis-driven accumulation of active colloids in low-mobility regions of fuel gradients. Sci Rep 2021; 11:4785. [PMID: 33637781 PMCID: PMC7910604 DOI: 10.1038/s41598-021-83963-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/02/2021] [Indexed: 12/31/2022] Open
Abstract
Many motile cells exhibit migratory behaviors, such as chemotaxis (motion up or down a chemical gradient) or chemokinesis (dependence of speed on chemical concentration), which enable them to carry out vital functions including immune response, egg fertilization, and predator evasion. These have inspired researchers to develop self-propelled colloidal analogues to biological microswimmers, known as active colloids, that perform similar feats. Here, we study the behavior of half-platinum half-gold (Pt/Au) self-propelled rods in antiparallel gradients of hydrogen peroxide fuel and salt, which tend to increase and decrease the rods' speed, respectively. Brownian Dynamics simulations, a Fokker-Planck theoretical model, and experiments demonstrate that, at steady state, the rods accumulate in low-speed (salt-rich, peroxide-poor) regions not because of chemotaxis, but because of chemokinesis. Chemokinesis is distinct from chemotaxis in that no directional sensing or reorientation capabilities are required. The agreement between simulations, model, and experiments bolsters the role of chemokinesis in this system. This work suggests a novel strategy of exploiting chemokinesis to effect accumulation of motile colloids in desired areas.
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Affiliation(s)
- Jeffrey L Moran
- Department of Mechanical Engineering, George Mason University, Fairfax, VA, USA.
| | - Philip M Wheat
- Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, USA
| | - Nathan A Marine
- Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, USA
| | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA. .,Department of Chemical Engineering, University of Washington, Seattle, WA, USA. .,Department of Family Medicine, School of Medicine, University of Washington, Seattle, WA, USA.
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12
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Sullivan BP, Bender AT, Ngyuen DN, Zhang JY, Posner JD. Nucleic acid sample preparation from whole blood in a paper microfluidic device using isotachophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2020; 1163:122494. [PMID: 33401049 DOI: 10.1016/j.jchromb.2020.122494] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 12/03/2020] [Accepted: 12/05/2020] [Indexed: 02/08/2023]
Abstract
Nucleic acid amplification tests (NAATs) are a crucial diagnostic and monitoring tool for infectious diseases. A key procedural step for NAATs is sample preparation: separating and purifying target nucleic acids from crude biological samples prior to nucleic acid amplification and detection. Traditionally, sample preparation has been performed with liquid- or solid-phase extraction, both of which require multiple trained user steps and significant laboratory equipment. The challenges associated with sample preparation have limited the dissemination of NAAT point-of-care diagnostics in low resource environments, including low- and middle-income countries. We report on a paper-based device for purification of nucleic acids from whole blood using isotachophoresis (ITP) for point-of-care NAATs. We show successful extraction and purification of target nucleic acids from large volumes (33 µL) of whole human blood samples with no moving parts and few user steps. Our device utilizes paper-based buffer reservoirs to fully contain the liquid ITP buffers and does not require complex filling procedures, instead relying on the natural wicking of integrated paper membranes. We perform on-device blood fractionation via filtration to remove leukocytes and erythrocytes from our sample, followed by integrated on-paper proteolytic digestion of endogenous plasma proteins to allow for successful isotachophoretic extraction. Paper-based isotachophoresis purifies and concentrates target nucleic acids that are added directly to recombinase polymerase amplification (RPA) reactions. We show consistent amplification of input copy concentrations of as low as 3 × 103 copies nucleic acid per mL input blood with extraction and purification taking only 30 min. By employing a paper architecture, we are able to incorporate these processes in a single, robust, low-cost design, enabling the direct processing of large volumes of blood, with the only intermediate user steps being the removal and addition of tape. Our device represents a step towards a simple, fully integrated sample preparation system for nucleic acid amplification tests at the point-of-care.
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Affiliation(s)
- Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Andrew T Bender
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Duy N Ngyuen
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
| | - Jane Yuqian Zhang
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA
| | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, WA, USA; Department of Chemical Engineering, University of Washington, Seattle, WA, USA; Department of Family Medicine, University of Washington, Seattle, WA, USA.
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13
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Mahamuni G, Rutherford J, Davis J, Molnar E, Posner JD, Seto E, Korshin G, Novosselov I. Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter. Environ Sci Technol 2020; 54:8198-8209. [PMID: 32479734 DOI: 10.1021/acs.est.0c01110] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Analysis of particulate matter (PM) is important for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM. Specifically, polycyclic aromatic hydrocarbons (PAHs) found in ultrafine PM have been linked to cardiovascular diseases and carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with lower molecular weight (LMW, 126 < MW < 202) and higher molecular weight (HMW, 226 < MW < 302), i.e., smaller and larger than Pyrene, in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. Laboratory combustion PM samples were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on ethylene and ethane. Fuel dilution by Ar in 0% to 90% range controlled the flame temperature. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature (Tmax,c ∼ 1791 to 1857 K) and the highest soot luminosity region temperature (T*c ∼ 1600 to 1650K). Principal component regression (PCR) analysis of the EEM spectra of IGFR samples correlates to GCMS data with R2 = 0.988 for LMW and 0.998 for HMW PAHs. PCR-EEM analysis trained on the IGFR samples was applied to PM samples from woodsmoke and diesel exhaust, the model accurately predicts HMW PAH concentrations with R2 = 0.976 and overestimates LMW PAHs.
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Affiliation(s)
- Gaurav Mahamuni
- University of Washington, Mechanical Engineering, Seattle, Washington 98195, United States
| | - Jay Rutherford
- University of Washington, Chemical Engineering, Seattle, Washington 98195, United States
| | - Justin Davis
- University of Washington, Molecular Engineering, Seattle, Washington 98195, United States
| | - Eric Molnar
- University of Washington, Mechanical Engineering, Seattle, Washington 98195, United States
| | - Jonathan D Posner
- University of Washington, Mechanical Engineering, Seattle, Washington 98195, United States
- University of Washington, Chemical Engineering, Seattle, Washington 98195, United States
| | - Edmund Seto
- University of Washington, Environmental and Occupational Health Sciences, Seattle, Washington 98195, United States
| | - Gregory Korshin
- University of Washington, Civil and Environmental Engineering, Seattle, Washington 98195, United States
| | - Igor Novosselov
- University of Washington, Mechanical Engineering, Seattle, Washington 98195, United States
- University of Washington, Environmental and Occupational Health Sciences, Seattle, Washington 98195, United States
- University of Washington, Institute for Nano-Engineered Systems, Seattle, Washington 98195, United States
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14
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Bender AT, Sullivan BP, Lillis L, Posner JD. Enzymatic and Chemical-Based Methods to Inactivate Endogenous Blood Ribonucleases for Nucleic Acid Diagnostics. J Mol Diagn 2020; 22:1030-1040. [PMID: 32450280 DOI: 10.1016/j.jmoldx.2020.04.211] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/20/2020] [Accepted: 04/28/2020] [Indexed: 01/28/2023] Open
Abstract
There are ongoing research efforts into simple and low-cost point-of-care nucleic acid amplification tests (NATs) addressing widespread diagnostic needs in resource-limited clinical settings. Nucleic acid testing for RNA targets in blood specimens typically requires sample preparation that inactivates robust blood ribonucleases (RNases) that can rapidly degrade exogenous RNA. Most NATs rely on decades-old methods that lyse pathogens and inactivate RNases with high concentrations of guanidinium salts. Herein, we investigate alternatives to standard guanidinium-based methods for RNase inactivation using an activity assay with an RNA substrate that fluoresces when cleaved. The effects of proteinase K, nonionic surfactants, SDS, dithiothreitol, and other additives on RNase activity in human serum are reported. Although proteinase K has been widely used in protocols for nuclease inactivation, it was found that high concentrations of proteinase K are unable to eliminate RNase activity in serum, unless used in concert with denaturing concentrations of SDS. It was observed that SDS must be combined with proteinase K, dithiothreitol, or both for irreversible and complete RNase inactivation in serum. This work provides an alternative chemistry for inactivating endogenous RNases for use in simple, low-cost point-of-care NATs for blood-borne pathogens.
