The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous de...The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous development of such recyclable polymers.Herein,PPDOPLLA-PU copolymers were synthesized from poly(p-dioxanone)-diol(PPDO-diol)and poly(L-lactide)-diol(PLLA-diol)by chain extension reaction.The chemical structures and microphase structures of PPDO-PLLA-PU were characterized,and their crystalline properties,mechanical properties,and degradation behaviors were further investigated.Significantly,the distribution of PLLA phase in the copolymer matrix showed a rod-like microstructure with a slight orientation,despite the thermodynamic incompatibility of PPDO and PLLA segments.Moreover,on the basis of this microphase separation,PPDO spherulites can crystallize using the interface of the two phases as nucleation sites.Accordingly,the combined effect of above two contributes to the enhanced mechanical properties.In addition,PPDO-PLLA-PU copolymers have good processability and recyclability,making them valuable for a wide range of applications.展开更多
Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical mic...Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix(ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties,biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone)(PDO) and poly(ester-urethane)ureas(PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break.Furthermore, human umbilical vein endothelial cells(HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats(60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.展开更多
The effects of temperature and relative humidity on the hydrolytic degradation of poly（p-dioxanone）（PPDO） were investigated. The hydrolytic degradation behaviors were monitored by tracing the changes of water abso...The effects of temperature and relative humidity on the hydrolytic degradation of poly（p-dioxanone）（PPDO） were investigated. The hydrolytic degradation behaviors were monitored by tracing the changes of water absorption, mechanical and crystalline properties, molecular weight and its distribution, surface morphologies, as well as infrared absorption peaks and hydrogen chemical shifts during the degradation. It is found that the water absorption increases whilst the intrinsic viscosity, tensile strength and elongation at break decrease as the temperature or relative humidity increases. With degradation time growing, the molecular weight drops and its distribution broadens. The crystallinity of PPDO has a tendency to increase at first and then to decrease, while the crystalline structure is not significantly changed. At the same time, some cracks are observed on the surface and keep growing and deepening. All results show that temperature plays more significant roles than relative humidity during the degradation. The analyses of Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy reveal that the degradation of PPDO is a predominant hydrolysis of ester linkages.展开更多
Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The p...Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The precursors and the composites were characterized by1 H NMR, FT-IR, GPC, SEM and TEM.The results demonstrate that a part of PCL segments grafted on the surface of OSEP and composites display a fine dispersion of OSEP fiber in nanoscale with low OSEP content. The shape memory effect（SME） was evaluated by DMA, the results reveal that the PPDO–PCL/OSEP nanocomposites exhibit desirable shape-memory performance. The reinforcement of composites by incorporation of trace OSEP nanofiber evokes an effective improvement in shape-memory recovery stress.展开更多
Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain ...Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy(1 H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO.展开更多
A series of novel poly(urethane-urea)(PUU)was synthesized from poly(lactide-co-p-dioxanone)macrodiol(HO-P(LA-co-PDO)-OH),hexamethylene diisocyanate(HDI)and butanediamine(BDA).The obtained PUU,which is recorded as P(LA...A series of novel poly(urethane-urea)(PUU)was synthesized from poly(lactide-co-p-dioxanone)macrodiol(HO-P(LA-co-PDO)-OH),hexamethylene diisocyanate(HDI)and butanediamine(BDA).The obtained PUU,which is recorded as P(LA-co-PDO)-PUU here,may demonstrate enhanced phase separation and thus improved shape memory property.FTIR was employed to characterize the copolymers,and the effects of NCO/OH molar ratios on Tg of PUU was investigated by means of differential scanning calorimetry(DSC).The results revealed the successful synthesis of P(LA-co-PDO)-PUU.In addition,the Tg of P(LA-co-PDO)-PUU increased from 37.9℃to 44.2℃with the increase NCO/OH ratios from 1.1 to 1.2.The P(LA-co-PDO)-PUU with Tg close to body temperature will have potential applications as shape memory polymers in biomedical fields,especially in minimally invasive surgery.展开更多
