Multifunctional G-quadruplex-based fluorescence probe coupled with DNA-templated AgNCs for simultaneous detection of multiple DNAs and MicroRNAs.

Abstract A rapid, label-free, and multifunctional fluorescent probe for simultaneous detection of multiple targets was fabricated based on G-quadruplexes and DNA-templated silver nanoclusters (AgNCs). In this work, a probe with two capitated recognized regions was coupled with a locked G-quadruplex at the 5′-terminus and dark AgNC at the 3′-terminus. Upon the addition of the virus subtype H5N1 gene or microRNA-141, only the sequence of the G-quadruplex was released and bound with Thioflavin T (ThT) for a specific fluorescent response. On the contrary, with the presence of the influenza virus subtype H1N1 gene or microRNA-21, the fluorescence intensity was enhanced because of two split AgNCs approaching closely to produce a nanocluster dimer. Subsequently, with multiple target addition, fluorescence signals were produced for both G-quadruplexes and AgNCs. Moreover, this single and duplex detection for virus DNAs and microRNAs, which provides a versatile platform for different targets, was sufficiently sensitive for the expected detection limit, and still possessed unique selectivity with similar oligonucleotides. The simultaneous detection of targets in biological fluids indicated that there is great opportunity for this strategy to be further applied in biomedical research and clinical diagnosis. Graphical abstract Image 1 Highlights • A rapid, label-free and multifunctional fluorescent probe was fabricated to overcome cumbersome labeling procedures. • The system based on G-quadruplexes and DNA-templated silver nanoclusters (AgNCs) was designed for improving the sensitivity for simultaneous detection of virus DNA and microRNA. • The proposed strategy exhibited special selectivity in similar oligonucleotides and could be well applied in biological fluids. • The detection limit for H5N1 and H1N1 was estimated to be 0.45 nM and 10 nM respectively, and for miRNA-141 and miRNA-21was 1 nM and 10 nM respectively. [ABSTRACT FROM AUTHOR]