Chlorhexidine-Loaded Zinc Nanoparticles: A Potent Antibacterial Agent Against Streptococcus pneumoniae

Nanoformulations deliver antibacterial agents synergistically. Positively charged Zn nanocomplexes were used as carriers for chlorhexidine (CHX), developed using ionic liquids. The CHX-loaded Zn nanoparticles (CHZNPs) were characterised through various techniques, including UV-visible Spectroscopy, TEM, FTIR, and Zeta potential analysis. The average diameters of ZNPs and CHZNPs were 27.43 and 29.66 nm, respectively. CHZNPs consistently released CHX, enhancing its antibacterial effect. Tests against antibiotic-resistant Streptococcus pneumoniae strain 7465 revealed that CHZNPs significantly reduced bacterial viability. At 100 μg/mL, CHX showed the highest antibacterial activity with the lowest minimal inhibitory concentration (MIC₉₀) and minimal bactericidal concentration (MBC₉₆) values, followed by CHZNPs, which had lower MIC and MBC values. While ZNPs demonstrated some bactericidal effect at intermediate dosages (12 and 25 μg/mL), they could not fully inhibit bacterial growth. CHZNPs outperformed ZNPs across all concentrations, with an MIC of 40 μg/mL compared to CHX's 80 μg/mL. ZNPs showed no MIC at tested concentrations. Overall, CHZNPs significantly reduced bacterial viability more effectively than CHX alone, highlighting their potential as a treatment for antibiotic-resistant S. pneumoniae infections.