title: Synthesis, characterization, and degradation behavior of amphiphilic poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide]-g-poly(epsilon-caprolactone).
abstract: A series of biodegradable amphiphilic graft polymers were successfully synthesized by grafting poly(epsilon-caprolactone) (PCL) sequences onto a water-soluble poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA) backbone. The graft copolymers were prepared through the ring-opening polymerization of epsilon-caprolactone (CL) initiated by the macroinitiator PHEA with pendant hydroxyl groups without adding any catalyst. By controlling the feed ratio of the macroinitiator to the monomer, the copolymers with different branch lengths and properties can be obtained. The successful grafting of PCL sequences onto the PHEA backbone was verified by FTIR, 1H NMR, and combined size-exclusion chromatography and multiangle laser light scattering (SEC-MALLS) analysis. The hydrolytic degradation and enzymatic degradation of these graft copolymers were investigated. The results show the hydrolytic degradation rate increases with increasing content of hydrophilic PHEA backbone. While the enzymatic degradation rate is affected by two competitive factors, the catalytic effect of Pseudomonas cepacia lipase on the degradation of PCL branches and the hydrophilicity which depends on the copolymer composition. In situ observation of the degradation under polarizing light microscope (PLM) demonstrates the different degradation rates of different regions in the polymer samples.
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education, Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Zhi-Mei
authors.initials: ZM
authors.lastname: Miao
authors.forename: Si-Xue
authors.initials: SX
authors.lastname: Cheng
authors.forename: Xian-Zheng
authors.initials: XZ
authors.lastname: Zhang
authors.forename: Ren-Xi
authors.initials: RX
authors.lastname: Zhuo
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002208:Caproates / Q000737:chemistry*; D002384:Catalysis; D002845:Chromatography; D004337:Drug Carriers; D016503:Drug Delivery Systems; D006358:Hot Temperature; D006868:Hydrolysis; D007783:Lactones / Q000737:chemistry*; D008027:Light; D008049:Lipase / Q000737:chemistry; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008823:Micelles; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry; D011092:Polyethylene Glycols; D011095:Polyethylenes; D011108:Polymers / Q000737:chemistry; D011549:Pseudomonas / Q000201:enzymology; D012542:Scattering, Radiation; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D002208:Caproates; D004337:Drug Carriers; D007783:Lactones; D046911:Macromolecular Substances; D008823:Micelles; D011091:Polyesters; D011095:Polyethylenes; D011108:Polymers; D001224:Aspartic Acid; D011092:Polyethylene Glycols; C121056:caprolactone; D008049:Lipase