Ligand‐Engineered Hydrophilic Perovskite Enabling Surface Potential‐Driven Anions Exchange for Multicolor Biosensing
Shuo Wang, Yi Liu, Gaoqiong Deng, Wanjun Long, Hengye Chen, Yuxiu Xiao, Yuanbin She, Haiyan Fu
Abstract
Abstract The difficulty in designing zwitterionic ligands impedes the water‐dispersed CsPbX 3 perovskite nanocrystals (NCs) and their application as fast anion exchange (FAE) probes in biosensing. This study proposes a design paradigm for zwitterionic ligands predicated upon revealing the mechanism of the S N 2 reaction between unsaturated alkylamines (Cn′) and haloalkanoic acids (HAAs). Among them, the C=C bond can enhance the nucleophilicity of Cn′ and promote the electrostatic adsorption of HAAs onto Cn′, i.e., the geometric preorganization process, thereby initiating the S N 2 reaction. Moreover, an appropriate “bridge” length enables HAAs to balance the geometric preorganization process and the Sigma hole intensity of the C−Br bond. Zwitterionic ligands derived from oleylamine (C18′) and 5‐bromovaleric acid (5‐BVA) endow CsPbBr 3 NCs with water dispersibility, an almost 100 % photoluminescence quantum yield, and enhanced surface potential, facilitating the capture of halide ions and driving the FAE reaction. Using AgI nanoparticles (NPs) as latent anion exchangers, a third FAE strategy is presented for multicolor biosensing. Such a robust biosensing strategy can generate wavelength shift and chromatic difference for biological target molecules, exemplified by H 2 S, and is ultimately applicable to multicolor assay in biological, environmental and food samples, demonstrating the immense potential of perovskite‐based FAE probes in biosensing.