Integrating poly（lactic acid） （PLA）, glycolic acid （GA） and ethylene glycol （EG） will hopefully result in a novel copolymer that combines such advantages as fastened and controllable release rate and improved ...Integrating poly（lactic acid） （PLA）, glycolic acid （GA） and ethylene glycol （EG） will hopefully result in a novel copolymer that combines such advantages as fastened and controllable release rate and improved flexibility together with good biocompatibility. In this study, p-dioxanone （PDO） was employed to copolymerize with DL-lactide （LA） via ring-opening melt polymerization using Sn（Oct）2 as an initiator and ethylene glycol as a co-initiator. The obtained degradable macrodiols （HO-P（LA-co-PDO）-OH） were just such a copolymer consisting of PLA, GA and EG. 1HNMR was employed to characterize the copolymers, and the effect of PDO/LA molar ratios in the feedstock on the molecular weights of HO-P（LA-co-PDO）-OH was investigated by means of endhydroxyl analysis, 1H NMR or GPC-MALLs. The results confirmed the successful synthesis of HO-P（LA-co-PDO）-OH and revealed that one end-hydroxyl of the micarodiols was donated by LA or PDO and the other one by the co-initiator EG. In addition, the molecular weights of HO-P（LA-co-PDO）-OH increased with decreasing PDO/LA ratios.展开更多
Poly（p-dioxanone）-block-polyethylene glycol diblock copolymers functionalized with pyrene moieties（Py-PPDO-b-PEG） at the chain ends of PPDO blocks were synthesized for preparing anisotropic micelles with improved ...Poly（p-dioxanone）-block-polyethylene glycol diblock copolymers functionalized with pyrene moieties（Py-PPDO-b-PEG） at the chain ends of PPDO blocks were synthesized for preparing anisotropic micelles with improved stability.The micellization and crystallization of the copolymers were investigated by nano differential scanning calorimetry（Nano DSC）,transmission electron microscopy（TEM）,UV-vis spectrophotometery,fluorophotometer,and dynamic light scattering（DLS）,respectively.The results indicated that the aggregation of pyrene induced by intermolecular interaction lead to micellization of Py-PPDO-b-PEG at much lower concentrations than those of PPDO-b-PEG copolymers without pyrene moieties.The aggregation of pyrene moieties may also serve as nucleation agent and therefore enhance the crystallization rate of PPDO blocks.Fluorescence measurements by using Nile Red as the fluorescent agent indicated that the micelles of Py-PPDO-b-PEG have high stability and load capacity for hydrophobic molecules.展开更多
Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The eff...Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In th...展开更多
In order to expand the application of poly（p-dioxanone） or PPDO in biomedical area,a series of novel copolymers were synthesized successfully by one-step,melted copolymerization of p-dioxanone（PDO） and L-phenylala...In order to expand the application of poly（p-dioxanone） or PPDO in biomedical area,a series of novel copolymers were synthesized successfully by one-step,melted copolymerization of p-dioxanone（PDO） and L-phenylalanine N-carboxyanhydride（L-Phe-NCA） monomers.With the in-feed molar ratio of L-PheNCA /PDO equal to 1/20,the conversions of the two kinds of monomers were calculated from 1H NMR. The average molecular weight and polydispersity of the copolymer increase with the increasing reaction time and catalyst concentration.However,the conversions of the two kinds of monomers did not change with the reaction conditions.A three-step mechanism is presented and proved by high resolution 1H NMR and IR spectrums.展开更多
Poly（d,l-lactide-co-p-dioxanone） （P（LA-co-PDO）） copolymers with different chain microstructures were synthesized by onestep or two-step bulk ring-opening polymerizations of d,l-lactide （LA） and p-dioxanone （...Poly（d,l-lactide-co-p-dioxanone） （P（LA-co-PDO）） copolymers with different chain microstructures were synthesized by onestep or two-step bulk ring-opening polymerizations of d,l-lactide （LA） and p-dioxanone （PDO） monomers using stannous octoate [Sn（Oct）2]/n-dodecanol as the initiating system. The average sequence lengths of the lactidyl （LLA） and dioxanyl （LpDo） units were calculated from the ^1H NMR spectra. It was found that both LLA and Lpoo values from the two-step syntheses were significantly longer than those from the corresponding one-step syntheses, indicating more blocky structure achieved for the twostep copolymers. Corresponding to this difference in microstructure, the two-step copolymers were semi-crystalline, while the one-step copolymers were completely amorphous. In conclusion, the crystallinity of P（LA-co-PDO） copolymers could be adjusted conveniently to meet specific applications by changing the microstructure of the copolymers via different polymerization routes.展开更多
