This work introduces a novel chitosan-based siRNA nanoparticle delivery system for RNA interference in vitro and in vivo. The formation of interpolyelectrolyte complexes between siRNA duplexes (21-mers) and chitosan polymer into nanoparticles, ranging from 40 to 600 nm, was shown using atomic force microscopy and photon correlation spectroscopy. Rapid uptake (1 h) of Cy5-labeled nanoparticles into NIH 3T3 cells, followed by accumulation over a 24 h period, was visualized using fluorescence microscopy. Nanoparticle-mediated knockdown of endogenous enhanced green fluorescent protein (EGFP) was demonstrated in both H1299 human lung carcinoma cells and murine peritoneal macrophages (77.9% and 89.3% reduction in EGFP fluorescence, respectively). In addition, Western analysis showed approximately 90% reduced expression of BCR/ABL-1 leukemia fusion protein while BCR expression was unaffected in K562 (Ph(+)) cells after transfection using nanoparticles containing siRNA specific to the BCR/ABL-1 junction sequence. Effective in vivo RNA interference was achieved in bronchiole epithelial cells of transgenic EGFP mice after nasal administration of chitosan/siRNA formulations (37% and 43% reduction compared to mismatch and untreated control, respectively). These findings highlight the potential application of this novel chitosan-based system in RNA-mediated therapy of systemic and mucosal disease.

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Novel amphiphilic chitosan derivatives (glycidol-chitosan-deoxycholic acid, G-CS-DCA) were synthesized by grafting hydrophobic moieties, deoxycholic acid (DCA), and hydrophilic moieties, glycidol, with the purpose of preparing carriers for poorly soluble drugs. Based on self-assembly, G-CS-DCA can form nanoparticles with size ranging from 160 to 210 nm, and G-CS-DCA nanoparticles maintained stable structure for about 3 months when stored in PBS (pH 7.4) at room temperature. The critical aggregation concentration decreased from 0.043 mg/mL to 0.013 mg/mL with the increase of degree of substitution (DS) of DCA. Doxorubicin (DOX) could be easily encapsulated into G-CS-DCA nanoparticles and keep a sustained release manner without burst release when exposed to PBS (pH 7.4) at 37 °C. Antitumor efficacy results showed that DOX-G-CS-DCA have significant antitumor activity when MCF-7 cells were incubated with different concentration of DOX-G-CS-DCA nanoparticles. The fluorescence imaging results indicated DOX-G-CS-DCA nanoparticles could easily be uptaken by MCF-7 cells. These results suggested that G-CS-DCA nanoparticles may be a promising carrier for DOX delivery in cancer therapy.