Defined polymeric materials for gene delivery.

For successful gene therapy, the delivery of the curative genetic information into target cells is the main hurdle and the development of efficient and safe gene delivery carriers the crucial challenge. Polymeric materials have been widely investigated as gene delivery agents, generating first promising results. However, the heterogeneity and polydispersity of polymers and lack of site specific modifications make it difficult to achieve accurate structure-activity relationship studies. Moreover it will hamper manufacturing of highly defined materials which could be used in clinical development. Therefore, polymers with precise chemical structure are required. In this review, we focus on the current design of defined polymeric materials for gene transfer. We first discuss the barriers for gene delivery, and then provide examples which illustrate defined polymeric vectors, including dendrimers, peptide carriers, and sequence-defined oligoaminoamides.