Synthesis, Characterization And Transfection Studies Of CD-DAB Copolymers

Gene delivery system was the key technology of gene therapy. Gene delivery systems could be divided into two kinds: viral vectors and nonviral vectors. Viral vectors had very high transfection efficiency but had some disadvantages as safety problems. Nonviral vectors were safer and had more potential. Polyethylenimine(PEI) was one of the most used nonviral vectors. There were some advantages for PEI that it had high transfection efficiency, good safety and could be prepared easily. But there were some disadvantages for PEI too. It could not be degraded by organism and had accumulation cytoxicity. One way of solving these problems was to conjugate some small molecules with some degradable units to macromolecule copolymers, which could be biodegradable with keeping the high transfection efficiency.Refer to some literatures, we found that polypropylenimine dendrimer (DAB) was a kind of highly branched molecule whose structure was similar to PEI and had some unique properties. Cyclodextrin(CD) was a kind of cyclic oligosaccharide which can reduce the cytoxicity of polycations. In this experiment, we conjugated them to CD-DAB copolymer and test it by IR, HNMR, MTT and transfection assay. We found that CD-DAB copolymer had the transfection efficiency close to PEI25K with biodegradability and lower cytoxicity. It was a kind of gene carrier with good future.