Antibacterial efficacy of chitosan nanoparticles against Enterococcus faecalis in planktonic and biofilm forms

This study aimed to evaluate the antibacterial efficacy of chitosan nanoparticles (CNPs) as a root canal irrigants against Enterococcus faecalis in planktonic and biofilm forms.

CNPs synthesized using high molecular weight (HMW) and low molecular weight (LMW) chitosan via modified ionic gelation were characterized. Enterococcus faecalis biofilm formation and CNPs antibacterial activity against mature biofilms were evaluated via crystal violet (CV) staining, scanning electron microscope (SEM), adenosine triphosphate assay, colony-forming unit counting, and live/dead staining. CNPs showed spherical morphology [size = 137.1 and 343 nm, polydispersity index = 0.12 and 0.14, and zeta potential = 43.45 and 42.49 mV (LMW and HMW, respectively)]. CNPs significantly reduced biofilm biomass and E. faecalis viability compared to negative control (P < 0.05) in biofilm formation. In mature biofilms, CV staining and SEM showed no biofilm biomass reduction in CNP groups. However, other assays revealed significantly lower E. faecalis viability in CNP groups than in the negative control (P < 0.05). HMW and LMW CNPs exhibited similar antibacterial properties.

CNPs, regardless of molecular weight, exhibited antibacterial efficacy against E. faecalis by decreasing biofilm formation and bacterial viability.