Article

Biomedical Microdevices

, Volume 13, Issue 3, pp 475-483

A blocking-free microfluidic fluorescence heterogeneous immunoassay for point-of-care diagnostics

  • Peng LiAffiliated withDepartment of Mechanical, Industrial and Systems Engineering, University of Rhode Island Email author 
  • , Alexander J. SherryAffiliated withDepartment of Mechanical, Industrial and Systems Engineering, University of Rhode Island
  • , Jairo A. CortesAffiliated withDepartment of Mechanical, Industrial and Systems Engineering, University of Rhode Island
  • , Constantine AnagnostopoulosAffiliated withDepartment of Mechanical, Industrial and Systems Engineering, University of Rhode Island
  • , Mohammad FaghriAffiliated withDepartment of Mechanical, Industrial and Systems Engineering, University of Rhode Island

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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.

Keywords

Microfluidic immunoassay Blocking-free Fluorescence detection C-reactive protein Point-of-care diagnostics Poly(dimethylsiloxane)