Ring-opening suspension polymerization of p-dioxanone（PDO） in supercritical carbon dioxide（scCO_2） was investigated in the presence of poly（caprolactone）-perfluropolyether-poly（caprolactone）（PCL-PFPE-PCL）.Th...Ring-opening suspension polymerization of p-dioxanone（PDO） in supercritical carbon dioxide（scCO_2） was investigated in the presence of poly（caprolactone）-perfluropolyether-poly（caprolactone）（PCL-PFPE-PCL）.The molecular weight,yield and particle morphology of poly（p-dioxanone）（PPDO） were studied.The stabilizer was effective to stabilize the ring-opening polymerization（ROP） of PDO in scCO_2,leading to the formation of resorbable microparticles in a＂one pot＂procedure.The mean size of PPDO microparticles obtained from suspension polymerizations was sensitive to the rate of agitation and the stabilizer concentration.The method to generate PPDO microparticles has overcome its unprocessable drawback with common organic solvents and provided new product form for biomedical applications.展开更多
To determine the possibility of blending 2, 3, 5-triiodobenzoic acid( TIBA) and poly( p-dioxanone)( PPDO) to produce X-ray visible PPDO filaments,melt-blended PPDO with different concentrations of TIBA was obtained. S...To determine the possibility of blending 2, 3, 5-triiodobenzoic acid( TIBA) and poly( p-dioxanone)( PPDO) to produce X-ray visible PPDO filaments,melt-blended PPDO with different concentrations of TIBA was obtained. Several radiopaque filaments of PPDO polymer filled with radiopaque TIBA particles were prepared via melt-blending. Material properties of the composite filaments were investigated using various material characterization techniques,including scanning electron microscope( SEM),thermogravimetric analysis( TGA),X-ray Diffraction( XRD),dynamic rheometry and micro-CT scan. In this article,the dispersion of TIBA in PPDO,the properties of the filament,and the ratio of PPDO and TIBA and the corresponding X-ray visibility in vivo were studied. SEM results showed the dispersion of the contrast imaging agent TIBA was relatively even in the PPDO polymer. Xray analysis in vitro confirmed the enhanced radiopacity of the filaments with respect to the pure PPDO filament. The presence of iodine element in the composite filament could allow the bioabsorbable material to be monitored in vivo, and made it potential to be used in biomedical applications.展开更多
Novel amphiphilic triblock copolymer poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate）-block-poly（ethylene glycol）-block-poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate） （p（PDO-co-BTMC）-b-PEG-b-p（...Novel amphiphilic triblock copolymer poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate）-block-poly（ethylene glycol）-block-poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate） （p（PDO-co-BTMC）-b-PEG-b-p（PDO-co-BTMC）） was successfully synthesized using immobilized porcine pancreas lipase on porous silica particles （IPPL） as the catalyst for the fLrSt time. 1H NMR, 13C NMR and GPC analysis were used to confirm the structures of resulting copolymers. The molecular weight （Mn） of the copolymer with feed ratio of 69：20：11 （BTMC： PDO： PEG ） was 31300 g/mol and the polydispersity was 1.85, while the Mn decreased to 25000 g/mol and polydispersity of 1.93 with the feed ratio of 50：40：10.展开更多
Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated P...Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.展开更多
The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to...The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.展开更多
