Silver nanocluster-lightened catalytic hairpin assembly for enzyme-free and label-free mRNA detection

Abstract

Quantitative mRNA expression level is very important for differential diagnosis and clinical diagnosis. In this work, an enzyme-free and label-free fluorescence assay based on DNA silver nanocluster-lightened catalytic hairpin assembly has been developed for detection of mRNA. The strategy employed two hairpin probes, their tails are reasonably designed to contain DNA-stabilized silver nanoclusters capture sequence and guanine-rich sequence. In the presence of the target mRNA, it can trigger the CHA cycle reaction and generated assembled products, thereby capture the prepared dark DNA/AgNCs, bring AgNCs and guanine-rich sequence in close proximity, which transform the dark green-emitting species into a bright red fluorescent DNA/AgNCs and lights up the CHA assembly products. The lightened DNA/AgNCs specifically to target mRNA, affording sensitivity for detection. In the range of 0.1–100 nM, the fluorescence intensity has a linear relationship with the logarithm of concentration of surviving mRNA with a detection limit is estimated about 45 pM. These results suggested that this developed strategy provided a useful platform for sensitive and cost-effective detection of mRNA and has shown great potential in the detection of disease-related biomarkers and early clinical theragnostic.