Modification in Toxicity of l-Histidine-Incorporated ZnO Nanoparticles toward Escherichia coli

Abstract

This paper presents a comparative study of the toxicity of pristine-ZnO and l-histidine-incorporated ZnO toward Escherichia coli (E. coli) as a Gram-negative model organism. Pristine-ZnO and l-histidine-incorporated ZnO with different l-histidine concentrations were synthesized using an open aqueous solution bath technique. XRD studies revealed the formation of polycrystalline wurtzite ZnO. The average crystallite size of the synthesized l-histidine-incorporated ZnO decreased as the concentration of l-histidine increased. The FTIR spectra showed the presence of Zn–O, CO2 –/CO3 –, and C–N (only in l-histidine-incorporated ZnO samples) and −OH bond vibration signals in all samples. The chemical purity of all the samples was ensured using XPS analysis. The microbial activity of these samples was investigated using E. coli. The solution with 100 μg/mL ZnO in sterile distilled water showed up to 94% growth inhibition of E. coli, establishing antibacterial activity. However, l-histidine incorporated in ZnO showed reduced antibacterial activity with the increase of the concentration of l-histidine in ZnO. Furthermore, flow cytometry studies during the interaction of ZnO and E. coli confirmed the generation of reactive oxygen species (ROS), validating its antibacterial activity. The interaction of l-histidine-incorporated ZnO and E. coli showed declining ROS with the increase in the l-histidine concentration, indicating a ZnO toxicity reduction.

The effects of nano-silver loaded zirconium phosphate on antibacterial properties, mechanical properties and biosafety of room temperature curing PMMA materials

“…These peaks are most pronounced in the 3.0%wt group, substantiating the successful integration of nano-Ag-ZrP into the PMMA materials.XPS (The results of XPS were analyzed by Avantage software) global spectrum analysis of nano-Ag-ZrP is presented in Figure 3D . The binding energies at 1022.80 eV and 1044.52 eV correspond to Zn2P 1/2 and Zn2P3 orbits, respectively ( Mahakal et al., 2023 ). According to the reagent manufacturer, the Ag-ZrP antibacterial agent incorporates a minimal quantity of zinc oxide (approximately 5.0~10.0%wt), primarily functioning as a dispersant, and the peak at 248.80 eV signifies the charge correction peak of C1s.…”