Novel sulfur-doped graphitic carbon nitride quantum dots (S-gCNQDs) are synthesized using a single-source precursor in a one-step solvothermal process. The S-gCNQDs with a size of ~ 5-nm displayed a strong green intrinsic fluorescence at 512 nm when excited at 400 nm, with a quantum yield of ~ 33% in aqueous solution. The prepared S-gCNQDs and Ag2S nanocrystals were applied as innovative functional materials to fabricate a biosensor for virus detection based on the conjugation of specific anti-human influenza A monoclonal antibody to the S-gCNQDs and Ag2S NCs, respectively. In the presence of the influenza A virus, an interaction between the S-gCNQDs/Ag2S-labeled antibody resulted in the formation of a nanosandwich structure, which is accompanied by the fluorescence enhancement of the S-gCNQDs. The change in fluorescence intensity linearly correlats with the concentration of the influenza A virus (H1N1) in the 10 fg/mL to 1.0 ng/mL range, with a limit of detection of 5.5 fg/mL. The assay was applied to the assay of clinically isolated influenza A virus (H3N2/Yokohama) mixed with human serum. The obtained limit of detection was 100 PFU/mL within the detection range of 102– 5 × 104 PFU/mL for the H3N2 virus. [Figure not available: see fulltext.].
Bibliographical noteFunding Information:
The authors sincerely thank Professor K. Morita of the Institute of Tropical Medicine, Nagasaki University, for providing the Zika virus. Dr. C. Kawakami of Yokohama City Institute of Health, Japan, is gratefully acknowledged for providing the clinically isolated influenza virus A/Yokohama/110/2009 (H3N2). We also wish to thank Dr. T.C. Li of the National Institute for Infectious Disease of Japan for providing HEV-LPs.
O.J.A and S. K. gratefully acknowledge the Japan Society for the Promotion of Science (JSPS) for a Postdoctoral Fellowship for Research in Japan (Standard) (Grant No. 19F19348) and the Grant-in-Aid for Scientific Research (S) (Grant No. 18H05240), respectively. Acknowledgments
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