采用熔融共混法制备了纳米氧化锌(ZnO)填充聚乳酸/聚丁二酸丁二酯(PLA/PBS)复合材料。研究了ZnO质量分数对复合材料的力学性能、结晶性能以及动态流变性能的影响。结果表明,随着ZnO含量的增加,复合材料的力学性能和结晶度先升高后降低,...采用熔融共混法制备了纳米氧化锌(ZnO)填充聚乳酸/聚丁二酸丁二酯(PLA/PBS)复合材料。研究了ZnO质量分数对复合材料的力学性能、结晶性能以及动态流变性能的影响。结果表明,随着ZnO含量的增加,复合材料的力学性能和结晶度先升高后降低,当ZnO质量分数为0.5%时,复合材料的拉伸强度和冲击强度分别达到最大值40.99 MPa和8.82 k J/m^2,比未添加ZnO时分别提高了6.3%和28.2%,同时结晶度达到24.4%。动态流变性能测试表明,ZnO的质量分数为0.5%时,复合材料的损耗模量和储能模量均为最大值,反映出此时复合材料内部氢键和交联网络最完善,协同作用效果达到最佳状态,因此力学性能也最优。在ZnO质量分数为0.5%的基础上,采用超临界二氧化碳发泡法对复合材料进行间歇发泡,结果显示添加ZnO的发泡材料泡孔密度比未添加的高出一个数量级,泡孔尺寸分布更加集中,体积膨胀率更高。展开更多
通过开环聚合合成了PTMC-LLA共聚物并采用PLGA纤维增强制备了新一代生物可降解心血管支架材料.使用1 H NMR、GPC和DSC等仪器分析了PTMC-LLA共聚物的化学结构和性能,采用静力拉伸测试了共聚物及其增强材料的拉伸强度.力学测试结果显示,通...通过开环聚合合成了PTMC-LLA共聚物并采用PLGA纤维增强制备了新一代生物可降解心血管支架材料.使用1 H NMR、GPC和DSC等仪器分析了PTMC-LLA共聚物的化学结构和性能,采用静力拉伸测试了共聚物及其增强材料的拉伸强度.力学测试结果显示,通过PLGA纤维增强,得到了拉伸强度为46MPa的复合材料,可作为支架材料使用.PTMC-LLA共聚物及其复合材料在pH为7.4的缓冲溶液中进行体外降解,结果表明比起PLLA和PTMC-LLA,复合材料失重率及其吸水率较高并且复合材料的分子量下降较快,这是由于PLGA较快的降解产生大量羧基而引起的内部自催化发应所致.展开更多
Background The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new...Background The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new potentially interesting transplant candidates. Our purpose was to observe the morphological and functional repair effects of the co-transplantation of neural stem cell （NSC）, Schwann ceils （SCs） and poly lactide-co-glycolide acid （PLGA） on the spinal cord injury of rats.Methods A scaffold of PLGA was fabricated. NSCs and SCs were cultured, with the NSCs labeled with 5-bromodeoxyuridine, and the complex of NSC/PLGA or NSC＋SCs/PLGA were constructed. Thirty-six Wistar rats were randomly divided into three groups： group A （transplantation of PLGA）, group B （transplantation of NSC/PLGA） and group C （transplantation of NSC＋SCs/PLGA）. The 3 mm length of the right hemicord was removed under the microscope in all rats. The PLGA or the complex of PLGA-celIs were implanted into the injury site. Basso-Beattie-Bresnahan （BBB）locomotion scores, motor and somatosensory evoked potential of lower limbs were examined to learn the rehabilitation of sensory and motor function at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. All the recovered spinal cord injury （SCI） tissues were observed with HE staining, immunohistochemistry, and transelectronmicroscopy to identify the survival, migration and differentiation of the transplanted cells and the regeneration of neural fibres at 4 weeks, 8 weeks,12 weeks and 24 weeks after injury.Results （1） From 4 weeks to 24 weeks after injury, the BBB locomotion scores of cell-transplanted groups were better than those of the non-cell-transplanted group, especially group C （P 〈0.05）. The amplitudes of the somatosensory evoked potential （SEP） and motor-evoked potential （MEP） were improved after injury in groups B and C, but the amplitude of SEP and MEP at 4 weeks was lower than that at 12 weeks and 24 weeks after injury. Com展开更多
Graphene nanoplatelets （GNPs） were used as multifunctional nanofiller to enhance thermal and mechanical properties as well as electrical conductivity of two different biodegradable thermoplastics： poly lactide （PL...Graphene nanoplatelets （GNPs） were used as multifunctional nanofiller to enhance thermal and mechanical properties as well as electrical conductivity of two different biodegradable thermoplastics： poly lactide （PLA） and poly （butylene adipate-co-terephthalate） （PBAT）. Morphological investigations showed different levels of GNP dispersion in the two matrices, and consequently physical properties of the two systems exhibited dissimilar behaviours with GNP incorporation. Crystallinity of PLA, determined from differential scanning calorimetry, was observed to increase markedly with addition of GNPs in contrast to the decrease in crystallinity of PBAT. Isothermal and non-isothermal thermogravimetric analyses also revealed a more significant delay in thermal decomposition of PLA upon addition of GNPs compared to that of PBAT. Furthermore, results showed that increasing GNP content of PLA and PBAT nanocomposites influenced their Young＇s modulus and electrical conductivity in different ways. Modulus of PBAT increased continuously with increasing GNP loading while that of PLA reached a maximum at 9wt% GNPs and then decreased. Moreover, despite the higher conductivity of pure PBAT compared to pure PLA, conductivity of PLA/GNP nanocomposites overtook that of PBATIGNP nanocomposites above a certain GNP concentration. This demonstrated the determining effect of nanoplatelets dispersion state on the matrices properties.展开更多
