A simple and efficient ultrasonication-assisted liquid exfoliation method is proposed to produce PtS2 nanosheets on a large scale and improve their dispersion in aqueous solution by surface polyethylene glycol modification. The interaction of polyethylene glycol-modified PtS2 (PEG-PtS2) nanosheets with fluorescent labeled DNA and the fluorescence quenching mechanism using FAM-labeled hpv16e6 gene fragment as a probe was investigated. The excitation and emission wavelengths were 468 and 517 nm, respectively. The fluorescence quenching mechanism of PEG-PtS2 nanosheets for double-stranded DNA (dsDNA) might stem from the static quenching effect. Based on the difference in fluorescence quenching capability of PEG-PtS2 nanosheets in fluorescent probe tagged single-stranded DNA (ssDNA) and dsDNA, a mix-and-detect method was proposed for determination of DNA. Without the need for probe immobilization and tedious washing steps, the genotyping of human papillomavirus (HPV) was easily achieved. The limit of detection was calculated to 0.44 nM, showing a good linear range within 0.05-10 nM. We believe this biosensor provides opportunities to develop a simple and low-cost strategy for molecular diagnostics. Graphical abstract.
Keywords: DNA fluorescence biosensor; Platinum disulfide nanosheets; Polyethylene glycol modification; Ultrasonication-assisted liquid exfoliation method.