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Affiliation(s)
- Andrew T Bender
- Department of Mechanical Engineering, University of Washington, Seattle, Washington
| | - Benjamin P Sullivan
- Department of Mechanical Engineering, University of Washington, Seattle, Washington
| | | | - Jonathan D Posner
- Department of Mechanical Engineering, University of Washington, Seattle, Washington; Department of Chemical Engineering, University of Washington, Seattle, Washington; Department of Family Medicine, University of Washington, Seattle, Washington.
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15
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Olanrewaju AO, Sullivan BP, Zhang JY, Bender AT, Sevenler D, Lo TJ, Fernandez-Suarez M, Drain PK, Posner JD. Enzymatic Assay for Rapid Measurement of Antiretroviral Drug Levels. ACS Sens 2020; 5:952-959. [PMID: 32248685 PMCID: PMC7183420 DOI: 10.1021/acssensors.9b02198] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Poor adherence to pre-exposure prophylaxis (PrEP) and antiretroviral therapy (ART) can lead to human immunodeficiency virus (HIV) acquisition and emergence of drug-resistant infections, respectively. Measurement of antiviral drug levels provides objective adherence information that may help prevent adverse health outcomes. Gold-standard drug-level measurement by liquid chromatography/mass spectrometry is centralized, heavily instrumented, and expensive and is thus unsuitable and unavailable for routine use in clinical settings. We developed the REverSe TRanscrIptase Chain Termination (RESTRICT) assay as a rapid and accessible measurement of drug levels indicative of long-term adherence to PrEP and ART. The assay uses designer single-stranded DNA templates and intercalating fluorescent dyes to measure complementary DNA (cDNA) formation by reverse transcriptase in the presence of nucleotide reverse transcriptase inhibitor drugs. We optimized the RESTRICT assay using aqueous solutions of tenofovir diphosphate (TFV-DP), a metabolite that indicates long-term adherence to ART and PrEP, at concentrations over 2 orders of magnitude above and below the clinically relevant range. We used dilution in water as a simple sample preparation strategy to detect TFV-DP spiked into whole blood and accurately distinguished TFV-DP drug levels corresponding to low and high PrEP adherences. The RESTRICT assay is a fast and accessible test that could be useful for patients and clinicians to measure and improve ART and PrEP adherence.
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Affiliation(s)
| | | | - Jane Y. Zhang
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - Andrew T. Bender
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - Derin Sevenler
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, Boston
| | - Tiffany J. Lo
- Department of Materials Science & Engineering, University of Washington, Seattle
| | | | - Paul K. Drain
- Department of Epidemiology, University of Washington, Seattle
- Department of Global Health, University of Washington, Seattle
- Department of Medicine, University of Washington, Seattle
| | - Jonathan D. Posner
- Department of Mechanical Engineering, University of Washington, Seattle, USA
- Department of Chemical Engineering, University of Washington, Seattle
- Department of Family Medicine, University of Washington, Seattle
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16
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Rutherford JW, Dawson-Elli N, Manicone AM, Korshin GV, Novosselov IV, Seto E, Posner JD. Excitation Emission Matrix Fluorescence Spectroscopy for Combustion Generated Particulate Matter Source Identification. Atmos Environ (1994) 2020; 220:117065. [PMID: 32256182 PMCID: PMC7111209 DOI: 10.1016/j.atmosenv.2019.117065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The inhalation of particulate matter (PM) is a significant health risk associated with reduced life expectancy due to increased cardio-pulmonary disease and exacerbation of respiratory diseases such as asthma and pneumonia. PM originates from natural and anthropogenic sources including combustion engines, cigarettes, agricultural burning, and forest fires. Identifying the source of PM can inform effective mitigation strategies and policies, but this is difficult to do using current techniques. Here we present a method for identifying PM source using excitation emission matrix (EEM) fluorescence spectroscopy and a machine learning algorithm. We collected combustion generated PM2.5 from wood burning, diesel exhaust, and cigarettes using filters. Filters were weighted to determine mass concentration followed by extraction into cyclohexane and analysis by EEM fluorescence spectroscopy. Spectra obtained from each source served as training data for a convolutional neural network (CNN) used for source identification in mixed samples. This method can predict the presence or absence of the three laboratory sources with an overall accuracy of 89% when the threshold for classifying a source as present is 1.1 μg/m3 in air over a 24-hour sampling time. The limit of detection for cigarette, diesel and wood are 0.7, 2.6, 0.9 μg/m3, respectively, in air assuming a 24-hour sampling time at an air sampling rate of 1.8 liters per minute. We applied the CNN algorithm developed using the laboratory training data to a small set of field samples and found the algorithm was effective in some cases but would require a training data set containing more samples to be more broadly applicable.
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Affiliation(s)
- Jay W. Rutherford
- Department of Chemical Engineering, Critical Care and Sleep Medicine University of Washington
| | - Neal Dawson-Elli
- Department of Chemical Engineering, Critical Care and Sleep Medicine University of Washington
| | - Anne. M. Manicone
- Department of Medicine: Pulmonary, Critical Care and Sleep Medicine University of Washington
| | - Gregory V. Korshin
- Department of Mechanical Engineering, Critical Care and Sleep Medicine University of Washington
| | - Igor V. Novosselov
- Department of Mechanical Engineering, Critical Care and Sleep Medicine University of Washington
| | - Edmund Seto
- Environmental and Occupational Health Sciences, Critical Care and Sleep Medicine University of Washington
| | - Jonathan D. Posner
- Department of Chemical Engineering, Critical Care and Sleep Medicine University of Washington
- Department of Mechanical Engineering, Critical Care and Sleep Medicine University of Washington
- Department of Family Medicine, Critical Care and Sleep Medicine University of Washington
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17
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Bender AT, Borysiak MD, Levenson AM, Lillis L, Boyle DS, Posner JD. Semiquantitative Nucleic Acid Test with Simultaneous Isotachophoretic Extraction and Amplification. Anal Chem 2018; 90:7221-7229. [PMID: 29761701 DOI: 10.1021/acs.analchem.8b00185] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nucleic acid amplification tests (NAATs) provide high diagnostic accuracy for infectious diseases and quantitative results for monitoring viral infections. The majority of NAATs require complex equipment, cold chain dependent reagents, and skilled technicians to perform the tests. This largely confines NAATs to centralized laboratories and can significantly delay appropriate patient care. Low-cost, point-of-care (POC) NAATs are especially needed in low-resource settings to provide patients with diagnosis and treatment planning in a single visit to improve patient care. In this work, we present a rapid POC NAAT with integrated sample preparation and amplification using electrokinetics and paper substrates. We use simultaneous isotachophoresis (ITP) and recombinase polymerase amplification (RPA) to rapidly extract, amplify, and detect target nucleic acids from serum and whole blood in a paper-based format. We demonstrate simultaneous ITP and RPA can consistently detect 5 copies per reaction in buffer and 10 000 copies per milliliter of human serum with no intermediate user steps. We also show preliminary extraction and amplification of DNA from whole blood samples. Our test is rapid (results in less than 20 min) and made from low-cost materials, indicating its potential for detecting infectious diseases and monitoring viral infections at the POC in low resource settings.
