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Cysteine-capped ZnS nanometer-sized fluorescent particles were produced by a colloidal aqueous synthesis. The functionalized nanoparticles are water-soluble and suitable for biological application. A synchronous fluorescence method has been developed for the rapid determination of DNA with functionalized nano-ZnS as a fluorescence probe, based on the synchronous fluorescence enhancement of cysteine-capped nano-ZnS in the presence of DNA. When Δλ=190 nm, maximum synchronous fluorescence is produced at 267 nm at pH 5.12. Under optimum conditions, the synchronous fluorescence intensity is proportional to the concentration of nucleic acids in the range 0.1–1.2 μg ml-1 for calf thymus DNA, 0.1–0.6 μg ml-1 for fish sperm DNA. The corresponding detection limit is 32.9 ng ml-1 for calf thymus DNA and 24.6 ng ml-1 for fish sperm DNA. This method is simple, inexpensive, rapid and sensitive. The recovery and relative standard deviation are satisfactory. [Copyright &y& Elsevier]

[Display omitted] • A fluorescent nanozyme with catechol oxidase activity was studied. • The nanozyme combines functions of catechol recognition and signal output. • Catechol sensing based on the nanozyme without addition of other agent. • The method is facile and shows good selectivity. Nanozymes, an unusual category of nanomaterials possessing enzymatic properties, and have generated considerable interest regarding their application feasibilities on several important fronts. In the present work, an innovative sensing device for catechol was established ground on a fluorescent nanozyme (Cu-BDC-NH 2) that exhibited catechol oxidase activity. The fluorescent nanozyme combines both functions of catechol recognition and response signal output, and can realize the sensing of catechol without the addition of other chromogenic agents. In the existence of Cu-BDC-NH 2 , catechol can be oxidized efficiently to produce quinones or polymers with strong electron absorption capacity, which immediately results in efficient fluorescence quenching of Cu-BDC-NH 2. However, other common phenolic compounds, such as phenol, the other two diphenols (hydroquinone and resorcinol), phloroglucinol, and chlorophenol, do not result in efficient fluorescence quenching of Cu-BDC-NH 2. The method shows a nice linear relationship between catechol concentration prep the fluorescence intensity of Cu-BDC-NH 2 in the scope of 0–10 μM, with a detection limit of 0.997 μM. The detection of catechol in actual water samples has also achieved the satisfactory consequences, which provides a new strategy for the convenient and selective detection of catechol. [ABSTRACT FROM AUTHOR]