1
|
Hertenstein T, Tang Y, Day AS, Reynolds J, Viboolmate PV, Yoon JY. Rapid and sensitive detection of miRNA via light scatter-aided emulsion-based isothermal amplification using a custom low-cost device. Biosens Bioelectron 2023; 237:115444. [PMID: 37329805 DOI: 10.1016/j.bios.2023.115444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/12/2023] [Accepted: 05/31/2023] [Indexed: 06/19/2023]
Abstract
MicroRNAs are likely to be a next-generation clinical biomarker for many diseases. While gold-standard technologies, e.g., reverse transcription-quantitative polymerase chain reaction (RT-qPCR), exist for microRNA detection, there is a need for rapid and low-cost testing. Here, an emulsion loop-mediated isothermal amplification (eLAMP) assay was developed for miRNA that compartmentalizes a LAMP reaction and shortens the time-to-detection. The miRNA was a primer to facilitate the overall amplification rate of template DNA. Light scatter intensity decreased when the emulsion droplet got smaller during the ongoing amplification, which was utilized to moitor the amplification non-invasively. A custom low-cost device was designed and fabricated using a computer cooling fan, a Peltier heater, an LED, a photoresistor, and a temperature controller. It allowed more stable vortexing and accurate light scatter detection. Three miRNAs, miR-21, miR-16, and miR-192, were successfully detected using the custom device. Specifically, new template and primer sequences were developed for miR-16 and miR-192. Zeta potential measurements and microscopic observations confirmed emulsion size reduction and amplicon adsorption. The detection limit was 0.01 fM, corresponding to 2.4 copies per reaction, and the detection could be made in 5 min. Since the assays were rapid and both template and miRNA + template could eventually be amplified, we introduced the success rate (compared to the 95% confidence interval of the template result) as a new measure, which worked well with lower concentrations and inefficient amplifications. This assay brings us one step closer to allowing circulating miRNA biomarker detection to become commonplace in the clinical world.
Collapse
Affiliation(s)
- Tyler Hertenstein
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, United States
| | - Yisha Tang
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, United States
| | - Alexander S Day
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, United States
| | - Jocelyn Reynolds
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, United States
| | - Patrick V Viboolmate
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ, 85721, United States
| | - Jeong-Yeol Yoon
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, United States.
| |
Collapse
|
2
|
Day AS, Ulep TH, Budiman E, Dieckhaus L, Safavinia B, Hertenstein T, Yoon JY. Contamination-resistant, rapid emulsion-based isothermal nucleic acid amplification with Mie-scatter inspired light scatter analysis for bacterial identification. Sci Rep 2021; 11:19933. [PMID: 34620908 PMCID: PMC8497611 DOI: 10.1038/s41598-021-99200-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 09/21/2021] [Indexed: 11/16/2022] Open
Abstract
An emulsion loop-mediated isothermal amplification (eLAMP) platform was developed to reduce the impact that contamination has on assay performance. Ongoing LAMP reactions within the emulsion droplets cause a decrease in interfacial tension, causing a decrease in droplet size, which results in decreased light scatter intensity due to Mie theory. Light scatter intensity was monitored via spectrophotometers and fiber optic cables placed at 30° and 60°. Light scatter intensities collected at 3 min, 30° were able to statistically differentiate 103 and 106 CFU/µL initial Escherichia coli O157:H7 concentrations compared to NTC (0 CFU/µL), while the intensity at 60° were able to statistically differentiate 106 CFU/µL initial concentrations and NTC. Control experiments were conducted to validate nucleic acid detection versus bacterial adsorption, finding that the light scatter intensities change is due specifically to ongoing LAMP amplification. After inducing contamination of bulk LAMP reagents, specificity lowered to 0% with conventional LAMP, while the eLAMP platform showed 87.5% specificity. We have demonstrated the use of angle-dependent light scatter intensity as a means of real-time monitoring of an emulsion LAMP platform and fabricated a smartphone-based monitoring system that showed similar trends as spectrophotometer light scatter data, validating the technology for a field deployable platform.
