Post-traumatic peritendinous adhesion presents a significant challenge in clinical medicine.This study proposes the use of diamond-like carbon(DLC)deposited on polylactic acid(PLA)membranes as a biophysical mechanism ...Post-traumatic peritendinous adhesion presents a significant challenge in clinical medicine.This study proposes the use of diamond-like carbon(DLC)deposited on polylactic acid(PLA)membranes as a biophysical mechanism for anti-adhesion barrier to encase ruptured tendons in tendon-injured rats.The results indicate that PLA/DLC composite membrane exhibits more efficient anti-adhesion effect than PLA membrane,with histological score decreasing from 3.12±0.27 to 2.20±0.22 and anti-adhesion effectiveness increasing from 21.61%to 44.72%.Mechanistically,the abundant C=O bond functional groups on the surface of DLC can reduce reactive oxygen species level effectively;thus,the phosphorylation of NF-κB and M1 polarization of macrophages are inhibited.Consequently,excessive inflammatory response augmented by M1 macrophage-originated cytokines including interleukin-6(IL-6),interleukin-1β(IL-1β),and tumor necrosis factor-α(TNF-α)is largely reduced.For biocompatibility evaluation,PLA/DLC membrane is slowly absorbed within tissue and displays prolonged barrier effects compared to traditional PLA membranes.Further studies show the DLC depositing decelerates the release of degradation product lactic acid and its induction of macrophage M2 polarization by interfering esterase and PLA ester bonds,which further delays the fibrosis process.It was found that the PLA/DLC membrane possess an efficient biophysical mechanism for treatment of peritendinous adhesion.展开更多
A selection of 22 low-melting polymers was thermally and rheologically evaluated to be used as hot-melt adhesives in mixed-substrate joining samples. The choice of polymers was based on the published melting point. It...A selection of 22 low-melting polymers was thermally and rheologically evaluated to be used as hot-melt adhesives in mixed-substrate joining samples. The choice of polymers was based on the published melting point. It was required to include a broad variety of different polymers backbones to study the influence of the different polymers comprehensively. A tool-box of widely applicable tests was developed to judge if a thermoplastic polymer is suitable for a hot-melt adhesive application. Melting temperature (onset, peak and offset temperature) and melting enthalpy were determined using standardized methods. Rheological methods were used to characterize the shear rate dependence and the flow behavior at the application temperature. The wetting behavior of the polymers was evaluated with contact angle measurements. The adhesive strength of the most promising candidates was analyzed using the Lumi Frac-adhesion method including the failure pattern.展开更多
Objective To investigatewhether antioxidants inhibit adhesion of leukocytes to endothelium and furthermore, whether all antioxidants regulate NF-KB activation through a redox sensitive mechanism. Methods The effect of...Objective To investigatewhether antioxidants inhibit adhesion of leukocytes to endothelium and furthermore, whether all antioxidants regulate NF-KB activation through a redox sensitive mechanism. Methods The effect of the antioxidative substances pyrrolidin dithiocarbamat (PDTC), dichloroisocumarin (DCI), chrysin and probucol on the endothelial leukocyte adhesion were examined under near physiological flow conditions. The antioxidative activity of antioxidants was measured in a DCF fluorescence assay with flow cytometry. The activation of NF-kB in endothelial cells was investigated in a gel shift assay. Results PDTC and probucol did not show an inhibitory effect to the formation of intracellular H2O2 in TNFa activated human vascular endothelial cells (HUVEC) . Chrysin showed a moderate effect. DCI showed a strong antioxidative effect. In contrast, PDTC and chrysin inhibited the adhesion of HL 60 cells to TNFa-stimulated HUVEC. DCI and probucol did not have influence on the adhesion within the area of the examined shear stresses. Only PDTC inhibited the TNFa-induced activation of NF-KB in endothelial cells. Conclusion The inhibition of the endothelial leukocyte adhesion by antioxidative substances is not to be explained by its antioxidative characteristics only. The inhibitory effect of PDTC on NF-KB activation was probably not related to its antioxidative properties. Endothelial cell Antioxidants NF-kappa-B展开更多
Poor interfacial adhesion between biobased thermoplastics and natural fibers is recognized as a major drawback for biocomposites.To be applicable for the large-scale production,a simple method to handle is of importan...Poor interfacial adhesion between biobased thermoplastics and natural fibers is recognized as a major drawback for biocomposites.To be applicable for the large-scale production,a simple method to handle is of importance.This work presented poly(lactic acid)(PLA)reinforced with short-fiber and three reactive agents including anhydride and epoxide groups were selected as compatibilizers.Biocomposites were prepared by one-step meltmixing methods.The influence of reactive agents on mechanical,dynamic mechanical properties and morphology of PLA biocomposites were investigated.Tensile strength and storage modulus of PLA biocomposites incorporated with epoxide-based reactive agent was increased 13.9%and 37.4%compared to non-compatibilized PLA biocomposite,which was higher than adding anhydride-based reactive agent.SEM micrographs and Molau test exhibited an improvement of interfacial fiber-matrix adhesion in the PLA biocomposites incorporated with epoxide-based reactive agent.FTIR revealed the chemical reaction between the fiber and PLA with the presence of epoxide-based reactive agents.展开更多
