(250d) Design of Biodegradable Layer-By-Layer Films for Efficient, Localized, and Sequential Gene Delivery

Layer-by-layer (LbL) films containing polyelectrolytes and bioactive molecules such as DNA are promising biomaterials for controlled and localized gene delivery for a number of biomedical applications including cancer vaccine delivery and tissue regeneration. Our research focuses on the synthesis and engineering of bioreducible poly(amido amine)s (PAAs) containing the disulfide bond as the gene delivery vector. This work contributes a method to achieve sequential DNA release from LbL films by strategically placing bioreducible and nonbioreducible polycations such as poly(ethylenimine) (PEI). In order to understand the relationship between film assembly and film disassembly, in situ atomic force microscopy, fluorescence spectroscopy, and dynamic light scattering were used study film disassembly. In order to improve transfection efficiency, which remains a persistent problem of non-viral gene delivery vectors, we incorporated a highly transfecting monomer, 5-amino-1-pentanol (APOL), into the PAA molecular structure. From the buffering capacity study in relevant intracellular pH range and in vitro polyplex transfection experiments using HEK 293, MC 3T3, NIH 3T3 cells, we found that the APOL-containing PAA has highest buffering capacity and transfection efficiency than all the other PAAs as well as PEI. The highly transfecting polyplex can be incorporated directly into the LbL film in order to improve transfection efficiency. Furthermore, adding fibronectin top layer, incorporating hyaluronic acid inside the film, and crosslinking the film were also used to improve the LbL film transfection efficiency. Our work demonstrates a simple method for the design of LbL films for sequential and sustained DNA release and contributes new molecular designs for the efficient nucleic acid delivery for biomedical applications.