Fluorometric determination of HIV DNA using molybdenum disulfide nanosheets and exonuclease III-assisted amplification
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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.
KeywordsLayered transition metal dichalcogenide nanosheets Enzyme amplification Fluorometric assay DNA biosensor
This work was financially supported by National Natural Science Foundation of China (No. 21775104, 21605026, 81672720), the National Quality Infrastructure Program of China (2017YFF0204605), and Shanghai Rising-Star Program (16QB1403100).
L.W., Y.W., G.L., and C.Z. designed the experiments and wrote the main manuscript ;L. W.,L.D., M. D. and Y.W. performed experiments; X.S. and J.W. contributed to datacuration and formal analysis. All authors reviewed the manuscript.
Compliance with ethical standards
The author(s) declare that they have no competing interests.