BACKGROUND：It has been reported that chitosan nerve conduits could support axon elongation and improve relevant function during in vivo nerve regeneration. OBJECTIVE： To investigate in vitro biocompatibility of thre...BACKGROUND：It has been reported that chitosan nerve conduits could support axon elongation and improve relevant function during in vivo nerve regeneration. OBJECTIVE： To investigate in vitro biocompatibility of three novel, chitosan/polycation composite materials for nerve regeneration in cultured mouse Schwann cells and PC12 cells. DESIGN, TIME AND SETTING： The observational, control experiments for nerve tissue engineering were performed at the Department of Biological Sciences and Biotechnology of Tsinghua University from August 2007 to January 2008. MATERIALS： Mouse Schwann cells were isolated from the sciatic nerve of 5–7-day-old BALB/C mice. PC12 cells were purchased from the American Type Culture Collection （ATCC, USA）. Chitosan was purchased from Tsingdao Haisheng Co., China. Poly-L-lysine hydrochloride （PLL）, polyethyleneimine （PEI） poly-L-ornithine hydrobromide （POR）, and S-100 antibody was purchased from Sigma Chemical Co., USA. Cell Counting Kit-8 （CCK-8） was purchased from Dojindo Chemical Co., Japan. METHODS： Three chitosan/polycation composite materials for nerve regeneration （PLL-0.25, PEI-0.25, and POR-0.25） were produced by blending chitosan with 0.25% （w/w） poly-L-lysine, polyethyleneimine, and poly-L-ornithine. Pure chitosan was utilized as the control. After 3 days of culture, the morphology of mouse Schwann and PC12 cells cultured on all substrates was observed with an inverted phase contrast microscope. Mouse Schwann cells were stained by immunofluorescence labeling S-100 protein and nuclei, followed by identification with a confocal laser-scanning microscope. The amount of proliferating mouse Schwann and PC12 cells was determined by CCK-8 after 1, 3, and 5 days in culture. The level of PC12 cell differentiation on all substrates was assessed by measuring neurite length at 1, 3, and 5 days after seeding. MAIN OUTCOME MEASURES： Morphology and amount of proliferation of mouse Schwann cells and PC12 cells cultured on chitosan and three polycation-modified materials, as well as amount of differentiation in PC12 cells on these substrates. RESULTS： （1） Morphology of mouse Schwann cells and PC12 cells on all substrates： after 3 days in culture on three different chitosan/polycation composite substrates, Schwann cells were connected to each other and exhibited greater proliferation, compared to the chitosan control. In particular, on PLL-0.25 and POR-0.25 substrates, some cells congregated and nearly reached confluence. The PC12 cells on chitosan substrate, after 3 days in culture, maintained a round shape; few exhibited a bipolar shape and began to form neurite extensions. However, on PLL-0.25 and POR-0.25 substrates, most PC12 cells displayed a bipolar shape with obvious neurite outgrowth, and almost grew as an adherent, spreading monolayer. （2） Proliferation of mouse Schwann cells and PC12 cells on all substrates： on the first day, Schwann cell proliferation on the three composite substrates was significantly greater than the cells on chitosan control （P 〈 0.01）. After 3 and 5 days in culture, PLL-0.25 and POR-0.25 substrates resulted in greater cell proliferation when compared to pure chitosan （P 〈 0.01）. On the third and fifth day in culture PC12 cell proliferation on PLL-0.25 and POR-0.25 was significantly greater than on chitosan substrate （P 〈 0.01）. （3） Differentiation of PC12 cells on all substrates： at all time points, the average neurite length of cells cultured on composite materials was significantly longer than on chitosan control （P 〈 0.05-0.01）. Cells on PLL-0.25 exhibited the longest average neurite length at days 3 and 5. CONCLUSION： Mouse Schwann cells and PC12 cells exhibit in vitro biocompatibility with poly-L-lysine-and poly-L-ornithine-modified substrates, which indicates that these substrates could serve as suitable substrates for peripheral nerve regeneration.展开更多
The continued evolution of bacterial and fungal species poses a significant difficulty for the treatment of disease of microbial origin. Given this situation, the prevention of transmission of such microbial diseases ...The continued evolution of bacterial and fungal species poses a significant difficulty for the treatment of disease of microbial origin. Given this situation, the prevention of transmission of such microbial diseases becomes of increasing importance. Efforts of this laboratory have been directed toward the destruction of microbial species on environmental surfaces as a prophylaxis toward infection, and we herein report on the efficacy of a system that demonstrates activity against both Gram-positive and Gram-negative bacteria, as well as fungi. We report specifically herein on the use of fabric materials so activated for the destruction of these microbial species, useful for a variety of surfaces within hospital and related settings wherein transmission of microbial disease is a major problem, while these approaches are also applicable for a variety of other types of surfaces.展开更多
