Studies On Folate-conjugated Polymeric Micelles For Tumor Targeting Drug Delivery

Tumor is one of the main diseases that influence people’s health. Duo to serious side effect, the usage of Chemotherapy drug is limited. Therefore, it is meaningful to develop a chemotherapy drug delivery system for tumor targeting. In this study, it aims to develop a Foltae-PEG-DSPE polymeric micelles as antitumor drug delivery system.The main content of this study is including as following:First,α-and y-Folate-PEG-DSPE was synthesis and determined. Second, the folate-conjugated polymeric micelles were prepared and characterized. Third, the DOX-loaded micelles were evaluated in-vitro and in-vivo for antitumor effect.Folate-Cys was synthesized via Fmoc-protected solid phase peptide synthesis strategy. In the past, there is the disputation in a-and y-Folate regioisomers activity binding with folate receptor. Therefore, we adopted preparative HPLC method to obtain both a-Folate-Cys and y-Folate-Cys. Since the maleimide of Mal-PEG-DSPE could react with hydrosulfide groups of Cys with specificity in high activity, we also synthesized a-and y-Folate-PEG-DSPE. All the products had high purity (95%) and were confirmed by1H-NMR analysis.Three types of micelles were prepared by film formation method, MPEG-DSPE-DOX andα-/γ-Folate-PEG-DSPE-DOX micelles. Transmission electron microscopy and dynamic light scattering analysis showed that the micelles were uniform with a mean hydrodynamic diameter around 20nm±5nm. The encapsulation efficiency was 80.4%±1.2%and the drug loading content was determined to be 13.2%±1.2%. These micelles would be sufficiently stable diluted in HEPES-buffered saline (pH 7.4) during storage at 4℃for 4 month. Moreover, the in vitro drug release result indicated the micelles have the different drug delayed release ability in different pH conditions.The fluorescence microscope revealed that folate-conjugated micelles exhibited greater extent of cellular uptake than MPEG-DSPE micelles against KB cells over-expressed folate receptors on the surface. The polymeric micelles could avoid the macrophages endocytosis in vitro. Foltae-conjugated micelles showed more cytotoxic as compared with foltae-unconjugated micelles. Moreover, using KB cells xenografted nude mice models, demonstrated that being systemically administered, the tumor size was regressed treated using folate-conjugated micelles as carriers for DOX. Compared with free DOX and MPEG-PEG-DSPE-DOX micelles, a-and y-Folate-PEG-DSPE-DOX had better antitumor effect with lower toxicity. No difference in vitro and in vivo antitumor effect was found between a-and y-Folate-PEG-DSPE-DOX micelles.