Study On2-Methoxyestradiol-loaded Solid Lipid Nanoparticles Hydrogel

2-Methoxyestradiol (2-ME), as an extremely valuable new wide spectrum of anti cancer drug,had been demonstrated with significant therapeutic effects on many kinds of solid tumors.When2-ME was administrated orally, phase I clinical trials showed some unsatisfying results,such as low blood drug concentration,low oral bioavailab ility,first-pass effect of hepar,fast excretion rate,individual differences of pharmacolo gical effects.In order to overcome the disadvantages existing in the clinical application, the two-phase delivery system of2-ME SLN loaded hydrogel was investigated in this paper.In the first step,2-ME SLN were prepared by hot homogenization-ultrasonication On the basis of single factor,we optimized the preparation prescription by orthogonal test.The volume average diameter determined by Zeta sizer-Nano-ZS90was150±17n m approximately, the encapsulation efficiency and drug loading were88.10%±2.23%and1.65%±0.05%determined by ultrafiltration method. Then the SLN suspension with cryo-protectant was lyophilized by a laboratory drier, and the scanning electron microscopy (SEM) showed that the morphology of nanoparticles was spherical.The DSC analysis results showed that most2-ME was in amorphous state. An in vitro drug release study showed that2-ME was released from the SLN in a slow but time-dependent manner,and the drug release followed Higuchi model.The celler uptake experiment of PC-3cell lines was studied by6-Coumarin fluorescence labeling SLN,the results showed a time-dependent manner. Celler quantitative uptake experiments showed that2-ME SLN has a higher uptake rate than2-ME solutoin. The cytotoxicity of2-ME SLN on four cell lines, breast cancer (MCF-7), prostatic carcinoma (PC-3), glioma (SK-N-SH) and4T1was evaluated respectively by sulforhodamineB (SRB) method,the results showed2-ME SLN was about17-fold on PC-3cells,6.8-fold on SK-N-SH cells and11.59-fold on4T1cells more effective than the solution respectively.The lyophilized2-ME SLN powder was directly incorporated into a certain concentration copolymer solution,then the in vitro characters of2-ME SLN loaded hydrogel were investigated, containing thermosensitiveness, viscosity, stability and nanoparticles in vitro release. The hydrogel loading2-ME SLN still revealed thermosensitivity in the temperature range of20～55℃and the viscosity values lower than1Pa-s when the temperature lower than20℃. Stability of SLN within and released from the hydrogel was confirmed by scanning electron microscope (SEM), particle size measurement, fluorescence labeled technique and free drug concentration determination in the release medium,we found that in the release medium, most of2-ME existed in SLN and intact2-ME SLN could be released from the hydrogel for prolonged period over46days following first-order model. The concentration of2-ME SLN showed significant effect on the release rate.The in vivo characters of2-ME SLN loaded hydrogel were investigated, such as biocompatibility,in vivo release, tissue distribution, tumoral delivery and antitumor effects. The results indicated that the mice treated with the2-ME SLN hydrogel or2-ME hydrogel all did not exhibit abnormal levels of white blood cells compared to the control group, demonstrating their better biocompatibility. The hydrogel could deliver fluorescence-marked SLN to tumor masses and cancer cells, and exhibiting a controlled release of2-ME SLN following a zero-order model. After treatment with2-ME SLN hydrogel, Balb/C mice that had been inoculated with syngeneic4T1breast cancer cells displayed significantly more tumor growth suppression than those treated with2-ME hydrogel, and corresponding tumor growth rate was90%and58%, respectively.In vitro and in vivo studies have shown that, the two-phase drug delivery system designed in this paper could avoid rapid clearance by Mononuclear macrophages.When the2-ME SLN hydrogel local subcutaneous injection,it could target2-ME SLN to tumor tissues or lymph nodes in a long-term, and can be overcome or delay the drug resistance, reduced the lymph node metastasis of advanced cancer and etc. This two-phase delivery system will be highly promising in increase the efficacy of cancer chemotherapy.