A versatile DNA detection scheme based on the quenching of fluorescent silver nanoclusters by MoS2 nanosheets: Application to aptamer-based determination of hepatitis B virus and of dopamine

The authors report that the fluorescence of polymer-capped silver nanoclusters (AgNCs) is quenched by MoS 2 nanosheets. However, in the presence of electrolytes such as sodium acetate (50 mM), the nanosheets tend to aggregate, and this causes fluorescence to be restored. If, however, ssDNA is added, it will be adsorbed on the surface of the MoS 2 nanosheets and stabilize them against aggregation. As a result, the emission of the AgNCs (best measured at excitation/emission wavelengths of 375/455 nm) is quenched again. If complementary oligonucleotide is added, a dsDNA will be formed that does no longer prevent aggregation and fluorescence is restored. Similarly, if an aptamer is adsorbed on the MoS 2 nanosheets and its substrate is then added to form a folded state, the fluorescence of the AgNCs also will be restored. As a proof of concept, the DNA sequences of hepatitis B virus and of a dopamine-selective aptamer were chosen as models. The resulting assays have low detection limits and linear ranges that extend from 5 to 30 nM for hepatitis B DNA, and from 0.3 to 1 μM for dopamine. In our perception, this method represents a universal platform for the detection of analytes for which complementary oligomers or aptamers are available. The blue fluorescence of AgNCs is quenched by MoS 2 nanosheets. MoS 2 nanosheets possess different affinity toward single-stranded DNA (ssDNA) versus double-stranded (dsDNA) and folded DNA. Based on this, multiple targets can be detected through changing the sequence of ssDNA.