Tannic Acid Carbon Dots with Both Antimicrobial Activity and Selectivity for Fe3+ Detection

Graphical In this study, novel negatively charged carbon quantum dots(CQDs) were synthesised by a one-step hydrothermal method using tannic acid as raw material. The synthesized CQDs not only inhibit the growth of common bacteria, but also have the potential to be used as fluorescent probes for Fe 3+ with selective fluorescence bursting behaviour towards Fe 3+ . In the field of antimicrobial nanomaterials, biomass-derived carbon quantum dots have attracted great attention from contemporary researchers due to their unique physicochemical properties and favorable biosafety. In this study, novel carbon quantum dots (CQDs) were synthesized from tannic acid by a one-step hydrothermal method. The polymeric CQDs have good surface functionality and hydrophilicity with a large number of hydroxyl, carboxyl and amino functional groups. Antimicrobial experiments showed that CQDs had a good inhibitory effect on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, as well as the drug-resistant bacterium methicillin-resistant Staphylococcus aureus. Scanning electron microscopy showed that the morphology of S.aureus cells treated with CQDs became shrivelled and irregular, the surface of E.coli cells protruded to form irregular vesicles, and the whole became shriveled up, whereas MRSA cells appeared to be depressed in the middle, and there was a residue of adherent CQDs on the cell surface. In addition, CQDs exhibit selective fluorescence bursting behavior for ferric ions and can be used as fluorescent probes for rapid, sensitive and selective detection of Fe 3+ . Therefore, CQDs not only possess good bacteriostatic properties, but also serve as fluorescent sensors for the detection of Fe 3+ . It can be used as a potential sensing array for selective detection of iron ions and bacterial abatement from contaminated water.