Dr. Aliasger Salem
Participation year
Project title

Combination of Chitosan and Dextran as a Novel Gene Delivery System


Chitosan is a naturally occurring cationic polymer that is an ideal candidate for drug/gene delivery. However, its transfection efficiency is poor. Our hypothesis is that chitosan binds too strongly to DNA thereby inhibiting its release. Thus, incorporation of an anionic polymer like dextran sulphate can improve its transfection efficiency. In this study we are evaluating if a chitosan and dextran combination is an efficient carrier for DNA. We have used pCpG Luciferase (pCpGLuc) as a model plasmid for testing the efficiency of this delivery system. The study was completed in two stages. The first stage involves preparation and characterization of nanocomplexes. Nanocomplexes were prepared using medium molecular weight chitosan (MM-HD) and low molecular weight chitosan (LM-HD) with pCpGLuc. N/P ratios of plasmid DNA: chitosan varying from 10 to 100 were studied to optimize the best delivery system. Size and charge of nanocomplexes were evaluated using a Nano ZS series zetasizer. In the second stage of this study, the transfection efficiency of nanocomplexes were tested in human embryonic kidney (HEK293) cells. Transfection efficiency was quantified using a luciferase assay. Our results show that an N/P ratio of 25 gave the best transfection. Low molecular weight chitosan was more efficient at delivery than high molecular weight chitosan.

Brian  Lewis
Columbia University