Impact of l-Arginine and l-Histidine on the structural, optical and antibacterial properties of Mg doped ZnO nanoparticles tested against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli.

Magnesium doped Zinc oxide nanoparticles (Mg:ZnO NPs) were synthesized by co-precipitation method. The synthesized Mg:ZnO NPs exhibited hexagonal wurtzite structure, which was confirmed by X-ray diffraction results. After structural confirmation of Mg doped ZnO NPs, base amino acids like l-Arginine and l-Histidine were separately incorporated with the Mg: ZnO NPs. l-Arginine added Mg:ZnO (Mg:ZnO:LA) and l-Histidine added Mg:ZnO (Mg:ZnO: LH) NPs retained the same wurtzite hexagonal structure and average crystallite sizes of Mg: ZnO:LA and Mg: ZnO:LH NPs were found to be 25 nm and 20 nm respectively. The sizes of Mg:ZnO:LH and Mg: ZnO: LA NPs decreased as compared to that of the Mg doped ZnO NPs. From the FT-IR spectra, the ZnO stretching frequencies were observed at 516, 517 and 518 cm for Mg:ZnO, Mg:ZnO: LA and Mg: ZnO:LH NPs respectively. From the FESEM images, the morphologies of ZnO:Mg and ZnO:Mg:LA NPs were spherical and the Mg: ZnO: LH NPs formed nano-flakes structure. From the EDAX study, the amount of elements incorporated in the samples was determined. The photoluminescence measurements revealed the existence of zinc vacancies, oxygen vacancies and surface defects of the samples. Antibacterial activity of the amino acid added Mg doped ZnO NPs was studied against extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli (E. coli).The Minimal Inhibitory Concentration (MIC) of the LH added ZnO:Mg NPs was found to be 1000 μg/ml for which the growth of E. coli completely inhibited. l-Histidine added Mg doped ZnO NPs showed the highest antibacterial activity as compared to that of the Mg:ZnO NPs and ZnO:Mg:LA NPs.