The Antimicrobial Effectiveness of the Hydroxyapatite Matrix Loaded with Metal Nanoparticles

Bone infections and trauma can significantly impact both the length and quality of a person’s life. The rise in antibiotic-resistant bacterial strains has become a pressing concern, necessitating the search for novel antibacterial agents that can help mitigate the growing burden of antibiotic resistance. Metal and metal oxide nanoparticles (NPs) have emerged as promising alternatives to traditional antibiotics, demonstrating intrinsic antibacterial activity against targeted bacterial pathogens. Due to their toxic effects against various bacterial strains, these nanomaterials have the potential for diverse biomedical applications, including drug delivery and tissue engineering. In this study, we synthesized composite materials based on hydroxyapatite (HA) with the incorporation of silver (Ag) and copper (Cu) nanoparticles and evaluated their antimicrobial activity against clinically significant antibiotic-resistant bacterial strains, including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. The results revealed that the minimum inhibitory concentration (MIC) of Ag NPs against these pathogens ranged from $2.5 \mu \mathrm{~g} / \mathrm{mL}$ to $5 \mu \mathrm{~g} / \mathrm{mL}$, whereas the MIC for copper nanoparticles was comparatively higher, ranging from $4 \mu \mathrm{~g} / \mathrm{mL}$ to $145.3 \mu \mathrm{~g} / \mathrm{mL}$. Furthermore, the composite materials exhibited contact inhibition against the multidrug-resistant strains for both types of nanoparticles, with Ag NPs demonstrating a more potent antibacterial effect when incorporated into HA compared to Cu NPs. This research provides insights into the potential use of HA-based composites with metal nanoparticles as effective antibacterial agents, which could play a crucial role in addressing antibiotic resistance and enhancing bone tissue engineering applications.