Functional modification of polymeric nanogels

The main goal of science has always been to better understand the world we live in. By studying our surroundings we can make better sense of the world around us. With the discovery of diseases came the need to understand and cure them. Science and medicine have evolved through time leading to various medical fields and research methodologies. In the past decade scientists have been focusing on utilizing macromolecules of the nanometer size range to optimize existing treatments or develop new ones. This field of nanomedicine comprises drug and gene delivery, bio-imaging, bio-sensing and tissue engineering. Actively delivering therapeutics to their destination as opposed to relying on their passive accumulation at receptor sites result in higher effectiveness. In gene therapy illnesses caused by modifications in the human genome are treated by silencing the gene(s) responsible for the disease, introducing a missing gene or repairing a faulty one. Oligonucleotides are quite fragile, thus requiring protection during their transport. In this thesis we synthesized a crosslinked polymer network to serve as a protective gene carrier. First the synthesis of GMA-EGDMA nanogels that contain a reactive epoxide moiety capable of undergoing post-polymerization reactions is described. GMA-EGDMA nanogels are not only versatile, their diameter is directly correlated to the monomer conversion, thus providing great control. GMA-EGDMA nanogels were given a cationic charge in order to bind anionic DNA. The choice was made for sulfonium as the positively charged moiety as opposed to the more commonly used ammonium. A variety of cell lines, uptake and transfection time and concentrations were tested on the sulfonium nanogels with no successful transfection. We suspected the reason for the failed transfection being the stability of the polyplexes, the surface charge of the nanogels or the nanogel construct itself. A final experiment comparing cell uptake of nanogels with cell uptake of polyplexes revealed that anionic pDNA on the surface of nanogels masked their cationic surface charge, hindering proper interaction with the cell membrane and thus minimal uptake.