SYNTHESIS OF AMPHIPHILIC GRAFT FLUORO-COPOLYMERS AND THEIR INTERACTION WITH BOVINE SERUM ALBUMIN

A series of amphiphilic graft copolymers PHFMA-g-PEG comprising of poly(hexafluorobutyl methacrylate) (PHFMA) backbones and poly (ethylene glycol) (PEG) side chains were synthesized by copolymerization of HFMA and an SPEG macromonomer with a p-vinylbenzyl end group. The SPEG macromonomer was synthesized by reaction of PEG with p-chloromethylstyrene in THF in the presence of NaH. The resultant macromonomer and amphiphilic graft copolymers were characterized by (1)H-NMR, (19)F-NMR and GPC. The HFMA contents in the graft copolymers were calculated by the (-OCH(2)-CF(2)-) protons (delta = 4.19) for HFMA and (CH(3)O-) proton (delta = 3.38) for SPEG macromonomers from (1)H-NMR spectra. The critical micelle concentration (CMC) of amphiphilic graft copolymers was measured by surface tension technique, and it showed that the CMC decreased with the increase of HFMA content in the graft copolymers. The interactions between PHFMA-g-PEG and bovine serum albumin (BSA) were studied by fluorescence spectroscopy, photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). The fluorescence spectrum showed that the fluorescence intensity of BSA increased In PHFMA-g-PEG/BSA solution driven by hydrophobic interactions of fluorinated segments, with increasing ratio of HEMA in PHFMA-g-PEG and increasing concentration of PHFMA-g-PEG, the fluorescence emission intensity of BSA also increased. PCS showed that when BSA was added into PEG-F39 aqueous solution, the hydrodynamic diameters and distribution Of micelles were increased. TEM micrographs showed that PHFMA-g-PEG mainly formed core-shell structure micelles, when BSA was added, micelles changed into vesicle like core-shell structures. This study may suggest, that PHFMA-g-PEG is a potential copolymer for loading proteins or other hydrophilic bioactive drugs.