Synthesis and antibacterial activity of polyhydroxybutyrate sheet impregnated with Ag/TiO2 and Ag/Cu nanocomposites

The integration of the nanostructures into polymer matrices offers a promising approach for the development of innovative antimicrobial materials. In this study, nanocomposites were synthesized by reducing metal ions (Ag+, Ti3+ and Cu2+) using plant extracts of Withania somnifera and Parkia biglandulosa. The resulting nanoparticles were characterised using X-ray diffraction (XRD) analysis. Two bimetallic nanocomposites, of Ag/TiO2 and Ag/Cu exhibited significant antibacterial activity against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853 and Escherichia coli DH5 alpha. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were found to be 0.056 mg/mL for nanocomposite Ag/Cu. MBC of Ag/TiO2 against S. aureus ATCC 25923 was found to be 0.04 mg/mL and against P. aeruginosa ATCC 27853, E. coli DH5 alpha, it was measured as 0.02 mg/mL. The antibacterial properties of polyhydroxybutyrate (PHB) sheets embedded with Ag/TiO2 and Ag/Cu nanocomposites were evaluated according to the ISO 22196:2007(E) standard. The PHB sheets demonstrated R-value of antibacterial activity >= 2, indicating effective surface inhibition of bacterial growth. These findings suggest that PHB sheets embedded with nanocomposites have significant potential for medical applications due to their biocompatibility and strong antibacterial properties.