Fluorescent hydrogel kit based on photonic crystal-enhanced DNA-templated silver nanoclusters for miRNA detection

MicroRNAs (miRNAs) are post-transcriptional gene regulators and promising tumor biomarkers. Traditional detection methods are limited by high cost and specialized equipment. DNA-templated silver nanoclusters (DNA-AgNCs) are attractive fluorescent materials for biosensing but suffer from suboptimal brightness, with existing fluorescence enhancement strategies lacking universality. This study introduces a novel hydrogel kit integrating photonic crystals (PCs) and DNA-AgNCs for portable detection of miRNA-21. The formation of AgNCs within hybridization chain reaction (HCR) monomers generates a fluorescence signal, which is further amplified by PCs. Upon addition of miRNA-21, the conformational changes induced by miRNA-21 in the monomers trigger a cascade of hybridization events. Meanwhile, the formation of silver nanoclusters (AgNCs) is inhibited, thereby leading to an obvious decrease in fluorescence signal that can be distinguished by the naked eye. Hence, through the synergy of HCR-mediated target recognition, fluorogenic AgNCs-based transduction units, and PCs-triggered signal amplification, the hydrogel kit enhances the convenience and specificity of miRNA detection. In conclusion, this kit enables high-throughput fluorescence detection with a range of 1.56 to 200 nM. Moreover, it exhibits robust anti-interference capability in serum analysis, with recovery rates ranging from 91.84 to 102.74%. Owing to its strong matrix tolerance, the kit facilitates facile miRNA-21 detection, overcomes the drawbacks of conventional approaches, and holds considerable promise for clinical tumor diagnostic applications.