Evaluation of the Antibacterial and Anti-Biofilm Activity of Chitosan-Arginine Nanoparticles and Sodium Fluoride against

Dental caries is among the most prevalent chronic diseases. It arises from bacterial
biofilm formation on tooth surfaces due to metabolic activity. Streptococcus mutans
(S. mutans) is a key pathogen implicated in the development of dental caries. As
bacterial resistance to conventional treatments increases, there is a growing interest in
using novel compounds that possess antibacterial and antibiofilm properties. This
study evaluated the effect of chitosan-arginine nanoparticles (CS-Arg NPs) and sodium
fluoride (NaF) on inhibiting S. mutans' growth. After synthesizing CS-Arg NPs, their
size, morphology, and chemical structure were evaluated. The broth microdilution
method determined the minimum inhibitory concentration (MIC) and minimum
bactericidal concentration (MBC) of CS-Arg NPs and NaF. The combined
antibacterial and antibiofilm effect of CS-Arg NPs and NaF was assessed using the
checkerboard method. The CS-Arg NPs had an average size of 269.9 nm with a zeta
potential of +38.3 mV. The MIC of S. mutans for CS-Arg NPs and NaF was 312 μg/mL
and 625 μg/mL, respectively, and the MBC for these NPs and NaF was 625 μg/mL
and 2500 μg/mL, respectively. The fractional inhibitory concentration index (FICI) of
the combination of CS-Arg NPs and NaF showed an additive effect (FICI = 1). The
inhibitory effect of different concentrations of CS-Arg NPs and NaF, alone or in
combination, on biofilm formation in the studied strain ranged from approximately
12% to 81%. This study demonstrated that CS-Arg NPs have antibacterial and
antibiofilm properties against S. mutans, and their combination with NaF can enhance
these antibacterial effects. These findings suggest that CS-Arg NPs and NaF, as a novel
combination, could effectively develop oral hygiene products.