Green synthesis of silver@carbon dots nanocomposites for enhancing the antimicrobial activity

Abstract

A facile green route method has been developed for synthesis of carbon dot-coated silver nanocomposites (Ag@c-dots NCs), in which fluorescent c-dots obtained from the rice straw waste were used as a reducing and stabilizing agent. To the best of our knowledge, this is the first study that reports the effect of c-dots coating on antibacterial activity of silver nanoparticles (Ag NPs). C-dots were prepared by hydrothermal process with the the optimal synthesis conditions were at a temperature of 180 °C and 4 h of reaction time. Sonochemical method was applied to produce the Ag@c-dots NCs. In order to characterize the optical properties and surface morphology of c-dots and Ag@c-dots NCs, UV-Vis and photoluminescence spectrophotometer as well as Transmission electron microscopy (TEM), respectively, were utilized. The results demonstrated that the modification of silver surface by c-dots was successfully developed with the average size below 50 nm. In the same concentration of 5 mg/mL, the antibacterial activity of c-dots-functionalized Ag NCs were slightly higher than bare Ag NPs towards both bacteria Escherichia coli and Staphylococcus aureus which were exhibited by the increment of inhibition zone diameter about 0.6 to 1 mm.