Delivery of bioactive agents from recombinant polymers

Since their conception, genetically engineered protein-based polymers have stimulated researchers with the novelty of the synthetic strategy that allows unprecedented control over the sequence and macromolecular architecture of the produced biomaterials. Recombinant polymer synthesis allows the systematic correlation of polymer structure with function, thus enabling customization to suit specific delivery needs. Over the past few years we have focused on the design and development of recombinant polymers for localized delivery of bioactive agents. In this article progress made in the application of silk-elastinlike protein polymers (SELPs) as matrices for the delivery of drugs, genes, viral vectors, and recently tissue engineering is reviewed. In addition the conceptual design, biosynthesis, characterization and biological evaluation of a new polymer consisting of lysine residues to condense plasmid DNA, histidine residues to allow endosomal escape, and the basic fibroblast growth factor as a targeting moiety, for systemic gene delivery applications is discussed. Finally comments are made about the prospects and challenges in the development of recombinant polymers for controlled delivery of bioactive agents.