title: Gel pad array chip for high throughput and multi-analyte microbead-based immunoassays.
abstract: We present here a gel pad array chip for high-throughput and multi-analyte microbead-based immunoassays. The chip is fabricated by photo-patterning of two polymeric gels, polyacrylamide gel and polyethylene glycol (PEG) gel, on a glass slide. The resulting chip consists of 40 polyacrylamide gel pad array units for the immobilization of microbeads and each gel pad array is surrounded with a PEG micropillar ring to confine the samples within the microarray. As a proof of concept, this chip was tested for quantitative immunoassays for two model cancer markers, human chorionic gonadotropin (hCG) and prostate specific antigen (PSA), in serum samples. Detection limits below the physiological threshold level for cancer diagnosis were achieved with good inter- and intra-chip reproducibility. Moreover, by using spatial encoded microbeads, simultaneous detection of both hCG and PSA on each gel pad array is achieved with single filter fluorescence imaging. This gel pad array chip is easy to use, easy to fabricate with low cost materials and minimal equipment and reusable. It could be a useful tool for common biolabs to customize their own microbead array for multi-analyte immunoassays.
authors.affiliation: Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore.
authors.forename: Qingdi
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore (NUS), Singapore. Electronic address: bietrau@nus.edu.sg.
authors.forename: Dieter
authors.initials: D
authors.lastname: Trau
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D014408:Biomarkers, Tumor / Q000097:blood; D015374:Biosensing Techniques / Q000295:instrumentation*; D006063:Chorionic Gonadotropin / Q000097:blood*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D057230:Limit of Detection; D046228:Microarray Analysis / Q000295:instrumentation*; D017430:Prostate-Specific Antigen / Q000097:blood*; D015203:Reproducibility of Results
chemical_list: D000180:Acrylic Resins; D014408:Biomarkers, Tumor; D006063:Chorionic Gonadotropin; C016680:polyacrylamide gels; D017430:Prostate-Specific Antigen
keywords: Gel-based microstructure array; High throughput analysis; Immunoassay; Microbead array; Multiple analytes