Immobilization of stabilized antimicrobial peptides into a bactericidal hydrogel coating

Abstract

This thesis describes the design and synthesis of a bactericidal poly(ethylene glycol)-based (PEG) hydrogel coating with covalently attached antimicrobial peptides (AMP) stabilized against proteolytic degradation. As such, mimics of the highly active AMP HHC10 (H-KRWWKWIRW-NH2) were designed for optimal stability in human serum while retaining strong antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis, the major causative agents of biomaterial associated infection. In order to investigate the selectivity of the AMPs, their hemolytic activity was determined. A N-terminal cysteine facilitated thiol−ene chemistry for a fast, single-step immobilization/photopolymerization strategy. The antimicrobial activity of the resulting thin layer hydrogel coating on a PET surface was established using the Japanese Industrial Standard (JIS) Z2801 assay, showing complete killing (>99.9%) of inocula of S. aureus, S. epidermidis, and E. coli. The bactericidal hydrogel was molecularly characterized via Coomassie and Lowry assay protein staining agents as well as by X-ray photoelectron spectroscopy. To gain further insight into the biological stability, the hydrogels were incubated with human serum prior to activity testing without loss of activity. These studies revealed a promising bactericidal hydrogel with good stability under physiological conditions. However, the in vivo activity in mice could not be demonstrated and should be further investigated to prove the full potential of this methodology.