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Hydrolyzed Protein-Based Highly Porous Hydrogels: Synthesis and Characteristics

Kurdtabar, Mehran | 2009

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 39653 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Pourjavadi, Ali
  7. Abstract:
  8. This thesis focuses on the preparation and super-swelling behavior of four highly porous hydrogels: 1. Firstly, we have developed a collagen-based highly porous hydrogel by neutralizing the grafted poly(acrylamide-co-acrylic acid) after gel formation. Systematically, the certain variables of the graft copolymerization were optimized to achieve maximum swelling capacity. Morphology of the samples was examined by scanning electron microscopy (SEM) and was shown the pores were induced into the hydrogel by water evaporation resulting from neutralization process. The absorbency under load (AUL) and centrifuge retention capacity (CRC) were measured. The synthesized hydrogel exhibited a pH-responsiveness character so that a swelling-collapsing pulsatile behavior was recorded at pH 2 and 8. This behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents. 2. To synthesis a highly porous hydrogel with superior salt- and pH-resisting properties, synthetic comonomers, i.e. acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), were polymerized and crosslinked in the presence of hydrolyzed collagen as a natural backbone. Experimental results indicate that the hydrogel has an absorbency of 360 and 73–82 g/g for distilled water and saline solutions, respectively. Water absorbency slightly changes from pH 3 to 8 and interestingly is more than of that in distilled water (~ 500 g/g). The hydrogel thus prepared was showing a better salt- and pH-resistance compared to collagen-g-PAA hydrogel due to the introduction of the AMPS segment and therefore is a suitable candidate for horticulture and tissue engineering applications. 3. To investigate the effect of bases and neutralization step on hydrogel microstructure, a series of porous hydrogels with various pore sizes were prepared by neutralizing a collagen-g-poly(acrylic acid) hydrogel after gel formation. SEM was used to characterize the microstructure of the porous hydrogels and was shown the pores were induced into the hydrogel by water evaporation and gas releasing resulting from neutralization process. Therefore, a simple method was used to prepare porous hydrogels. 4. To compare the effect of protein backbone on the swelling behavior, we have developed a gelatin-based highly porous hydrogel by neutralizing the grafted poly(acrylic acid) after gel formation using sodium bicarbonate (NaHCO3).

  9. Keywords:
  10. Graft Copolymerization ; Acrylic Acid ; Acryle Amide ; Gelatin ; Porous Hydrogel ; Hydrolyzed Collagen

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