Two-in-one: Portable piezoelectric and plasmonic exciton effect-based co-enhanced photoelectrochemical biosensor for point-of-care testing of low-abundance cancer markers

In-depth exploration of the local surface plasmon resonance and piezoelectric effects associated with metal can help develop efficient biosensors. Here, we presented for the first time the localized surface plasmon resonance (LSPR) and piezoelectric effects co-enhance the construction of an efficient intra-body phase electric field for the construction of efficient photoelectrochemical (PEC) biosensors. Briefly, the LSPR enhancement and piezoelectric enhancement effects between Ag nanoparticles and the piezoelectric material NaNbO3 were investigated in a PEC biosensor system under the excitation of portable UV light. Notably, the simplified treatment of the basic building blocks of the PEC sensor, including a handheld UV flashlight instead of a physical excitation light source and a digital multimeter instead of an electrochemical workstation. The capture and immunoincubation process of target PSA occurs on separated microtiter plates and hydrogen peroxide, generated by enzyme-linked immunization, induces the directional separation of electrons and holes in the composite heterogeneous material under the excitation of light. The coupling with a digital multimeter allows for real-time monitoring of photocurrents. Further, the effect of Ag deposition on piezoelectric perovskite NaNbO3 was obtained by density functional theory (DFT) calculations. Impressively, under optimized conditions, the system exhibits an ultra-wide linear range and ultra-low detection limits for the target PSA. The system is also comparable to commercially available ELISA kits at the 95% confidence level. This work provides a novel idea of enhanced PEC biosensor for rapid and accurate detection of cancer-related proteins.