2.1.8.2. Absorbency Under Load (AUL) - BADA
2.1.8.2. Absorbency Under Load (AUL) - BADA 2.1.8.2. Absorbency Under Load (AUL) - BADA
The swollen crosslinked polymer may be called a gel, but if the gel particles are very small (300- 1000 μ), they are called microgels that act as strongly packed spheres can be suspended in solvents, so they have interested with development of solid-phase synthesis and techniques for immobilizing catalysts in recent years*. There are two categories for crosslinking which is described in following: 1- Physical crosslinking 2- Chemical crosslinking Polymer chains doesn’t join together *www.chemheritage.org Polymer chains joined together by crosslinking agent (shown in red) to form a single molecule Figure 8. Schematic structure of crosslinked and uncrosslinked polymers 19
1.7.1. Physical Crosslinking of Proteins Physical hydrogels have three dimensional networks in absent of chemical cross- linking agent. High energy irradiations can separate electrons from atoms or molecules to form a free radical as an active initiator for crosslinking reaction. Many soluble proteins with this configuration can build physical hydrogels, but the weaknesses of such gels are low mechanically strength.In order to increase the mechanical strength, the protein should modify with chemical crosslinkers (see section 1.7.2). In this overview, some different physical crosslinking methods used for the purpose of biodegradable hydrogels are summarized as fallow. 1.7.1.1. Crosslinking by Thermal Method Thermal denaturation has been used to crosslink proteins. Albumin and some other proteins such as collagen can crosslink by heating. The proteins become coagulate and insoluble by formation of inter-reaction between chains due to amide bond. By this way proteins are usually heated at a high temperature (around 140 o C) for a day and dehydrated at greater than 100 o C for a few days [30] . The albumin hydrogel microspheres are a good example for heat crosslinking method. The extent of crosslinking of albumin hydrogel depends on the temperature and time. These thermal denaturized albumin microspheres were used to deliver various drugs including anticancer agent such as fluorouracil or mitomycin [31] . Also thermal decomposed gelatin causes water-insoluble, although it still swells to a certain extent [32] . 1.7.1.2. Crosslinking by Ultrasound Method Ultrasound was employed to make protein hydrogel microspheres. At the first ultrasound separates small droplets of oil or other non-polar organic liquids containing protein in water, similar to emulsification process used to produce mayonnaise. This method creates cavitation which cause to homolysis of water molecules due to produce radicals (H • and OH • ) [33] . 20
- Page 2 and 3: BIOSUPERABSORBENT FROM PROTEINS Sar
- Page 4 and 5: ACKNOWLEDGMENTS We would like to ap
- Page 6 and 7: CONTENTS ACKNOWLEDGMENTS ………
- Page 8 and 9: 3.4.Ⅰ. Kinetic of Swelling……
- Page 10 and 11: 22- Effect of Glutaraldehyde concen
- Page 12 and 13: 1 INTRODUCTION Superabsorbent hydro
- Page 14 and 15: 1.1. Definition of Superabsorbency
- Page 16 and 17: 1.3.1. Protein Structure Protein fo
- Page 18 and 19: 2- Side chains of polar residues wi
- Page 20 and 21: 1.3.3. Ovalbumin , Good Source for
- Page 22 and 23: One of the paper preparation proces
- Page 24 and 25: ……………………………
- Page 26 and 27: 1.5. The Thermodynamic of Protein F
- Page 28 and 29: In order to chemical modification o
- Page 32 and 33: 1.7.1.3. Crosslinking by UV-Irradia
- Page 34 and 35: 1.7.2.1. Non-specific Crosslinking
- Page 36 and 37: 1.8. Determination the Degree of cr
- Page 38 and 39: These preparations contain consider
- Page 40 and 41: MATERIALS AND METHODS 2.1. Method o
- Page 42 and 43: ased on the solubility of the prote
- Page 44 and 45: 2.1.2.2. Determination of Zygomycet
- Page 46 and 47: 2.1.3. Modification of proteins Alb
- Page 48 and 49: The first step was weighted a 30 mg
- Page 50 and 51: 2.1.8.1. Centrifuge Retention Capac
- Page 52 and 53: Figure 17. Schematic of device used
- Page 54 and 55: Results showed the effect of ethano
- Page 56 and 57: Preparation of protein solution (1%
- Page 58 and 59: PART Ⅰ ALBUMIN SUPERABSORBENT HYD
- Page 60 and 61: 3.3.Ⅰ. Effect of Buffer solution
- Page 62 and 63: Swelling (g/g) 300 200 100 0 1 0.01
- Page 64 and 65: Swelling (g /g ) 350 300 250 200 15
- Page 66 and 67: 3.8.Ⅰ. Effect of Temperature Prot
- Page 68 and 69: In this rearrangement the R─ grou
- Page 70 and 71: Calculations As a result by solving
- Page 72 and 73: In the present work, increasing the
- Page 74 and 75: In detail, Figure 36 shows the comp
- Page 76 and 77: Sample Table 5. Comparison of swell
- Page 78 and 79: The IZP-hydrogel compared with unmo
The swollen crosslinked polymer may be called a gel, but if the gel particles are very small (300-<br />
1000 μ), they are called microgels that act as strongly packed spheres can be suspended in<br />
solvents, so they have interested with development of solid-phase synthesis and techniques for<br />
immobilizing catalysts in recent years*. There are two categories for crosslinking which is<br />
described in following:<br />
1- Physical crosslinking<br />
2- Chemical crosslinking<br />
Polymer chains doesn’t join together<br />
*www.chemheritage.org<br />
Polymer chains joined together by<br />
crosslinking agent (shown in red)<br />
to form a single molecule<br />
Figure 8. Schematic structure of crosslinked and uncrosslinked polymers<br />
19
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