Developing functionality in elastin-like polymers by increasing their molecular complexity:: the power of the genetic engineering approach

In spite of the enormous possibilities presented by macromolecules for the development of advanced materials with increased functionality, the achievement of functionality is often limited by the randomness associated with polymer synthesis and the exponential increase in technical difficulties encountered in attaining a desired degree of complexity in the molecular design. This paper describes an increasingly important approach to the design of complex and highly functional macromolecules, i.e. the genetic engineering of protein-based macromolecules. The exploitation of the efficient machinery of protein synthesis in living cells opens a route to precisely defined and complex macromolecules. A series of molecular designs with increasing complexity are presented to show how this controlled increase yields materials with increasingly selective and sophisticated multifunctionality. The simplest designs already show interesting mechanical properties, but the adequate introduction of given chemical functions along the polymer chain provides an opportunity to expand the range of properties to smart behavior and self-assembly. Finally, examples are given where the molecular designs further incorporate selected bioactivities in order to develop materials for the most cutting-edge applications in f biomedicine and nanobiotechnology. (c) 2005 Elsevier Ltd. All rights reserved.