Molybdenum trioxide(MoO_(3))can be employed as an excellent host for intercalation due to its 2D lay-ered structure that connected by van der Waals interactions.Herein,a series of polyoxometalate-based MoO_(3) composi...Molybdenum trioxide(MoO_(3))can be employed as an excellent host for intercalation due to its 2D lay-ered structure that connected by van der Waals interactions.Herein,a series of polyoxometalate-based MoO_(3) composites(Al_(13)@MoO_(3))were successfully prepared by interpolating the Keggin-type polycationic AlO_(4)Al_(12)(OH)_(24)H_(2)O_(12)^(7+)(Al_(13))into MoO_(3)gallery.These composites can be applied to rapidly adsorb the anionic dye methyl orange(MO)through strong electrostatic interactions lead to compact and sta-ble gathering in the surrounding of the numerous charged Al_(13).Adsorption behaviors of composites with the different amount of Al_(13) were determined,these results revealed that Al_(13)-3.34%@MoO_(3)exhibited the most remarkable adsorption capacity.More importantly,the composite maintains superior adsorption capacity for five consecutive adsorption/desorption cycles,suggesting that Al_(13)@MoO_(3)can be an efficient and durable adsorbent.展开更多
F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase beha...F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes. Our results show that formation of polymer-actin complexes is cooperative, and morphology and growth of polymer-actin complexes depend on polycation species and concentrations of polycation and salt in a constant actin concentration. We found that the longitudinal growth and lateral growth of polymer-actin complexes are dominated by different factors. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolytc system have been discussed. Our results indicate that the semi-flexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth ofactin architectures in cell.展开更多
Background: Abdominal adhesions develop on damaged peritoneal surfaces and constitute a significant health related problem. Previous animal studies have shown promising anti-adhesive effects when administering the pol...Background: Abdominal adhesions develop on damaged peritoneal surfaces and constitute a significant health related problem. Previous animal studies have shown promising anti-adhesive effects when administering the polycation α-poly-L-lysine (αPL) and the polyanion poly-L-glutamate (PG) together. The objective of the study was to examine the effect of these differently charged polypeptides when administered by spraying and to evaluate any possible effect on fibrinolysis, fibrosis and inflammation. Methods: Rabbits were treated with PLPG after cecal abrasive surgery and analysis from peritoneal biopsies of active tPa/PAI-1 complex and from peritoneal fluid of IL-6 and active TGFb1 at day 0, 1, 4 and 10 were measured after surgery. Histological specimens were analyzed on day 10 regarding inflammation and fibrosis. Peritoneal adhesions were evaluated by adhesion score. All values were compared to the control group (NaCl). Results: PLPG-treated rabbits had a significant diminished adhesion score on day 10 as compared to the control group (p < 0.005). Significantly reduced collagen depositions on the peritoneum were seen in the PLPG group when evaluating the histological specimens (p < 0.05). No significant differences between the experimental and control groups were seen in peritoneal fluid when analyzing for active protein levels. Conclusion: This is the first study to investigate the effect on key parameters in adhesion formation as well as the preventive effect of the PLPG complex on abdominal adhesions in rabbits and also the first study where administration by spraying the polypeptides was used. PLPG was non-toxic in this setting and without significant differences in adhesion formation parameters and a significant reduction in adhesions was observed. This was verified both macroscopically and histologically.展开更多
基金National Basic Research Program of China, ("973" Program), No. 2005CB623905Tsinghua-Yue-Yuen Medical Science Fund, Beijing Municipal Science & Technology Commission, No. H060920050430the National Natural Science Foundation of China, No. 30670528, 30700848, 30772443
