Synergistic Integration of Water-Stable 2D Perovskite Heterojunctions and Self-Priming DNA Walkers for Sensitive Photoelectrochemical Biosensing

Abstract Two-dimensional Ruddlesden−Popper (2D RP) perovskites hold immense promise as light-harvesting photoactive materials for photoelectrochemical (PEC) bioanalysis, yet their poor aqueous durability and suboptimal charge-carrier dynamics severely restrict PEC sensing implementation. Herein, we report a dual-functional strategy that simultaneously addresses both challenges through the in-situ construction of a Z-scheme heterojunction, (BA)2PbI4−Pb(OH)2 (BA = butylammonium), via Lewis base vapor diffusion. The Pb(OH)2 barrier formed during synthesis acts as a robust protective shield that preserves the perovskite’s structural integrity, while the intimate Z-scheme heterointerface constructed in the heterojunction remains functional and continues to accelerate spatial charge separation even after three years of immersion in ultrapure water, as corroborated by electron paramagnetic resonance spectroscopy, photo-assisted Kelvin probe force microscopy, and density functional theory calculations. To further amplify the PEC signal, we engineer a circular DNA scaffold-supported tripedal DNA walker powered by self-priming polymerization, eliminating the requirement for exogenous primers in traditional polymerase-driven DNA nanomachines. Target-triggered autonomous walking of the tripedal DNA nanomachine continuously disassembles surface-tethered hairpin tracks, drastically mitigating interfacial steric hindrance and yielding prominent photocurrent enhancement. Synergizing the ultra-stable Z-scheme RP perovskite photoelectrode with the primer-free DNA walker, the integrated PEC sensing platform achieves ultrasensitive quantification of acetamiprid with a wide linear range spanning 10−13 to 10−6 M. This work establishes a new paradigm for rationally designing aqueous-stable perovskites and coupling them with intelligent molecular devices, paving the way for high-performance PEC sensing platforms.