Polymer-free Gels are different from conventional hydrogel structures in that they can form hydrogels through the self-assembly of short peptides. These short peptides often contain 2 or 7 amino acids, which can be further assembled into fibers by hydrogen bonding or π-π stacking to form β-folds, thus forming hydrogels. Due to their low toxicity, biocompatibility, biodegradation through non-covalent interactions derived from amino acids and their derivatives supramolecular hydrogels have been widely used as biomaterials for pharmaceutical, tissue engineering, biosensor, protein isolation and wound healing applications. CD Formulation offers the development of polymer-free gels, i.e. peptide hydrogels, and We provide the corresponding assays.
Peptide-based supramolecular gelling agents follow a 3D percolation model generated by non-covalent interactions to form self-assembled fibrillar networks, whose post-developed structures lead to gel formation by encapsulating solvents. Nanofibers with 3D peptide network structure are associated with α-helix, β-fold, vesicle, micelle, fiber, band, tube and coil-like morphologies. Peptide-based hydrogels are very important due to their biocompatibility and low toxicity, thus innovating different applications in the biomedical field. They can be prepared by simple heating, cooling, sonication and by adjusting the pH of the solution. In peptides, as the sequence increases from dipeptides to tripeptides to oligonucleotides and polypeptides, the number of peptide (-CONH-) bonds increases, thus contributing to the formation of more intermolecular hydrogen bonds in the system. This changes the physical properties of the peptide, including mechanical properties, which are used in different systems. Moreover, depending on the nature of the amino acids in the peptide, hydrophobicity and hydrophilicity change, thus affecting the physical and chemical properties of the gel.
The hydrogel environment allows the protection of cells and drugs and the modification of peptides with cell adhesion ligands. Due to the thixotropic nature, gels can be formed at body temperature/ pH, so that drug-laden gels can be injected into the body as liquids, and peptide molecules usually have very low biocompatibility.
CD Formulation allows the development of mechanically strong peptide hydrogels with thixotropic properties, prepared by adding nanofillers or using long chain peptides (with a large number of H-bonding interactions with -CONH- groups). The mechanical properties can be improved by introducing an aromatic part in the peptide chain due to π-stacking interactions.
Spectroscopic techniques, including infrared spectroscopy, Raman spectroscopy, NMR hydrogen/carbon spectroscopy, UV spectroscopy, etc., can be used to determine the macromolecular structure of hydrogels and also to determine whether new chemical bonds, functional groups, etc., are formed in the hydrogel network.
Microscopy techniques are often used to study the morphology and microstructure of hydrogels, mainly including scanning electron microscopy, transmission electron microscopy and atomic force microscopy.
Light scattering techniques include X-ray neutron scattering and laser light scattering, among which laser light scattering techniques can be used to determine the size of hydrogels and discuss the size distribution of the gels.
Dynamic rheological techniques can be used to determine the mechanical properties and gelation transition mechanism of hydrogels, providing a theoretical basis for their application in biomedical and food industries.