Integration of Immunosyringe Sensors with Bar-Chart Chips for Prick-and-Read Testing of Prostate Specific Antigen

Pressure-based signal transduction is of promise in developing microfluidic immunoassays such as volumetric bar-chart chips (V-chips), but new working principles are required to further simplify the methods in point-of-care testing (POCT). Herein, we developed immunosyringe sensors and integrated them with bar-chart chips for simple prick-and-read testing of prostate specific antigen (PSA) as a model target. Disposable syringes served as the host for the construction of the sandwich-type immuno-recognition system. Platinum nanoparticles (Pt NPs) as the peroxidase-mimicking detection probe catalyzed the decomposition of H₂O₂ to produce O₂ in the syringe cylinders, enabling the pressure-driven automatic injection of liquids from the syringes. The immuno-recognition event in the syringes was thereby converted into the quantitative autoinjection behavior of the syringes, namely, immunosyringe sensors. By simply pricking the sensors to bar-chart chips, we visually and quantitatively read the immunoassay signals as the bar-chart injection distance of liquids from the syringes in channels of the chips. The immunoassay showed a limit of detection (LOD) of 0.41 ng/mL in PSA detection with satisfactory accuracy in testing clinical serum samples. Owing to the integration with the immunosyringe sensors, this method, in comparison with conventional V-chips, works in a simpler prick-and-read manner without complex chip configurations and specialized chip operations (e.g., on-chip loading of microvolume reagents and sealing treatments). Therefore, the immunoassay shows great potential in POCT applications.