Linoleic acid-grafted chitosan oligosaccharide micelles for intracellular drug delivery and reverse drug resistance of tumor cells

Intracellular drug delivery is an important rout to reverse drug resistance of tumor cells. In this study, the linoleic acid (LA)-grafted chitosan oligosaccharide (CSO) was synthesized to construct a micellar delivery system for intracellular delivery. The synthesized linoleic acid-grafted chitosan oligosaccharide (CSO-LA) with 10.3% graft ratio of LA could form micelles in aqueous with 86.69 μg/ml critical micellar concentration (CMC). The CSO-LA micelle had 46.2±3.6 nm number average diameter and 36.0±3.3 mV zeta potential. Taking doxorubicin base (DOX) as a model drug, the drug-loaded CSO-LA micelles (CSO-LA/DOX) was then prepared. The drug encapsulation efficiencies of CSO-LA/DOX were as high as 80%, and the drug loading capacity could be improved by increasing the charged DOX. Using MCF-7, Doxorubicin·HCl resistant MCF-7 (MCF-7/ADR), K562 and Doxorubicin·HCl resistant K562 (K562/ADR) cells as model drug sensitive and drug resistant tumor cells, the experiments demonstrated the CSO-LA had excellent cellular uptake ability by either drug sensitive tumor cells or drug resistance tumor cells. The CSO-LA micelles could deliver DOX into tumor cells, and the DOX in cells was increased with incubation time. As a result, the cytotoxicities of DOX encapsulated in CSO-LA micelles against drug resistance tumor cells were improved significantly, comparing to that of Doxorubicin·HCl solution.