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Gurukandure A, Somasundaram S, Kurian ASN, Khuda N, Easley CJ. Building a Nucleic Acid Nanostructure with DNA-Epitope Conjugates for a Versatile Approach to Electrochemical Protein Detection. Anal Chem 2023; 95:18122-18129. [PMID: 38032341 PMCID: PMC10720615 DOI: 10.1021/acs.analchem.3c03512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 12/01/2023]
Abstract
The recent surge of effort in nucleic-acid-based electrochemical (EC) sensors has been fruitful, yet there remains a need for more generalizable EC platforms for sensing multiple classes of clinically relevant targets. We recently reported a nucleic acid nanostructure for simple, economical, and more generalizable EC readout of a range of analytes, including small molecules, peptides, proteins, and antibodies. The nanostructure is built through on-electrode enzymatic ligation of three oligonucleotides for attachment, binding, and signaling. However, the generalizable detection of larger proteins remains a challenge. Here, we adapted the sensor to quantify larger proteins in a more generic manner through conjugating the protein's minimized antibody-binding epitope to the central DNA strand. This concept was verified using creatine kinase (CK-MM), a biomarker of muscle damage and several disorders for which rapid clinical sensing is important. DNA-epitope conjugates permitted a competitive immunoassay for the CK protein at the electrode via square-wave voltammetry (SWV). Sensing through a signal-off mechanism, the anti-CK antibody limit of detection (LOD) was 5 nM with a response time as low as 3 min. Antibody displacement by native protein analytes gave a signal-on response with the CK sensing range from the LOD of 14 nM up to 100 nM, overlapping with the normal (nonelevated) human clinical range (3-37 nM), and the sensor was validated in 98% human serum. While a need for improved DNA-epitope conjugate purification was identified, overall, this approach allows the quantification of a generic protein- or peptide-binding antibody and should facilitate future quantitative EC readouts of clinically relevant proteins that were previously inaccessible to EC techniques.
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Affiliation(s)
- Asanka Gurukandure
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Subramaniam Somasundaram
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Amanda S. N. Kurian
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Niamat Khuda
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Christopher J. Easley
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Kayirangwa Y, Mohibullah M, Easley CJ. Droplet-based μChopper device with a 3D-printed pneumatic valving layer and a simple photometer for absorbance based fructosamine quantification in human serum. Analyst 2023; 148:4810-4819. [PMID: 37605899 PMCID: PMC10530610 DOI: 10.1039/d3an01149f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
The development of microfluidic systems for biological assays presents challenges, particularly in adapting traditional optical absorbance assays to smaller volumes or to microfluidic formats. This often requires assay modification or translation to a fluorescence version, which can be impractical. To address this issue, our group has developed the μChopper device, which uses microfluidic droplet formation as a surrogate for an optical beam chopper, allowing for lock-in analysis and improved limits of detection with both absorbance and fluorescence optics without modifying the optical path length. Here, we have adapted the μChopper to low-cost optics using a light-emitting diode (LED) source and photodiode detector, and we have fabricated the pnuematically valved devices entirely by 3D printing instead of traditional photolithography. Using a hybrid device structure, fluidic channels were made in polydimethylsiloxane (PDMS) by moulding onto a 3D-printed master then bonding to a prefabricated thin layer, and the pneumatic layer was directly made of 3D-printed resin. This hybrid structure allowed an optical slit to be fabricated directly under fluidic channels, with the LED interfaced closely above the channel. Vacuum-operated, normally closed valves provided precise temporal control of droplet formation from 0.6 to 2.0 Hz. The system was validated against the standard plate reader format using a colorimetric fructosamine assay and by quantifying fructosamine in human serum from normal and diabetic patients, where strong correlation was shown. Showing a standard benefit of microfluidics in analysis, the device required 6.4-fold less serum volume for each assay. This μChopper device and lower cost optical system should be applicable to various absorbance based assays in low volumes, and the reliance on inexpensive 3D printers makes it more accessible to users without cleanroom facilities.
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Affiliation(s)
- Yvette Kayirangwa
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA.
| | - Md Mohibullah
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA.
