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

Shraddha Mahakal; Habib M Pathan; Mohit Prasad; Sachin Rondiya; Shashikant P Patole; Sandesh R Jadkar

doi:10.1021/acsomega.3c01183

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

ACS Omega. 2023 Sep 13;8(38):34354-34363. doi: 10.1021/acsomega.3c01183. eCollection 2023 Sep 26.

Authors

Shraddha Mahakal¹, Habib M Pathan¹, Mohit Prasad^{1

2}, Sachin Rondiya³, Shashikant P Patole⁴, Sandesh R Jadkar¹

Affiliations

¹ Department of Physics, Savitribai Phule Pune University, Pune 411 007, India.
² Department of Applied Science and Humanities, Pimpri Chinchwad College Of Engineering (PCCOE), Nigdi, Pune 411 004, India.
³ Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012, India.
⁴ Department of Physics, Khalifa University of Science and Technology, Abu Dhabi 127788, UAE.

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.