title: Poly(L-lysine)-based star-block copolymers as pH-responsive nanocarriers for anionic drugs.
abstract: Star-block copolymers PEI-g-(PLL-b-PEG) with a branched polyethylenimine (PEI) core, a poly(l-lysine) (PLL) inner shell, and a poly(ethylene glycol) (PEG) outer shell have been synthesised and evaluated as potential nanocarriers for anionic drugs. The star-block copolymers were synthesised by a ring-opening polymerisation of ɛ-benzyloxycarbonyl-L-lysine N-carboxyanhydride initiated by the peripheral primary amino groups of PEI, surface modification with activated PEG 4-nitrophenyl carbonate, and subsequent deprotection of benzyl groups on the side chains of the PLL inner shell. The synthesised star-block copolymers were characterised by (1)H NMR, gel permeation chromatography (GPC), and dynamic light scattering (DLS). The encapsulation properties of these star-block copolymers were characterised by spectrophotometric titration and dialysis. These techniques demonstrated that anionic model dyes, such as methyl orange and rose Bengal, and the model drug diclofenac sodium can be encapsulated efficiently by PEI-g-(PLL-b-PEG) at physiological pH. The entrapped model compounds demonstrated sustained release at physiological pH and accelerated release when the pH was either increased to 10.0-11.0 or decreased to 2.0-3.0. The efficient encapsulation as well as the pH-responsive releasing properties of these star-block copolymers could be potentially used in the controlled release of anionic drugs.
authors.affiliation: Medical College, Shantou University, 22 Xinling Road, Shantou 515041, PR China.
authors.forename: Yunsong
authors.initials: Y
authors.lastname: Yan
authors.forename: Jiayan
authors.initials: J
authors.lastname: Li
authors.forename: Jinhong
authors.initials: J
authors.lastname: Zheng
authors.forename: Ying
authors.initials: Y
authors.lastname: Pan
authors.forename: Jinzhi
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaoying
authors.initials: X
authors.lastname: He
authors.forename: Lumian
authors.initials: L
authors.lastname: Zhang
authors.forename: Daojun
authors.initials: D
authors.lastname: Liu
mesh_terms: D000838:Anions / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*
chemical_list: D000838:Anions; D004364:Pharmaceutical Preparations; D011107:Polylysine; D011092:Polyethylene Glycols; D011094:Polyethyleneimine