Consisting of natural histidine residues,polyhistidine(PHis)simulates functional proteins.Traditional approaches towards PHis require the protection of imidazole groups before monomer synthesis and polymerization to p...Consisting of natural histidine residues,polyhistidine(PHis)simulates functional proteins.Traditional approaches towards PHis require the protection of imidazole groups before monomer synthesis and polymerization to prevent degradation and side reactions.In the contribution,histidine N-thiocarboxyanhydride(His-NTA)is directly synthesized in aqueous solution without protection.With the self-catalysis of the imidazole side group,the ring-closing reaction to form His-NTA does not require any activating reagent(e.g.,phosphorus tribromide),which is elucidated by density functional theory(DFT)calculations.His-NTA directly polymerizes into PHis bearing unprotected imidazole groups with designable molecular weights(4.2-7.7 kg/mol)and low dispersities(1.10-1.19).Kinetic experiments and Monte Carlo simulations reveal the elementary reactions and the relationship between the conversion of His-NTA and time during polymerization.Block copolymerization of His-NTA with sarcosine N-thiocarboxyanhydride(Sar-NTA)demonstrate versatile construction of functional polypept(o)ides.The triblock copoly(amino acid)PHis-b-PSar-b-PHis is capable to reversibly coordinate with transition metal ions(Fe^(2+),Co^(2+),Ni^(2+),Cu^(2+)and Zn^(2+))to form pH-sensitive hydrogels.展开更多
The rising prevalence of drug-resistant Gram-positive pathogens,particularly methicillin-resistant Staphy-lococcus aureus(MRSA)and vancomycin-resistant Enterococci(VRE),poses a substantial clinical challenge.Biofilm-a...The rising prevalence of drug-resistant Gram-positive pathogens,particularly methicillin-resistant Staphy-lococcus aureus(MRSA)and vancomycin-resistant Enterococci(VRE),poses a substantial clinical challenge.Biofilm-associated infections exacerbate this problem due to their inherent antibiotic resistance and complex structure.Current antibiotic treatments struggle to penetrate biofilms and eradicate persister cells,leading to prolonged antibiotic use and increased resistance.Host defense peptides(HDPs)have shown promise,but their clinical application is limited by factors such as enzymatic degradation and difficulty in largescale preparation.Synthetic HDP mimics,such as poly(2-oxazoline),have emerged as effective alter-natives.Herein,we found that the poly(2-oxazoline),Gly-POX_(20),demonstrated rapid and potent activity against clinically isolated multidrug-resistant Gram-positive strains.Gly-POX_(20) showed greater stability under physiological conditions compared to natural peptides,including resistance to protease degradation.Importantly,Gly-POX_(20) inhibited biofilm formation and eradicated mature biofilm and demonstrated superior in vivo therapeutic efficacy to vancomycin in a MRSA biofilm-associated mouse keratitis model,suggesting its potential as a novel antimicrobial agent against drug-resistant Gram-positive bacteria,especially biofilm-associated infections.展开更多
基金financially supported by the National Key R&D Program of China(No.2021YFB3801901)the National Natural Science Foundation of China(Nos.52403138 and U19A2095)+1 种基金Institutional Research Fund from Sichuan University(No.2020SCUNL205)Fundamental Research Funds for the Central Universities,and 111 Project(No.B20001)。
文摘The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous development of such recyclable polymers.Herein,PPDOPLLA-PU copolymers were synthesized from poly(p-dioxanone)-diol(PPDO-diol)and poly(L-lactide)-diol(PLLA-diol)by chain extension reaction.The chemical structures and microphase structures of PPDO-PLLA-PU were characterized,and their crystalline properties,mechanical properties,and degradation behaviors were further investigated.Significantly,the distribution of PLLA phase in the copolymer matrix showed a rod-like microstructure with a slight orientation,despite the thermodynamic incompatibility of PPDO and PLLA segments.Moreover,on the basis of this microphase separation,PPDO spherulites can crystallize using the interface of the two phases as nucleation sites.Accordingly,the combined effect of above two contributes to the enhanced mechanical properties.In addition,PPDO-PLLA-PU copolymers have good processability and recyclability,making them valuable for a wide range of applications.
基金financially supported by the Capacity Building Project of Some Local Colleges and Universities in Shanghai (No. 17030501200)the National Natural Science Foundation of China (No. 81501595)+2 种基金Youth Foundation of Zhongshan Hospital (No. 2015ZSQN09)Talent Training Program Foundation for the Excellent Youth Supported by Zhongshan Hospital (No. 2017ZSYQ24)Innovation Fund of Zhongshan Hospital (No. 2017ZSCX05)
文摘Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix(ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties,biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone)(PDO) and poly(ester-urethane)ureas(PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break.Furthermore, human umbilical vein endothelial cells(HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats(60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.
