Abstract:
Carbon nanotubes (CNT) have been explored as a non-viral system for gene delivery due to their unique structure and properties. Various functionalised carbon nanotubes can act as a vehicle for the systemic delivery of siRNA-based therapeutics. Here, we investigated the functionalisation of commercially available high-purity HiPCo® SWNT by non-covalent adsorption of phospholipid-polyethylene glycol (PL-PEG) with terminal amine (PL-PEG-NH2; PA) or maleimide groups (PL-PEG-maleimide; MA). The stable aqueous suspensions of PL-PEG functionalised SWNT were then conjugated with siRNA as the delivery cargos for siRNA. The conjugates were found to
successfully silenced genes in various cell lines (HeLa, HEK-293, H1299 and MCF-7) without causing much cytotoxicity. A dual targeting model was also established by investigating the possibility of the conjugates to silence two genes of interest
simultaneously via conjugating two different siRNA to the SWNT. The mechanism of cellular uptake of SWNT-siRNA conjugates by the epithelial cells was studied and was found to be energy dependent. Over-expression of ABCB1 gene (multiple drug
resistance gene) was found not to affect the siRNA delivery by the SWNT. Finally, we investigated the effect of SWNT-020PA-S-S-siLUC in luciferase gene knock-down mouse xenograft model. The conjugates successfully delivered the siRNA to the tumour site and carried out the RNAi mechanism without much acute toxicity being observed. This shows that functionalised SWNT-siRNA conjugates could induce sustainable RNAi mechanism upon the selection of a suitable siRNA which is the niche to the survival of the cancer cells for anti-cancer treatment.
