Study On Targeted Polymeric Drug Carriers Biotinylated Pluronic/Poly(Lactic Acid)

Drugs loaded in targeted polymeric nanoparticles can be targeted to tumors, thus improving the selectivity of drug delivery and the effectiveness of the treatment for the disease, reducing the distribution of free drug in normal tissue, and thereby reducing the variety of adverse reactions and side effects from the drug. Biotinylated polymeric nanoparticles can become biological targeted nanoparticles through the non-covalent interactions between biotin and the antibiotic protein (avidin).In this thesis, four kinds of biotinylated polymers, biotin-Pluronic-polylactic acid (B-Pluronic-PLA), were first designed and synthesized. They are B-F127-PLA-87, B-F127-PLA-61, B-F87-PLA and B-P85-PLA. B-Pluronic-PLA nanoparticles were prepared by the dialysis method. The size and morphology of nanoparticle were tested by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The results show that the morphologies of B-F127-PLA-61, B-F87-PLA and B-P85-PLA nanoparticles are spherical micelles, and their diameters are198nm,228.7nm and256.7nm, respectively. B-F127-PLA-87nanoparticles were formed by the two forms of nanoparticles, i.e. spherical micelles and large compound micelles. The diameters of B-F127-PLA-87nanoparticles are126.6nm and906nm, respectively.An anti-cancer drug, paclitaxel (Taxol), was loaded in B-Pluronic-PLA nanoparticles. The in vitro release behaviors of Taxol-loaded B-Pluronic-PLA nanoparticles were investigated by high-performance liquid chromatography (HPLC). It was observed that Taxol-loaded B-Pluronic-PLA nanoparticles presented an initial rapid release (up to6h) followed by a slow release. The highest release values of Taxol (20-24%) achieved about4days later.The in vitro and in vivo targeting behaviors of B-Pluronic-PLA nanoparticles were studied through a three step biotin-avidin method. Results from in vitro cell cultures show that Taxol-loaded B-Pluronic-PLA nanoparticles were delivered more effectively to OVCAR-3cells under the specific interaction between the biotin groups on the surface of B-Pluronic-PLA nanoparticles and the avidin/biotinylated MAb X306/CA-125antigen complexes on the surface of OVCAR-3cells. It was also observed from the in vivo tumor monitoring that the effective targeted behaviors can be achieved in vivo throught the three-step biotin-avidin method.The intracellular distribution of B-F127-PLA nanoparticles was further studied by fluorescence microscropy (FM). It was observed that B-F127-PLA-61nanoparticles are mainly localized within the cytoplasm of OVCAR-3cells.