Evaluation of the effects of chitosan-loaded Curcumin-Vancomycin nanoparticles on biofilm formation in Staphylococcus aureus

Abstract

Staphylococcus aureus is a major opportunistic pathogen responsible for persistent and device-related infections, largely due to its strong biofilm-forming capacity and increasing antimicrobial resistance. This study aimed to evaluate the antibiofilm effects of chitosan-loaded curcumin-vancomycin nanoparticles against S. aureus clinical isolates. Nanoparticles were synthesized via ionic gelation and characterized using dynamic light scattering and electrophoretic light scattering techniques. Biofilm formation was quantified using the crystal violet microtiter plate assay, and gene expression analysis of the icaA gene was performed in biofilm-producing S. aureus exposed to sub-minimum inhibitory concentration (MIC) concentrations of nanoparticles using real-time PCR and the 2^-ΔΔCt method. Results showed a significant reduction in icaA expression following treatment with curcumin, vancomycin, and particularly curcumin-vancomycin-loaded chitosan nanoparticles compared to untreated controls (P <0.05). The greatest suppression of icaA expression was observed in the nanoparticle-treated group, indicating enhanced antibiofilm activity. The mean hydrodynamic diameter was 333.8 ± 9.2 nm with a polydispersity index (PDI) of 0.236, indicating a relatively uniform size distribution. The zeta potential was +28.9 mV, confirming good colloidal stability. All tested isolates were strong biofilm producers. MIC of nanoparticles ranged from 64 to 256 µg/mL, demonstrating strain-dependent antimicrobial activity. The findings demonstrate that curcumin-vancomycin-loaded chitosan nanoparticles effectively inhibit biofilm formation and downregulate key biofilm-associated genes in S. aureus. This synergistic nano-formulation offers a promising strategy for overcoming biofilm-associated infections and improving the efficacy of conventional antibiotics.