Multimode MicroRNA Sensing via Multiple Enzyme-Free Signal Amplification and Cation-Exchange Reaction

The detection of biomarkers requires not only high sensitivity but also different signal reading methods depending on the actual situation. Herein, the luminescent properties of CdTe quantum dots (QDs) were exploited, where CdTe QDs were used as shared signal molecules. Combining multiple types of nucleic acid and chemical signal amplification techniques, and various signal detection techniques, a magnetic nanoparticle(NP) and filter-assisted separation multimode sensing strategy has been developed. In this work, miRNA-141 was selected as a representative target, which can trigger the catalyzed hairpin assembly and hybrid chain reaction enzyme-free nucleic acid signal amplification that generates long double-stranded DNA. Subsequently, the chemical amplification of silver NPs (Ag NPs) that release a large amount of Ag+ was introduced into the system. Finally, the cation-exchange reaction between CdTe QDs and Ag+ was utilized to quench the fluorescence (FL) of the CdTe QDs, releasing free Cd2+. The visual...