A dual-model strategy for fluorometric determination of ascorbic acid and of ascorbic acid oxidase activity by using DNA-templated gold-silver nanoclusters.

Methods are described for the fluorometric and colorimetric determination of ascorbic acid (AA) and the activity of ascorbic acid oxidase (AA-Ox). The method for AA is based on AA-induced growth and aggregation of DNA-templated gold/silver nanoclusters (DNA-Au/Ag NC), which is accompanied by quenching of fluorescence emission at 605 nm upon 260 nm excitation and a visible color change of the solution from colorless transparent to yellow. The determination of the activity of AA-Ox is based on the finding that it catalyzes the oxidation of AA which results in the inhibition of growth and aggregation. AA can be determined with a 0.6 µmol·L-1 detection limit over the 5 to 150 µmol·L-1 concentration range. AA-Ox can be determined with a 0.0048 U·mL-1 detection limit over the 0.01 to 0.20 U·mL-1 range. Graphical abstract Schematic of a novel fluorometric and colorimetric platform for determination of ascorbic acid and ascorbic acid oxidase activity based on the use of DNA-templated gold-silver nanoclusters.