The development of a redox-sensitive curcumin conjugated chitosan oligosaccharide nanocarrier for the efficient delivery of docetaxel to glioma cells

BACKGROUND: A redox-sensitive nanoscale delivery system was developed, based on the hydrophilic chitosan oligosaccharide-ss-hydrophobic curcumin conjugate (CSO-ss-CUR) loaded with docetaxel (DTX), for the targeting and synergistic treatment of gliomas. METHODS: Redox-sensitive nanoparticles were loaded with DTX (DTX/CSO-ss-CUR) using the improved ultrasonic-dialysis approach. The morphology and particle size of the loaded nanoparticles were examined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The cytotoxicity and cellular uptake of the nanoparticles were assessed in vitro using the C6 glial cell line. The in vivo antitumor efficacy and in vivo biodistribution studies were evaluated using the C6 tumor-bearing Balb/c female mouse model. RESULTS: The DTX/CSO-ss-CUR nanoparticles were generally spherical in shape and exhibited desirable particle size (under 250 nm) with high drug loading efficiency (DL) (8.96%±0.56%) and encapsulation efficiency (EE) (35.23%±3.26%). In vitro, the drug was released from the nanoparticles in a redox-sensitive manner. The DTX/CSO-ss-CUR nanoparticles exhibited superior hemocompatibility in the hemolytic test and in vitro cytotoxicity and live/dead cell staining experiments revealed a higher cytotoxicity to glioma cells compared to the free drug. Furthermore, in vitro uptake experiments using C6 glioma cells demonstrated that the CSO-ss-CUR nanoparticles had good cell penetration ability. The in vivo antitumor efficacy and in vivo biodistribution studies suggested that the CSO-ss-CUR nanoparticles could effectively inhibit C6 tumor growth. More importantly, after intravenous injection, more CSO-ss-CUR nanoparticles were concentrated in the brain of the mice than free 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide (DiR) group. CONCLUSIONS: A unique drug delivery system formed by the self-assembly of CSO-ss-CUR was developed and shown to effectively cross the blood-brain barrier (BBB), enriching the abundance of the drug in the brain tissues. This may represent a potential therapeutic strategy for the treatment of gliomas. KEYWORDS: Chitosan oligosaccharide (CSO); curcumin (CUR); docetaxel (DTX); glioma