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

Abstract

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-b-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 E. coli viability, with cryogels exhibiting up to 95.6% reduction in viable E. coli 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.

Amphiphilic Polymer Conetworks Based on Interconnected Hydrophobic Star Block Copolymers: Synthesis and Characterization

“…Other, recent publications on APCNs report constant rate antibiotic release from a contact lens based on three APCN layers, with the two external layers imbibed with vitamin E which acts as a diffusion barrier, and tissue regeneration from ovine corneal endothelial cells attached on crystallizable and degradable APCNs . Further investigations in the field of APCNs describe the fabrication of biocidal macroporous cryogel APCNs based on cross‐linked diblock copolypeptides, the development of highly conductive, tough, ion APCNs, the formation of APCNs comprising highly interacting poly(propylene glycol) and poly( N ‐vinylimidazole) segments, the preparation of microcrystalline APCNs based on all‐oxazoline blocks, and the synthesis of carboxylate‐bearing APCNs, non‐susceptible to abrupt shrinkage in the presence of calcium cations . In all these studies, phase separation on the nanoscale and resulting morphologies appear to be key APCN properties, crucial for their applications.…”

“…More hydrophobic APCN samples swell less in water, thus exposing any defects to only a smaller extent, favoring morphologies with longer‐range order. Such more regular morphologies will result in APCNs better‐suited for all above‐mentioned applications …”

Supermacroporous polydivinylbenzene cryogels with high surface area: Synthesis by solvothermal postcrosslinking and their adsorption behaviors for carbon dioxide and aniline

“…Nowadays, only a few investigations are explored on hydrophobic cryogels, in contrast to most of literature focusing on preparation and application of hydrophilic cryogels that are obtained basically using ice crystals as porogens . In most of hydrophobic cryogels‐related studies, polymer precursors including polystyrene, butyl rubber, and polydimethylsiloxane were crosslinked to form supermacroporous structures in proper organic solvents under the nondeeply frozen conditions, where the solvent crystals were used as porogens .…”

Amino Acid Block Copolymers with Broad Antimicrobial Activity and Barrier Properties

“…Synthetic cationic polypeptides, especially those containing an abundance of l ‐lysine residues, can display antimicrobial activity and are attractive for their degradability . Recently, this work has been expanded to include soluble statistical copolymers of lysine with various hydrophobic amino acids, graft copolymers on other polymer or particle substrates, and chemically crosslinked hydrogels . These studies point to the potential of using advanced synthetic biopolymers to combine antimicrobial activity with desirable chemical properties, such as degradability.…”