Development of Charged Polyampholyte Interfaces: Synthesis, Properties, and Antifouling Application.

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Microbiology

Background:

• Biocompatible hydroxyapatite (HA) is crucial for dental and bone tissue regeneration but is susceptible to pathogenic biofilms, a major cause of infections.
• Zwitterionic polymers are known for antifouling properties, but charged polyampholytes remain under-explored for preventing microbial adhesion on biomaterials.
• Polyampholytes, synthesized from monomers with opposite charges, offer tunable surface properties (neutral, cationic, anionic) for potential antifouling applications.

Purpose of the Study:

• To synthesize charged polyampholytes with tunable surface charges using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization.
• To coat hydroxyapatite (HA) discs with these polyampholytes and evaluate their antifouling capabilities against bacterial adhesion.
• To assess the biocompatibility and protein adsorption resistance of the modified HA surfaces.

Main Methods:

• Charged polyampholytes were synthesized via RAFT polymerization using cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETMA) and anionic sodium-p-vinylbenzenesulfonate (VBS).
• Hydroxyapatite (HA) discs were coated with polyampholytes to create surfaces (HAP1-HAP5) with systematically varied net charges.
• Bacterial adhesion studies using Streptococcus mutans (S. mutans) and protein adsorption assays were performed, alongside cytotoxicity tests with NIH-3T3 fibroblast cells.

Main Results:

• Cytotoxicity assessments confirmed the biocompatibility of the polymer-coated HA surfaces.
• The HAP1-HAP5 surfaces exhibited systematically tuned net charges from fully positive to fully negative.
• The HAP3 surface demonstrated the least bacterial adhesion and superior resistance to protein adsorption compared to uncoated HA, indicating effective antifouling properties.

Conclusions:

• Charged polyampholytes can be effectively synthesized and coated onto HA surfaces to create antifouling biomaterials.
• The HAP3 coating, with its specific charge profile, significantly inhibited S. mutans adhesion and protein adsorption.
• These findings highlight the potential of tunable charged polyampholytes as a promising strategy to combat biofilm formation on HA-based medical implants.