title: A blocking-free microfluidic fluorescence heterogeneous immunoassay for point-of-care diagnostics.
abstract: In this article, a rapid, sensitive, and disposable microfluidic immunosensor is presented for point-of-care (POC) testing and clinical diagnosis. For the first time, the blocking process is eliminated from a microfluidic heterogeneous immunoassay by using protein A functionalized polydimethylsiloxane microchannels. The nonspecific binding of the assay is maintained around the chip background level by using a pair of antibodies with different affinity to protein A under optimized experimental conditions. C-reactive protein (CRP), a biomarker for inflammation and cardiovascular disease risk assessment, is selected as a model analyte to demonstrate the sensitivity of this blocking-free microfluidic heterogeneous immunoassay. A four parameter logistic function is used to model and assess the data. The limit of detection obtained is 0.54 μg/mL, which is lower than the cut-off value for clinical diagnosis. The overall assay is completed in 5 min. The protein A modified PDMS chips wet-stored at 4°C can maintain biofunctionality up to 14 months. The developed blocking-free microfluidic heterogeneous immunoassay will immediately provide benefits to most immunosensing microdevices targeted for POC diagnostics by shortening analysis time, simplifying fluid transportation, reducing sample consumption, and lowering waste generation.
authors.affiliation: Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, RI 02881, USA. lip@egr.uri.edu
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Sherry
authors.forename: Jairo A
authors.initials: JA
authors.lastname: Cortes
authors.forename: Constantine
authors.initials: C
authors.lastname: Anagnostopoulos
authors.forename: Mohammad
authors.initials: M
authors.lastname: Faghri
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation*; D002097:C-Reactive Protein / Q000032:analysis / Q000276:immunology; D003933:Diagnosis; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D057230:Limit of Detection; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D019095:Point-of-Care Systems; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D055910:Antibodies, Immobilized; D004129:Dimethylpolysiloxanes; C013830:baysilon; D002097:C-Reactive Protein