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-ofcare 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 H 2 O 2 to produce O 2 in the syringe cylinders, enabling the pressure-driven automatic injection of liquids from the syringes. The immunorecognition 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.
