Self-assembled Micelles Of Linoleic Acid-Modified Pullulan And Their Application As Drug Carrier

Despite the discovery and development of anticancer drugs for the treatment of cancers, their clinical outcomes have been disappointing due to the lack of tumor selectivity and severe side effect. While, nanoparticles can change drug biodistribution in the body, target drug to tumor tissue, prolong circulation time, and reduce the toxic effect, therefore, the nanoparticles are promising in cancer therapy.Amphiphilic linoleic acid (LA) modified pullulan polymers were synthesized by the formation of ester linkages through EDC-mediated reaction. Three kinds of PULA polymers (PULA1, PULA2and PULA3) were synthesized by changing the mole ratio of LA to pullulan. The chemical structures of PULA polymers were confirmed by FTIR and1H NMR. PULA polymers can easily self-assembled into nanomicelles by dialysis method, fluorescence spectrum showed that the critical micelles concentrations (CMC) were70,62,50μg/mL for PULA1, PULA2and PULA3respectively. Dynamic light scattering (DLS) and Transmission electron microscopy (TEM) demonstrated the diameter of PULA nanomicelles were in the range of80.1～156.8nm, with spherical shape. Hemolysis study showed PULA nanomicelles had no effect on cell membrane integrity, suggesting that PULA nanomicelles are suitable for drug delivery.Doxorubicin (DOX), widely used as anticancer drug, was successfully loaded into PULA nanomicelles by dialysis method, the highest LC of PULA3/DOX nanomicelles can reach up to8.05%, with EE up to88.6%. DOX-loaded micelles were bigger than blank nanomicelles, with good stability. Under the condition of pH=7.4,37℃, in vitro release of DOX from PULA/DOX micelles in Phosphate Buffer Solution (PBS) showed sustained release over96h, the release rate of DOX became higher when the pH of release mediun became lower, which is useful for the cumulative release of DOX around cancer tissue.The cellular uptake experiment showed PULA/DOX nanomicelles can be internalized into MCF-7and SMMC-7721cells easily and the uptake of the micelles mainly depended on energy-dependent and actin polymerization-associated endocytic process. Flow cytometry showed PULA/DOX nanomicelles had an effect on S phase of cell cycle, which led to cell apoptosis. Confocal laser scanning microscopy (CLSM) was used to investigate subcellular localization and distribution of PULA/DOX within cells, revealing that PULA/DOX were internalized, transported into lysosomes, and accumulated around nuclei of cell. MTT assay demonstrated that blank PULA nanomicelles were non-toxic to normal cells, the viability of cancer cells incubated with PULA/DOX nanomicelles showed time and dose-dependent. Pharmacokinetics study showed that PULA2/DOX nanomicelles had higher retention time and improved release profiles of DOX.These results suggested that PULA nanomicelles were biocompatible materials and offer considerable potential to be used to load hydrophobic anticancer drug in cancer therapy.