Hybrid Pt/ZrO₂ Nanoparticles as a Multifunctional Antibacterial Platform against Clinical MDR Acinetobacter baumannii and Staphylococcus hominis: Synthesis, Characterization, and Biological Evaluation

Abstract

The rise of multidrug-resistant (MDR) bacteria represents a major global health challenge, contributing to increased morbidity, mortality, and healthcare costs. The declining effectiveness of conventional antibiotics has emphasized the need for alternative antimicrobial strategies. Nanotechnology has emerged as a promising approach for enhancing the treatment of bacterial infections. This study investigated the synergistic antibacterial and antibiofilm activities of hybrid Pt/ZrO₂ nanoparticles against MDR bacterial pathogens, namely, Acinetobacter baumannii (A. baumannii) and Staphylococcus hominis (S. hominis). Platinum nanoparticles (PtNPs), zirconia nanoparticles (ZrO₂NPs), and hybrid Pt/ZrO₂NPs were synthesized using chemical methods and characterized by UV–Vis spectroscopy, FTIR, XRD, FESEM, and TEM analyses. FESEM analysis revealed spherical PtNPs with an average size of 29 ± 12 nm and ZrO₂NPs with an average size of 24 ± 8 nm. Following Pt deposition, hybrid Pt/ZrO₂NPs formed three-dimensional aggregates with an average size of 40 ± 12 nm, confirming successful loading of Pt onto the ZrO₂ surface. The characterization results demonstrated preservation of the crystalline structure of ZrO₂ and strong evidence of interaction between Pt and ZrO₂ within the hybrid nanostructure. FTIR spectra showed characteristic bands at 3437 cm⁻¹ (O–H stretching), 2926–2854 cm⁻¹ (C–H stretching), and 418 cm⁻¹ (Pt–O vibration). XRD analysis revealed crystalline platinum peaks at 38.9°, 46.2°, and 67.2° with crystallite sizes ranging from 6 to 8 nm, together with well-defined monoclinic zirconia peaks. Peak broadening after platinum deposition further supported successful hybrid nanoparticle formation. Biological evaluation demonstrated potent antibacterial activity against both bacterial species. The MIC values of Pt/ZrO₂NPs were 18.75 ± 0.11 µg mL⁻¹ for A. baumannii and 4.69 ± 0.34 µg mL⁻¹ for S. hominis, while MBC values showed similar results confirmed the bactericidal nature of the nanocomposite. At 300 µg mL⁻¹, Pt/ZrO₂NPs produced inhibition zones of 32.00 ± 1.13 mm against A. baumannii and 40.00 ± 2.10 mm against S. hominis, demonstrating superior antibacterial efficacy compared with the individual nanoparticles. Furthermore, the hybrid nanocomposite exhibited enhanced antibiofilm activity, attributable to the combined effects of platinum and zirconia. In addition, Pt/ZrO₂NPs showed favorable hemocompatibility and significant antioxidant activity. Overall, the findings indicate that the enhanced biological performance of Pt/ZrO₂NPs arises from synergistic metal–support interactions within the hybrid nanostructure, highlighting their potential as a promising platform for combating MDR bacterial infections.

Graphical Abstract