Biodegradable poly （D,L-lactide） （PLA）/carboxyl-functionalized multi-walled carbon nanotubes （c-MWCNTs） composites were achieved via in-situ polymerization. These as-prepared composite materials were characteriz...Biodegradable poly （D,L-lactide） （PLA）/carboxyl-functionalized multi-walled carbon nanotubes （c-MWCNTs） composites were achieved via in-situ polymerization. These as-prepared composite materials were characterized with FT-IR, XRD, TG, DSC, SEM, and high insulation resistance meter. The results demonstrate that the multi-walled carbon nanotube was carboxyl functionalized, which improved the collection between c-MWCNTs and PLA, and further realized the graft copolymerization of c-MWCNTs and PLA. There is a higher glass transition temperature and a lower pyrolysis temperature of PLA/c-MWCNTs composites than pure PLA. The c-MWCNTs gave a better dispersion than unmodified MWCNTs in the PLA matrix, and an even coating of PLA on the surface of c-MWCNTs was obtained, which increased the interfacial interaction. High insulation resistance analysis showed that the addition of c-MWCNTs increased the electric conductivity, and c-MWCNTs performed against the large dielectric coefficient and electrostatic state of PLA. These results demonstrated that c-MWCNTs modified PLA composites were beneficial for potential application in the development of heat-resisting and conductivity plastic engineering.展开更多
Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synt...Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synthesis of sulfonic acid immobilized organic nanoparticles （nanoacid） and its application in catalyzing urethane formation, are elaborated. The nanoacid can be simply prepared by miniemulsion polymerization with a reactive surfacrant, namely sodium 4-（（perfluoronon-8-en-l-yl）oxy）benzenesulfonate, followed by an acidification. From the images of scanning electron microscope, the nanoacid obtained is found to be narrowly dispersed and the average diameter is around 90 nm. The measured sulfur content is 0.5%, from which the content of sulfonic acid in the nanoparticles is calculated to be 0.16 mmol/g. When catalyzing urethane formation based on hexamethylene diisocyanate and n-butanol, the nanoacid catalyst exhibits considerable efficiency.展开更多
Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these ...Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.展开更多
Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl ...Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.展开更多
A comparison of thermal and photochemical degradation of poly （lactic acid） film materials （10/am） containing nanosilver are studied by FTlR （Fourier transform infrared） spectroscopy and DSC （differential scann...A comparison of thermal and photochemical degradation of poly （lactic acid） film materials （10/am） containing nanosilver are studied by FTlR （Fourier transform infrared） spectroscopy and DSC （differential scanning calorimetry）. Rates of thermal and photochemical degradation are determined by measuring the relative changes of absorbance （A/Ao） of selected bands in PLA （polylactic acid） spectra. Comparison of the effect of both degradation on PLA structure showed that nanosilver act as a stabilizer for photodegradation at 254 nm. As oppose, thermal degradation at 80 ~C indicate, that nanosilver accelerates PLA degradation at the temperature. Glass transition and crystallization/melting processes occurring in PLA and PLA/Ag nanocomposites during both degradation processes were also compared.展开更多
Recent work regarding the Layer by Layer （LbL） engineering of poly（lactide-co-glycolide） nanoparticles （PLGA NPs） is reviewed here. The LbL engineering of PLGA NPs is applied as a means of generating advanced dr...Recent work regarding the Layer by Layer （LbL） engineering of poly（lactide-co-glycolide） nanoparticles （PLGA NPs） is reviewed here. The LbL engineering of PLGA NPs is applied as a means of generating advanced drug delivery devices with tailored recognition, protection, cargo and release properties. LbL in combination with covalent chemistry is used to attach PEG and folic acid to control cell uptake and direct it towards cancer cells. LbL coatings composed of chitosan and alginate show low protein interactions and can be used as an alternative to Pegylation. The assembly on top of LbL coatings of lipid layers composed of variable percentages of 1,2-dioleoyl-sn-glycero-3-choline （DOPC） and 1,2-dioleoyl-sn-glycero-3-phospho- L-serine （DOPS） increases NP uptake and directs the NPs towards the endoplasmic reticulum. The antibody anti-TNF-ct is encapsulated forming a complex with alginate that is assembled LbL on top of PLGA NPs. The antibody is released in cell culture following first order kinetics. The release kinetics of encapsulated molecules inside PLGA NPs are studied when the PLGA NPs are coated via LbL with different polyelectrolytes. The intracellular release of encapsulated Doxorubicin is studied in the HepG2 cell line by means of Fluorescence Lifetime Imaging.展开更多
The key to improve the therapeutic efficacy for cancer treatment is to increase the delivery of drugs to tumors.For this purpose, tumor-microenvironment stimuliresponsive materials have great potential. Here, we prepa...The key to improve the therapeutic efficacy for cancer treatment is to increase the delivery of drugs to tumors.For this purpose, tumor-microenvironment stimuliresponsive materials have great potential. Here, we prepared a new nanomedicine by bonding the conjugate of honokiol(HNK) and 5,6-dimethylxanthenone-4-acetic acid(DMXAA)to a glutathione(GSH)-responsive nanocarrier, poly(α-lipoic acid) polyethylene glycol. The nanomedicine would disintegrate due to the high level of GSH at the tumor sites,achieving the co-delivery of HNK and DMXAA, and realizing the combination therapy through close-range killing by HNK and long-range striking by DMXAA together. In a murine 4T1 breast tumor model, this strategy exhibited high tumor inhibition rate of 93%, and provided a valuable therapeutic choice for cancer therapy.展开更多
基金Projects(21107032,51073072)supported by the National Natural Science Foundation of ChinaProjects(Y406469,Y4110555,Y4100745)supported by Natural Science Foundation of Zhejiang Province,ChinaProjects(2011AY1048-5,2011AY1030)supported by the Science Foundation of Jiaxing Science and Technology Bureau,China
文摘Biodegradable poly （D,L-lactide） （PLA）/carboxyl-functionalized multi-walled carbon nanotubes （c-MWCNTs） composites were achieved via in-situ polymerization. These as-prepared composite materials were characterized with FT-IR, XRD, TG, DSC, SEM, and high insulation resistance meter. The results demonstrate that the multi-walled carbon nanotube was carboxyl functionalized, which improved the collection between c-MWCNTs and PLA, and further realized the graft copolymerization of c-MWCNTs and PLA. There is a higher glass transition temperature and a lower pyrolysis temperature of PLA/c-MWCNTs composites than pure PLA. The c-MWCNTs gave a better dispersion than unmodified MWCNTs in the PLA matrix, and an even coating of PLA on the surface of c-MWCNTs was obtained, which increased the interfacial interaction. High insulation resistance analysis showed that the addition of c-MWCNTs increased the electric conductivity, and c-MWCNTs performed against the large dielectric coefficient and electrostatic state of PLA. These results demonstrated that c-MWCNTs modified PLA composites were beneficial for potential application in the development of heat-resisting and conductivity plastic engineering.
