Thiourea functionalized b-cyclodextrin as green reducing and stabilizing agent for silver nanocomposites with enhanced antimicrobial and antioxidant properties †

Rapid development of microbial resistance against traditional antibiotics has generated a need for the synthesis of new more potent, less toxic, target specific, cost effective and biodegradable antimicrobial agents. Biopolymer based Ag-nanocomposites are a good alternative for this purpose. With the auxiliary privilege of being utilized as prospective stabilizer and emulsifier, a biopolymer reaffirms the edge over traditionally used chemicals in nano-chemistry. In view of the above context, the present investigation involves microwave assisted facile and green method for the synthesis of b-cyclodextrin silver nanocomposites (Ag-NPs). Herein, sulphur functionalized b-cyclodextrin itself acts as a green reducing and capping agent for silver ion. The constitution and framework of the synthesized thiomer and nanocomposite were characterized using FTIR, XRD and TEM techniques. These studies indicated the homogeneity of the silver nanocomposites with average size of B4 nm via XRD results. Functionalized nanocomposites, with unique properties of –SH group and Ag-NP, were screened for broad spectrum antimicrobial and antioxidant activity. The antimicrobial results disclosed excellent antimicrobial performance with maximum inhibition zone of 38 mm and MIC value of 0.9 mg mL 1 against E. coli. The sulphur functionalized b-cyclodextrin and their synthesized nanocomposites also exhibited eminent antioxidant properties even at 100 ppm.