In Vitro Evaluation Of Two Series Of Self-assemble Drug Delivery System Based On The Amphiphilic Polyphosphazene

In this study, two new series of amphiphilic methoxy-poly(ethylene glycol) grafted polyphosphazenes with different hydrophobic side groups including glycine ethyl ester (GlyEt),ethyl 4-aminobenzoate(EAB) and, N,N-diisopropylethylenediamine(DPA) (DPA) were synthesized and characterized. Differential synthesis strategies of amphiphilic graft polyphosphazenes were established to achieve controlled hydrophilic ratio of each copolymer with relatively high product yield. Copolymer structure was characterized by NMR, UV, DSC and GPC.Fluorescence probe was adopted to determine the critical micelle concentration (CMC) of amphiphilic copolymers, and the results revealed that the CMC will decrease with the increasing hydrophobic content of amphiphilic copolymers. The morphology of assemblies was observed by TEM. It was found that aggregates with various shaps can be formed in aqueous sulution. For the amphiphilic graft polyphosphazenes that using GlyEt as hydrophobic groups, rod-like micelles were observed when copolymer has high GlyEt content, as the weight ratio of hydrophobic groups decreased, micelles with multiple morphology obtained, where the rods and spherical micelles are coexistent, micelles of copolymer with low GlyEt content are all in spherical shape. For copolymers with N,N-diisopropylethylenediamine(DPA) as hydrophobic groups, they demonstrate pH-sensitive charicteristics. In vitro study of amphiphilic self-assemble copolymer. The MTT assay was used to test cellular cytotoxicity in different cell strains; Cell nucleus were extracted and tested by Flow cytometry to analyze the difference of nuclear distribution of DOX-loaded micelle and free ADR; acidic organelles were stained with fluorescent materials to study the DND-26 cellular distribution carried by pH-responsive nanoparticles observed under CLSM; Low temperature and glucose depletion methods were used to study the connection between p-glycoprotein and celluar uptake of polymer.All these results suggest that those two amphiphilic self-assemble drug delivery system based on the polyphosphazene exhibit potentials as carriers for anti-cancer drug delivery system, and it is worth in-depth study.