Enhanced Antibacterial Efficacy of Chlorhexidine- Loaded Iron Oxide Nanoparticles Against Streptococcus pneumoniae

Abstract

Nanoformulations offer a synergistic approach to delivering antibacterial agents. In this study, positively charged Iron nanocomplexes were developed as nanocarriers for chlorhexidine (CHX) using ionic liquids. Chlorhexidine-loaded Iron nanoparticles (CHFNPs) were thoroughly characterized using various biophysical techniques, including UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. Additionally, the loading efficiency and controlled release profile of CHX from the nanocomplex were evaluated. The average diameters of Iron nanoparticles (FNPs) and CHFNPs were determined to be 27.43 nm and 29.66 nm, respectively, with CHFNPs demonstrating a sustained release of CHX, positioning them as a potent antibacterial agent. Antibacterial efficacy tests against the antibiotic-resistant Streptococcus pneumoniae strain 7465 revealed that CHFNPs significantly reduced bacterial viability. At a concentration of 100 ?g/mL, CHX alone showed the highest antibacterial activity, with minimal inhibitory concentration (MIC90) and minimal bactericidal concentration (MBC96) values, followed by CHFNPs, which displayed lower MIC and MBC values. FNPs at intermediate concentrations (12 and 25 ?g/mL) exhibited a bactericidal effect comparable to CHX, although they were not potent enough to completely inhibit S. pneumoniae growth. Notably, CHFNPs exhibited a significantly greater antibacterial effect than FNPs at all tested concentrations, with an MIC value of 40 ?g/mL compared to 80 ?g/mL for CHX. No MIC was detected for FNPs at the tested formulation concentrations. Overall, CHFNPs demonstrated a significant reduction in bacterial viability compared to CHX alone, highlighting their potential as a promising treatment option for combating infections caused by antibiotic-resistant S. pneumoniae.