| Docetaxel（DOC） is considered as a kind of semi-synthetic new anti-tumor hydrophobic drug.In this paper,in order to improve the utilization rate of DOC and reduce the toxic and side effects,poly（2-ethyl-2-oxazoline）-cholesteryl methyl carbonate（PEOZ-CHMC）was used to construct nanomicelle drug delivery system to deliver DOC.Determination methods for concentration of DOC and Coumarin-6（C6）were established,which were high-performance liquid chromatography and fluorescence spectrophotometry,and systematic methodological investigations were performed on the determination methods of the two model drugs.DOC and C6 had good linearity in the range of 1-60μg/m L and10-1000 ng/m L,respectively,and both precision and recovery were in accordance with the experimental requirements.The critical micelle concentration（CMC） of the polymer micelles was measured by hydrazine fluorescence probe method.The results showed that the CMC of PEOZ-CHMC was 9.26μg/m L(4.63×10-6mol/L).The DOC-PEOZ-CHMC micelles（DOC-M）,blank PEOZ-CHMC micelles（BM）and C6-PEOZ-CHMC micelles（C6-M）were prepared by the film dispersion method.The entrapment efficiency of DOC-M and C6-M were（60.1±2.41）%and（58.9±2.11）%,respectively by Sephadex column centrifugation.The particle sizes of two drug-loaded micelles were（122.42±1.07）nm and（141.77±0.93）nm,respectively by the Malvern particle size analyzer.The transmission electron microscope（TEM） and scanning electron microscope（SEM）were used to observe the morphology of the micelles.It was found that the micelles had a spherical or spheroidal structure with a smooth surface.Infrared spectroscopy（IR）and x-ray diffraction（XRD）were used to characterize the freeze-dried micelle preparations.The results showed that the drug-loaded micelles were successfully prepared.Micelles were co-incubated with fetal bovine serum and the stability of the micelles was evaluated.The results showed that there was no significant decrease in the light transmittance of micelles under pH 7.4,which indicated that the micelles had a better stability under pH 7.4.In vitro release experiments showed that the cumulative drug release rate in the micelles was 15%and 72%at24 h at pH 7.4 and pH 6.4 respectively,which indicated that the micelles had a certain pH sensitivity.HeLa cell inhibition experiment results showed that the cell survival rate of drug-loaded micelles was significantly reduced when pH was lowered,which indicated that low pH of the environment could increase the cell number uptake of the micelles.Inverted fluorescence microscopy and flow cytometry results showed that DOC-M uptake rates were higher than that of free DOC at different pH values;DOC-M cells uptake significantly increased when pH was lowered,which indicated that the micelles had better pH susceptibility. |
