Elastin-Mimetic Covalently Crosslinked Synthetic Protein Networks: Solvent and Temperature Dependent Morphological Features Imaged by SEM

Extract

Gel networks that mimic the properties of naturally occurring mammalian elastin have been synthesized for the development of novel biomaterials. Hydrogels with controllable and predictable mechanical properties are pursued for use in drug encapsulation and delivery systems, as scaffolds for tissue engineering and for the development of prosthetic implantable devices. The techniques of genetic engineering and microbial expression have been used to produce a 90KD recombinant protein based starting material that was polymerized into a solvent swollen gel network by the introduction of covalent bifunctional crosslinks at regularly spaced lysyl residues. SEM methods have been used to describe solvent and temperature dependent structural features.

The polypeptide precursor to the elastin-mimetic gels, poly[(VPGVG)₄VPGKG], was obtained through bacterial expression (pET system) of an oligomerized gene coding for tandem repeats of the monomer. Gel networks were formed by crosslinking the protein with a bifunctional NHS-ester in both water and anhydrous DMSO. For conventional below-lens SEM studies, samples were dehydrated in an ethanol gradient, critical point dried from CO₂(l), mounted on stubs with carbon tape and sputter coated with a 4-6 nm layer of Au/Pd.