Target-triggered core-satellite assemblies with fluorescence-SERS cascade amplification for intracellular microRNA detection

Abstract

Controllable DNA-assembled plasmonic nanosensing platforms represent a promising approach for intracellular nucleic acid detection based on the significant optical signal changes induced by target recognition. In this work, we engineered a target-triggered self-assembly strategy for intracellular microRNA-21 (miRNA-21) detection with fluorescence-SERS cascade amplification. This strategy employs telomerase (TE) as the catalytic driver, gold nanoparticles and gold nanorods as the assembled components, and a strand displacement amplification (SDA) reaction as the linking tool. In the presence of both miRNA-21 and TE, the platform undergoes target-triggered core-satellite assemblies, enabling fluorescence recovery and SERS signal enhancement via plasmonic coupling-induced "hot spots". By this sensing strategy, the target miRNA-21 can be detected in a wide linear range (10 fM to 100 pM) with a limit of detection of 0.165 fM in the SERS mode and 0.196 fM in the fluorescence mode. This highly specific dual-signal response minimizes false positives, addressing cancer biomarker heterogeneity and improving the reliability of early cancer diagnosis. By integrating sensitivity, specificity, and a multi-dimensional optical readout, this strategy represents a potential tool in live-cell sensing and biomarker-driven cancer diagnostics.