Subject Area物理化学
Adsorption of Fibrinogen onto Alginate-Chitosan-Alginate Microcapsules
Xie HG(谢红国); Li XX(李晓霞); Ma XJ(马小军); Xiaojun MA
Conference NameThe 2nd Asian Symposium on Emulsion Polymerization and Functional Polymeric Microspheres
Conference Date2007-9-9
Conference Place中国
Alternative Title海藻酸钠-壳聚糖-海藻酸钠微胶囊对纤维蛋白原的吸附
Funding Organization中科院过程所
AbstractAlginate-chitosan-alginate (ACA) microcapsules, consisting completely of natural polysaccharides, are fabricated by transferring Ca-alginate beads into chitosan solution to form the membrane on the surface of the beads by the reaction of negatively charged alginate with positively charged chitosan. It has been widely investigated for applications such as cell transplantation, drug delivery systems, biosensors and enzyme immobilization. The successful use of microcapsules is based on their long term functionality. However, long-term in vivo applications have been hampered by early graft rejection owing to overgrowth and then a process of fibrosis. It is generally believed that protein adsorption onto the surface of implanted devices is the first step in the triggering of immunological responses by the body. Fibrinogen (Fgn) has been shown in some cases to form Fgn layers at implant interface and lead to rejection of an implant. Thus, understanding the factors that influence the adsorption of Fgn onto the biomaterial surfaces is a key to development and application of ACA microcapsules. In this work, the adsorption experiment was carried out by gently shaking Fgn solution of known concentration containing pre-weighed microcapsules at 37 ± 0.5 oC. After a definite period, the protein solution without any microcapsules was collected and the remaining concentration of Fgn was assayed by the Bradford method. The progress of the adsorption was followed by determining the amounts of adsorbed Fgn at various time intervals. The time profiles show that the amount of Fgn adsorbed increases during the first 30 min (rate constant, k=0.214 min-1) and is almost constant for the next 6 hours, and then another increase occur. This “tri-phasic” pattern might result from different possible orientation and/or conformations of Fgn depending on the adsorption history, because Fgn is an extra cellular protein with a size of 45 nm × 9 nm × 6 nm and a molecular weight of 340 kDa. The effects of media pH, alginate composition (G/M ratios) and chitosan composition (degree of deacetylation, DD) on the adsorption of Fgn have been investigated. Five pH values (4.9, 5.3, 6.0, 6.8 and 7.4) are selected in these cases. When pH is 5.3, near the pI (5.1) of Fgn, the amount of Fgn adsorbed reaches its maximum value, with significant decrease with the rise in pH. The result indicates that hydrophobic interaction may be a major interaction between Fgn and ACA microcapsules. Four different alginates (21.0 cP, FG=0.33, 22.5 cP, FG=0.39, 122.5 cP, FG=0.33, 117.1 cP, FG=0.64, 1%, 25 oC) and three different chitosans (DD=0.7, 0.8, 0.9) have been selected. The results show that the amount of Fgn adsorbed onto the surface of the microcapsules increases with the increasing of G/M ratios of alginates or DD of chitosan, which indicates that electrostatic interaction is another major interaction between Fgn and ACA microcapsules.
Document Type会议论文
Corresponding AuthorXiaojun MA
Recommended Citation
GB/T 7714
Xie HG,Li XX,Ma XJ,et al. Adsorption of Fibrinogen onto Alginate-Chitosan-Alginate Microcapsules[C],2007:46/1.
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