Mikrochim Acta 2019 Apr 13;186(5):282. Epub 2019 Apr 13.
College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, Shandong, China.
A fluorometric turn-on assay is described for ascorbic acid (AA). It is based on the controlled release of polyallylamine-stabilized gold nanoclusters (polyallylamine-AuNCs) from MnO nanosheets. In an aqueous solution of near-neutral pH value, the positively charged capped AuNCs are adsorbed on the surface of the negatively charged MnO nanosheets. The adsorption leads to the quenching of the fluorescence of the AuNCs. However, in the presence of AA, MnO is reduced to Mn. This causes the destruction of the MnO nanosheets. As a result, the fluorescence of the polyallylamine-AuNCs at 615 nm is recovered. This method for determination of AA is inexpensive, sensitive, and selective. It works in the 0.01 to 200 μM concentration range and has a 3.2 nM detection limit (for S/N = 3). Graphical abstract Gold nanoclusters (AuNCs) and polyallylamine can form polyallylamine-AuNCs to enhance the orange fluorescence of AuNCs. MnO nanosheets can absorb polyallylamine-AuNCs, and this results in fluorescence quenching of polyallylamine-AuNCs. Ascorbic acid (AA) can reduce MnO nanosheets, in this results in the fluorescence recovery of polyallylamine-AuNCs.