Fluorescent Ag nanoclusters templated by carboxymethyl-β-cyclodextrin (CM-β-CD) and their in vitro antimicrobial activity

A green and environment-friendly method for synthesis of water-soluble and fluorescent Ag nanoclusters was developed using carboxymethyl-β-cyclodextrin (CM-β-CD) as both reducing and stabilizing reagent. The optical properties of Ag nanoclusters were characterized using the photoluminescence, ultraviolet–visible absorption, and laser desorption time of flight mass spectroscopies. The role of carboxylic groups was discussed in the photoactivated synthesis of Ag nanoclusters. Increasing the substitute of carboxylic groups on CM-β-CD was propitious to the formation of Ag nanoclusters and the stability of the produced silver nanoclusters was greatly improved. The in vitro antimicrobial ability of the produced Ag nanoclusters was tested. Compared with a silver nitrate solution and a typical Ag colloid, Ag nanoclusters stabilized by CM-β-CD exhibited greatly strong antimicrobial ability.