Catalytic Synthesis and Characterization of Biodegradable ...

More documents

Recommendations

Info

Chapter 6 vivo cytotoxicity was also determined by injecting the micelles solution into the kunming mice (ca. 17~23 g). 0.5 mL of micelles solution at concentrations of 2 mg/mL, 5mg/mL and 15mg/ml were injected into the five kunming mice in each group. All the mice were observed to show no significant indisposed nor death during the 2 day’s observation, indicating the good in vivo biocompatibility of the micelles. Figure 6.8 MTT cell toxicity assay. B1: MPEG-b-PLA; B2: MPEG-b-PTAm; B3: MPEG-b-PLA-b-PTAm. 6.7 Conclusions Amphiphilic triblock copolymer containing stable nitroxyl radicals was successfully prepared by combination of ring-opening polymerization and RAFT technique. The RAFT polymerization towards TAP monomer was monitored to show living features by using MPEG-CPAD as the CTA. Amphiphilic diblock copolymer containing stable nitroxyl radicals but without PLA segment was also prepared for the control study. The block copolymer structures were confirmed by 1 H NMR and GPC characterization. Both of the copolymers can self-assemble into micelles in aqueous solution with nitroxyl radicals in the hydrophobic core. All the micelles prepared from either triblock or diblock copolymer can produce EPR signal and protect the free radicals from being reduced for a longer time as compared to the free TEMPOL radicals in the presence of high concentration Vc. Additionally, the micellar structure also endow the two materials with low cytotoxicity. Therefore, such micelles with stable free radicals in the core should be promising to be used as the EPR probe for in vivo imaging application. ‐ 122 ‐
6.8 Experimental section Materials and methods Synthesis of Amphiphilic Triblock Copolymers of Acrylamide, Lactate, and Ethyleneoxide 2,2’-Azoisobutyronitrile (AIBN, Beijing Chemical Co., China) was recrystallized twice from methanol. Monomethoxy poly(ethylene glycol) (MPEG Mw=5000 Da), 4-hydroxyl-TEMPO (TEMPOL, 97%) N,N'-Dicyclohexylcarbodiimide (DCC, 99%) and 4-dimethylaminopyridine (DMAP, 98%) were purchased from Aldrich Chemical Co. and used as received. 4-Cyanopentnoic acid dithiobenzoate (CPAD) was prepared as described in the literature 21. 26 4-Amino-2,2,6,6-tetramethylpiperidine (TCI, >97%) and Acryloyl chloride (Alfa Aesar, 96%) were used without purification to prepare the 2,2,6,6-tetramethylpiperidinyl acrylamide (TAP) monomer. 27 All other reagents were used without further purification. 1 H NMR spectra were recorded on Bruker AV 300 or Bruker AV 600 NMR spectrometer in CDCl3. Gel permeation chromatography was performed with 0.1 M LiCl DMF eluent using a Tosoh HLC-8220 instrument, and the molecular weight and polydispersity were calibrated with polystyrene standards. For kinetic study, gel permeation chromatography was performed with a Schamback SFD GmnH mGPC2000 instrument using 0.1 M LiCl DMF as the eluent at 40 o C, and the molecular weight and polydispersity were calibrated with polystyrene standards. Dynamic light scattering (DLS) were determined by DAWN EOS 18 Angles Laser Light Scattering Instructment (Wyatt Technology). Transmission electron microscopy (TEM JEM-2010 electron microscope, JEOL, Japan) was also used to characterize the morphology of the micelles. Electron paramagnetic resonance (EPR) spectra were recorded on a JES-FA200 EPR spectrometer. Synthesis of Macromolecular CTA: MPEG-CPAD and MPEG-b-PLA-CPAD. Typically, MPEG5k 2.5 g (0.5 mmol), CPAD 0.28 g (1mmol) DCC 0.42 g (2 mmol) and DMAP 0.025 g (0.2 mmol) were dissolved in 20 mL anhydrous methylene chloride. The solution was stirred at room temperature for 48 hours. After filtration of the precipitate, the solution was poured into 200 mL cold ethyl ether, yielding pink precipitate. The pink precipitate was redissolved in methylene chloride and precipitated again in cold ethyl ether. After washing with additional two times with ethyl ether, the pink product MPEG-CPAD was finally obtained, yield 92%. The preparation of MPEG-b-PLA-CPAD was similar as MPEG-CPAD, yield 89%. The structure of the two macromolecular CTA was verified by 1 H ‐ 123 ‐
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 11 and 12:
Page 13 and 14:
1.2.2 Aluminum Catalysts - 7 - Poly
Page 15 and 16:
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 23 and 24:
Page 25 and 26:
Page 27 and 28:
1.5.1.4 Polyaniline (PANi) - 21 - P
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
1.6.1 Radical Polymers for Organic
Page 49 and 50:
Page 51 and 52:
initialization of the device by app
Page 53 and 54:
Page 55 and 56:
1.6.2.4 Others - 49 - Polymerizatio
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
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
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79:
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 94 and 95: Chapter 4 4.1 Introduction Stimulus
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
Page 117 and 118: ‐ 109 ‐ Synthesis of Triblock C
Page 119: ‐ 111 ‐ Synthesis of Triblock C
Page 124 and 125: Chapter 6 6.1 Introduction Since th
Page 126 and 127: Chapter 6 6.3 Synthesis of MPEG-b-P
Page 128 and 129: Chapter 6 used to characterize the
Page 130 and 131: Chapter 6 Figure 6.6 Cyclic voltamm
Page 134 and 135: Chapter 6 NMR. Characterization of
Page 136 and 137: Chapter 6 CO2 for 24 h. RSC96 cells
Page 141 and 142: Chapter 7 Conclusion and Future Pro
Page 143 and 144: ‐ 131 ‐ Conclusion and Future P
Page 145 and 146: ‐ 133 ‐ Conclusion and Future P
Page 147 and 148: 13. Xuan Pang, Xuesi Chen, Xiuli Zh
Page 149: Acknowledgments The present thesis
show all

Catalytic Synthesis and Characterization of Biodegradable ...

Create successful ePaper yourself

Delete template?

Save as template?