Tens of billion metric tons of anthropogenic CO_2 discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO_2 to desirable, economical chemicals ...Tens of billion metric tons of anthropogenic CO_2 discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO_2 to desirable, economical chemicals and materials. Poly（propylene carbonate）（PPC） is an emerging CO_2-based material. Herein, we report the design, synthesis and characterization of the reactive hot melt polyurethane adhesive（RHMPA） based on PPC polyol. The resultant RHMPAs exhibit good adhesion properties to multiple substrates including plastics（PC, PMMA, ABS） and metals（aluminium, steel）, which is comparable to or even better than conventional RHMPAs prepared from petro-based polyol. Furthermore, the PPC-based RHMPAs have tunable mechanical properties, and are thermally stable in the typical working range of bonding process（up to 270 °C）. The study is expected to expand the applications of PPC and provide a new type of CO_2-based renewable and eco-friendly materials.展开更多
To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a o...To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a one-step solvent-free modification method.The effects of KH560 as a compatibilizer on the morphology,chemical structure,crystallization behavior,thermal degradative behavior as well as mechanical strength of the PLA/lignin composites were analyzed in detail.It was found that,after modification by KH560,the fractured surfaces of composites became smooth,suggested sufficient bonding between the lignin and PLA in the composites with KH560 coupling agent molecules.This result further proved by 1H NMR and ATR spectra of the composites that lignin and PLA formed stable chemical bonds with KH560.Due to the toughening effect of KH560,mainly affect the molecular chain mobility,the thermodynamic properties of LG-KH560/PLA composites were all reduced.When compared to the conventional solution modification method of adding silane coupling agents into PLA/lignin,the composites were synthesized via a single-step reactive extrusion modification procedure in this work showed relatively low tensile strength,which mainly because the existence of the free radicals due to coupling agents result in the composite’s deterioration and subsequent weakening of the tensile properties.展开更多
Background The vascular endothelial growth factor （VEGF） is involved in the initiation of retinal vascular leakage and nonperfusion in diabetes. The intracellular adhesion molecule-1 （ICAM-1） is the key mediator o...Background The vascular endothelial growth factor （VEGF） is involved in the initiation of retinal vascular leakage and nonperfusion in diabetes. The intracellular adhesion molecule-1 （ICAM-1） is the key mediator of the effect of VEGFs on retinal leukostasis. Although the VEGF is expressed in an early-stage diabetic retina, whether it directly up-regulates ICAM-1 in retinal endothelial cells （ECs） is unknown. In this study, we provided a new mechanism to explain that VEGF does up-regulate the expression of ICAM-1 in retinal ECs. Methods Bovine retinal ECs （BRECs） were isolated and cultured. Immunohistochemical staining was performed to identify BRECs. The cultured cells were divided into corresponding groups. Then, VEGF （100 ng/ml） and other inhibitors were used to treat the cells. Cell lysate and the cultured supernatant were collected, and then, the protein level of ICAM-1 and phosphorylation of the endothelial nitric oxide synthase （eNOS） were detected using Western blotting. Griess reaction was used to detect nitric oxide （NO）. Results Western blotting showed that the VEGF up-regulated the expression of ICAM-1 protein and increased phosphorylation of the eNOS in retinal ECs. Neither the block of NO nor protein kinase C （PKC） altered the expression of ICAM-1 or the phosphorylation of eNOS. The result of the Western blotting also showed that inhibition of phosphatidylinositol 3-kinase （PI3K） or reactive oxygen species （ROS） significantly reduced the expression of ICAM-1. Inhibition of PI3K also reduced phosphorylation of eNOS. Griess reaction showed that VEGF significantly increased during NO production. When eNOS was blocked by L-NAME or PI3K was blocked by LY294002, the basal level of NO production and the increment of NO caused by VEGF could be significantly decreased. Conclusion ROS-NO coupling in the retinal endothelium may be a new mechanism that could help to explain why VEGF induces ICAM-1 expression and the resulting leukostasis in diabetic retinopathy.展开更多
基金supported by the National Natural Science Foundation of China(No.82172408,81772314,and 81922045)the Original Exploration project(22ZR1480300)+5 种基金Outstanding Academic Leaders(Youth)project(21XD1422900)of Shanghai Science and Technology Innovation Action PlanPrinciple Investigator Innovation Team of Both Shanghai Sixth People’s Hospital and Shanghai Institute of Nutrition and Health,Shanghai Jiao Tong University Medical College“Two-hundred Talent”Program(No.20191829)The Second Three-Year Action Plan for Promoting Clinical Skills and Clinical Innovation in Municipal Hospitals of Shanghai Shenkang(No.SHDC2020CR4032)Shanghai Excellent Academic Leader ProgramShanghai Engineering Research Center for Orthopaedic Material Innovation and Tissue Regeneration(No.20DZ2254100)China Postdoctoral Science Foundation(2023M742347).
