Synthesis and characterization of novel antimicrobial agent with inorganic nanoparticles and composites

Abstract

Nanoparticles and nanocomposites are now considered as one of the emerging therapeutic approach against infectious diseases. To explore this further, a laboratory based study has been conducted to prepare and characterize different antibacterial agents and to evaluate their inhibition activity/capacity by shake flask method and plate culture method (zone of inhibition method). Escherichia coli growth was evaluated against different concentrations of chitosan, zinc oxide (ZnO) and graphene oxide (GO) nanoparticles, silver/zinc zeolite (Ag/Zn-Ze) and graphene oxide-silver (GO-Ag) nanocomposites. Then inhibition capacity was expressed in terms of the values of Minimum Inhibitory Concentration (MIC), antibacterial concentration at which 50% cells are inhibited (IC50), Minimum Bactericidal Concentration (MBC). For initial bacterial concentration of 105 cells/ml, MICs were found around 20, 120, 10, 30, and 30 µg/ml for chitosan, ZnO, Ag/Zn-Ze, GO and GO-Ag, respectively and 150, 250, 47, 90, and 78 µg/ml were found as IC50, respectively. The results indicate that Ag/Zn-Ze, and GO-Ag have comparatively higher inhibition capacity. MBCs were found as <1280, <160, <320, <320 µg/ml for chitosan, Ag/Zn-Ze, GO and GO-Ag, respectively and in case of ZnO, no MBC was found. It was found that the effectiveness of antibacterial agents is highly dependent on initial bacterial concentration when evaluated with 107 cells/ml. However, in case of plate culture method, quite similar inhibition capacity was found for chitosan, ZnO, Ag/Zn-Ze, and GO-Ag, whereas GO showed lower capacity to inhibit E. coli. In addition, the antibacterial surface prepared with GO-Ag nanocomposites performed better than the surface prepared with Ag/Zn-Ze. However, in cytotoxicity test, Ag/Zn-Ze showed no toxicity on Vero cells, whereas GO-Ag exhibited severe toxicity at higher concentrations. It is expected that the antibacterial potency of the nanoparticles and composites will led to the upsurge in the research on novel antimicrobials surfaces for varying applications.