Point-of-care testing for C-reactive protein in a sequential microfluidic device

Point-of-care testing (POCT) devices are currently available for the detection of various important diseases owing to their easy-to-use, portable, and user-friendly nature. However, the multistep regent manipulation still impedes the performance of the device for end-users. To address this issue, we present a novel sequential flow-through microfluidic device that incorporates dual flow behaviors (fast-flow/delayed) into a single device for assessing the risk of cardiovascular disease (CVDs) using C-reactive protein (CRP) as the model analyte. The device features a fast-flow channel for automated washing of unbound CRP antigens and a delayed channel for flow of a redox reagent for electrochemical analysis. It requires only a single buffer loading, resulting in a total analysis time of 15 min. To overcome challenges related to storage stability and the affinity of antibodies in the manufacturing process, we integrated the P3-CRP peptide as a new bioreceptor for CRP detection. The performance of both the P3-CRP peptide and antibodies was assessed and examined using chronocoulometry. The proposed device exhibited a limit of detection at 47 pg mL−1 with a wide linear range (5 orders of magnitude). To validate its applicability, the device was tested with serum, plasma, and whole blood samples, yielding satisfactory results.