文摘BACKGROUND：It has been reported that chitosan nerve conduits could support axon elongation and improve relevant function during in vivo nerve regeneration. OBJECTIVE： To investigate in vitro biocompatibility of three novel, chitosan/polycation composite materials for nerve regeneration in cultured mouse Schwann cells and PC12 cells. DESIGN, TIME AND SETTING： The observational, control experiments for nerve tissue engineering were performed at the Department of Biological Sciences and Biotechnology of Tsinghua University from August 2007 to January 2008. MATERIALS： Mouse Schwann cells were isolated from the sciatic nerve of 5–7-day-old BALB/C mice. PC12 cells were purchased from the American Type Culture Collection （ATCC, USA）. Chitosan was purchased from Tsingdao Haisheng Co., China. Poly-L-lysine hydrochloride （PLL）, polyethyleneimine （PEI） poly-L-ornithine hydrobromide （POR）, and S-100 antibody was purchased from Sigma Chemical Co., USA. Cell Counting Kit-8 （CCK-8） was purchased from Dojindo Chemical Co., Japan. METHODS： Three chitosan/polycation composite materials for nerve regeneration （PLL-0.25, PEI-0.25, and POR-0.25） were produced by blending chitosan with 0.25% （w/w） poly-L-lysine, polyethyleneimine, and poly-L-ornithine. Pure chitosan was utilized as the control. After 3 days of culture, the morphology of mouse Schwann and PC12 cells cultured on all substrates was observed with an inverted phase contrast microscope. Mouse Schwann cells were stained by immunofluorescence labeling S-100 protein and nuclei, followed by identification with a confocal laser-scanning microscope. The amount of proliferating mouse Schwann and PC12 cells was determined by CCK-8 after 1, 3, and 5 days in culture. The level of PC12 cell differentiation on all substrates was assessed by measuring neurite length at 1, 3, and 5 days after seeding. MAIN OUTCOME MEASURES： Morphology and amount of proliferation of mouse Schwann cells and PC12 cells cultured on chitosan and three polycation-modified materials, as well as amount of differentiation in PC12 cells on these substrates. RESULTS： （1） Morphology of mouse Schwann cells and PC12 cells on all substrates： after 3 days in culture on three different chitosan/polycation composite substrates, Schwann cells were connected to each other and exhibited greater proliferation, compared to the chitosan control. In particular, on PLL-0.25 and POR-0.25 substrates, some cells congregated and nearly reached confluence. The PC12 cells on chitosan substrate, after 3 days in culture, maintained a round shape; few exhibited a bipolar shape and began to form neurite extensions. However, on PLL-0.25 and POR-0.25 substrates, most PC12 cells displayed a bipolar shape with obvious neurite outgrowth, and almost grew as an adherent, spreading monolayer. （2） Proliferation of mouse Schwann cells and PC12 cells on all substrates： on the first day, Schwann cell proliferation on the three composite substrates was significantly greater than the cells on chitosan control （P 〈 0.01）. After 3 and 5 days in culture, PLL-0.25 and POR-0.25 substrates resulted in greater cell proliferation when compared to pure chitosan （P 〈 0.01）. On the third and fifth day in culture PC12 cell proliferation on PLL-0.25 and POR-0.25 was significantly greater than on chitosan substrate （P 〈 0.01）. （3） Differentiation of PC12 cells on all substrates： at all time points, the average neurite length of cells cultured on composite materials was significantly longer than on chitosan control （P 〈 0.05-0.01）. Cells on PLL-0.25 exhibited the longest average neurite length at days 3 and 5. CONCLUSION： Mouse Schwann cells and PC12 cells exhibit in vitro biocompatibility with poly-L-lysine-and poly-L-ornithine-modified substrates, which indicates that these substrates could serve as suitable substrates for peripheral nerve regeneration.
文摘The continued evolution of bacterial and fungal species poses a significant difficulty for the treatment of disease of microbial origin. Given this situation, the prevention of transmission of such microbial diseases becomes of increasing importance. Efforts of this laboratory have been directed toward the destruction of microbial species on environmental surfaces as a prophylaxis toward infection, and we herein report on the efficacy of a system that demonstrates activity against both Gram-positive and Gram-negative bacteria, as well as fungi. We report specifically herein on the use of fabric materials so activated for the destruction of these microbial species, useful for a variety of surfaces within hospital and related settings wherein transmission of microbial disease is a major problem, while these approaches are also applicable for a variety of other types of surfaces.
基金the National Natural Science Foundation of China(Nos.21872021,21671033,22172022 and 22071019).
