Antimicrobial and anti-virulence effects of functionalized cobalt nanoparticles against multidrug-resistant...

The increasing prevalence of multidrug-resistant (MDR) Escherichia coli and its ability to form biofilms pose a significant public health threat, particularly in urinary tract infections (UTIs). This study aimed to investigate the antibacterial, antibiofilm, and gene expression-modulating effects of gallic acid-stabilized cobalt nanoparticles (Co-GANPs) and their hyaluronic acid-modified versions (Co-GANPs-HA) against clinical E. coli isolates obtained from Ramadi Children's and Gynecology Hospital and Hit General Hospital. Nanoparticles were successfully synthesized and characterized using techniques such as XRD, FT-IR, SEM, TEM, and EDX. Physicochemical analyses confirmed the production of stable, spherical, and well-dispersed nanostructures with a crystallite size of 8.8 nm. Biological evaluations demonstrated that Co-GANPs-HA exhibited superior antibacterial activity compared to Co-GANPs, with a lower Minimum Inhibitory Concentration (MIC) of 3.1 mg/mL versus 6.2 mg/mL. The nanoparticles effectively inhibited both planktonic cells and biofilm formation, including in antibiotic-resistant isolates. Gene expression analysis revealed that both nanoparticle formulations significantly downregulated the expression of qclb, a key virulence gene. These findings suggest that functionalized cobalt nanoparticles, with their multifactorial mechanism of action that bypasses traditional resistance, could be a powerful therapeutic alternative or adjunct for MDR and biofilm-related UTIs.