文摘Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synthesis of sulfonic acid immobilized organic nanoparticles （nanoacid） and its application in catalyzing urethane formation, are elaborated. The nanoacid can be simply prepared by miniemulsion polymerization with a reactive surfacrant, namely sodium 4-（（perfluoronon-8-en-l-yl）oxy）benzenesulfonate, followed by an acidification. From the images of scanning electron microscope, the nanoacid obtained is found to be narrowly dispersed and the average diameter is around 90 nm. The measured sulfur content is 0.5%, from which the content of sulfonic acid in the nanoparticles is calculated to be 0.16 mmol/g. When catalyzing urethane formation based on hexamethylene diisocyanate and n-butanol, the nanoacid catalyst exhibits considerable efficiency.
基金supported by the Program for Creation of Interdisciplinary Research and Ensemble Program of Frontier Research Institute for Interdisciplinary Sciences,Tohoku University。
文摘Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.
文摘Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.
文摘A comparison of thermal and photochemical degradation of poly （lactic acid） film materials （10/am） containing nanosilver are studied by FTlR （Fourier transform infrared） spectroscopy and DSC （differential scanning calorimetry）. Rates of thermal and photochemical degradation are determined by measuring the relative changes of absorbance （A/Ao） of selected bands in PLA （polylactic acid） spectra. Comparison of the effect of both degradation on PLA structure showed that nanosilver act as a stabilizer for photodegradation at 254 nm. As oppose, thermal degradation at 80 ~C indicate, that nanosilver accelerates PLA degradation at the temperature. Glass transition and crystallization/melting processes occurring in PLA and PLA/Ag nanocomposites during both degradation processes were also compared.
基金funded by the Spanish Ministry of Science and Innovation(MAT2010-18995)the Marie Curie project "Transport Studies on Polymer Based Nanodevices and Assemblies for Delivery and Sensing"(TRASNADE) (- FP7 People International Research Staff Exchange Scheme Grant reference:247656)the Marie Curie Project "Design of Novel Polyelectrolyte Multilayer Based Delivery Systems for Therapeutic Antibodies and siRNA" (DeSIRNA) (FP7-People IAPP Grant reference 251646)
文摘Recent work regarding the Layer by Layer （LbL） engineering of poly（lactide-co-glycolide） nanoparticles （PLGA NPs） is reviewed here. The LbL engineering of PLGA NPs is applied as a means of generating advanced drug delivery devices with tailored recognition, protection, cargo and release properties. LbL in combination with covalent chemistry is used to attach PEG and folic acid to control cell uptake and direct it towards cancer cells. LbL coatings composed of chitosan and alginate show low protein interactions and can be used as an alternative to Pegylation. The assembly on top of LbL coatings of lipid layers composed of variable percentages of 1,2-dioleoyl-sn-glycero-3-choline （DOPC） and 1,2-dioleoyl-sn-glycero-3-phospho- L-serine （DOPS） increases NP uptake and directs the NPs towards the endoplasmic reticulum. The antibody anti-TNF-ct is encapsulated forming a complex with alginate that is assembled LbL on top of PLGA NPs. The antibody is released in cell culture following first order kinetics. The release kinetics of encapsulated molecules inside PLGA NPs are studied when the PLGA NPs are coated via LbL with different polyelectrolytes. The intracellular release of encapsulated Doxorubicin is studied in the HepG2 cell line by means of Fluorescence Lifetime Imaging.
基金supported by the Ministry of Science and Technology of China (2018ZX09711003-012)the National Natural Science Foundation of China (51873206, 51673189, 51829302, 51503202, 51833010 and 51520105004)the Program of Scientific Development of Jilin Province (20190103033JH)
文摘The key to improve the therapeutic efficacy for cancer treatment is to increase the delivery of drugs to tumors.For this purpose, tumor-microenvironment stimuliresponsive materials have great potential. Here, we prepared a new nanomedicine by bonding the conjugate of honokiol(HNK) and 5,6-dimethylxanthenone-4-acetic acid(DMXAA)to a glutathione(GSH)-responsive nanocarrier, poly(α-lipoic acid) polyethylene glycol. The nanomedicine would disintegrate due to the high level of GSH at the tumor sites,achieving the co-delivery of HNK and DMXAA, and realizing the combination therapy through close-range killing by HNK and long-range striking by DMXAA together. In a murine 4T1 breast tumor model, this strategy exhibited high tumor inhibition rate of 93%, and provided a valuable therapeutic choice for cancer therapy.
