(485bm) Synthesis and Characterization of Poly(acrylic acid)-Based Vectors for siRNA Delivery

Over the past two decades, gene therapy has emerged as a promising technique to treat many chronic diseases, genetic disorders and even cancer. More recently, the discovery that RNA interference could be used as an approach to eliminate undesirable protein expression in mammalian systems sparked a revolution for alternative treatments using siRNA. siRNA-based therapy induces gene silencing by sequence-specific cleavage of undesirable endogenous messenger RNA, the molecule responsible for protein production. Unfortunately, many challenges have arisen, due to the complexity of the underlying human biology. One of the major challenges in gene delivery is to design a vector that can efficiently and safely transport and deliver the gene to its site of action by overcoming several barriers that hinder the delivery pathway (i.e. gene packing, cell targeting, internalization and gene release). Polymeric vectors offer an attractive synthetic platform from which siRNA delivery systems can be based. They afford a well-defined chemistry, thermodynamic stability and control over their molecular composition. The goal of this research is to employ a combinatorial chemistry approach to design polymeric vectors for enhanced siRNA delivery through a mechanistic understanding of their structure-function relationships. Toward this goal we synthesized poly (acrylic acid) with three different molecular weights, 10 KDa, 30 KDa and 50 KDa, which will serve as polymeric precursors. Based on these polymeric precursors, a library of polymers was synthesized by conjugating two distinct moieties, galactose and agmatine, at different ratios. Both of these functional groups impart specific gene transfer functionalities which will enhance the delivery efficiency. The efficacy of these vectors will be determined by analyzing transfection efficiencies and cytotoxicity effects of these systems. In addition, biophysical analyses will be performed to correlate the polymer structure with gene delivery and optimize the design of these vectors.