文摘Molybdenum trioxide(MoO_(3))can be employed as an excellent host for intercalation due to its 2D lay-ered structure that connected by van der Waals interactions.Herein,a series of polyoxometalate-based MoO_(3) composites(Al_(13)@MoO_(3))were successfully prepared by interpolating the Keggin-type polycationic AlO_(4)Al_(12)(OH)_(24)H_(2)O_(12)^(7+)(Al_(13))into MoO_(3)gallery.These composites can be applied to rapidly adsorb the anionic dye methyl orange(MO)through strong electrostatic interactions lead to compact and sta-ble gathering in the surrounding of the numerous charged Al_(13).Adsorption behaviors of composites with the different amount of Al_(13) were determined,these results revealed that Al_(13)-3.34%@MoO_(3)exhibited the most remarkable adsorption capacity.More importantly,the composite maintains superior adsorption capacity for five consecutive adsorption/desorption cycles,suggesting that Al_(13)@MoO_(3)can be an efficient and durable adsorbent.
基金This research is financially supported by SORST, JST and the Ministry of Education, Science, Sports, and Culture, Japan (Grant-in-Aid of Creative Scientific Research).
文摘F-actins are semi-flexible polyelectrolytes and can be assembled into large polymer-actin complex with polymorphism through electrostatic interaction with polycations. This study investigates the structural phase behavior and the growth of polymer-actin complexes in terms of its longitudinal and lateral sizes. Our results show that formation of polymer-actin complexes is cooperative, and morphology and growth of polymer-actin complexes depend on polycation species and concentrations of polycation and salt in a constant actin concentration. We found that the longitudinal growth and lateral growth of polymer-actin complexes are dominated by different factors. This induces the structural polymorphism of polymer-actin complexes. Major factors to influence the polymorphism of polymer-actin complexes in polyelectrolytc system have been discussed. Our results indicate that the semi-flexible polyelectrolyte nature of F-actins is important for controlling the morphology and growth ofactin architectures in cell.
文摘脂肪酶广泛应用于食品加工、生物柴油制备等领域。为了有效提高微生物脂肪酶的可利用度,将来源于南极嗜冷杆菌属(antarctic psychrotrophic bacterium,Psychrobacter sp.7195)的嗜冷脂肪酶(Lip7195)在大肠杆菌系统中进行高效可溶性表达优化,并进行酶学性能表征。首先对Lip7195基因进行大肠杆菌偏好密码子优化,并通过添加多聚阳离子氨基酸标签等手段,优化重组Lip7195的可溶性表达。结果显示,添加多聚阳离子氨基酸标签的方法有效增加了目的蛋白的可溶性。对纯化后的重组酶进行酶学定性,结果显示,在40℃、p H 9.0时,重组Lip7195酶活性最高,比酶活最高达10.9 U/mg;在30~40℃、p H 8.0~10.0范围,重组Lip7195具有较好的稳定性;Co^(2+)对酶活力有激活作用。研究结果表明,在保持嗜冷脂肪酶特有的酶学性质基础上,添加多聚阳离子氨基酸标签有效改善了其在原核表达中易形成包涵体的问题。
基金performed in parts due to grants from Ake Wiberg Foundation,Magnus Bergvall Foundation,Zoegas foundation and Regional hospital funds.
文摘Background: Abdominal adhesions develop on damaged peritoneal surfaces and constitute a significant health related problem. Previous animal studies have shown promising anti-adhesive effects when administering the polycation α-poly-L-lysine (αPL) and the polyanion poly-L-glutamate (PG) together. The objective of the study was to examine the effect of these differently charged polypeptides when administered by spraying and to evaluate any possible effect on fibrinolysis, fibrosis and inflammation. Methods: Rabbits were treated with PLPG after cecal abrasive surgery and analysis from peritoneal biopsies of active tPa/PAI-1 complex and from peritoneal fluid of IL-6 and active TGFb1 at day 0, 1, 4 and 10 were measured after surgery. Histological specimens were analyzed on day 10 regarding inflammation and fibrosis. Peritoneal adhesions were evaluated by adhesion score. All values were compared to the control group (NaCl). Results: PLPG-treated rabbits had a significant diminished adhesion score on day 10 as compared to the control group (p < 0.005). Significantly reduced collagen depositions on the peritoneum were seen in the PLPG group when evaluating the histological specimens (p < 0.05). No significant differences between the experimental and control groups were seen in peritoneal fluid when analyzing for active protein levels. Conclusion: This is the first study to investigate the effect on key parameters in adhesion formation as well as the preventive effect of the PLPG complex on abdominal adhesions in rabbits and also the first study where administration by spraying the polypeptides was used. PLPG was non-toxic in this setting and without significant differences in adhesion formation parameters and a significant reduction in adhesions was observed. This was verified both macroscopically and histologically.
