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Li Q, Bencherif SA, Su M. Edge-Enhanced Microwell Immunoassay for Highly Sensitive Protein Detection. Anal Chem 2021; 93:10292-10300. [PMID: 34251806 DOI: 10.1021/acs.analchem.1c01754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Highly sensitive biosensors that can detect low concentrations of protein biomarkers at the early stages of diseases or proteins secreted from single cells are of importance for disease diagnosis and treatment assessment. This work reports a new signal amplification mechanism, that is, edge enhancement based on the vertical sidewalls of microwells for ultra-sensitive protein detection. The fluorescence emission at the edge of the microwells is highly amplified due to the microscopic axial resolution (depth of field) and demonstrates a microring effect. The enhanced fluorescence intensity from microrings is calibrated for bovine serum albumin detection, which shows a 6-fold sensitivity enhancement and a lower limit of detection at the microwell edge, compared to those obtained on a flat surface. The microwell chip is used to separate single cells, and the wall of each microwell is used to detect interferon-γ secretion from T cells stimulated with a peptide and whole cancer cells. Given its edge-enhancement ability, the microwell technique can be a highly sensitive biosensing platform for disease diagnosis at an early stage and for assessing potential treatments at the single-cell level.
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Affiliation(s)
- Qingxuan Li
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Sidi A Bencherif
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States.,Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ming Su
- Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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Garcia-Hernando M, Calatayud-Sanchez A, Etxebarria-Elezgarai J, de Pancorbo MM, Benito-Lopez F, Basabe-Desmonts L. Optical Single Cell Resolution Cytotoxicity Biosensor Based on Single Cell Adhesion Dot Arrays. Anal Chem 2020; 92:9658-9665. [PMID: 32460483 DOI: 10.1021/acs.analchem.0c00940] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Low cost, easy to use cell viability tests are needed in the pharmaceutical, biomaterial, and environmental industries to measure adverse cellular effects. We present a new methodology to track cell death with high resolution. Adherent cells commonly detach from the surface when they die, but some toxic compounds promote cell adhesion. A methodology that enables both dynamic detachment monitoring but also rapid detection of toxic effects of compounds that promote cell adhesion would constitute a step forward toward high-throughput cytotoxicity measurements. We achieved dynamic digital quantification of cell viability by simple optical imaging using "single cell adhesion dot arrays" (SCADA), fibronectin (FN) dot arrays designed to accommodate a single cell on each fibronectin dot. For cytotoxicity measurements, cell-filled SCADA substrates were exposed to K2CrO4, HgSO4 salts, and dimethyl sulfoxide (DMSO). The toxic effect of DMSO and K2CrO4 was dynamically monitored by measuring the cell detachment rate during more than 30 h by quantifying the number of occupied dots in the SCADA array. HgSO4 inhibited cellular detachment from the surface, and cytotoxicity was monitored using the trypan blue life/death assay directly on the surface. In all cases, the cytotoxicity effects were easily monitored with single cell resolution, and the results were comparable to previous reports. SCADA enabled dynamic measurements at the highest resolution due to the digital measuring in this method. The integration of SCADA substrates into microfluidic platforms will provide a practical tool that will extend to fundamental research and commercial applications.
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Affiliation(s)
- Maite Garcia-Hernando
- BIOMICs-Microfluidics Research Group, Microfluidics & BIOMICS Cluster UPV/EHU, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain.,Analytical Microsystems & Materials for Lab-on-a-Chip (AMMa-LOAC) Group, Microfluidics & BIOMICS Cluster UPV/EHU, Analytical Chemistry Department, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Alba Calatayud-Sanchez
- BIOMICs-Microfluidics Research Group, Microfluidics & BIOMICS Cluster UPV/EHU, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Jaione Etxebarria-Elezgarai
- BIOMICs-Microfluidics Research Group, Microfluidics & BIOMICS Cluster UPV/EHU, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Marian M de Pancorbo
- BIOMICS Research Group, Microfluidics & BIOMICS Cluster UPV/EHU, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Fernando Benito-Lopez
- Analytical Microsystems & Materials for Lab-on-a-Chip (AMMa-LOAC) Group, Microfluidics & BIOMICS Cluster UPV/EHU, Analytical Chemistry Department, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Lourdes Basabe-Desmonts
- BIOMICs-Microfluidics Research Group, Microfluidics & BIOMICS Cluster UPV/EHU, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain.,IKERBASQUE, Basque Foundation of Science, 48013 Bilbao, Bizkaia, Spain
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