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Affiliation(s)
- Andrew T Bender
- Mechanical Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - Mark D Borysiak
- Chemical Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - Amanda M Levenson
- Chemical Engineering , University of Washington , Seattle , Washington 98195 , United States
| | | | | | - Jonathan D Posner
- Mechanical Engineering , University of Washington , Seattle , Washington 98195 , United States.,Chemical Engineering , University of Washington , Seattle , Washington 98195 , United States
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18
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Cartwright MM, Schmuck SC, Corredor C, Wang B, Scoville DK, Chisholm CR, Wilkerson HW, Afsharinejad Z, Bammler TK, Posner JD, Shutthanandan V, Baer DR, Mitra S, Altemeier WA, Kavanagh TJ. The pulmonary inflammatory response to multiwalled carbon nanotubes is influenced by gender and glutathione synthesis. Redox Biol 2016; 9:264-275. [PMID: 27596734 PMCID: PMC5013253 DOI: 10.1016/j.redox.2016.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 12/14/2022] Open
Abstract
Inhalation of multiwalled carbon nanotubes (MWCNTs) during their manufacture or incorporation into various commercial products may cause lung inflammation, fibrosis, and oxidative stress in exposed workers. Some workers may be more susceptible to these effects because of differences in their ability to synthesize the major antioxidant and immune system modulator glutathione (GSH). Accordingly, in this study we examined the influence of GSH synthesis and gender on MWCNT-induced lung inflammation in C57BL/6 mice. GSH synthesis was impaired through genetic manipulation of Gclm, the modifier subunit of glutamate cysteine ligase, the rate-limiting enzyme in GSH synthesis. Twenty-four hours after aspirating 25µg of MWCNTs, all male mice developed neutrophilia in their lungs, regardless of Gclm genotype. However, female mice with moderate (Gclm heterozygous) and severe (Gclm null) GSH deficiencies developed significantly less neutrophilia. We found no indications of MWCNT-induced oxidative stress as reflected in the GSH content of lung tissue and epithelial lining fluid, 3-nitrotyrosine formation, or altered mRNA or protein expression of several redox-responsive enzymes. Our results indicate that GSH-deficient female mice are rendered uniquely susceptible to an attenuated neutrophil response. If the same effects occur in humans, GSH-deficient women manufacturing MWCNTs may be at greater risk for impaired neutrophil-dependent clearance of MWCNTs from the lung. In contrast, men may have effective neutrophil-dependent clearance, but may be at risk for lung neutrophilia regardless of their GSH levels.
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Affiliation(s)
- Megan M Cartwright
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Stefanie C Schmuck
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Charlie Corredor
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Bingbing Wang
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - David K Scoville
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Claire R Chisholm
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Hui-Wen Wilkerson
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Zahra Afsharinejad
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Theodor K Bammler
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Jonathan D Posner
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA; Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
| | | | - Donald R Baer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Somenath Mitra
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | | | - Terrance J Kavanagh
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA.
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19
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Borysiak MD, Thompson MJ, Posner JD. Translating diagnostic assays from the laboratory to the clinic: analytical and clinical metrics for device development and evaluation. Lab Chip 2016; 16:1293-1313. [PMID: 27043204 DOI: 10.1039/c6lc00015k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
As lab-on-a-chip health diagnostic technologies mature, there is a push to translate them from the laboratory to the clinic. For these diagnostics to achieve maximum impact on patient care, scientists and engineers developing the tests should understand the analytical and clinical statistical metrics that determine the efficacy of the test. Appreciating and using these metrics will benefit test developers by providing consistent measures to evaluate analytical and clinical test performance, as well as guide the design of tests that will most benefit clinicians and patients. This paper is broken into four sections that discuss metrics related to general stages of development including: (1) laboratory assay development (analytical sensitivity, limit of detection, analytical selectivity, and trueness/precision), (2) pre-clinical development (diagnostic sensitivity, diagnostic specificity, clinical cutoffs, and receiver-operator curves), (3) clinical use (prevalence, predictive values, and likelihood ratios), and (4) case studies from existing clinical data for tests relevant to the lab-on-a-chip community (HIV, group A strep, and chlamydia). Each section contains definitions of recommended statistical measures, as well as examples demonstrating the importance of these metrics at various stages of the development process. Increasing the use of these metrics in lab-on-a-chip research will improve the rigor of diagnostic performance reporting and provide a better understanding of how to design tests that will ultimately meet clinical needs.
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Affiliation(s)
- Mark D Borysiak
- Chemical Engineering, University of Washington, Seattle, WA 98195, USA.
| | - Matthew J Thompson
- Department of Family Medicine, University of Washington, Seattle, WA 98195, USA
| | - Jonathan D Posner
- Chemical Engineering, University of Washington, Seattle, WA 98195, USA. and Department of Family Medicine, University of Washington, Seattle, WA 98195, USA and Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
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20
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Gilbertson LM, Albalghiti EM, Fishman ZS, Perreault F, Corredor C, Posner JD, Elimelech M, Pfefferle LD, Zimmerman JB. Shape-Dependent Surface Reactivity and Antimicrobial Activity of Nano-Cupric Oxide. Environ Sci Technol 2016; 50:3975-3984. [PMID: 26943499 DOI: 10.1021/acs.est.5b05734] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Shape of engineered nanomaterials (ENMs) can be used as a design handle to achieve controlled manipulation of physicochemical properties. This tailored material property approach necessitates the establishment of relationships between specific ENM properties that result from such manipulations (e.g., surface area, reactivity, or charge) and the observed trend in behavior, from both a functional performance and hazard perspective. In this study, these structure-property-function (SPF) and structure-property-hazard (SPH) relationships are established for nano-cupric oxide (n-CuO) as a function of shape, including nanospheres and nanosheets. In addition to comparing these shapes at the nanoscale, bulk CuO is studied to compare across length scales. The results from comprehensive material characterization revealed correlations between CuO surface reactivity and bacterial toxicity with CuO nanosheets having the highest surface reactivity, electrochemical activity, and antimicrobial activity. While less active than the nanosheets, CuO nanoparticles (sphere-like shape) demonstrated enhanced reactivity compared to the bulk CuO. This is in agreement with previous studies investigating differences across length-scales. To elucidate the underlying mechanisms of action to further explain the shape-dependent behavior, kinetic models applied to the toxicity data. In addition to revealing different CuO material kinetics, trends in observed response cannot be explained by surface area alone. The compiled results contribute to further elucidate pathways toward controlled design of ENMs.
