Catalytic Synthesis and Characterization of Biodegradable ...

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Chapter 1 1.5.2.1 Tissue engineering applications The electroactive polymer, being electrical stimulus responsive, has become the focus of research after the demonstration that electrical signals can regulate cell attachment, proliferation and differentiation. 96 Lots of efforts had been made to use the electroactive polymers to regulate the proliferation and differentiation of cells. And they had been widely used in biological systems due to the key advantage of facile control of the intensity and duration of stimulation. PPy was one of the first electroactive polymers studied for its effect on cells. And it has been demonstrated to support adhesion and growth of a number of different cell types. The investigation of biocompatibility of PPy was just the first step. Its most attractive property is electroactivity. Figure 1.5.3 Photomicrograph of endothelial cells cultured on fibronectin-coated PPy doped with p-toluene sulfonate (PPyTS) for 4 h: (A) PPy in native oxidized state and (B) PPyTs reduced by application of -0.5V for 4 h(Magnify: ×700). 116 Some reports have shown the possibility of using PPy to modulate cellular response via electrical stimulation. Wong et al. assessed the suitability of electroactive polymers for sustaining cell growth and controlling cell function. 116 In their study, aortic endothelial cells were cultured on fibronectin (FN)-coated PPy films which were in different oxidation state (Figure 1.5.3). It was found that neutral state PPy caused cell rounding and a concomitant drop (~98%) in DNA synthesis, and the oxidation of PPy resulted in cell spreading. Interestingly, cell viability (>90%) and adhesion were very good on both oxidized and neutral PPy despite the change in cellular morphology. Schmidt et al. have also made great ‐ 22 ‐
- 23 - Polymerization and Applications of Biodegradable Polyesters contribution to the application of PPy in the biomedical field. They reported that electrical stimulation of PPy in its oxidized form can also be used to modulate cell function. 119 In their experiment, rat pheochromocytoma cell line (PC-12) cells on poly(styrene sulfonate) (PSS)-doped PPy films were found to exhibit a ~91% increase in median neurite length in the presence of a direct current lasted for 2 h (Figure 1.5.4). These studies demonstrate that the electrical stimulus can significantly enhance PC-12 neurite outgrowth and spreading. Moreover, the reason why PPy could enhance the cell extension was studied and they concluded that the electrical stimulation increases the adsorption of serum proteins, which help to improve the growth and proliferation of cells. Subsequently, Lakard et al., 120 George et al., 121 and several other groups investigated adhesion and proliferation of cell cultured different cell lines on PPy. 122-124 Figure 1.5.4 PC-12 cell differentiation on poly(styrene sulfonate)-doped PPy films. (A) Cells grown for 48 h but not subjected to electrical stimulation are shown for comparison. (B) PC-12 cells were grown on PPy for 24 h in the presence of nerve growth factor, then exposed to electrical stimulation (100 mV) across the polymer film. Images were acquired 24 h after stimulation. Scale bar = 100 μm. 119 The limitation of PPy as a favorable biomaterial is that it lacks biological activity. In order to endow it bioactivity, many biomolecules, such as adenosine 5'-triphosphate (ATP) 125-127 and nerve growth factor (NGF) 128 were entrap in PPy. The introduction of biologically active molecules endows the material new properties. Thus, the resulted materials can modulate the growth of different cell types simply by varying the biomolecules. For example, Collier et al.
Page 1 and 2: Catalytic Synthesis and Characteriz
Page 3 and 4: Preface Biodegradable polyesters ha
Page 5 and 6: Chapter 3 Polymerization of Lactic
Page 7 and 8: Chapter 1 Polymerization and Applic
Page 9 and 10: - 3 - Polymerization and Applicatio
Page 13 and 14: 1.2.2 Aluminum Catalysts - 7 - Poly
Page 17 and 18: 1.3 Polylactide 1.3.1 Introduction
Page 19 and 20: - 13 - Polymerization and Applicati
Page 21 and 22: 1.3.4 Application of PLA Figure 1.3
Page 27: 1.5.1.4 Polyaniline (PANi) - 21 - P
Page 47 and 48: 1.6.1 Radical Polymers for Organic
Page 51 and 52: initialization of the device by app
Page 55 and 56: 1.6.2.4 Others - 49 - Polymerizatio
Page 63 and 64: 182. R. B. Weller, J. Invest. Derma
Page 65 and 66: Chapter 2 Synthesis and Electrochem
Page 67 and 68: Synthesis and Electrochemistry of S
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Synthesis and Electrochemistry of S
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Chapter 3 3.1 Introduction Poly(lac
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Chapter 3 polydispersity index (PDI
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Chapter 3 aluminum based complexes
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Chapter 3 3.5 Conclusions Co(III) c
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Chapter 3 22. Z. H. Tang, X. S. Che
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Chapter 4 4.1 Introduction Stimulus
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Chapter 4 the proton of methenyl gr
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Chapter 4 attributed to the amide g
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Chapter 4 4.4 Thermal Properties Th
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Chapter 4 Figure 4.8 MTT assay for
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Chapter 4 The 1 H NMR and 13 C NMR
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Chapter 4 Cell viability (%) = (Asa
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Chapter 5 Synthesis of Triblock Cop
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5.2 Synthesis of Triblock Copolymer
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Sample Table 1. Feed and result com
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= 25 μm. B: MTT assay for the cyto
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‐ 109 ‐ Synthesis of Triblock C
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‐ 111 ‐ Synthesis of Triblock C
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Chapter 6 6.1 Introduction Since th
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Chapter 6 6.3 Synthesis of MPEG-b-P
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Chapter 6 used to characterize the
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Chapter 6 Figure 6.6 Cyclic voltamm
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Chapter 6 vivo cytotoxicity was als
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Chapter 6 NMR. Characterization of
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Chapter 6 CO2 for 24 h. RSC96 cells
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Chapter 7 Conclusion and Future Pro
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‐ 131 ‐ Conclusion and Future P
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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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