A self-powered sensor with cascade signal amplification strategy based on CuS@Au heterojunctions/Ti₃C₂ MXene for...

IgA Nephropathy (IgAN) was a common primary glomerular disease. However, there was a lack of reliable rapid urine detection methods for monitoring the disease progression of IgAN. Herein, this study has developed a novel biofuel cell self-powered sensor based on CuS@Au NP heterojunction as power generation unit and Ti₃C₂ MXene as cascade amplification unit for the detection of miRNA-23b-3p in urine. In this self-powered sensing system, CuS@Au NP heterojunction achieved cascade catalysis of glucose through the Gox-like activity of Au NPs and the POD-like activity of CuS NPs on the anode. Furthermore, the catalytic hairpin assembly strategy was designed in the self-powered sensing system for the quantitative detection of miRNA-23b-3p. The subsequent conjugation of MXene with the high conductivity and excellent pseudocapacitive properties can realize the rapid charge storage and release in the sensor, which provided a cascade amplification effect on the open-circuit voltage (E^OCV) response. Therefore, the CuS@Au NP heterojunction/MXene-based self-powered sensor exhibited good linearity in the range of 1 pM to 1 μM of miRNA-23b-3p with a detection limit of 0.74 pM. Finally, this self-powered sensor with Bluetooth connectivity and real-time monitoring ability provided a novel, feasible strategy for non-invasive, rapid auxiliary diagnosis of IgAN. The results revealed that miRNA-23b-3p levels in urine from IgAN patients was significantly lower than that form healthy controls.