Collapse
Affiliation(s)
- Alexander S Day
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Tiffany-Heather Ulep
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Elizabeth Budiman
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Laurel Dieckhaus
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Babak Safavinia
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Tyler Hertenstein
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Jeong-Yeol Yoon
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA.
| |
Collapse
|
3
|
Day AS, Ulep TH, Safavinia B, Hertenstein T, Budiman E, Dieckhaus L, Yoon JY. Emulsion-based isothermal nucleic acid amplification for rapid SARS-CoV-2 detection via angle-dependent light scatter analysis. Biosens Bioelectron 2021; 179:113099. [PMID: 33640656 PMCID: PMC7892303 DOI: 10.1016/j.bios.2021.113099] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/13/2021] [Accepted: 02/14/2021] [Indexed: 12/23/2022]
Abstract
The SARS-CoV-2 pandemic, an ongoing global health crisis, has revealed the need for new technologies that integrate the sensitivity and specificity of RT-PCR tests with a faster time-to-detection. Here, an emulsion loop-mediated isothermal amplification (eLAMP) platform was developed to allow for the compartmentalization of LAMP reactions, leading to faster changes in emulsion characteristics, and thus lowering time-to-detection. Within these droplets, ongoing LAMP reactions lead to adsorption of amplicons to the water-oil interface, causing a decrease in interfacial tension, resulting in smaller emulsion diameters. Changes in emulsion diameter allow for the monitoring of the reaction by use of angle-dependent light scatter (based off Mie scatter theory). Mie scatter simulations confirmed that light scatter intensity is diameter-dependent and smaller colloids have lower intensity values compared to larger colloids. Via spectrophotometers and fiber optic cables placed at 30° and 60°, light scatter intensity was monitored. Scatter intensities collected at 5 min, 30° could statistically differentiate 10, 103, and 105 copies/μL initial concentrations compared to NTC. Similarly, 5 min scatter intensities collected at 60° could statistically differentiate 105 copies/μL initial concentrations in comparison to NTC. The use of both angles during the eLAMP assay allows for distinction between high and low initial target concentrations. The efficacy of a smartphone-based platform was also tested and had a similar limit of detection and assay time of less than 10 min. Furthermore, fluorescence-labeled primers were used to validate target nucleic acid amplification. Compared to existing LAMP assays for SARS-CoV-2 detection, these times-to-detections are very rapid.
Collapse
Affiliation(s)
- Alexander S Day
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Tiffany-Heather Ulep
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Babak Safavinia
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Tyler Hertenstein
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Elizabeth Budiman
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Laurel Dieckhaus
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States
| | - Jeong-Yeol Yoon
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721, United States.
| |
Collapse
|
4
|
Jiao X, Li M, Cheng Z, Yu X, Yang S, Zhang Y. Recyclable Superhydrophobic, Antimoisture-Activated Carbon Pellets for Air and Water Purification. ACS APPLIED MATERIALS & INTERFACES 2020; 12:25345-25352. [PMID: 32390416 DOI: 10.1021/acsami.0c06274] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Activated carbon (AC) is a low-cost, highly porous material with large internal surface areas. It is highly efficient in absorbing moisture and a variety of chemical pollutants. Therefore, it has been widely used in air and water purification. However, the strong affinity to moisture often dominates, thus limiting AC's adsorption capacity of other pollutants in a humid environment and reducing its overall lifetime. In the study, superhydrophobic and anti-moisture AC (SA-AC) pellets are fabricated through one-step modification of commercially available AC with a solution consisting of superhydrophobic silica nanoparticles. The SA-AC pellets exhibit excellent water repellency with a static water contact angle reaching 160.3°. More importantly, they are moisture-resistant and air-permeable. Therefore, they preferably adsorb organic gases at humid conditions. The absorbed organic vapor can be released when they are transferred back to the dry atmosphere, for example, releasing approximately 35% of absorbed ethanol. The recoverability significantly reduces energy requirement compared to calcination or conventional extraction. Great adsorption capacity of organic dyes such as methylene blue, removal of oil-in-water microemulsions, and recyclability of SA-AC pellets are demonstrated. The morphology of the microporous structures of the SA-AC pellets is characterized against processing conditions, surface functional groups, and hierarchical structures tailored by the deposition of low-surface energy silica nanoparticles. The resulting micro-/sub-micropores on the pellet surface promote droplet condensation, thus displaying greater damp-proof performance than those treated by traditional modification. The study here presents a promising alternative for the efficient purification on large-scale air/water treatment.
