A Sensitive Microchip‐Based Immunosensor for Electrochemical Detection of Low‐Level Biomarker S100B

A sensitive microchip‐based electrochemical immunosensor has been developed for quantification of low level S100B, which is an important biomarker of neurological diseases. Poly(ethyleneimine) (PEI), containing NH2 groups, was firstly modified on the surface of the poly(methyl methacrylate) (PMMA) microchannel to capture monoclonal anti‐S100B. Afterward, S100B and second polyclonal anti‐S100 were sequentially coupled by antigen‐antibody specific interaction, and the alkaline phosphatase conjugates (ALP‐conjugates) were bound to the second antibodies in a PMMA microchannnel. Using differential pulse voltammetry (DPV), the immunosensor achieved the detection limit of 0.1 pg mL−1 with the linear concentration range of 0.1 pg mL−1–100 pg mL−1. The results indicate that the proposed strategy not only has high specificity and sensitivity, but also resists nonspecific protein adsorption. The disposable microchip immunosensor shows good promise for clinical screening of important biomarkers and convenient point‐of‐care diagnostics.