An in vitro study on the antibacterial effects of chlorhexidine-loaded positively charged silver nanoparticles on Enterococcus faecalis

This study successfully developed a positively charged silver nanocomplex as a nanocarrier for chlorhexidine (CHX) using ionic liquids. This nanocomplex can interestingly deliver the antibacterial agent with a synergistic effect. In this study, we synthetized and characterized a positively charged silver nanocomplex (AgNPs+) and CHX-loaded positively charged silver nanoparticles (CHX@AgNPs+) using UV-visible spectroscopy, transmission electron microscopy, X-ray diffractometer, Fourier transform infrared spectroscopy, and Zetasizer. Then, the loading efficiency and release profile of XHX from nanocomplex were evaluated. The antibacterial activity was evaluated by employing two standard microdilution tests to obtain the minimum bactericidal and inhibitory concentrations. The average sizes of 27.43 nm and 29.66 nm were obtained for AgNPs+ and CHX@AgNPs+, respectively. The CHX@AgNPs+ showed a constant release of CHX, making them a more effective antibacterial agent against Enterococcus faecalis (E. faecalis) than CHX or AgNPs+ alone. Antibacterial assays showed that CHX@AgNPs+ significantly reduced the viability of the bacterial strain compared to CHX as the standard irrigant. AgNPs+ had an antibacterial effect similar to CHX only at intermediate concentrations (12 and 25 μg/mL), and their effects were significantly less than those of CHX at other concentrations (3, 6, 50, and 100 μg/mL). The effects of CHX@AgNPs+ were statistically greater than those of AgNPs+ at all concentrations tested. The MIC values of CHX@AgNPs+ and CHX were 50 and 100 μg/mL. However, AgNPs+ were not showed MIC value at tested concentrations. Therefore, the designed nanocomplex can be regarded as a potential root canal disinfectant with clinical applications for bacterial infections.