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Synthesis of Biodegradable Silicon Functionalized Polyester Scaffolds for Bone Tissue Engineering

Yan, Xiang
http://rave.ohiolink.edu/etdc/view?acc_num=akron1417705961

Abstract Details

2014, Doctor of Philosophy, University of Akron, Polymer Science.
Tissue engineering technology may offer new hope for patients with injuries, end stage organ failure, or other clinical issues. The three main `pillars’ that support bone tissue engineering include cells, biochemical factors and scaffolds. The biomaterials for scaffolds in tissue engineering have gone through three generations. As the third generation of biomaterials, biodegradable polymer scaffolds have great application in tissue engineering. Since silicon is an essential element in bone and connective tissue formation, silicon-functionalized copolymer scaffolds was prepared. The silicon-functionalized copolymer was synthesized using a poly(lactic acid) (PLA) pre-polymer as macroinitiator by atom transfer radical polymerization (ATRP). The PLA macroinitiator (Mn = 1.8 × 104 g/mol; Ð = 2.58) was prepared by acid-catalyzed copolyesterification of LA and 2-bromo-3-hydroxypropanoic acid. We established the graft copolymerization of LA and methyl methacylate (MMA) conditions using an initiator that models the brominated repeat unit of the macroinitiator: methyl 2-bromo-3-acetoxypropionate. This polymerization was well controlled using CuCl as the catalyst in toluene at 90 0C, as demonstrated by the linear first order monomer conversion and linear growth in number-average molecular weight as well as by the narrow polydispersity (Ð < 1.20). The number-average degree of polymerization (DPn) and glass transition temperature (Tg) of the corresponding graft copolymer also increased with increasing ratios of the monomer to initiating sites, whereas the Ð index decreased relative to the macroinitiator. 1H NMR analysis, molecular weight data, and refractive index increments confirmed that the graft copolymers contained both PLA and PMMA in the same molecules. Since bromine atoms were applied in ATRP, to begin with, the bromine cell toxicity should be investigated. The graft copolymers contained both PLA, PMMA, and poly(2-hydroxylethyl methacrylate) (PHEMA) in the same molecules was synthesized with a high molecular weight (Mn = 5.00 × 104 g/mol to 10.0 × 104 g/mol) by single electron transfer living radical polymerization (SET-LRP). Macroinitiator for this graft copolymer was a copolymer of lactic acid and 2-bromo-3-hydroxypropionic acid. Graft copolymers with different bromine concentration (0.5 mole%, 1 mole%, and 2 mole%) were synthesized. Scaffolds were prepared through compression casting mode with 5000 PSI as pressure and sterilized with ethylene oxide. The size of scaffolds for bromine cell toxicity was 1 mm thickness and 1 cm diameter. µCT characterization showed the porosity of scaffolds was 69%. A silicon-functionalized polymer was synthesized with functional PLA as macroinitiator. No hydrolysis was detected by GPC. To increase the hydrophilicity of the scaffolds, graft copolymers of MMA, HEMA and 3-(triethoxysilyl)propyl methacrylate (TESPMA) were synthesized with a macroinitiator. From NMR spectroscopy, the composition of the final polymer was [MMA]:[HEMA]:[TESPMA] = 92:7:1.
Coleen Pugh, Dr. (Advisor)
William Landis, Dr. (Committee Member)
Nita Sahai, Dr. (Committee Member)
Abraham Joy, Dr. (Committee Member)
Chrys Wesdemiotis, Dr. (Committee Member)
196 p.
Polymer Chemistry

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Citations

  • Yan, X. (2014). Synthesis of Biodegradable Silicon Functionalized Polyester Scaffolds for Bone Tissue Engineering [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1417705961

    APA Style (7th edition)

  • Yan, Xiang. Synthesis of Biodegradable Silicon Functionalized Polyester Scaffolds for Bone Tissue Engineering. 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1417705961.

    MLA Style (8th edition)

  • Yan, Xiang. "Synthesis of Biodegradable Silicon Functionalized Polyester Scaffolds for Bone Tissue Engineering." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1417705961

    Chicago Manual of Style (17th edition)

akron1417705961
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© 2014, some rights reserved.Creative Commons License Synthesis of Biodegradable Silicon Functionalized Polyester Scaffolds for Bone Tissue Engineering by Xiang Yan is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Akron and OhioLINK.