A ratiometric fluorescent biosensor based on magnetic-assisted hybridization chain reaction and DNA-templated silver nanoclusters for sensitive microRNA detection

Abstract

A biosensor was designed for sensitive detection of microRNA (miR)-144-3p, a potential miR biomarker for nasopharyngeal cancer, by integrating magnetic beads (MBs) into a hybridization chain reaction-silver nanoclusters (HCR-AgNCs) system. Through careful design, each component in the MBs-HCR-AgNCs biosensor was able to perform well without affecting subsequent steps. The target miR-144-3p was first magnetically separated with MBs coated with capture probes and short assistant probes. The collected miR was then amplified via HCR and detected using fluorogenic AgNCs that were prepared in situ. The DNA hairpins used in HCR were designed to host a AgNCs nucleation sequence that is capable of dual-emissive fluorescence response, thus enabling a ratiometric analysis. The novel MBs-HCR-AgNCs biosensor exhibits a good fluorescence response towards the target miR-144-3p with a wide linear detection range of 10 fM–1 μM and a detection limit of 4.88 fM. Moreover, it shows remarkable selectivity towards the target miR and good reproducibility even in raw human serum samples. Our findings suggest that the MBs-HCR-AgNCs can be a promising tool for sensitive miR detection in clinical diagnostics, without the need for complex sample preparation.