Biomimetic Materials: from Modelatine to Viromimic
Prof.Dr.Martien Cohen Stuart (Wageningen University)
To the polymer chemist, the biosynthetic machinery by which Nature makes proteins is a miracle of precision. In contrast to standard synthetic methods it offers control over monomer sequence and chain length. Moreover, modern genetic engineering provides the tools to fabricate the DNA template for aminoacid polymers of any design. The perspective is a plethora of molecules with interesting and functional secondary, tertiairy and quaternary (self-assembled) structures which in principle can be directed to any desired property.
We are exploring this approach to make new protein materials with biomimetic properties. We express designed and constructed genes using the yeast Pichia Pastoris as host, and we then study the properties of the materials, often in a biomedical context. As specific examples, I shall discuss two systems. The first is a symmetric triblock-like dyktiogenic (networkforming) polymer which makes hydrogels with a precisely controlled and tunable melting and gelling behaviour. The second is a family of polymers designed to ‘package’ nucleic acids like viral capsid proteins do. I shall show that with the right design, these polymers indeed co-assemble with DNA in a way which is very reminiscent of that of natural viruses, allowing for efficient protection of the nucleic acid against enzymatic attack, without compromising the weak binding which is needed for easy ‘unpacking’ whenever reproduction must occur.