DNA-Engineered CsPbBr Superlattices with Enhanced Electronic Coupling for High-Performance Electrochemiluminescence Biosensing.

Perovskite quantum dots (PQDs), particularly CsPbBr QDs, are highly promising electrochemiluminescent (ECL) materials due to their excellent optical properties. However, the key challenge in developing PQD materials for practical applications lies in balancing the contradiction between their intrinsic instability in aqueous environments and ECL efficiency. To address this challenge, we employed DNA nanosheets as templates to direct the self-assembly of CsPbBr QDs, into highly ordered two-dimensional superlattices. This strategy enhances electronic coupling effects through long-range ordered arrangement, enabling rapid charge-carrier transport. High-resolution XPS confirmed charge transfer between CsPbBr QDs, while AFM characterization reveals that the nanosheets possess a periodic structure with a spacing of 63.4 nm. Compared to unassembled CsPbBr QDs, the ECL intensity of CsPbBr/DNA NSs increased by 2.5-fold, with a respectably high ECL efficiency of 65.5%. Remarkably, they retain 83.3% of the initial ECL intensity retained after 10 days in aqueous conditions, significantly surpassing the stability of unprotected CsPbBr. Furthermore, these nanosheets were successfully applied in a ratiometric ECL biosensor for miRNA-221 detection, achieving a detection limit of 6.05 aM. This study presents a novel strategy that simultaneously addresses the aqueous instability and enhances the ECL efficiency of CsPbBr QDs, significantly advancing their applications in biosensing.