Amino Acid Block Copolymers with Broad Antimicrobial Activity and Barrier Properties

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Microbiology

Background:

• Wound infections pose a significant clinical challenge, often exacerbated by multidrug-resistant (MDR) pathogens.
• Current treatments for wound infections can be limited by efficacy and the development of resistance.
• There is a need for innovative biomaterials that offer both direct antimicrobial action and physical barrier properties.

Purpose of the Study:

• To synthesize and characterize a novel amino acid block copolymer, K100L40 (poly(l-lysine·hydrochloride)100-b-poly(l-leucine)40).
• To evaluate the antimicrobial efficacy of K100L40 against a broad spectrum of microorganisms, including MDR strains.
• To assess the potential of K100L40 as a wound dressing material by evaluating its hydrogel formation and barrier properties against microbial contamination.

Main Methods:

• Synthesis and characterization of the K100L40 block copolymer.
• Time-kill assays were performed using Gram-positive bacteria, Gram-negative bacteria, and yeast at various concentrations (10-100 µg mL-1).
• In vitro wound models using porcine skin explants, porcine open wounds, and rodent closed wounds were used to assess barrier properties and microbial reduction.

Main Results:

• K100L40 demonstrated rapid, multi-log reductions in viable bacterial and yeast counts within 5-60 minutes.
• The copolymer effectively inhibited both Gram-positive and Gram-negative bacteria, including MDR strains.
• K100L40 formed self-supporting hydrogels at 2 wt% and provided a significant barrier against microbial contamination in various wound models.

Conclusions:

• The synthetic amino acid block copolymer K100L40 exhibits potent, broad-spectrum antimicrobial activity.
• K100L40 possesses desirable physical properties, forming hydrogels that act as effective barriers against microbial contamination.
• This biopolymer offers a promising new strategy for the prevention and treatment of wound infections by combining direct antimicrobial effects with physical protection.