| Poly (ethylene imine) (PEI) was special designed and modified via three different strategies to fabricate the new gene delivery system and gene-drug co-delivery system.First of all, "pH-shifting" multilayers for localized releasing DNA were constructed by layer-by-layer assemble of "pH-shifting" polyelectrolyte and PEI-DNA polyplexes. Cyclohexanedicarboxylic anhydride functionalized PEI (CPEI) has been successfully synthesized and proved to be sensitive to pH value by zeta potential. The value of zeta potential in pH 7.4 was about -20mV, while in pH 4.0 was+2.0mV. The growth of multilayers from CPEI and PEI-DNA nanoparticles was successfully traced by UV-Vis spectrophotometer, ellipsometry and Quartz Crystal Microbalance with Dissipation, with the thickness above 100nm of 12 bilayers. pH stimulus-responding release behavior of films was followed by UV-Vis spectrophotometer indicating that DNA could be released from films in acid due to the charge shift of CPEI and the behavior can be controlled by adjusting the pH value of environment. Transmission electron microscope images shows that the components were released as the form of polyplexes. The pH-responsive ultrathin film of DNA might provide new possibility of localized delivery DNA.Secondly, drug-gene co-delivery multilayers were constructed by layer-by-layer assembly of sulfate dextran (DS) and gene-drug co-delivery nanoparticles. Ferrocene-modified branched poly (ethylene imine) (BPEI-Fc) was synthesized and the value of critical micelle concentration (CMC) was 0.046mg/mL. Doxorubicine (DOX) was loaded into BPEI-Fc micelles with the load level of 7.7%. DNA was combined with DOX-loaded micelles to form gene-drug co-delivery nanoparticles. The co-delivery multilayers were constructed through DS and BPEI-Fc-DOX-DNA alternately, and the total amount of DOX in 50 bilayers was 6.95μg/cm2. The reducing group, ferrocene, allowed the multilayers to be responded to redox stimulus and release DOX. With the present of H2O2, nearly 90% DOX in the films were released in 48h, while in PBS the value was only 40%. The results of in vitro cell experiment showed that HEPG2 cells growth were suppressed after treated by DOX-loaded multilayers, and the pEGFP DNA coated in the films were successfully expressed by both HEPG2 and HEK 293 cell lines. These BPEI-Fc based multilayers might provide potential application in cancer therapy.Last but not least, beta-cyclodextrin (β-CD) enhanced gene delivery nanoparticles were constructed by BPEI-Fc via host- and guest- interactions. BPEI-Fc was coated with P-CD to form particles with the size of 169nm. Different N/P ratios of BPEI-Fc-CD-DNA complexes were constructed; the physical and chemical properties were studied through the measurement of diameters, zeta-potentials and gel electrophoresis. The results showed that when N/P> 7, DNA was condensed by BPEI-Fc-CD completely. The expression efficiency of plasmid DNA in HEK293 cell lines was further measured, indicating twice of the value for traditional PEI-DNA polyplexes. This result showed that theβ-CD enhanced gene delivery nanoparticles via host- and guest- interactions might provide a convenient way to construct non-viral vectors with high transfection efficiency.
|
PDF Full Text Request