Antibacterial properties of main-chain cationic polymers prepared through amine-epoxy 'Click' polymerization

Area of Science:

• Polymer Chemistry
• Antimicrobial Agents
• Biomaterials

Background:

• Development of new antimicrobial agents is crucial due to rising antibiotic resistance.
• Poly(β-hydroxyl amine)s offer a versatile polymer backbone for functionalization.
• Quaternary ammonium salts are known for their antimicrobial properties.

Purpose of the Study:

• To synthesize poly(β-hydroxyl amine)s via an amine-epoxy click polymerization.
• To investigate the antimicrobial efficacy of these polymers against various bacterial strains.
• To explore the mechanism of bacterial cell death induced by the polymers.

Main Methods:

• Amine-epoxy 'click' polymerization in aqueous solution under ambient conditions.
• Post-polymerization modification to introduce quaternary ammonium salts.
• Antimicrobial activity testing against Escherichia coli, Staphylococcus aureus, and Mycobacterium smegmatis.
• Hemolysis assay to assess cytotoxicity towards red blood cells.

Main Results:

• Poly(β-hydroxyl amine)s with butyl chains exhibited significant antimicrobial activity against E. coli and S. aureus at low concentrations (10-20 μg mL⁻¹).
• One polymer candidate showed efficacy against Mycobacterium smegmatis, a model for tuberculosis drug development.
• Hemolysis assays confirmed minimal disruption of red blood cell membranes, indicating good biocompatibility.

Conclusions:

• Poly(β-hydroxyl amine)s, particularly those with quaternary ammonium salts, are effective broad-spectrum antimicrobial agents.
• The polymers demonstrate potential as novel therapeutic agents against bacterial infections, including tuberculosis.
• Cell wall disruption is identified as the primary mechanism of bacterial inactivation by these cationic polymers.