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Affiliation(s)
- Leanne M Gilbertson
- Department of Civil and Environmental Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | | | | | - François Perreault
- School of Sustainable Engineering and the Built Environment, Arizona State University , Tempe, Arizona 85287, United States
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21
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Borysiak MD, Kimura KW, Posner JD. NAIL: Nucleic Acid detection using Isotachophoresis and Loop-mediated isothermal amplification. Lab Chip 2015; 15:1697-707. [PMID: 25666345 DOI: 10.1039/c4lc01479k] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Nucleic acid amplification tests are the gold standard for many infectious disease diagnoses due to high sensitivity and specificity, rapid operation, and low limits of detection. Despite the advantages of nucleic acid amplification tests, they currently offer limited point-of-care (POC) utility due to the need for complex instruments and laborious sample preparation. We report the development of the Nucleic Acid Isotachophoresis LAMP (NAIL) diagnostic device. NAIL uses isotachophoresis (ITP) and loop-mediated isothermal amplification (LAMP) to extract and amplify nucleic acids from complex matrices in less than one hour inside of an integrated chip. ITP is an electrokinetic separation technique that uses an electric field and two buffers to extract and purify nucleic acids in a single step. LAMP amplifies nucleic acids at constant temperature and produces large amounts of DNA that can be easily detected. A mobile phone images the amplification results to eliminate the need for laser fluorescent detection. The device requires minimal user intervention because capillary valves and heated air chambers act as passive valves and pumps for automated fluid actuation. In this paper, we describe NAIL device design and operation, and demonstrate the extraction and detection of pathogenic E. coli O157:H7 cells from whole milk samples. We use the Clinical and Laboratory Standards Institute (CLSI) limit of detection (LoD) definitions that take into account the variance from both positive and negative samples to determine the diagnostic LoD. According to the CLSI definition, the NAIL device has a limit of detection (LoD) of 1000 CFU mL(-1) for E. coli cells artificially inoculated into whole milk, which is two orders of magnitude improvement to standard tube-LAMP reactions with diluted milk samples and comparable to lab-based methods. The NAIL device potentially offers significant reductions in the complexity and cost of traditional nucleic acid diagnostics for POC applications.
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Affiliation(s)
- Mark D Borysiak
- Chemical Engineering Department, University of Washington, Seattle, WA 98195, USA. E-mail:
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22
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Corredor C, Borysiak MD, Wolfer J, Westerhoff P, Posner JD. Colorimetric detection of catalytic reactivity of nanoparticles in complex matrices. Environ Sci Technol 2015; 49:3611-3618. [PMID: 25635807 DOI: 10.1021/es504350j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
There is a need for new methodologies to quickly assess the presence and reactivity of nanoparticles (NPs) in commercial, environmental, and biological samples since current detection techniques require expensive and complex analytical instrumentation. Here, we investigate a simple and portable colorimetric detection assay that assesses the surface reactivity of NPs, which can be used to detect the presence of NPs, in complex matrices (e.g., environmental waters, serum, urine, and in dissolved organic matter) at as low as part per billion (ppb) or ng/mL concentration levels. Surface redox reactivity is a key emerging property related to potential toxicity of NPs with living cells, and is used in our assays as a key surrogate for the presence of NPs and a first tier analytical strategy toward assessing NP exposures. We detect a wide range of metal (e.g., Ag and Au) and oxide (e.g., CeO2, SiO2, VO2) NPs with a diameter range of 5 to 400 nm and multiple capping agents (tannic acid (TA), polyvinylpyrrolidone (PVP), branched polyethylenimine (BPEI), polyethylene glycol (PEG)). This method is sufficiently sensitive (ppb levels) to measure concentrations typically used in toxicological studies, and uses inexpensive, commercially available reagents.
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Affiliation(s)
- Charlie Corredor
- †Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Mark D Borysiak
- †Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Jay Wolfer
- ‡Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Paul Westerhoff
- §School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287, United States
| | - Jonathan D Posner
- †Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
- ‡Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States
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23
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Moghadam BY, Connelly KT, Posner JD. Two Orders of Magnitude Improvement in Detection Limit of Lateral Flow Assays Using Isotachophoresis. Anal Chem 2015; 87:1009-17. [DOI: 10.1021/ac504552r] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Babak Y. Moghadam
- Mechanical
Engineering Department, University of Washington, Seattle, Washington 98195, United States
| | - Kelly T. Connelly
- Mechanical
Engineering Department, University of Washington, Seattle, Washington 98195, United States
| | - Jonathan D. Posner
- Mechanical
Engineering Department, University of Washington, Seattle, Washington 98195, United States
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24
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Abstract
Paper substrates have been widely used to construct point-of-care lateral flow immunoassay (LFIA) diagnostic devices. Paper based microfluidic devices are robust and relatively simple to operate, compared to channel microfluidic devices, which is perhaps their greatest advantage and the reason they have reached a high level of commercial success. However, paper devices may not be well suited for integrated sample preparation, such as sample extraction and preconcentration, which is required in complex samples with low analyte concentrations. In this study, we investigate integration of isotachophoresis (ITP), an electrokinetic preconcentration and extraction technique, onto nitrocellulose-based paper microfluidic devices with the goal to improve the limit of detection of LFIA. ITP has been largely used in traditional capillary based microfluidic devices as a pretreatment method to preconcentrate and separate a variety of ionic compounds. Our findings show that ITP on nitrocellulose is capable of up to a 900 fold increase in initial sample concentration and up to 60% extraction from 100 μL samples and more than 80% extraction from smaller sample volumes. Paper based ITP is challenged by Joule heating and evaporation because it is open to the environment. We achieved high preconcentration by mitigating evaporation induced dispersion using novel cross-shaped device structures that keep the paper hydrated. We show that ITP on the nitrocellulose membrane can be powered and run several times by a small button battery suggesting that it could be integrated to a portable point-of-care diagnostic device. These results highlight the potential of ITP to increase the sensitivity of paper based LFIA under conditions where small analyte concentrations are present in complex biological samples.
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Affiliation(s)
- Babak Y Moghadam
- Department of Mechanical Engineering, University of Washington , Seattle, Washington 98195, United States
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25
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Abstract
Styrene-ethylene/butylene-styrene (SEBS) copolymers combine thermoplastic and elastomeric properties to provide microdevices with the advantageous properties of hard thermoplastics and ease of fabrication similar to PDMS. This work describes the electrical surface properties of SEBS block copolymers using current monitoring experiments to determine zeta potential. We show that SEBS exhibits a stable and relatively high zeta potential magnitude compared to similar polymers. The zeta potential of SEBS is stable when stored in air over time, and no significant differences are observed between different batches and devices, demonstrating reproducibility of results. We show zeta potential trends for varying pH and counterion concentration and demonstrate that SEBS has a repeatable surface potential comparable to glass. Oxygen plasma treatment greatly increases the zeta potential magnitude immediately following treatment before undergoing a moderate hydrophobic recovery to a stable zeta potential. SEBS copolymers also offer simple rapid prototyping fabrication and mass production potential. The presented electrokinetic properties combined with simple, low-cost fabrication of microdevices make SEBS a quality material for electrokinetic research and application development.