基金financially supported by the National Natural Science Foundation of China(No.51121001)High-Tech Research&Development Program(No.2012AA062904)the Program for Changjiang Scholars and Innovative Research Teams in Universities of China(IRT 1026)
文摘The effects of temperature and relative humidity on the hydrolytic degradation of poly（p-dioxanone）（PPDO） were investigated. The hydrolytic degradation behaviors were monitored by tracing the changes of water absorption, mechanical and crystalline properties, molecular weight and its distribution, surface morphologies, as well as infrared absorption peaks and hydrogen chemical shifts during the degradation. It is found that the water absorption increases whilst the intrinsic viscosity, tensile strength and elongation at break decrease as the temperature or relative humidity increases. With degradation time growing, the molecular weight drops and its distribution broadens. The crystallinity of PPDO has a tendency to increase at first and then to decrease, while the crystalline structure is not significantly changed. At the same time, some cracks are observed on the surface and keep growing and deepening. All results show that temperature plays more significant roles than relative humidity during the degradation. The analyses of Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy reveal that the degradation of PPDO is a predominant hydrolysis of ester linkages.
基金supported financially by the National Science Foundation of China (Nos. 51473096, 51421061, J1103315)Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (No. IRT 1026)
文摘Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The precursors and the composites were characterized by1 H NMR, FT-IR, GPC, SEM and TEM.The results demonstrate that a part of PCL segments grafted on the surface of OSEP and composites display a fine dispersion of OSEP fiber in nanoscale with low OSEP content. The shape memory effect（SME） was evaluated by DMA, the results reveal that the PPDO–PCL/OSEP nanocomposites exhibit desirable shape-memory performance. The reinforcement of composites by incorporation of trace OSEP nanofiber evokes an effective improvement in shape-memory recovery stress.
基金supported by the National Natural Science Foundation of China (No. U19A2095)the Sichuan Science and Technology Program (No. 2017SZDZX0015)the Fundamental Research Funds for the Central Universities。
文摘Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy(1 H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO.
基金supported by the National Key Technologies R&D Program of China(No.2006BA103B04)the Natural Key Scientific and Technological Project of Chongqing(No.CSTC 2008AB0027)
文摘A series of novel poly(urethane-urea)(PUU)was synthesized from poly(lactide-co-p-dioxanone)macrodiol(HO-P(LA-co-PDO)-OH),hexamethylene diisocyanate(HDI)and butanediamine(BDA).The obtained PUU,which is recorded as P(LA-co-PDO)-PUU here,may demonstrate enhanced phase separation and thus improved shape memory property.FTIR was employed to characterize the copolymers,and the effects of NCO/OH molar ratios on Tg of PUU was investigated by means of differential scanning calorimetry(DSC).The results revealed the successful synthesis of P(LA-co-PDO)-PUU.In addition,the Tg of P(LA-co-PDO)-PUU increased from 37.9℃to 44.2℃with the increase NCO/OH ratios from 1.1 to 1.2.The P(LA-co-PDO)-PUU with Tg close to body temperature will have potential applications as shape memory polymers in biomedical fields,especially in minimally invasive surgery.
基金supported by the National Key Technologies R&D Program of China(No.2006BA103B04)the Natural Key Scientific and Technological Project of Chongqing(No.CSTC 2008AB0027)
文摘Integrating poly（lactic acid） （PLA）, glycolic acid （GA） and ethylene glycol （EG） will hopefully result in a novel copolymer that combines such advantages as fastened and controllable release rate and improved flexibility together with good biocompatibility. In this study, p-dioxanone （PDO） was employed to copolymerize with DL-lactide （LA） via ring-opening melt polymerization using Sn（Oct）2 as an initiator and ethylene glycol as a co-initiator. The obtained degradable macrodiols （HO-P（LA-co-PDO）-OH） were just such a copolymer consisting of PLA, GA and EG. 1HNMR was employed to characterize the copolymers, and the effect of PDO/LA molar ratios in the feedstock on the molecular weights of HO-P（LA-co-PDO）-OH was investigated by means of endhydroxyl analysis, 1H NMR or GPC-MALLs. The results confirmed the successful synthesis of HO-P（LA-co-PDO）-OH and revealed that one end-hydroxyl of the micarodiols was donated by LA or PDO and the other one by the co-initiator EG. In addition, the molecular weights of HO-P（LA-co-PDO）-OH increased with decreasing PDO/LA ratios.
