Antimicrobial Perspectives of Active SiO2FexOy/ZnO Composites

Florin Matusoiu; Adina Negrea; Nicoleta Sorina Nemes; Catalin Ianasi; Mihaela Ciopec; Petru Negrea; Narcis Duteanu; Paula Ianasi; Daniel Duda-Seiman; Delia Muntean

doi:10.3390/pharmaceutics14102063

Antimicrobial Perspectives of Active SiO₂Fe_xO_y/ZnO Composites

Pharmaceutics. 2022 Sep 27;14(10):2063. doi: 10.3390/pharmaceutics14102063.

Authors

Affiliations

¹ Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University Timisoara, Victoriei Square, No. 2, 300006 Timişoara, Romania.
² Renewable Energy Research Institute-ICER, Politehnica University Timisoara, 138 Gavril Musicescu Street, 300501 Timişoara, Romania.
³ "Coriolan Drăgulescu" Institute of Chemistry, Bv. Mihai Viteazul, No. 24, 300223 Timişoara, Romania.
⁴ National Institute for Research and Development in Electrochemistry and Condensed Matter, 144th Dr. A. P. Podeanu Street, 300569 Timişoara, Romania.
⁵ Department of Cardiology, "Victor Babeş" University of Medicine and Pharmacy Timişoara, 2 Piata Eftimie Murgu, 300041 Timişoara, Romania.
⁶ Multidisciplinary Research Centre on Antimicrobial Resistance, Department of Microbiology, "Victor Babeş" University of Medicine and Pharmacy Timişoara, 2 Eftimie Murgu Square, 300041 Timişoara, Romania.

Abstract

The antibacterial activity of zinc oxide particles has received significant interest worldwide, especially through the implementation of technology to synthesize particles in the nanometer range. This study aimed to determine the antimicrobial efficacy of silica-based iron oxide matrix (SiO₂Fe_xO_y) synthesized with various amounts of ZnO (SiO₂Fe_xO_yZnO) against various pathogens. It is observed that, with the addition of ZnO to the system, the average size of the porosity of the material increases, showing increasingly effective antibacterial properties. Zinc-iron-silica oxide matrix composites were synthesized using the sol-gel method. The synthesized materials were investigated physicochemically to highlight their structural properties, through scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FT-IR). At the same time, surface area, pore size and total pore volume were determined for materials synthesized using the Brunauer-Emmett-Teller (BET) method. Although the material with 0.0001 g ZnO (600 m²/g) has the highest specific surface area, the best antimicrobial activity was obtained for the material with 1.0 g ZnO, when the average pore volume is the largest (~8 nm) for a specific surface of 306 m²/g. This indicates that the main role in the antibacterial effect has reactive oxygen species (ROS) generated by the ZnO that are located in the pores of the composite materials. The point of zero charge (pH_pZc) is a very important parameter for the characterization of materials that indicate the acid-base behaviour. The pH_pZc value varies between 4.9 and 6.3 and is influenced by the amount of ZnO with which the iron-silica oxide matrix is doped. From the antimicrobial studies carried out, it was found that for S. aureus the total antibacterial effect was obtained at the amount of 1.0 g ZnO. For Gram-negative bacteria, a total antibacterial effect was observed in S. flexneri (for the material with 0.1 g ZnO), followed by E. coli (for 1.0 g ZnO). For P. aeruginosa, the maximum inhibition rate obtained for the material with 1.0 g ZnO was approximately 49%.

Keywords: antimicrobial activity; composites; silica matrix; zinc oxide.

Grants and funding

This research received no external funding.