Antimicrobial activity of zinc oxide particles on five micro-organisms of the Challenge Tests related to their...

Area of Science:

• Materials Science
• Microbiology
• Pharmaceutical Science

Background:

• Zinc oxide (ZnO) possesses antimicrobial properties beneficial for pharmaceutical products.
• Its potential as a preservative in topical formulations remains underexplored.
• Understanding structure-activity relationships is key to optimizing ZnO's preservative efficacy.

Purpose of the Study:

• To investigate the antimicrobial activity of ZnO powders against key microbial strains.
• To evaluate ZnO as a potential preservative in topical formulations.
• To correlate ZnO particle structural parameters with antimicrobial efficacy.

Main Methods:

• Three grades of ZnO powders were characterized for physicochemical properties.
• Antimicrobial efficacy was assessed against *Escherichia coli*, *Staphylococcus aureus*, *Pseudomonas aeruginosa*, *Candida albicans*, and *Aspergillus brasiliensis*.
• Disc diffusion susceptibility tests and broth dilution methods (MIC and MBC) were employed.

Main Results:

• All ZnO grades exhibited concentration-dependent bactericidal and antifungal activity.
• Smaller particle size, larger specific surface area, and higher porosity correlated with increased antimicrobial activity.
• ZnO demonstrated efficacy against all five tested microbial strains.

Conclusions:

• Zinc oxide is a viable candidate for preservative use in topical formulations.
• Optimizing ZnO particle characteristics, such as size and surface area, can enhance antimicrobial performance.
• Further research into ZnO's antimicrobial mechanisms and formulation compatibility is warranted.