基金supported by the National Natural Science Foundation of China(Nos.21274093 and 51121001)Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(No.IRT1026)National High-Tech Research and Development Program(863 Program) of China(No.2012AA062904)
文摘Poly（p-dioxanone）-block-polyethylene glycol diblock copolymers functionalized with pyrene moieties（Py-PPDO-b-PEG） at the chain ends of PPDO blocks were synthesized for preparing anisotropic micelles with improved stability.The micellization and crystallization of the copolymers were investigated by nano differential scanning calorimetry（Nano DSC）,transmission electron microscopy（TEM）,UV-vis spectrophotometery,fluorophotometer,and dynamic light scattering（DLS）,respectively.The results indicated that the aggregation of pyrene induced by intermolecular interaction lead to micellization of Py-PPDO-b-PEG at much lower concentrations than those of PPDO-b-PEG copolymers without pyrene moieties.The aggregation of pyrene moieties may also serve as nucleation agent and therefore enhance the crystallization rate of PPDO blocks.Fluorescence measurements by using Nile Red as the fluorescent agent indicated that the micelles of Py-PPDO-b-PEG have high stability and load capacity for hydrophobic molecules.
文摘Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In th...
基金supported financially by the "Western Light" joint researcher program of Chinese Academy of Science
文摘In order to expand the application of poly（p-dioxanone） or PPDO in biomedical area,a series of novel copolymers were synthesized successfully by one-step,melted copolymerization of p-dioxanone（PDO） and L-phenylalanine N-carboxyanhydride（L-Phe-NCA） monomers.With the in-feed molar ratio of L-PheNCA /PDO equal to 1/20,the conversions of the two kinds of monomers were calculated from 1H NMR. The average molecular weight and polydispersity of the copolymer increase with the increasing reaction time and catalyst concentration.However,the conversions of the two kinds of monomers did not change with the reaction conditions.A three-step mechanism is presented and proved by high resolution 1H NMR and IR spectrums.
基金supported by the National Natural Sciences Fund of China(No.50603025)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University).
文摘Poly（d,l-lactide-co-p-dioxanone） （P（LA-co-PDO）） copolymers with different chain microstructures were synthesized by onestep or two-step bulk ring-opening polymerizations of d,l-lactide （LA） and p-dioxanone （PDO） monomers using stannous octoate [Sn（Oct）2]/n-dodecanol as the initiating system. The average sequence lengths of the lactidyl （LLA） and dioxanyl （LpDo） units were calculated from the ^1H NMR spectra. It was found that both LLA and Lpoo values from the two-step syntheses were significantly longer than those from the corresponding one-step syntheses, indicating more blocky structure achieved for the twostep copolymers. Corresponding to this difference in microstructure, the two-step copolymers were semi-crystalline, while the one-step copolymers were completely amorphous. In conclusion, the crystallinity of P（LA-co-PDO） copolymers could be adjusted conveniently to meet specific applications by changing the microstructure of the copolymers via different polymerization routes.
基金supported by the National Natural Sciences Fund of China(No.30970725) the Fund of Science and Technology Development from China Academy of Engineering Physics(No.2008A0302012)
文摘Ring-opening suspension polymerization of p-dioxanone（PDO） in supercritical carbon dioxide（scCO_2） was investigated in the presence of poly（caprolactone）-perfluropolyether-poly（caprolactone）（PCL-PFPE-PCL）.The molecular weight,yield and particle morphology of poly（p-dioxanone）（PPDO） were studied.The stabilizer was effective to stabilize the ring-opening polymerization（ROP） of PDO in scCO_2,leading to the formation of resorbable microparticles in a＂one pot＂procedure.The mean size of PPDO microparticles obtained from suspension polymerizations was sensitive to the rate of agitation and the stabilizer concentration.The method to generate PPDO microparticles has overcome its unprocessable drawback with common organic solvents and provided new product form for biomedical applications.