文摘Post-traumatic peritendinous adhesion presents a significant challenge in clinical medicine.This study proposes the use of diamond-like carbon(DLC)deposited on polylactic acid(PLA)membranes as a biophysical mechanism for anti-adhesion barrier to encase ruptured tendons in tendon-injured rats.The results indicate that PLA/DLC composite membrane exhibits more efficient anti-adhesion effect than PLA membrane,with histological score decreasing from 3.12±0.27 to 2.20±0.22 and anti-adhesion effectiveness increasing from 21.61%to 44.72%.Mechanistically,the abundant C=O bond functional groups on the surface of DLC can reduce reactive oxygen species level effectively;thus,the phosphorylation of NF-κB and M1 polarization of macrophages are inhibited.Consequently,excessive inflammatory response augmented by M1 macrophage-originated cytokines including interleukin-6(IL-6),interleukin-1β(IL-1β),and tumor necrosis factor-α(TNF-α)is largely reduced.For biocompatibility evaluation,PLA/DLC membrane is slowly absorbed within tissue and displays prolonged barrier effects compared to traditional PLA membranes.Further studies show the DLC depositing decelerates the release of degradation product lactic acid and its induction of macrophage M2 polarization by interfering esterase and PLA ester bonds,which further delays the fibrosis process.It was found that the PLA/DLC membrane possess an efficient biophysical mechanism for treatment of peritendinous adhesion.
文摘A selection of 22 low-melting polymers was thermally and rheologically evaluated to be used as hot-melt adhesives in mixed-substrate joining samples. The choice of polymers was based on the published melting point. It was required to include a broad variety of different polymers backbones to study the influence of the different polymers comprehensively. A tool-box of widely applicable tests was developed to judge if a thermoplastic polymer is suitable for a hot-melt adhesive application. Melting temperature (onset, peak and offset temperature) and melting enthalpy were determined using standardized methods. Rheological methods were used to characterize the shear rate dependence and the flow behavior at the application temperature. The wetting behavior of the polymers was evaluated with contact angle measurements. The adhesive strength of the most promising candidates was analyzed using the Lumi Frac-adhesion method including the failure pattern.
文摘Objective To investigatewhether antioxidants inhibit adhesion of leukocytes to endothelium and furthermore, whether all antioxidants regulate NF-KB activation through a redox sensitive mechanism. Methods The effect of the antioxidative substances pyrrolidin dithiocarbamat (PDTC), dichloroisocumarin (DCI), chrysin and probucol on the endothelial leukocyte adhesion were examined under near physiological flow conditions. The antioxidative activity of antioxidants was measured in a DCF fluorescence assay with flow cytometry. The activation of NF-kB in endothelial cells was investigated in a gel shift assay. Results PDTC and probucol did not show an inhibitory effect to the formation of intracellular H2O2 in TNFa activated human vascular endothelial cells (HUVEC) . Chrysin showed a moderate effect. DCI showed a strong antioxidative effect. In contrast, PDTC and chrysin inhibited the adhesion of HL 60 cells to TNFa-stimulated HUVEC. DCI and probucol did not have influence on the adhesion within the area of the examined shear stresses. Only PDTC inhibited the TNFa-induced activation of NF-KB in endothelial cells. Conclusion The inhibition of the endothelial leukocyte adhesion by antioxidative substances is not to be explained by its antioxidative characteristics only. The inhibitory effect of PDTC on NF-KB activation was probably not related to its antioxidative properties. Endothelial cell Antioxidants NF-kappa-B
文摘Poor interfacial adhesion between biobased thermoplastics and natural fibers is recognized as a major drawback for biocomposites.To be applicable for the large-scale production,a simple method to handle is of importance.This work presented poly(lactic acid)(PLA)reinforced with short-fiber and three reactive agents including anhydride and epoxide groups were selected as compatibilizers.Biocomposites were prepared by one-step meltmixing methods.The influence of reactive agents on mechanical,dynamic mechanical properties and morphology of PLA biocomposites were investigated.Tensile strength and storage modulus of PLA biocomposites incorporated with epoxide-based reactive agent was increased 13.9%and 37.4%compared to non-compatibilized PLA biocomposite,which was higher than adding anhydride-based reactive agent.SEM micrographs and Molau test exhibited an improvement of interfacial fiber-matrix adhesion in the PLA biocomposites incorporated with epoxide-based reactive agent.FTIR revealed the chemical reaction between the fiber and PLA with the presence of epoxide-based reactive agents.
