A novel dual-targeting strategy to suppress cariogenic bacteria and biofilms with engineered ARG/FBG bioactive composites

Dental caries is a biofilm-mediated disease primarily driven by Streptococcus mutans (S. mutans), which ferments dietary sugars to produce acids that demineralize enamel. This study developed a novel composite combining L-arginine (ARG) and fluoride-containing bioactive glass (FBG) to achieve dual antibacterial and antibiofilm effects. The ARG/FBG composite (1:1 mass ratio) was assessed in vitro against S. mutans. Antibacterial activity was quantified by AlamarBlue assay and colony-forming unit (CFU) counts, while antibiofilm efficacy was evaluated using scanning electron microscopy and confocal laser scanning microscopy. ARG inhibited planktonic growth but showed limited biofilm disruption, whereas FBG effectively disrupted biofilm architecture without affecting planktonic growth. The composite (7.5 mg/mL ARG + 7.5 mg/mL FBG) demonstrated enhanced complementary action, achieving near-complete eradication of planktonic cells (∼6-log10 CFU reduction at 24 h) and profound biofilm destruction. TEM-EDS revealed intracellular co-localization of fluoride, calcium, and phosphorus within treated bacteria. RNA sequencing and RT-qPCR showed downregulated key virulence genes (ldh and luxS) and disrupted metabolic pathways related to carbon utilization and acid production. The composites exhibited favorable biocompatibility. These findings indicate that ARG/FBG bioactive composites potently suppress S. mutans through biofilm disruption, metabolic inhibition, and potential in-situ mineralization, offering a promising strategy for caries prevention.