Electrostatically Controlled Hydrogelation of Oligopeptides and Protein Entrapment

Peptide-based hydrogels have gained interest for biomedical applications as a result of their biodegradability and bioresorbability. For in vivo applications, these hydrogels should be able to easily assemble in a controlled manner and should possess compatibility with entrapped biomolecules. Mutually attractive but self-repulsive oligopeptides were designed to achieve electrostatically controlled assembly. These peptide modules assembled into a hydrogel network upon changing pH or ionic strength or mixing of oppositely charged modules. Mixing-induced hydrogels are particularly attractive as they can be easily assembled by simple mixing of peptide solutions prior to application. Another advantage of mixing-induced gelation is that it preserves the pH and ionic strength of the original peptide solutions. The compatibility of these hydrogels with entrapped biomolecules (molecular biocompatibility) was confirmed using high-resolution, 1 H− 15 N heteronuclear NMR spectroscopy. These novel biomaterials are highly elastic (revealed in dynamic rheological measurements), have fibrillar morphology, and are able to entrap and preserve proteins in their native form. These properties make them a good candidate for biomedical applications such as tissue engineering and drug delivery.