Paper-based microfluidic devices for electrochemical immunofiltration analysis of human chorionic gonadotropin

An electrochemical immunofiltration analysis was introduced into microfluidic paper-based analytical devices (μPADs) for the first time, which was based on photolithography and screen-printing technology. The hydrophilic test zones of the aldehyde-functionalized screen-printed electrodes (SPEs) were biofunctionalized with capture antibodies (Ab1). A sensitive immune detection method was developed by using primary signal antibody functionalized gold nanoparticles (GNPs/Ab2) and alkaline phosphatase conjugated secondary antibody (ALP-IgG). Differential pulse voltammetry (DPV) was performed to detect the electrochemical response. The microfluidic paper-based electrochemical immunosensor (μ-PEI) was optimized and characterized for the detection of human chorionic gonadotropin (HCG), a model analyte, in a linear range from 1.0 mIU mL−1 to 100.0 IU mL−1 with a detection limit of 0.36 mIU mL−1. Additionally, the proposed μ-PEI was used to test HCG in real human serum and obtained satisfactory results. The disposable, efficient, sensitive and low-cost μ-PEI has exhibited great potential for the development of point-of-care testing (POCT) devices that can be applicated in healthcare monitoring.