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Affiliation(s)
- Mark D Borysiak
- Department of Chemical Engineering, University of Washington , Seattle, Washington 98195, United States
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26
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Posner JD, Marine NA. Reply to Comment on “Partition Coefficient Measurements in Picoliter Drops Using a Segmented Flow Microfluidic Device”. Anal Chem 2013; 85:10623-4. [DOI: 10.1021/ac402799v] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jonathan D. Posner
- Department
of Mechanical Engineering, University of Washington, Seattle, Washington 98125, United States
| | - Nathan A. Marine
- Mechanical
Engineering, Arizona State University, Tempe, Arizona 85287, United States
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27
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Corredor C, Hou WC, Klein SA, Moghadam BY, Goryll M, Doudrick K, Westerhoff P, Posner JD. Disruption of Model Cell Membranes by Carbon Nanotubes. Carbon N Y 2013; 60:67-75. [PMID: 31007268 PMCID: PMC6474754 DOI: 10.1016/j.carbon.2013.03.057] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Carbon nanotubes (CNTs) have one of the highest production volumes among carbonaceous engineered nanoparticles (ENPs) worldwide and are have potential uses in applications including biomedicine, nanocomposites, and energy conversion. However, CNTs possible widespread usage and associated likelihood for biological exposures have driven concerns regarding their nanotoxicity and ecological impact. In this work, we probe the responses of planar suspended lipid bilayer membranes, used as model cell membranes, to functionalized multi-walled carbon nanotubes (MWCNT), CdSe/ZnS quantum dots, and a control organic compound, melittin, using an electrophysiological measurement platform. The electrophysiological measurements show that MWCNTs in a concentration range of 1.6 to 12 ppm disrupt lipid membranes by inducing significant transmembrane current fluxes, which suggest that MWCNTs insert and traverse the lipid bilayer membrane, forming transmembrane carbon nanotubes channels that allow the transport of ions. This paper demonstrates a direct measurement of ion migration across lipid bilayers induced by CNTs. Electrophysiological measurements can provide unique insights into the lipid bilayer-ENPs interactions and have the potential to serve as a preliminary screening tool for nanotoxicity.
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Affiliation(s)
- Charlie Corredor
- Chemical Engineering, University of Washington, Seattle, WA 98115
| | - Wen-Che Hou
- Environmental Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Steven A. Klein
- Mechanical Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | | | - Michael Goryll
- Electrical Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Kyle Doudrick
- Environmental Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Paul Westerhoff
- Environmental Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Jonathan D. Posner
- Chemical Engineering, University of Washington, Seattle, WA 98115
- Mechanical Engineering, University of Washington, Seattle, WA 98115
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Borysiak MD, Bielawski KS, Sniadecki NJ, Jenkel CF, Vogt BD, Posner JD. Simple replica micromolding of biocompatible styrenic elastomers. Lab Chip 2013; 13:2773-84. [PMID: 23670166 PMCID: PMC3799950 DOI: 10.1039/c3lc50426c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this work, we introduce a simple solvent-assisted micromolding technique for the fabrication of high-fidelity styrene-ethylene/butylene-styrene (SEBS) microfluidic devices with high polystyrene (PS) content (42 wt% PS, SEBS42). SEBS triblock copolymers are styrenic thermoplastic elastomers that exhibit both glassy thermoplastic and elastomeric properties resulting from their respective hard PS and rubbery ethylene/butylene segments. The PS fraction gives SEBS microdevices many of the appealing properties of pure PS devices, while the elastomeric properties simplify fabrication of the devices, similar to PDMS. SEBS42 devices have wettable, stable surfaces (both contact angle and zeta potential) that support cell attachment and proliferation consistent with tissue culture dish substrates, do not adsorb hydrophobic molecules, and have high bond strength to wide range of substrates (glass, PS, SEBS). Furthermore, SEBS42 devices are mechanically robust, thermally stable, as well as exhibit low auto-fluorescence and high transmissivity. We characterize SEBS42 surface properties by contact angle measurements, cell culture studies, zeta potential measurements, and the adsorption of hydrophobic molecules. The PS surface composition of SEBS microdevices cast on different substrates is determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The attractive SEBS42 material properties, coupled with the simple fabrication method, make SEBS42 a quality substrate for microfluidic applications where the properties of PS are desired but the ease of PDMS micromolding is favoured.
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Affiliation(s)
- Mark D. Borysiak
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Kevin S. Bielawski
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Nathan J. Sniadecki
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Colin F. Jenkel
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Bryan D. Vogt
- Department of Polymer Engineering, University of Akron, Akron, OH 44325, USA
| | - Jonathan D. Posner
- Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
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29
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Marine NA, Wheat PM, Ault J, Posner JD. Diffusive behaviors of circle-swimming motors. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 87:052305. [PMID: 23767538 DOI: 10.1103/physreve.87.052305] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 04/29/2013] [Indexed: 06/02/2023]
Abstract
Spherical catalytic micromotors fabricated as described in Wheat et al. [Langmuir 26, 13052 (2010)] show fuel concentration dependent translational and rotational velocity. The motors possess short-time and long-time diffusivities that scale with the translational and rotational velocity with respect to fuel concentration. The short-time diffusivities are two to three orders of magnitude larger than the diffusivity of a Brownian sphere of the same size, increase linearly with concentration, and scale as v(2)/2ω. The measured long-time diffusivities are five times lower than the short-time diffusivities, scale as v(2)/{2D(r)[1+(ω/D(r))(2)]}, and exhibit a maximum as a function of concentration. Maximums of effective diffusivity can be achieved when the rotational velocity has a higher order of dependence on the controlling parameter(s), for example fuel concentration, than the translational velocity. A maximum in diffusivity suggests that motors can be separated or concentrated using gradients in fuel concentration. The decrease of diffusivity with time suggests that motors will have a high collision probability in confined spaces and over short times; but will not disperse over relatively long distances and times. The combination of concentration dependent diffusive time scales and nonmonotonic diffusivity of circle-swimming motors suggests that we can expect complex particle responses in confined geometries and in spatially dependent fuel concentration gradients.
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Affiliation(s)
- Nathan A Marine
- Department of Mechanical Engineering, Arizona State University, Tempe, Arizona 85287, USA
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30
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Negoda A, Liu Y, Hou WC, Corredor C, Moghadam BY, Musolff C, Li N, Walker W, Westerhoff P, Mason AJ, Duxbury P, Posner JD, Worden RM. Engineered nanomaterial interactions with bilayer lipid membranes: screening platforms to assess nanoparticle toxicity. ACTA ACUST UNITED AC 2013. [DOI: 10.1504/ijbnn.2013.054512] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Hou WC, Westerhoff P, Posner JD. Biological accumulation of engineered nanomaterials: a review of current knowledge. Environ Sci Process Impacts 2013; 15:103-122. [PMID: 24592431 DOI: 10.1039/c2em30686g] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Due to the widespread use of engineered nanomaterials (ENMs) in consumer and industrial products, concerns have been raised over their impacts once released into the ecosystems. While there has been a wealth of studies on the short-term acute toxic effects of ENMs over the past decade, work on the chronic endpoints, such as biological accumulation, has just begun to increase in last 2–3 years. Here, we comprehensively review over 65 papers on the biological accumulation of ENMs under a range of ecologically relevant exposure conditions in water, soil or sediment with the focus on quantitative comparison among these existing studies. We found that daphnid, fish, and earthworm are the most commonly studied ecological receptors. Current evidence suggests that ENM accumulation level is generally low in fish and earthworms with logarithmic bioconcentration concentration factor and biota-sediment accumulation factor ranging from 0.85–3.43 (L kg−1) and −2.21–0.4 (kg kg−1), respectively. ENMs accumulated in organisms at the lower trophic level can transfer to higher trophic level animals with the occurrence of biomagnification varying depending on the specific food chain studied. We conclude the review by identifying the challenges and knowledge gaps and propose paths forward.
