Preparation Of Biocompatible "Core-Shell"Cross-Linked Micelles As Drug Delivery Via RAFT Polymerization

Macro-molecular materials with the special properties of controlled releasing andtargeting can be used for drug delivery. It not only provides new ideas, but also offersa new direction for biomedical development.“Core-Shell” micelles formed via theself-assembly of amphiphilic block copolymer in aqueous solution have attractedincreasing attention. As the defective stability of the self-assembed micelles themselv-es, the scientists propose the concept of “core-shell” cross-linked micelles. As thecross-linked position of “core-shell” cross-linked micelles are in the middle of coreand shell, therefore, the micellar system shows perfect stability in the blood （orcirculation system）. Moreover, it has effective and efficient drug loading capacity.The essay designed and prepared a new type of “core-shell” cross-linked micelleD,L-P（LA）₁₉₉-b-P（PEGMA）₂₂₄-P（EDA）54×2as drug carrier. Firstly, the amphiphilicblock copolymer D,L-P（LA）₁₉₉-b-P（PEGMA）₂₂₄was prepared via the anionic ringopen polymerization and reversible addition fragmentation chain transfer （RAFT）polymerization. Then, D,L-P（LA）₁₉₉-b-P（PEGMA）₂₂₄formed the self-assembled mic-elles in aqueous solution. Finally, D,L-P（LA）₁₉₉-b-P（PEGMA）₂₂₄-P（EDA）54×2wassynthesized by cross-linking with EDA via RAFT polymerization. The “core-shell”cross-linked micelles generated in the reaction revealed the living behavior with theconversion rate and molecular weight （Mn） increasing with time; what is more, thevalue of PDI is lower. The diameter of “core-shell” cross-linked micelles and uncross-linked micelles were nano-scale particals measured by both DLS and TEM.The drug （riboflavin） loading content and the loading efficiency of “core-shell”cross-linked micelle was higher than that of the uncross-linked self-assembed micelle.And the uncross-linked self-assembed micelle and the cross-linked micelle exhibitedsimilar pseudofirst-order release kinetic. The drug releasing efficiency of “core-shell”cross-linked micelle was higher than that of uncross-linked self-assembed micelle.Thecytotoxicity assay showed that uncross-linked self-assembly micelle and “core-shell”cross-linked micelle presented little effect on cell viability and proliferation.