Dual-mode biosensors based on upconversion nanoparticles and quantum dots combined with a signal amplification strategy for the detection of miRNAs.

MicroRNAs (miRNAs) play a role in regulating cell proliferation and differentiation and are linked to the initiation and progression of cancers. Studies indicate that miRNA-21 is upregulated in the serum of lung cancer patients and may serve as a promising biomarker for early detection and therapeutic intervention in lung cancer patients. Herein, a dual-signal biosensing platform utilizing aptamers was developed for miRNA-21 analysis via catalytic hairpin assembly (CHA) cycle amplification and nanomaterial-enhanced cation exchange reactions (CERs). When target miRNA-21 is present, the C-Ag+-C structure probe formed by hairpin DNA1 (H1) with BHQ-2 and Ag+ can be opened, which then initiates the CHA cascade, resulting in the release of Ag+ and upconversion luminescence (UCL) recovery of upconversion nanoparticles. The incorporated CdTe quantum dots (QDs) serve as additional signal transducers, quenching fluorescence (FL) signals from "on" to "off" via CERs with Ag+. On the basis of this novel detection mechanism, the constructed dual-mode (UCL/FL) biosensor exhibited outstanding analytical performance, achieving detection limits of 0.096 nM (UCL) and 0.428 nM (FL). Furthermore, this dual-mode platform can detect miRNA-21 in serum samples, with recoveries ranging from 99.3 % ∼ 105.8 %. These results suggest that the developed dual-mode detection strategy holds great promise as a sensitive, accurate approach for analyzing biomarkers in biological samples.