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32
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Kim SJ, Ko SH, Kwak R, Posner JD, Kang KH, Han J. Multi-vortical flow inducing electrokinetic instability in ion concentration polarization layer. Nanoscale 2012; 4:7406-10. [PMID: 23085964 DOI: 10.1039/c2nr32467a] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes was directly confirmed by experiments using particle tracers and interdigitated electrodes were used to measure the local concentration profile inside the ICP layer. At larger applied electric fields, we observed aperiodic fluid motion due to electrokinetic instabilities which develop from a coupling of applied electric fields and electrical conductivity gradients induced by the ICP. The electrokinetic instability at micro-nanofluidic interfaces is important in the development of various electro-chemical-mechanical applications such as fuel cells, bio-analytical preconcentration methods, water purification/desalination and the fundamental study of ion electromigration through nanochannels and nonporous perm-selective membranes.
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Affiliation(s)
- Sung Jae Kim
- Department of Electrical and Computer Engineering/Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-744, Republic of Korea.
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33
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Moghadam BY, Hou WC, Corredor C, Westerhoff P, Posner JD. Role of nanoparticle surface functionality in the disruption of model cell membranes. Langmuir 2012; 28:16318-26. [PMID: 22921268 PMCID: PMC3508167 DOI: 10.1021/la302654s] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Lipid bilayers are biomembranes common to cellular life and constitute a continuous barrier between cells and their environment. Understanding the interaction of engineered nanomaterials (ENMs) with lipid bilayers is an important step toward predicting subsequent biological effects. In this study, we assess the effect of varying the surface functionality and concentration of 10-nm-diameter gold (Au) and titanium dioxide (TiO(2)) ENMs on the disruption of negatively charged lipid bilayer vesicles (liposomes) using a dye-leakage assay. Our findings show that Au ENMs having both positive and negative surface charge induce leakage that reaches a steady state after several hours. Positively charged particles with identical surface functionality and different core compositions show similar leakage effects and result in faster and greater leakage than negatively charged particles, which suggests that surface functionality, not particle core composition, is a critical factor in determining the interaction between ENMs and lipid bilayers. The results suggest that particles permanently adsorb to bilayers and that only one positively charged particle is required to disrupt a liposome and trigger the leakage of its entire contents in contrast to mellitin molecules, the most widely studied membrane lytic peptide, which requires hundred of molecules to generate leakage.
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Affiliation(s)
- Babak Y. Moghadam
- Mechanical Engineering, Chemical Engineering, University of Washington, Seattle, WA 98195
| | - Wen-Che Hou
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-5306
| | - Charlie Corredor
- Mechanical Engineering, Chemical Engineering, University of Washington, Seattle, WA 98195
| | - Paul Westerhoff
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-5306
| | - Jonathan D. Posner
- Mechanical Engineering, Chemical Engineering, University of Washington, Seattle, WA 98195
- Corresponding Author: (J.D.P). Tel: +1 (206) 543-9834. Fax: +1 (206) 685-8047
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34
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Hou WC, Moghadam BY, Corredor C, Westerhoff P, Posner JD. Distribution of functionalized gold nanoparticles between water and lipid bilayers as model cell membranes. Environ Sci Technol 2012; 46:1869-76. [PMID: 22242832 DOI: 10.1021/es203661k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Lipid bilayers are biomembranes common to cellular life and constitute a continuous barrier between cells and their environment. Understanding the interaction of nanoparticles with lipid bilayers is an important step toward predicting subsequent biological effects. In this study, we assessed the affinity of functionalized gold nanoparticles (Au NPs) with sizes from 5 to 100 nm to lipid bilayers by determining the Au NP distribution between aqueous electrolytes and lipid bilayers. The Au NP distribution to lipid bilayers reached an apparent steady state in 24 h with smaller Au NPs distributing onto lipid bilayers more rapidly than larger ones. Au NPs distributed to lipid bilayers to a larger extent at lower pH. Tannic acid-functionalized Au NPs exhibited greater distribution to lipid bilayers than polyvinylpyrrolidone-functionalized Au NPs of the same size. Across the various Au NP sizes, we measure the lipid bilayer-water distribution coefficient (K(lipw) = C(lip)/C(w)) as 450 L/kg lipid, which is independent of dosimetric units. This work suggests that the nanoparticle-cell membrane interaction is dependent on solution chemistry and nanoparticle surface functionality. The K(lipw) value may be used to predict the affinity of spherical Au NPs across a certain size range toward lipid membranes.
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Affiliation(s)
- Wen-Che Hou
- Mechanical Engineering, Chemical Engineering, University of Washington, Seattle, Washington 98195-2600, United States.
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35
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Hou WC, Moghadam BY, Westerhoff P, Posner JD. Distribution of fullerene nanomaterials between water and model biological membranes. Langmuir 2011; 27:11899-11905. [PMID: 21854052 DOI: 10.1021/la2017837] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Biological membranes are one of the important interfaces between cells and pollutants. Many polar and hydrophobic chemicals can accumulate within these membranes. For this reason, artificial biological membranes are appealing surrogates to complex organisms for assessing the bioaccumulation potential of engineered nanomaterials (ENMs). To our knowledge, this work presents the first quantitative study on the distribution of fullerene ENMs between lipid bilayers, used as model biological membranes, and water. We evaluated the lipid bilayer-water association coefficients (K(lipw)) of aqueous fullerene aggregates (nC(60)) and fullerol (C(60)(ONa)(x)(OH)(y), x + y = 24). Kinetic studies indicated that fullerol reached apparent equilibrium more rapidly than nC(60) (2 h versus >9 h). Nonlinear isotherms can describe the distribution behavior of nC(60) and fullerol. The lipid bilayer-water distributions of both nC(60) and fullerol were pH-dependent with the accumulation in lipid bilayers increasing systematically as the pH decreased from 8.6 (natural water pH) to 3 (the low end of physiologically relevant pH). This pH dependency varies with the zeta potentials of the ENMs and leads to patterns similar to those previously observed for the lipid bilayer-water distribution behavior of ionizable organic pollutants. The K(lipw) value for nC(60) was larger than that of fullerol at a given pH, indicating a greater propensity for nC(60) to interact with lipid bilayers. For example, at pH 7.4 and an aqueous concentration of 10 mg/L, K(lipw) was 3.5 times greater for nC(60) (log K(lipw) = 2.99) relative to fullerol (log K(lipw) = 2.45). Comparisons with existing aquatic organism bioaccumulation studies suggested that the lipid bilayer-water distribution is a potential method for assessing the bioaccumulation potentials of ENMs.
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Affiliation(s)
- Wen-Che Hou
- Mechanical Engineering and Chemical Engineering, Arizona State University, Tempe, Arizona 85287, USA.
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36
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Hristovski KD, Westerhoff PK, Posner JD. Octanol-water distribution of engineered nanomaterials. J Environ Sci Health A Tox Hazard Subst Environ Eng 2011; 46:636-647. [PMID: 21547819 DOI: 10.1080/10934529.2011.562859] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The goal of this study was to examine the effects of pH and ionic strength on octanol-water distribution of five model engineered nanomaterials. Distribution experiments resulted in a spectrum of three broadly classified scenarios: distribution in the aqueous phase, distribution in the octanol, and distribution into the octanol-water interface. Two distribution coefficients were derived to describe the distribution of nanoparticles among octanol, water and their interface. The results show that particle surface charge, surface functionalization, and composition, as well as the solvent ionic strength and presence of natural organic matter, dramatically impact this distribution. Distributions of nanoparticles into the interface were significant for nanomaterials that exhibit low surface charge in natural pH ranges. Increased ionic strengths also contributed to increased distributions of nanoparticle into the interface. Similarly to the octanol-water distribution coefficients, which represent a starting point in predicting the environmental fate, bioavailability and transport of organic pollutants, distribution coefficients such as the ones described in this study could help to easily predict the fate, bioavailability, and transport of engineered nanomaterials in the environment.
