No abstract

Chitosan amphiphiles self‐assemble into nanoparticles that are used for drug delivery. These chitosan amphiphile nanoparticles significantly enhance the oral absorption of hydrophobic drugs such as cyclosporine A for example.

We have designed an efficient, synthetic nucleic acid vector, which is relatively non-toxic. [N-(2-ethylamino)-6-O-glycolchitosan - EAGC] polymers were 10-50 fold less toxic than Lipofectamine 2000, able to complex DNA, mRNA and siRNA into positively charged (zeta potential=+40 - 50mV), 50-450nm nanoparticles. The level of tertiary amine N-2-ethylamino substitution (DS) was inversely proportional to the IC50 of the EAGC polymers in the A431 cell line: IC50=6.18DS, r=0.9991. EAGC polyplexes were stable against a heparin challenge, able to protect the nucleic acids from nuclease degradation and achieve levels of transfection comparable to Lipofectamine 2000 formulations. The relative biocompatibility of the vector allowed 10 fold higher doses of DNA (1μg compared to 0.1μg per well with Lipofectamine 2000) and siRNA (10.7μg per well vs 1.3μg with Lipofectamine 2000) to be applied to cells, when compared to Lipofectamine 2000. Finally intranasal application of EAGC - siRNA complexes resulted in siRNA transfer to the neurons of the olfactory bulb.

Gene silencing may be achieved by harnessing the RNA interference mechanism to effect down-regulation of protein expression. The therapeutic use of siRNA is dependent on its delivery to the intracellular space. This chapter describes the delivery of siRNA by N-(2-ethylamino)-6-O-glycolchitosan (EAGC). EAGC is a chitosan-based polymer, which binds to siRNA to form nanoparticles (NPs). The steps necessary to determine the delivery capacity of a polymer are presented in this chapter using EAGC as an example. The steps include: the transfection of cells with EAGC-siRNA polyplexes and protein detection by a Western Blotting assay.