Catalytic Synthesis and Characterization of Biodegradable ...

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Chapter 4 4.1 Introduction Stimulus-responsive polymers show great potential application as new “smart” biomaterials. 1 The electroactive polymer, being electrical stimulus responsive, has attracted increasing attentions since it has been established that variety of cells, including many of fibroblasts, nerve cells and osteoblasts are sensitive to the electrical effects generated from the electrodes in vitro or in vivo. 2, 3 Besides, they had been widely used in biological systems due to the key advantage of facile control of the intensity and duration of stimulation. So far, polypyrrole (PPy) and polyaniline (PANi) are still the most widely used two kinds of electroactive materials in tissue engineering although the researches on them have lasted a long time. 4-7 More recently, there are some new electroactive polymers being developed, such as polythiophene (PT) and other types of conductive polymers. 8 However, there are still few examples attempting to explore the application of new electroactive materials in tissue engineering. In recent years, polymers with stable free radicals, known as radical polymers, have attracted more and more attention due to their potential applications as electron transport materials and organic ferromagnets. 9, 10 Radical polymers are readily oxidized and reduced electrochemically, which allowed the use in charge-storage applications for new-types of batteries. 11, 12 However, little attention has been paid to investigate the application of nitroxide radical-containing polymers in the field of biomedical materials. Chu et al. synthesized biodegradable nitroxide radical-containing polymers through the condensation of 4-amino-2,2,6,6-tetramethylpiperidine-1-oxy and polyglycolide. This material showed profound retardation of the proliferation of smooth muscle cell in vitro. 13, 14 However, the hydrolytic degradation of PGA will lead to the release of nitroxide radicals which may have adverse side effects to the body. Using radical polymers as the source of stable radical is an alternative way to solve this problem. These polymers usually have non-biodegradable backbones which will avoid the release of radical agents after the degradation of the main-chain. PTAm and its analogs are typical radical polymers and mostly examined as the cathode materials. 15, 16 To the best of our knowledge, there has few work to investigate the biomedical application of the radical polymers such as PTAm. In this chapter, we copolymerized it with a biodegradable polylactide (PLA) macromonomer, to obtain a novel biologically active and biocompatible copolymer. PLA are well known as very important synthetic biodegradable materials. Due to its low immunogenicity, good biocompatibility and ‐ 86 ‐
‐ 87 ‐ Synthesis of Lactide‐Grafted Poly(TEMPO‐acrylamide) and its Electrochemical Property and Biocompatibility excellent mechanical properties, they are widely used in pharmaceutical and other medical applications, such as sutures, implants for bone fixation, carriers in drug delivery, and temporary matrices or scaffolds in tissue engineering. 17-19 The incorporation of PLA fragment into PTAm will improve the biocompatibility of PTAm, and the resulting biomaterials will have promising application in tissue engineering. 4.2 Synthesis of PTAm-g-PLA The synthetic route of PTAP-g-PLA was shown in Scheme 4.1. Firstly, double bond ended PLA was synthesized by the ring-opening polymerization of lactide initiated by HEMA. Then the macromonomer was copolymerized with 2,2,6,6-tetrametylpiperidine-4-yl acrylamide prepared by the reaction of 4-amino-2,2,6,6-tetrametylpiperidine with acryl chloride according to our previous method. 20 The resulted copolymer was oxidized by the peroxide to give PTAm-g-PLA. Scheme 4.1 Synthetic routes of PTAm-g-PLA. As shown in Figure 4.1A, the peaks around 6.13 and 5.58 ppm were assigned to the characteristic peaks of the double bond of HEMA, and the peak at 5.19 ppm was attributed to
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Catalytic Synthesis and Characteriz
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Preface Biodegradable polyesters ha
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Chapter 3 Polymerization of Lactic
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Chapter 1 Polymerization and Applic
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- 3 - Polymerization and Applicatio
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1.2.2 Aluminum Catalysts - 7 - Poly
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1.3 Polylactide 1.3.1 Introduction
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- 13 - Polymerization and Applicati
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1.3.4 Application of PLA Figure 1.3
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1.5.1.4 Polyaniline (PANi) - 21 - P
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Page 67 and 68: Synthesis and Electrochemistry of S
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Page 84 and 85: Chapter 3 3.1 Introduction Poly(lac
Page 86 and 87: Chapter 3 polydispersity index (PDI
Page 88 and 89: Chapter 3 aluminum based complexes
Page 90 and 91: Chapter 3 3.5 Conclusions Co(III) c
Page 92 and 93: Chapter 3 22. Z. H. Tang, X. S. Che
Page 96 and 97: Chapter 4 the proton of methenyl gr
Page 98 and 99: Chapter 4 attributed to the amide g
Page 100 and 101: Chapter 4 4.4 Thermal Properties Th
Page 102 and 103: Chapter 4 Figure 4.8 MTT assay for
Page 104 and 105: Chapter 4 The 1 H NMR and 13 C NMR
Page 106 and 107: Chapter 4 Cell viability (%) = (Asa
Page 109 and 110: Chapter 5 Synthesis of Triblock Cop
Page 111 and 112: 5.2 Synthesis of Triblock Copolymer
Page 113 and 114: Sample Table 1. Feed and result com
Page 115 and 116: = 25 μm. B: MTT assay for the cyto
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Page 126 and 127: Chapter 6 6.3 Synthesis of MPEG-b-P
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Page 130 and 131: Chapter 6 Figure 6.6 Cyclic voltamm
Page 132 and 133: Chapter 6 vivo cytotoxicity was als
Page 134 and 135: Chapter 6 NMR. Characterization of
Page 136 and 137: Chapter 6 CO2 for 24 h. RSC96 cells
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‐ 133 ‐ Conclusion and Future P
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13. Xuan Pang, Xuesi Chen, Xiuli Zh
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Acknowledgments The present thesis
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