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Affiliation(s)
- Kiril D Hristovski
- Environmental Technology, College of Technology and Innovation, Arizona State University-Polytechnic Campus, Mesa, Arizona 85212, USA.
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Abstract
Nanosilver has become one of the most widely used nanomaterials in consumer products because of its antimicrobial properties. Public concern over the potential adverse effects of nanosilver's environmental release has prompted discussion of federal regulation. In this paper, we assess several classes of consumer products for their silver content and potential to release nanosilver into water, air, or soil. Silver was quantified in a shirt, a medical mask and cloth, toothpaste, shampoo, detergent, a towel, a toy teddy bear, and two humidifiers. Silver concentrations ranged from 1.4 to 270,000 microg Ag g product(-1). Products were washed in 500 mL of tap water to assess the potential release of silver into aqueous environmental matrices (wastewater, surface water, saliva, etc.). Silver was released in quantities up to 45 microg Ag g product(-1), and size fractions were both larger and smaller than 100 nm. Scanning electron microscopy confirmed the presence of nanoparticle silver in most products as well as in the wash water samples. Four products were subjected to a toxicity characterization leaching procedure to assess the release of silver in a landfill. The medical cloth released an amount of silver comparable to the toxicity characterization limit. This paper presents methodologies that can be used to quantify and characterize silver and other nanomaterials in consumer products. The quantities of silver in consumer products can in turn be used to estimate real-world human and environmental exposure levels.
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Affiliation(s)
- Troy Benn
- School of Sustainable Engineering and the Built Environment, Arizona State Univ., PO Box 875306, Tempe, AZ 85287-5306, USA.
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38
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Abstract
Catalytic bimetallic nanomotors can swim at 100 body lengths per second as well as pick up, haul, and release micrometer-scale cargo. The electrokinetic locomotion of bimetallic nanomotors is driven by the electrocatalytic decomposition of hydrogen peroxide. The motors are typically fabricated by electrodeposition-based template synthesis techniques that result in heterogeneous samples and require specialized knowledge of electrochemistry, a three-electrode potentiostat setup, cyanide-based chemistry, and porous membranes. This paper presents a rapid and facile method for fabrication of spherical bimetallic motors that only requires access to metal deposition equipment and commercially available microspheres. The resulting spherical motors swim at speeds comparable to rod-shaped motors with the same dimensions and composition. The spherical motors' velocity increases with fuel concentration and decreasing diameter.
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Affiliation(s)
- Philip M Wheat
- Mechanical Engineering, Chemical Engineering, Arizona State University, Tempe, Arizona 85287, USA
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39
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Abstract
We report a diverse set of coherent fluid flow instabilities, particle patterns, and traveling waves that develop when an ac electric field is applied to nondilute colloidal dispersions with volume fractions that span 3 orders of magnitude. Novel observed phenomena include the following: vortices with steady and unsteady axes of rotation, unsteady time evolution of vortices formation and vortex merging, as well as traveling waves that propagate through the dispersion. Vortical flows are influenced by strong interactions between particle electrical dipoles as well as electric body forces due to electric fields coupled with gradients in particle volume fraction. We use a 1D Burgers equation to predict the existence of traveling waves in colloidal dispersions.
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Affiliation(s)
- Carlos L Pérez
- Mechanical Engineering, Chemical Engineering, Arizona State University, Tempe, Arizona 85287, USA
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40
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Moran JL, Wheat PM, Posner JD. Locomotion of electrocatalytic nanomotors due to reaction induced charge autoelectrophoresis. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:065302. [PMID: 20866469 DOI: 10.1103/physreve.81.065302] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Indexed: 05/29/2023]
Abstract
Bimetallic rod-shaped nanomotors swim autonomously in hydrogen peroxide solutions. Here, we present a scaling analysis, computational simulations, and experimental data that show that the nanomotor locomotion is driven by fluid slip around the nanomotor surface due to electrical body forces. The body forces are generated by a coupling of charge density and electric fields induced by electrochemical reactions occurring on the nanomotor surface. We describe the dependence of nanomotor motion on the nanomotor surface potential and reaction-driven flux.
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Affiliation(s)
- J L Moran
- Mechanical Engineering and Chemical Engineering, Arizona State University, Tempe, Arizona 85287, USA
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41
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Jung JY, Joshi P, Petrossian L, Thornton TJ, Posner JD. Electromigration Current Rectification in a Cylindrical Nanopore Due to Asymmetric Concentration Polarization. Anal Chem 2009; 81:3128-33. [DOI: 10.1021/ac900318j] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Jung-Yeul Jung
- Departments of Mechanical and Aerospace Engineering, Electrical Engineering, Chemical Engineering, and Arizona Institute of Nanoelectronics, Arizona State University, Tempe, Arizona 85287
| | - Punarvasu Joshi
- Departments of Mechanical and Aerospace Engineering, Electrical Engineering, Chemical Engineering, and Arizona Institute of Nanoelectronics, Arizona State University, Tempe, Arizona 85287
| | - Leo Petrossian
- Departments of Mechanical and Aerospace Engineering, Electrical Engineering, Chemical Engineering, and Arizona Institute of Nanoelectronics, Arizona State University, Tempe, Arizona 85287
| | - Trevor J. Thornton
- Departments of Mechanical and Aerospace Engineering, Electrical Engineering, Chemical Engineering, and Arizona Institute of Nanoelectronics, Arizona State University, Tempe, Arizona 85287
| | - Jonathan D. Posner
- Departments of Mechanical and Aerospace Engineering, Electrical Engineering, Chemical Engineering, and Arizona Institute of Nanoelectronics, Arizona State University, Tempe, Arizona 85287
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42
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Marine NA, Klein SA, Posner JD. Partition Coefficient Measurements in Picoliter Drops Using a Segmented Flow Microfluidic Device. Anal Chem 2009; 81:1471-6. [DOI: 10.1021/ac801673w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nathan A. Marine
- Mechanical Engineering, and Chemical Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Steven A. Klein
- Mechanical Engineering, and Chemical Engineering, Arizona State University, Tempe, Arizona 85287-6106
| | - Jonathan D. Posner
- Mechanical Engineering, and Chemical Engineering, Arizona State University, Tempe, Arizona 85287-6106
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43
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Moran JL, Wheat PM, Posner JD. Submicron scale patterning in sintered silica colloidal crystal films using a focused ion beam. Langmuir 2008; 24:10532-10536. [PMID: 18712938 DOI: 10.1021/la801772q] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Focused ion beam milling is used to fabricate micron and submicron scale patterns in sintered silica colloidal crystal films. Rectangular cavities with both solid and porous boundaries, fluidic channels, and isolation of a small number of packed spheres are patterned. The ion beam can pattern sintered films of individual submicron size spheres and create patterns that cover up to 40 mum in less than 15 min. The experiments in this work indicate that the amount of redeposited material on the surface of a milled cavity determines whether the surface will be porous or solid. FIB direct patterning has applications in colloidal crystal based lithography, integrated photonic devices, optofluidic devices, and micrototal-analytical systems.