Collapse
Affiliation(s)
- Xuan Jiao
- Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Southeast Road 2nd, Nanjing 211189, P. R. China
| | - Meiting Li
- Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Southeast Road 2nd, Nanjing 211189, P. R. China
| | - Zhen Cheng
- Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Southeast Road 2nd, Nanjing 211189, P. R. China
| | - Xinquan Yu
- Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Southeast Road 2nd, Nanjing 211189, P. R. China
| | - Shu Yang
- Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104, United States
| | - Youfa Zhang
- Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Southeast Road 2nd, Nanjing 211189, P. R. China
| |
Collapse
|
5
|
Tao Y, Huang X, Gao D, Wang X, Chen C, Liang H, van Loosdrecht MCM. NanoSIMS reveals unusual enrichment of acetate and propionate by an anammox consortium dominated by Jettenia asiatica. WATER RESEARCH 2019; 159:223-232. [PMID: 31100576 DOI: 10.1016/j.watres.2019.05.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 05/02/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Anaerobic ammonium-oxidizing (anammox) bacteria convert ammonium and nitrite into N2 in a chemolithoautotrophic way, meaning that they utilize CO2/HCO3 solely as their carbon sources. Such autotrophic behavior limits their competitiveness with heterotrophic microorganisms in both natural environments and engineered systems. Recently, environmental metagenomic results have indicated the capability of anammox bacteria to metabolize short-chain fatty acids, further confirmed by limited experimental evidence based on highly enriched cultures. However, clear evidence is difficult to get because of the limits of traditional methodologies which rely on the availability of a pure anammox culture. In this study, we identified and quantified the uptake of acetate and propionate, on a single-cell level, by an anammox consortium that was dominated by Candidatus Jettenia asiatica (relative abundance of 96%). The consortium, growing in granular form with an average relative abundance of anammox bacteria of 96.0%, was firstly incubated in a13C-labelled acetate or propionate medium; then microtome sections were scanned by a nanometer-scale secondary ion mass spectrometer (NanoSIMS). The NanoSIMS scannings revealed that the consortium enriched acetate and propionate at a >10 times higher efficiency than bicarbonate incorporation. Our results also suggest that acetate or propionate was likely not assimilated by J. asiatica directly, but firstly oxidized to CO2, which then served as carbon sources for the follow-up autotrophy in J. asiatica cells. Furthermore, more [15N]ammonium was enriched by the propionate-fed consortium than the acetate-fed consortium despite that exactly the same amount of 13C atoms were supplied. Our study strongly indicates an alternative lifestyle, namely organotrophy, in addition to chemolithoautotrophy of anammox bacteria, making it more versatile than often expected. It suggests that the niche of anammox bacteria in both natural and engineered ecosystems can be much broader than usual assumed. Recognising this is important for their role in wastewater treatment and the global nitrogen turn-over rates.
Collapse
Affiliation(s)
- Yu Tao
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Xiaoli Huang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Dawen Gao
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China; School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
| | - Xiaolong Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Chunhong Chen
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Hong Liang
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China
| | | |
Collapse
|
6
|
Ulep TH, Day AS, Sosnowski K, Shumaker A, Yoon JY. Interfacial Effect-Based Quantification of Droplet Isothermal Nucleic Acid Amplification for Bacterial Infection. Sci Rep 2019; 9:9629. [PMID: 31270374 PMCID: PMC6610113 DOI: 10.1038/s41598-019-46028-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/17/2019] [Indexed: 02/08/2023] Open
Abstract
Bacterial infection is a widespread problem in humans that can potentially lead to hospitalization and morbidity. The largest obstacle for physicians/clinicians is the time delay in accurately identifying infectious bacteria, especially their sub-species, in order to adequately treat and diagnose such infected patients. Loop-mediated amplification (LAMP) is a nucleic acid amplification method that has been widely used in diagnostic applications due to its simplicity of constant temperature, use of up to 4 to 6 primers (rendering it highly specific), and capability of amplifying low copies of target sequences. Use of interfacial effect-based monitoring is expected to dramatically shorten the time-to-results of nucleic acid amplification techniques. In this work, we developed a LAMP-based point-of-care platform for detection of bacterial infection, utilizing smartphone measurement of contact angle from oil-immersed droplet LAMP reactions. Whole bacteria (Escherichia coli O157:H7) were assayed in buffer as well as 5% diluted human whole blood. Monitoring of droplet LAMP reactions was demonstrated in a three-compartment, isothermal proportional-integrated-derived (PID)-controlled chip. Smartphone-captured images of droplet LAMP reactions, and their contact angles, were evaluated. Contact angle decreased substantially upon target amplification in both buffer and whole blood samples. In comparison, no-target control (NTC) droplets remained stable throughout the 30 min isothermal reactions. These results were explained by the pre-adsorption of plasma proteins to an oil-water interface (lowering contact angle), followed by time-dependent amplicon formation and their preferential adsorption to the plasma protein-occupied oil-water interface. Time-to-results was as fast as 5 min, allowing physicians to quickly make their decision for infected patients. The developed assay demonstrated quantification of bacteria concentration, with a limit-of-detection at 102 CFU/μL for buffer samples, and binary target or no-target identification with a limit-of-detection at 10 CFU/μL for 5% diluted whole blood samples.
