Novel Hydrogel-forming elastin-like recombinamers for biomedical applications

Abstract

There is an increasing interest in developing advanced biomaterials with improved biocompatibility and functionality that might find uses in the field of biomedicine, for example in tissue engineering and regenerative medicine (TERM). Nowadays, recombinant polypeptides or polymers are one of the most prominent types of biomaterials, due to their nature. They are obtained through recombinant DNA technology, which allows the controlled biosynthesis of tailored polypeptides that may be designed to include combinations of polymeric amino acid sequences and/or bioactive domains. Within this type of biomaterials we can find elastin-like polypeptides (ELPs), which have also been recently termed elastin-like recombinamers (ELRs), according to their recombinant origin. These ELRs are composed of repetitions of the VPGXG (Val-Pro-Gly-X-Gly) pentapeptide, in which X (guest residue) can be any amino acid expect L-Proline. This composition confers the ELRs a smart behaviour of thermoresponsiveness defined by the so-called Inverse Temperature Transition (ITT) occurring above the Transition Temperature (Tt), which implies a phase transition of the dissolved ELR when this Tt is reached. Therefore, this thermal response is of great interest, since it has been shown to promote the formation of different structures, such as hydrogels that mimic the extracellular matrix, at the physiological temperature, whereas an ELR solution can be easily handled (e.g. injected in vivo) below the Tt. Furthermore, the Tt can be modulated depending on the polarity of the side chain of the amino acid chosen as guest residue. Moreover, if this residue contains functional goups, it can also be used for further chemical modifications in order to achieve, for instance, chemically (covalently) cross-linked hydrogels.