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Affiliation(s)
- Jeffrey L Moran
- Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287-6106, USA
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44
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Burdick J, Laocharoensuk R, Wheat PM, Posner JD, Wang J. Synthetic nanomotors in microchannel networks: directional microchip motion and controlled manipulation of cargo. J Am Chem Soc 2008; 130:8164-5. [PMID: 18533716 DOI: 10.1021/ja803529u] [Citation(s) in RCA: 202] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We illustrate the use of catalytic nanowire motors for directional motion and microscale transport of cargo within microfluidic channel networks. The CNT-based synthetic nanomotor can propel a large cargo load at high speeds through predetermined paths and junctions of the microchannel network. The magnetic properties of the nickel-containing nanomotors offer controlled cargo manipulations, including en-route load, drag, and release. Such use of synthetic nanomachines can lead to chemically powered versatile laboratory-on-a-chip devices performing a series of tasks simultaneously or sequentially.
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Affiliation(s)
- Jared Burdick
- Department of Mechanical & Aerospace Engineering, Arizona State University, Tempe, Arizona 85287-5801, USA
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45
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Abstract
This paper investigates a hydrodynamic particle separation technique that employs pinching of particles to a narrow microchannel. The particles are subject to a sudden expansion which results in a size-based particle separation transverse to the flow direction. The separation resolution and particle dispersion are measured using epifluorescence microscopy. The resolution and dispersion are predicted using a compact theoretical model. Devices are fabricated using conventional soft lithography of polydimethylsiloxane. The results show that the separation resolution is a function of the microchannel aspect ratio, particle size difference, and the microchannel sidewall roughness. A separation resolution as large as 3.8 is obtained in this work. This work shows that particles with diameters on the order of the sidewall roughness cannot be separated using pinched flow fractionation.
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Affiliation(s)
- Abhishek Jain
- Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, Arizona 85287, USA
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46
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Minerick AR, Ugaz VM, Murthy SK, Posner JD. Review of electrophoresis and BioMEMS in 2007: American Electrophoresis Society 24th Annual Meeting. J Capill Electrophor Microchip Technol 2008; 10:101-109. [PMID: 18982910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Researchers came together for the 24th Annual Meeting of the American Electrophoresis Society (AES), which was held November 4-9, 2007, at the Salt Palace Convention Center in Salt Lake City, UT, U.S.A. The Annual AES meeting is held in conjunction with the annual meeting of the American Institute of Chemical Engineers (AIChE). This year's meeting had a significant emphasis on theoretical and experimental advances in Biological Micro Electro Mechanical Systems (BioMEMS), electrokinetics, and proteomics technologies. A total of 15 sessions were held, within which 71 presentations and 18 posters were discussed. This review provides a brief sampling of the exciting research presented at the conference.
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Affiliation(s)
- Adrienne R Minerick
- Dave C. Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762, USA.
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47
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Posner JD, Dunn-Rankin D. Temperature field measurements of small, nonpremixed flames with use of an Abel inversion of holographic interferograms. Appl Opt 2003; 42:952-959. [PMID: 12617209 DOI: 10.1364/ao.42.000952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Interferometry has been used for many years as a semi-quantitative image-based diagnostic for combustion research. In this paper, we use image-plane, double-pulse holographic interferograms of axisymmetric flames to infer their radial temperature distribution. An Abel inversion is performed on the fringe data to account for line-of-sight integration through the flame. The sensitivity of nonresonant refractive diagnostics decreases inversely with temperature, and the accuracy of the technique is discussed in this context. A small, nonpremixed capillary flame is investigated, and the temperatures inferred from interferometry are compared with those obtained with N2 coherent anti-Stokes Raman spectroscopy thermometry. Additionally, the thermal field of a burning monodisperse methanol droplet stream is investigated interferometrically. Because of their small size, both of these flames challenge the performance limit of temperature interferometery.
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Affiliation(s)
- Jonathan D Posner
- Department of Mechanical and Aerospace Engineering, University of California Irvine, Irvine, California 92697, USA
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48
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Abstract
Coherent anti-Stokes Raman spectroscopy (CARS) is a nonlinear optical wave mixing process that is used in gas-phase systems to determine the energy distribution of the probed species (usually N2) and, through a fitting procedure, the temperature giving rise to it. CARS signal strengths are maximized when the phase matching condition is met. Because gases are generally non-dispersive, this phase matching condition can be found geometrically as a function of the crossing angles between the CARS beams and their wavelengths. In addition, perfect phase matching in non-dispersive media occurs automatically for collinear beams. To improve spatial resolution, however, intersecting the laser beams is desirable. Being a third-order process, phase matching for CARS in gases typically requires three input laser beams. This paper discusses and demonstrates the issues of phase matching for CARS when the medium is dispersive, and the ability for CARS phase matching to occur with only two crossed laser beams (one pump and one probe). This two-beam X-CARS in dispersive media can be used as an alignment tool for gas-phase CARS and may be relevant as a simpler diagnostic in high-pressure environments. The paper also discusses the effects of non-ideal phase matching in dispersive and non-dispersive media.
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Affiliation(s)
- Michael J Papac
- Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92697-3975, USA
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49
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Abstract
Pain in the elderly hospice patient presents a complex clinical problem that requires special attention because of the multiple physiologic changes in the older patient. Pain in the elderly is often under-treated despite the fact that this pain can be managed effectively and safely. A basic knowledge of the physiologic changes of aging, as well as the changes in pharmacokinetics, can help the clinician and the hospice team treat pain effectively while minimizing side effects for the patient and the family.
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Affiliation(s)
- M T Hofmann
- Department of Internal Medicine, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania, USA
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50
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McCully KK, Landsberg L, Suarez M, Hofmann M, Posner JD. Identification of peripheral vascular disease in elderly subjects using optical spectroscopy. J Gerontol A Biol Sci Med Sci 1997; 52:B159-65. [PMID: 9158550 DOI: 10.1093/gerona/52a.3.b159] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The purpose of this study was to determine the usefulness of near-infrared spectroscopy (NIRS) measurements to identify peripheral vascular disease (PVD). Usefulness was determined by the frequency of a successful test, as well as comparison with standard clinical assessments. Study subjects (N = 117, mean age = 67.8 +/- 8.1 yrs) responded to a free screening for PVD. NIRS was used to measure the relative O2 saturation of hemoglobin in the soleus muscle. The time to 1/2 recovery of O2 saturation (O2T1/2) was measured after 1 minute of repeated plantar flexions using a Cybex Eagle seated calf machine. O2T1/2 was used as many subjects had recovery curves that did not have an exponential line shape. The test was done on both legs and the worst leg was used for analysis. For comparative purposes, a clinical history and physical examination were performed by a physician or nurse practitioner, which included questions on intermittent claudication, examination of peripheral pulses, and questions to identify cardiovascular risk factors. NIRS signals were obtained on 105 of 117 subjects (89% success rate). Subjects with body mass index (BMI) values above 32 appeared to have NIRS O2T1/2 values that were less reliable than subjects with BMI values < or = 32 (77% success rate). The O2T1/2 was longer in subjects with claudication and reduced pulses than in subjects without these conditions. Sensitivity comparing O2T1/2 to claudication and reduced pulse varied from 51-76% and specificity from 65-80%, depending on the cutoff value for O2T1/2 that was used (normal value plus 1 or 2 SD). A longer O2T1/2 was significantly associated with incidence of diabetes, smoking, hypercholesterol, and coronary bypass surgery. In summary, successful NIRS O2T1/2 measurements were made in 77% of the subjects, with failure primarily occurring in obese subjects. NIRS O2T1/2 measurements showed reasonable although not strong agreements with clinical assessment of PVD, and with some risk factors for cardiovascular disease.
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Affiliation(s)
- K K McCully
- Department of Medicine, Allegheny University of the Health Sciences, Philadelphia, USA.
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