Synthesis of protein-based hydrogel for pharmaceutical and biomedical applications

Natural polymers, such as proteins, are materials extensively investigated due to their biocompatibility, biodegradability and non-toxic and non-immunogenic characteristics. Enclosing these biomacromolecules in a complex structure, these features can be transferred to a biomaterial in order to extend the performance of the device. Thus, the covalent conjugation of a biodegradable macromolecule, as a protein, represents a versatile strategy to produce intelligent biodegradable hydrogels, suitable for pharmaceutical and biomedical applications. The cross-linking of biomacromolecules is somewhat important in these fields because it increase the mechanical properties of the hydrogels without to affect, in severe degree, the biodegradability. Basically, albumin and gelatin represents the protein mainly used in the biomedical field and their insertion in a polymeric network was performed employing different synthetic strategy involving the functional groups in the side chain of the polypeptides. Hydrogel containing proteic moieties in the polymeric network can be achieved by thermal denaturation of the protein either by direct reaction between functional groups (usually carboxyl and amino goups) in the polypeptide side chains and also by use chemical cross-linking agents as bifunctional carbonyl reagents. Finally, involving the protein in a radical process innovative synthetic procedures were proposed in order to modify polymeric network composition and to design hydrogels with appropriate and mouldable physicochemical properties.