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 to 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), Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM) imaging and rheological analyses. The microscopic imaging studies suggest the formation of a nanofibrillar three-dimensional (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 practical applicability due to its biocompatibility with human red blood cells and human fibroblast cells. Interestingly, this hydrogel shows high resistance toward 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 nongelator molecule under similar conditions, but it also has a significant negative impact on its bactericidal character.

Poly(N-isopropylacrylamide)-Based Thermoresponsive Composite Hydrogels for Biomedical Applications

“…Injectable hydrogels are one kind of novel biomedical materials that keep fluid state outside body and transform into gels after injection into body [15,99,100]. Injectable hydrogels are ideal therapeutic materials because they can be loaded with therapeutic agents and form a 3D network in situ at the diseased sites, forming a drug release depot for pharmaceutics [101,102].…”

Controlling self-assembly of diphenylalanine peptides at high pH using heterocyclic capping groups

“…Whereas microscopy techniques such as transmission electron microscopy (TEM) and atomic force microscopy (AFM) are liable to suffer from the presence of sample preparation artefacts, small angle scattering is conducted on the native hydrogel, providing an accurate statistical three dimensional perspective of the actual hydrogel structure. SANS measurements have been extensively used to probe the native structure of peptide-based hydrogels, most often on hydrogel samples which already exhibit a well-defined network151617181920212223242526. Less well studied is small angle scattering on transitions within gelators; however there are examples of SANS being used to examine the transition of a hexapeptide from ribbons to fibers27 and using SANS to look at the evolution of a pyromellitamide organogel over several days28.…”

A dipeptide‐based superhydrogel: Removal of toxic dyes and heavy metal ions from waste water

“…Amino acid/peptide‐based gels are endowed with variety of applications including drug delivery, tissue engineering, oil‐spill recovery, and waste water treatment . They can also be used for making nanoclusters and nanoparticles, photo‐switching materials and for other biomedical applications …”

“…[36,37] They can also be used for making nanoclusters and nanoparticles, [38][39][40] photo-switching materials [7,41,42] and for other biomedical applications. [43][44][45][46][47] Since the last two decades water pollution due to the textile and organic dyes is a matter of great concern to nature. [48,49] This is because many dyes are known to get reduced into toxic substances inside living organisms that can cause damage to genetic material which may affect the organism in the long run although they are often not expressed immediately.…”