文摘采用熔融共混法制备了纳米氧化锌(ZnO)填充聚乳酸/聚丁二酸丁二酯(PLA/PBS)复合材料。研究了ZnO质量分数对复合材料的力学性能、结晶性能以及动态流变性能的影响。结果表明,随着ZnO含量的增加,复合材料的力学性能和结晶度先升高后降低,当ZnO质量分数为0.5%时,复合材料的拉伸强度和冲击强度分别达到最大值40.99 MPa和8.82 k J/m^2,比未添加ZnO时分别提高了6.3%和28.2%,同时结晶度达到24.4%。动态流变性能测试表明,ZnO的质量分数为0.5%时,复合材料的损耗模量和储能模量均为最大值,反映出此时复合材料内部氢键和交联网络最完善,协同作用效果达到最佳状态,因此力学性能也最优。在ZnO质量分数为0.5%的基础上,采用超临界二氧化碳发泡法对复合材料进行间歇发泡,结果显示添加ZnO的发泡材料泡孔密度比未添加的高出一个数量级,泡孔尺寸分布更加集中,体积膨胀率更高。
文摘通过开环聚合合成了PTMC-LLA共聚物并采用PLGA纤维增强制备了新一代生物可降解心血管支架材料.使用1 H NMR、GPC和DSC等仪器分析了PTMC-LLA共聚物的化学结构和性能,采用静力拉伸测试了共聚物及其增强材料的拉伸强度.力学测试结果显示,通过PLGA纤维增强,得到了拉伸强度为46MPa的复合材料,可作为支架材料使用.PTMC-LLA共聚物及其复合材料在pH为7.4的缓冲溶液中进行体外降解,结果表明比起PLLA和PTMC-LLA,复合材料失重率及其吸水率较高并且复合材料的分子量下降较快,这是由于PLGA较快的降解产生大量羧基而引起的内部自催化发应所致.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 30370543, No. 30540450581）.
文摘Background The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new potentially interesting transplant candidates. Our purpose was to observe the morphological and functional repair effects of the co-transplantation of neural stem cell （NSC）, Schwann ceils （SCs） and poly lactide-co-glycolide acid （PLGA） on the spinal cord injury of rats.Methods A scaffold of PLGA was fabricated. NSCs and SCs were cultured, with the NSCs labeled with 5-bromodeoxyuridine, and the complex of NSC/PLGA or NSC＋SCs/PLGA were constructed. Thirty-six Wistar rats were randomly divided into three groups： group A （transplantation of PLGA）, group B （transplantation of NSC/PLGA） and group C （transplantation of NSC＋SCs/PLGA）. The 3 mm length of the right hemicord was removed under the microscope in all rats. The PLGA or the complex of PLGA-celIs were implanted into the injury site. Basso-Beattie-Bresnahan （BBB）locomotion scores, motor and somatosensory evoked potential of lower limbs were examined to learn the rehabilitation of sensory and motor function at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. All the recovered spinal cord injury （SCI） tissues were observed with HE staining, immunohistochemistry, and transelectronmicroscopy to identify the survival, migration and differentiation of the transplanted cells and the regeneration of neural fibres at 4 weeks, 8 weeks,12 weeks and 24 weeks after injury.Results （1） From 4 weeks to 24 weeks after injury, the BBB locomotion scores of cell-transplanted groups were better than those of the non-cell-transplanted group, especially group C （P 〈0.05）. The amplitudes of the somatosensory evoked potential （SEP） and motor-evoked potential （MEP） were improved after injury in groups B and C, but the amplitude of SEP and MEP at 4 weeks was lower than that at 12 weeks and 24 weeks after injury. Com
基金the support received from the Australian Government through a Research Training Program(RTP)Scholarshipthe support received from the School of Engineering,RMIT Universitythe support received from the Australian Research Council(ARC)Research Hub for Future Fibres(IH140100018)funded by the Australian Government
文摘Graphene nanoplatelets （GNPs） were used as multifunctional nanofiller to enhance thermal and mechanical properties as well as electrical conductivity of two different biodegradable thermoplastics： poly lactide （PLA） and poly （butylene adipate-co-terephthalate） （PBAT）. Morphological investigations showed different levels of GNP dispersion in the two matrices, and consequently physical properties of the two systems exhibited dissimilar behaviours with GNP incorporation. Crystallinity of PLA, determined from differential scanning calorimetry, was observed to increase markedly with addition of GNPs in contrast to the decrease in crystallinity of PBAT. Isothermal and non-isothermal thermogravimetric analyses also revealed a more significant delay in thermal decomposition of PLA upon addition of GNPs compared to that of PBAT. Furthermore, results showed that increasing GNP content of PLA and PBAT nanocomposites influenced their Young＇s modulus and electrical conductivity in different ways. Modulus of PBAT increased continuously with increasing GNP loading while that of PLA reached a maximum at 9wt% GNPs and then decreased. Moreover, despite the higher conductivity of pure PBAT compared to pure PLA, conductivity of PLA/GNP nanocomposites overtook that of PBATIGNP nanocomposites above a certain GNP concentration. This demonstrated the determining effect of nanoplatelets dispersion state on the matrices properties.
