Ratiometric Multicolor Analysis of Intracellular MicroRNA Using a Chain Hybrid Substitution-Triggered Self-Assembly of Silver Nanocluster-Based Label-Free Sensing Platform

A simple and label-free sensing platform with low background based on the chain-displacement triggered self-assembly of Ag NCs was developed for ratiometric visual analysis of intracellular miRNA-21. Based on this sensitively ratiometric sensing approach, a picomole limit detection for miRNA-21 can be obtained. Most importantly, compared with the traditional single base mismatch detection method, our proposed method can realize single base mismatch detection according to the remarkable fluorescence color conversion, rather than simple fluorescence intensity change, which can obviously improve the accuracy and reliability. In addition, successful multicolor real-time monitoring of intracellular miRNA-21 makes the probe a potential candidate for miRNA-21 inhibiting drug screening. Furthermore, MCF-7, HeLa, and normal L02 cells can also be visually differentiated according to the fluorescence color by using the label-free sensing platform, showing its potential prospect in target visual analysis.