A Peptide-Based Mechano-sensitive, Proteolytically Stable Hydrogel with Remarkable Antibacterial Properties

Abstract

A long chain amino acid containing dipeptide has been found to form a hydrogel in phosphate buffer whose pH ranges from 6.0-8.8. The hydrogel formed at pH 7.46 has been characterized by small angle X-ray scattering (SAXS), wide angle powder X-ray diffraction (PXRD), FT-IR, field emission scanning electron microscopic (FE-SEM), high-resolution transmission electron microscopic (HR-TEM) imaging and rheological analyses. The microscopic imaging studies suggest the formation of a nanofibrillar 3D network for the hydrogel. As observed visually and confirmed rheologically, the hydrogel at pH 7.46 exhibits thixotropy. This thixotropic property can be exploited to inject the peptide. Furthermore, the hydrogel exhibits remarkable antibacterial activity against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa which are responsible for many common diseases. The hydrogel has potential applications due to biocompatibility with human red blood cells and human fibroblast cells. Interestingly, this hydrogel shows high resistance towards proteolytic enzymes making it a new potential antimicrobial agent for future applications. It has also been observed that a small change in molecular structure of the gelator peptide not only turns the gelator into a non-gelator molecule under similar conditions but also has a significant negative impact on its bactericidal character.