Construction, bioproduction and characterization of Protein Based Polymers: exploiting the sequence of naturally occurring Elastin and Silk fibroin

With the development of protein engineering and nano(bio)technologies it is now possible to use amino acids to design and produce genetically engineered Protein-Based Polymers (PBPs). Advances in recombinant DNA technology allows to precisely control the composition, sequence and length of large molecular weight PBPs. PBPs occur in a wide range of biological systems, fulfilling precise functional roles. Its properties are due to the presence of short repeating oligopeptide sequences contained in the fibrous proteins, such as silk fibroin (GAGAGS) and mammalian elastin (VPGVG). ElastinLike Polymers (ELPs) are biopolymers that reversibly coacervate above a critical temperature (Tt), showing a visible transition phase that was explored as a purification method. The ability of ELPs to self-assemble into nanostructures in response to environmental signals allows them to be explored for controlled drug delivery devices or nanosensors. In the present work we’ve constructed and produced a new thermal responsive, biologically synthesized ELP based on the (VPAVG)220 sequence and a new set of copolymers (Silk-ElastinLike Polymers – SELPs) consisting of flexible ELP blocks and crystalline silk-like blocks (GAGAGS) in different proportions. By combining the silk and elastin-like blocks in various ratios, it is possible to produce a variety of biomaterials with diverse material properties, such as viscosity (dependent on number of elastin-blocks) and gelation time (dependent on number of silk-like blocks). The stability of these SELPs in combination with their biocompatibility and unique mechanical properties provides the basis to exploit them for biomedical applications.ElastM POCI/CTM/57177/2004 supported by FEDER and the Fundação para a Ciência e Tecnologia. Acções Luso-Espanholas/2005/06 Acção/E84/05 in collaboration with M. Casal and J.C.R. Cabello.