Polypeptide-Based Macroporous Cryogels with Inherent Antimicrobial Properties: The Importance of a Macroporous Structure.

Synthetic polypeptide-based macroporous cryogels with inherent antimicrobial properties were prepared for potential water purification applications. Gels were chemically cross-linked through the amine residue of a polycationic polylysine--polyvaline block copolymer with glutaraldehyde as cross-linker under cryogenic conditions. These cryogels exhibited excellent water swelling and highly compressible mechanical properties owing to their macroporous structure. The antibacterial performance was evaluated based on viability, with cryogels exhibiting up to 95.6% reduction in viable after a brief 1 h incubation. In comparison to the hydrogel control, the presence of macropores is shown to be vital to the antimicrobial effect of the gels. The confined environment and increased antimicrobial surface area of the macropores is believed to result in a "trap and kill" mechanism. Mechanical strength and pore integrity of cryogels were also found to be determinants for antibacterial activity. Along with the lack of toxic leaching, these cryogels with inherent antimicrobial properties pose as potential candidates for use in biological and environmentally friendly water purification applications.