title: Photosensitive cross-linked block copolymers with controllable release.
abstract: We intend to form photosensitive block copolymer micelles for controllable release of encapsulated substances. Here, we designed and synthesized a new photocleavable cross-linker (2-nitrophenyl ethylene glycol dimethacrylate) for methyl methacrylate (MMA) atom transfer radical polymerization. Four different ratios (0:1, 1:26, 1:16, 1:8.8) of the photocleavable cross-linker to MMA monomer were used and four block copolymers (P0, P1, P2, P3) were synthesized with PEO-Br as the macroinitiator. Gel permeation chromatography and (1) H NMR studies showed that linear polymer molecules could be cross-linked by the photocleavable linker. The fluorescence studies of the encapsulated Nile Red (NR) showed that there were lower critical micelle concentrations for the polymer P1, P2 and P3 than polymer P0. And dynamic light scattering and SEM confirmed the formation of polymer micelles. Photolysis experiments demonstrated that NR encapsulated in the polymer micelles could be released upon UV irradiation (365 nm, 11 mW cm(-2)) due to the breakage of the photocleavable linker and the generation of more hydrophilic acid moieties, which destabilized polymer micelles. Our study shows a new strategy for the possibility of photocontrollable drug release for hydrophobic drugs.
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Yu
authors.forename: Cong
authors.initials: C
authors.lastname: Lv
authors.forename: LiZhu
authors.initials: L
authors.lastname: Wu
authors.forename: ChenHo
authors.initials: C
authors.lastname: Tung
authors.forename: WanLiang
authors.initials: W
authors.lastname: Lv
authors.forename: ZhongJin
authors.initials: Z
authors.lastname: Li
authors.forename: XinJing
authors.initials: X
authors.lastname: Tang
mesh_terms: D002850:Chromatography, Gel; D003692:Delayed-Action Preparations / Q000138:chemical synthesis / Q000378:metabolism*; D004337:Drug Carriers / Q000138:chemical synthesis / Q000378:metabolism*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000138:chemical synthesis / Q000378:metabolism*; D008823:Micelles; D008855:Microscopy, Electron, Scanning; D009596:Nitrophenols / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010078:Oxazines / Q000378:metabolism*; D010782:Photolysis / Q000528:radiation effects*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D008689:Methacrylates; D008823:Micelles; D009596:Nitrophenols; D010078:Oxazines; D011108:Polymers; D011092:Polyethylene Glycols; C004919:ethylene dimethacrylate; C044808:nile red