Targeting Cariogenic Streptococcus mutans in Oral Biofilms with Charge-Switching Smart Antimicrobial Polymers.

Area of Science:

• Biomaterials Science
• Microbiology
• Dental Research

Background:

• Dental caries is caused by acidic microenvironments produced by cariogenic biofilms.
• Streptococcus mutans is a key bacterial species in these biofilms.

Purpose of the Study:

• To develop a pH-responsive, charge-switching smart copolymer for selective targeting and eradication of bacteria in cariogenic biofilms.
• To investigate the efficacy and safety of the copolymer, Poly-1A.

Main Methods:

• Synthesized a ternary copolymer (Poly-1A) with cationic, carboxylic, and hydrophobic groups.
• Evaluated charge-switching behavior in response to pH changes.
• Assessed bactericidal activity against planktonic and biofilm Streptococcus mutans at different pH levels.
• Tested cytotoxicity against human gingival fibroblasts and periodontal ligament stem cells.

Main Results:

• Poly-1A exhibited charge neutrality at neutral pH and became cationic in acidic conditions (pH 4.5).
• The cationic Poly-1A effectively bound to the anionic surface of oral bacteria, disrupting membranes and causing cell death.
• Poly-1A demonstrated significant reduction in Streptococcus mutans viability at pH 4.5 but not at pH 7.4.
• No significant cytotoxicity was observed for human gingival fibroblasts and periodontal ligament stem cells after 1-hour incubation.

Conclusions:

• The pH-responsive, charge-switching copolymer Poly-1A selectively targets and eradicates cariogenic bacteria in acidic environments.
• Poly-1A shows potential as a therapeutic agent for dental caries, offering targeted bacterial killing with minimal impact on host cells.