基金financially supported by the National Natural Science Foundation of China(Nos.21574019 and 21304015)the Fundamental Research Funds for the Central Universities and the DHU Distinguished Young Professor Program(No.B201303)
文摘Tens of billion metric tons of anthropogenic CO_2 discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO_2 to desirable, economical chemicals and materials. Poly（propylene carbonate）（PPC） is an emerging CO_2-based material. Herein, we report the design, synthesis and characterization of the reactive hot melt polyurethane adhesive（RHMPA） based on PPC polyol. The resultant RHMPAs exhibit good adhesion properties to multiple substrates including plastics（PC, PMMA, ABS） and metals（aluminium, steel）, which is comparable to or even better than conventional RHMPAs prepared from petro-based polyol. Furthermore, the PPC-based RHMPAs have tunable mechanical properties, and are thermally stable in the typical working range of bonding process（up to 270 °C）. The study is expected to expand the applications of PPC and provide a new type of CO_2-based renewable and eco-friendly materials.
基金funded by the National Key Research and Development Program of China(grant number:2019YFD1101201)the National Natural Science Foundation of China(grant numbers:51773005 and 21905008)the Beijing Natural Science Foundation(grant number:2194071).
文摘To clarify the effects of lignin as a biodegradable filler added into the PLA matrix,PLA/lignin composites with or without silane coupling agent ofγ-(2,3-epoxypropoxy)propy trimethoxysilane(KH560)were prepared by a one-step solvent-free modification method.The effects of KH560 as a compatibilizer on the morphology,chemical structure,crystallization behavior,thermal degradative behavior as well as mechanical strength of the PLA/lignin composites were analyzed in detail.It was found that,after modification by KH560,the fractured surfaces of composites became smooth,suggested sufficient bonding between the lignin and PLA in the composites with KH560 coupling agent molecules.This result further proved by 1H NMR and ATR spectra of the composites that lignin and PLA formed stable chemical bonds with KH560.Due to the toughening effect of KH560,mainly affect the molecular chain mobility,the thermodynamic properties of LG-KH560/PLA composites were all reduced.When compared to the conventional solution modification method of adding silane coupling agents into PLA/lignin,the composites were synthesized via a single-step reactive extrusion modification procedure in this work showed relatively low tensile strength,which mainly because the existence of the free radicals due to coupling agents result in the composite’s deterioration and subsequent weakening of the tensile properties.
基金This study was supported in part by grants from the National Natural Science Foundation of China （No. 30571994, No. 30570713 and No. 30630032）.
文摘Background The vascular endothelial growth factor （VEGF） is involved in the initiation of retinal vascular leakage and nonperfusion in diabetes. The intracellular adhesion molecule-1 （ICAM-1） is the key mediator of the effect of VEGFs on retinal leukostasis. Although the VEGF is expressed in an early-stage diabetic retina, whether it directly up-regulates ICAM-1 in retinal endothelial cells （ECs） is unknown. In this study, we provided a new mechanism to explain that VEGF does up-regulate the expression of ICAM-1 in retinal ECs. Methods Bovine retinal ECs （BRECs） were isolated and cultured. Immunohistochemical staining was performed to identify BRECs. The cultured cells were divided into corresponding groups. Then, VEGF （100 ng/ml） and other inhibitors were used to treat the cells. Cell lysate and the cultured supernatant were collected, and then, the protein level of ICAM-1 and phosphorylation of the endothelial nitric oxide synthase （eNOS） were detected using Western blotting. Griess reaction was used to detect nitric oxide （NO）. Results Western blotting showed that the VEGF up-regulated the expression of ICAM-1 protein and increased phosphorylation of the eNOS in retinal ECs. Neither the block of NO nor protein kinase C （PKC） altered the expression of ICAM-1 or the phosphorylation of eNOS. The result of the Western blotting also showed that inhibition of phosphatidylinositol 3-kinase （PI3K） or reactive oxygen species （ROS） significantly reduced the expression of ICAM-1. Inhibition of PI3K also reduced phosphorylation of eNOS. Griess reaction showed that VEGF significantly increased during NO production. When eNOS was blocked by L-NAME or PI3K was blocked by LY294002, the basal level of NO production and the increment of NO caused by VEGF could be significantly decreased. Conclusion ROS-NO coupling in the retinal endothelium may be a new mechanism that could help to explain why VEGF induces ICAM-1 expression and the resulting leukostasis in diabetic retinopathy.
