Dual-Mode Biointerface Engineering of Black Phosphorus via Electrostatic and Aptamer Recognition for Enhanced DNA Loading and Biosensing

Black phosphorus (BP) holds significant promise as a DNA anchoring platform. However, its application is currently limited by inefficient single-stranded DNA (ssDNA) loading arising from electrostatic repulsion and surface corrugation. Herein, we present a dual-mode biointerface engineering strategy utilizing cytochrome c (Cyt c) to bridge the interface between BP and DNA. Unlike simple electrostatic adsorption, Cyt c enhances loading through a synergistic mechanism combining electrostatic attraction with specific protein-aptamer recognition. This dual-mode approach significantly improved the loading efficiency of a Cy5-modified Cyt c aptamer (Cy5-Cyt c Apt) from 21.7% to 66.5% compared to bare BP. The engineered BP/Cyt c interface facilitated effective static fluorescence quenching, enabling the construction of a proof-of-concept biosensing nanoplatform with enhanced capacity in buffer conditions. Mechanistic investigation using proteins with varying isoelectric points confirmed the critical role of specific recognition in this enhancement. This work establishes a simple, rapid, and effective model for constructing robust BP/DNA nanoplatforms with enhanced analytical performance.