Collapse
Affiliation(s)
- Tiffany-Heather Ulep
- Department of Biomedical Engineering, The University of Arizona, Tucson, Arizona, 85721, United States
| | - Alexander S Day
- Department of Biomedical Engineering, The University of Arizona, Tucson, Arizona, 85721, United States
| | - Katelyn Sosnowski
- Department of Biomedical Engineering, The University of Arizona, Tucson, Arizona, 85721, United States
| | - Alexa Shumaker
- Department of Biomedical Engineering, The University of Arizona, Tucson, Arizona, 85721, United States
| | - Jeong-Yeol Yoon
- Department of Biomedical Engineering, The University of Arizona, Tucson, Arizona, 85721, United States.
| |
Collapse
|
7
|
Nicolini AM, Toth TD, Kim SY, Mandel MA, Galbraith DW, Yoon JY. Mie Scatter and Interfacial Tension Based Real-Time Quantification of Colloidal Emulsion Nucleic Acid Amplification. ADVANCED BIOSYSTEMS 2017; 1:e1700098. [PMID: 32646190 DOI: 10.1002/adbi.201700098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/25/2017] [Indexed: 06/11/2023]
Abstract
This work demonstrates for the first time rapid, real-time Mie scatter sensing of colloidal emulsion nucleic acid amplification directly from emulsion droplets. Loop-mediated isothermal amplification is used in this study, and, to our knowledge, has not previously been used in a colloidal emulsion platform. Interfacial tension values (γ) associated with bulk protein adsorption and denaturation at the oil-water interface exhibit characteristic changes in the absence or presence of amplification. In the presence of target and amplicon, emulsions maintain a constant 300-400 nm diameter, whereas emulsions formed with no target control show a rapid decrease in droplet diameter to <100 nm over the first 20 min of incubation. This method is validated using whole bacteria (Staphylococcus aureus MSSA and Escherichia coli O157:H7) and whole virus (Potato virus Y and Zika virus) samples suspended in water, buffer, or serum-like matrices. Short-term formation of colloidal emulsion is quantified via 60° scatter monitoring, where the initial slope of scattering intensity is utilized to confirm target amplification in less than 5 min. The unique benefits of this method render it more cost-effective and field-deployable than existing methods, while being adaptable to a multitude of targets, sample matrices, and nucleic acid amplification tests.
Collapse
Affiliation(s)
- Ariana M Nicolini
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Tyler D Toth
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - Samuel Y Kim
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| | - M Alejandra Mandel
- School of Plant Sciences, The University of Arizona, Tucson, AZ, 85721, USA
| | - David W Galbraith
- School of Plant Sciences, The University of Arizona, Tucson, AZ, 85721, USA
| | - Jeong-Yeol Yoon
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, 85721, USA
| |
Collapse
|
8
|
Nicolini AM, McCracken KE, Yoon JY. Future developments in biosensors for field-ready Zika virus diagnostics. J Biol Eng 2017; 11:7. [PMID: 28127399 PMCID: PMC5260080 DOI: 10.1186/s13036-016-0046-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/27/2016] [Indexed: 12/11/2022] Open
Abstract
Since early reports of the recent Zika virus outbreak in May 2015, much has been learned and discussed regarding Zika virus infection and transmission. However, many opportunities still remain for translating these findings into field-ready sensors and diagnostics. In this brief review, we discuss current diagnostic methods, consider the prospects of translating other flavivirus biosensors directly to Zika virus sensing, and look toward the future developments needed for high-sensitivity and high-specificity biosensors to come.
Collapse
Affiliation(s)
- Ariana M. Nicolini
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721 USA
| | - Katherine E. McCracken
- Department of Agricultural and Biosystems Engineering, The University of Arizona, Tucson, AZ 85721 USA
| | - Jeong-Yeol Yoon
- Biomedical Engineering Graduate Interdisciplinary Program and Department of Biomedical Engineering, The University of Arizona, Tucson, AZ 85721 USA
- Department of Agricultural and Biosystems Engineering, The University of Arizona, Tucson, AZ 85721 USA
| |
Collapse
|
9
|
|
10
|
Rasooly R, Bruck HA, Balsam J, Prickril B, Ossandon M, Rasooly A. Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health. Diagnostics (Basel) 2016; 6:E19. [PMID: 27196933 PMCID: PMC4931414 DOI: 10.3390/diagnostics6020019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/19/2016] [Accepted: 05/06/2016] [Indexed: 12/20/2022] Open
Abstract
Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings.
Collapse
Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94706, USA.
| | - Hugh Alan Bruck
- Department of Mechanical Engineering, University of Maryland College Park (UMCP), College Park, MD 20742, USA.
| | - Joshua Balsam
- Division of Chemistry and Toxicology Devices, Office of In Vitro Diagnostics and Radiological Health, FDA, Silver Spring, MD 20993, USA.
| | - Ben Prickril
- National Cancer Institute, Rockville, MD 208503, USA.
| | | | | |
Collapse
|