α- and β-chitosan with molecular weight of 190,000 and 800,000 respectively, were depolymerized by e-beam irradiation with various doses. The radiation yield of scission (Gs) and degradation rate of the chitosans we...α- and β-chitosan with molecular weight of 190,000 and 800,000 respectively, were depolymerized by e-beam irradiation with various doses. The radiation yield of scission (Gs) and degradation rate of the chitosans were identified. The synergistic chemical degradation in the presence of hydrogen peroxide is more effective at lower doses. Mw of β-chitosan was dramatically decreased from 800,000 to 21,030 at the irradiation dose 5 kGy, on the other hand, that of α-chitosan was decreased much more gradually from 190,000 to 36,000. The values of Gs at 10 kGy in the solution without H2O2 and with H2O2 were respectively 6.09 × 10-5 mol/cal and 30.6 × 10-5 mol/cal for α-Chitosan, and 8.18 × 10-5 mol/cal and 43.8 × 10-5 mol/cal for β-chitosan. It was obviously effective on depolymerization by using the combination of e-beam and H2O2. α-Chitosan molecules are likely to adopt a diffuse conformation in the solution and make the different morphologies depending on the concentration.展开更多
Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard...Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard to their ability to adsorb bile acids in vitro. More than 70% of taurocholate dissolved in solution was taken up by Alg-Ca containing 100 mg β-CS, sim. ilar to the degree of uptake observed with Alg-Ca containing α-CS salt. The adsorption of bile acid was affected by the absolute amount of β-CS and/or the acid concentration of the preparation. A secondary bile acid, taurodeoxycholate, was also adsorbed by Alg-Ca containing weak acid salts of β-CS. Therefore, β-CS might be used to adsorb bile acids within the gastrointestinal tract in the same manner as an anion-exchange resin, and thus serve as a complementary means by which to prevent hyperlipidemia.展开更多
We developed a fixation method and evaluate bone regrowth in the cavities of a Ф4 mm× 8 mm titanium（Ti）tube through porous hydroxyapatite（HAP）/β-tricalcium phosphate（β-TCP）composite filling（group A）,ch...We developed a fixation method and evaluate bone regrowth in the cavities of a Ф4 mm× 8 mm titanium（Ti）tube through porous hydroxyapatite（HAP）/β-tricalcium phosphate（β-TCP）composite filling（group A）,chitosan/calcium phosphate composite filling（group B）,and HAP particle modification（group C）.After 2 and 5 months of implantation in dog tibia defects,new bone formation in the three groups was studied by histology and histomorphometry.Group A displayed the most bone regenerated area in both 2 and 5 months post-operation.The chitosan/calcium phosphate composite in group B mostly degraded 2 months after implantation,leading to fibrous tissue invasion after 5 months.By contrast,less bone formation was observed in group C.These results indicated that filling the cavities of metalprostheses with a porous HAP/β-TCP composite can be used for stable long-term fixation in clinicalsettings.展开更多
文摘α- and β-chitosan with molecular weight of 190,000 and 800,000 respectively, were depolymerized by e-beam irradiation with various doses. The radiation yield of scission (Gs) and degradation rate of the chitosans were identified. The synergistic chemical degradation in the presence of hydrogen peroxide is more effective at lower doses. Mw of β-chitosan was dramatically decreased from 800,000 to 21,030 at the irradiation dose 5 kGy, on the other hand, that of α-chitosan was decreased much more gradually from 190,000 to 36,000. The values of Gs at 10 kGy in the solution without H2O2 and with H2O2 were respectively 6.09 × 10-5 mol/cal and 30.6 × 10-5 mol/cal for α-Chitosan, and 8.18 × 10-5 mol/cal and 43.8 × 10-5 mol/cal for β-chitosan. It was obviously effective on depolymerization by using the combination of e-beam and H2O2. α-Chitosan molecules are likely to adopt a diffuse conformation in the solution and make the different morphologies depending on the concentration.
文摘Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard to their ability to adsorb bile acids in vitro. More than 70% of taurocholate dissolved in solution was taken up by Alg-Ca containing 100 mg β-CS, sim. ilar to the degree of uptake observed with Alg-Ca containing α-CS salt. The adsorption of bile acid was affected by the absolute amount of β-CS and/or the acid concentration of the preparation. A secondary bile acid, taurodeoxycholate, was also adsorbed by Alg-Ca containing weak acid salts of β-CS. Therefore, β-CS might be used to adsorb bile acids within the gastrointestinal tract in the same manner as an anion-exchange resin, and thus serve as a complementary means by which to prevent hyperlipidemia.
基金Funded by the Science and Technology Planning Project of Guangdong Province(2013B010402019)the Natural Science Foundation of Guangdong Province(2015A030310345)the Medical Scientific Research Foundation of Guangdong Province(A2015352)
文摘We developed a fixation method and evaluate bone regrowth in the cavities of a Ф4 mm× 8 mm titanium（Ti）tube through porous hydroxyapatite（HAP）/β-tricalcium phosphate（β-TCP）composite filling（group A）,chitosan/calcium phosphate composite filling（group B）,and HAP particle modification（group C）.After 2 and 5 months of implantation in dog tibia defects,new bone formation in the three groups was studied by histology and histomorphometry.Group A displayed the most bone regenerated area in both 2 and 5 months post-operation.The chitosan/calcium phosphate composite in group B mostly degraded 2 months after implantation,leading to fibrous tissue invasion after 5 months.By contrast,less bone formation was observed in group C.These results indicated that filling the cavities of metalprostheses with a porous HAP/β-TCP composite can be used for stable long-term fixation in clinicalsettings.