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Guo G, Wu X, Liu D, Liao L, Zhang D, Zhang Y, Mao T, He Y, Huang P, Wang W, Su L, Wang S, Liu Q, Ma X, Shi N, Guan Y. A Self-Regulated Microfluidic Device with Thermal Bubble Micropumps. MICROMACHINES 2022; 13:mi13101620. [PMID: 36295973 PMCID: PMC9612009 DOI: 10.3390/mi13101620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/26/2022] [Accepted: 09/26/2022] [Indexed: 06/12/2023]
Abstract
Currently, many microchips must rely on an external force (such as syringe pump, electro-hydrodynamic pump, and peristaltic pump, etc.) to control the solution in the microchannels, which probably adds manual operating errors, affects the accuracy of fluid manipulation, and enlarges the noise of signal. In addition, the reasonable integration of micropump and microchip remain the stumbling block for the commercialization of microfluidic technique. To solve those two problems, we designed and fabricated a thermal bubble micropump based on MEMS (micro-electro-mechanical systems) technique. Many parameters (voltage, pulse time, cycle delay time, etc.) affecting the performance of this micropump were explored in this work. The experimental results showed the flow rate of solution with the assistance of a micropump reached more than 15 μL/min in the optimal condition. Finally, a method about measuring total aflatoxin in Chinese herbs was successfully developed based on the integrated platform contained competitive immunoassay and our micropump-based microfluidics. Additionally, the limit of detection in quantifying total aflatoxin (AF) was 0.0615 pg/mL in this platform. The data indicate this combined technique of biochemical assays and micropump based microchip have huge potential in automatically, rapidly, and sensitively measuring other low concentration of biochemical samples with small volume.
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Affiliation(s)
- Gang Guo
- Department of Microelectronics, Shanghai University, Shanghai 200000, China
| | - Xuanye Wu
- Department of Microelectronics, Shanghai University, Shanghai 200000, China
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Demeng Liu
- Department of Microelectronics, Shanghai University, Shanghai 200000, China
- Shanghai Aure Technology limited Company, Shanghai 200000, China
| | - Lingni Liao
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Di Zhang
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Yi Zhang
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Tianjiao Mao
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Yuhan He
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Peng Huang
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Wei Wang
- Shanghai Aure Technology limited Company, Shanghai 200000, China
| | - Lin Su
- Shanghai Aure Technology limited Company, Shanghai 200000, China
| | - Shuhua Wang
- Shanghai Aure Technology limited Company, Shanghai 200000, China
| | - Qi Liu
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
| | - Xingfeng Ma
- Department of Microelectronics, Shanghai University, Shanghai 200000, China
| | - Nan Shi
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
- Institute of Translational Medicine, Shanghai University, Shanghai 200000, China
| | - Yimin Guan
- Department of Microelectronics, Shanghai University, Shanghai 200000, China
- Shanghai Industrial μTechnology Research Institute, Shanghai 200000, China
- Shanghai Aure Technology limited Company, Shanghai 200000, China
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Shi N, Mohibullah M, Easley CJ. Active Flow Control and Dynamic Analysis in Droplet Microfluidics. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2021; 14:133-153. [PMID: 33979546 PMCID: PMC8956363 DOI: 10.1146/annurev-anchem-122120-042627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Droplet-based microfluidics has emerged as an important subfield within the microfluidic and general analytical communities. Indeed, several unique applications such as digital assay readout and single-cell sequencing now have commercial systems based on droplet microfluidics. Yet there remains room for this research area to grow. To date, most analytical readouts are optical in nature, relatively few studies have integrated sample preparation, and passive means for droplet formation and manipulation have dominated the field. Analytical scientists continue to expand capabilities by developing droplet-compatible method adaptations, for example, by interfacing to mass spectrometers or automating droplet sampling for temporally resolved analysis. In this review, we highlight recently developed fluidic control techniques and unique integrations of analytical methodology with droplet microfluidics-focusing on automation and the connections to analog/digital domains-and we conclude by offering a perspective on current challenges and future applications.
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Affiliation(s)
- Nan Shi
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
| | - Md Mohibullah
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
| | - Christopher J Easley
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
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Brouzes E, Li S. Editorial for the Special Issue on Droplet Microfluidics. MICROMACHINES 2020; 11:mi11121086. [PMID: 33302340 PMCID: PMC7762390 DOI: 10.3390/mi11121086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/04/2022]
Affiliation(s)
- Eric Brouzes
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
- Cancer Center, Stony Brook School of Medicine, Stony Brook, NY 11794, USA
- Institute for Engineering Driven Medicine, Stony Brook University, Stony Brook, NY 11794, USA
- Correspondence: (E.B.); (S.L.)
| | - Siran Li
- Cold Spring Harbor Laboratories, Cold Spring Harbor, NY 11724, USA
- Correspondence: (E.B.); (S.L.)
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