Fluorometric determination of HIV DNA using molybdenum disulfide nanosheets and exonuclease III-assisted...

A convenient and ultrasensitive fluorometric method is described for the determination of HIV DNA. It exploits the strong difference in the affinities of MoS₂ nanosheets for long ssDNA versus short oligonucleotide fragments. In addition, efficient signal amplification is accomplished by exonuclease III-assisted target recycling. When absorbed on the MoS₂ nanosheets, the fluorescence of the FAM-labeled ssDNA probe (FP) is quenched. However, in the presence of HIV DNA, the FP hybridizes with target to form a duplex. As a result, the FP in the duplex will be stepwise hydrolyzed into short fragments by Exo III, and the fluorescence signal thus is retained because short fragments have low affinity for the MoS₂ nanosheets. By using the Exo III-assisted target recycling amplification, the detection sensitivity is strongly improved. The sensor can detect DNA in a concentration as low as 5.3 pM (at an S/N ratio of 3), and the analytical range extends from 0.01 nM to 10 nM. The assay is simple, sensitive and specific, and conceivably represents a valuable tool in clinical studies related to the HIV. Graphical abstract Schematic presentation of fluorometric determination of HIV DNA based on molybdenum disulfide nanosheets and Exo III. When the fluorescence-tagged ssDNA probe hybridized with target to form a duplex, the Exo III-assisted target recycling amplification is generated. The method can detect as low as 5.3 pM HIV DNA.