Salicylic-Zinc Nanocomposites with Enhanced Antibacterial Activity

Abstract

Numerous infectious diseases and microorganisms with high drug resistance have motivated researchers to develop nanocomposite particles as antimicrobial agents. Herein, we report on nanocomposites of salicylic acid (SA) and 5-sulfosalicylic acid (5-SSA) with zinc oxide (ZnO), namely SA-ZnO and 5-SSA-ZnO nanoparticles (NPs), with antibacterial and cytotoxic properties. Ultraviolet-visible and Fourier-transform infrared spectroscopy of the synthesized SA-ZnO and 5-SSA-ZnO NPs indicated the functionalization of ZnO with SA and 5-SSA. X-ray diffraction revealed the crystalline structures of the synthesized NPs. The zeta potentials of the SA-ZnO, 5-SSA-ZnO, and ZnO NPs were 1.42, −5.98, and −0.172, respectively. The SA-ZnO and 5-SSA-ZnO NPs were spherical. Besides, the results of the antimicrobial assay indicated a significant reduction (p < 0.05) in the growth of Escherichia coli and Bacillus cereus by SA-ZnO and 5-SSA-ZnO NPs (0.1%). Scanning electron microscopy of NP-treated bacteria revealed cell death. Moreover, SA-ZnO and 5-SSA-ZnO NPs did not exhibit substantial toxicity against human HaCaT cells even at a high concentration (200 µg/mL). Overall, SA-ZnO and 5-SSA-ZnO NPs exhibited antibiotic-mimicking activity against bacteria with no cytotoxicity.