基金Biomedical Textile Materials Science and Technolgy(111 Project),China(No.B07024)the Fundamendtal Research funds for the Central Universities,China(Samples 2232015A3-02,16D 110119)+1 种基金Science and Technology Support Program of Shanghai,China(No.16441903803)National Postdoctoral Foundation,China(No.2016M590299)
文摘To determine the possibility of blending 2, 3, 5-triiodobenzoic acid( TIBA) and poly( p-dioxanone)( PPDO) to produce X-ray visible PPDO filaments,melt-blended PPDO with different concentrations of TIBA was obtained. Several radiopaque filaments of PPDO polymer filled with radiopaque TIBA particles were prepared via melt-blending. Material properties of the composite filaments were investigated using various material characterization techniques,including scanning electron microscope( SEM),thermogravimetric analysis( TGA),X-ray Diffraction( XRD),dynamic rheometry and micro-CT scan. In this article,the dispersion of TIBA in PPDO,the properties of the filament,and the ratio of PPDO and TIBA and the corresponding X-ray visibility in vivo were studied. SEM results showed the dispersion of the contrast imaging agent TIBA was relatively even in the PPDO polymer. Xray analysis in vitro confirmed the enhanced radiopacity of the filaments with respect to the pure PPDO filament. The presence of iodine element in the composite filament could allow the bioabsorbable material to be monitored in vivo, and made it potential to be used in biomedical applications.
基金the financial support of the National Natural Science Foundation of China(No.20104005).
文摘Novel amphiphilic triblock copolymer poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate）-block-poly（ethylene glycol）-block-poly（p-dioxanone-co-5-benzyloxytrimethylene carbonate） （p（PDO-co-BTMC）-b-PEG-b-p（PDO-co-BTMC）） was successfully synthesized using immobilized porcine pancreas lipase on porous silica particles （IPPL） as the catalyst for the fLrSt time. 1H NMR, 13C NMR and GPC analysis were used to confirm the structures of resulting copolymers. The molecular weight （Mn） of the copolymer with feed ratio of 69：20：11 （BTMC： PDO： PEG ） was 31300 g/mol and the polydispersity was 1.85, while the Mn decreased to 25000 g/mol and polydispersity of 1.93 with the feed ratio of 50：40：10.
文摘Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.
基金supported by the National Natural Science Foundation of China(Nos.31971741 and 31760195)the Yunnan Fundamental Research Projects(Nos.2018FB066 and 202001AT070141)the Yunnan Agricultural Basic Research Special Projects(No.202101BD070001-086).
文摘The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.
基金financially supported by the National Natural Science Foundation of China(Nos.22271252 and 22201105)。
文摘Consisting of natural histidine residues,polyhistidine(PHis)simulates functional proteins.Traditional approaches towards PHis require the protection of imidazole groups before monomer synthesis and polymerization to prevent degradation and side reactions.In the contribution,histidine N-thiocarboxyanhydride(His-NTA)is directly synthesized in aqueous solution without protection.With the self-catalysis of the imidazole side group,the ring-closing reaction to form His-NTA does not require any activating reagent(e.g.,phosphorus tribromide),which is elucidated by density functional theory(DFT)calculations.His-NTA directly polymerizes into PHis bearing unprotected imidazole groups with designable molecular weights(4.2-7.7 kg/mol)and low dispersities(1.10-1.19).Kinetic experiments and Monte Carlo simulations reveal the elementary reactions and the relationship between the conversion of His-NTA and time during polymerization.Block copolymerization of His-NTA with sarcosine N-thiocarboxyanhydride(Sar-NTA)demonstrate versatile construction of functional polypept(o)ides.The triblock copoly(amino acid)PHis-b-PSar-b-PHis is capable to reversibly coordinate with transition metal ions(Fe^(2+),Co^(2+),Ni^(2+),Cu^(2+)and Zn^(2+))to form pH-sensitive hydrogels.
基金financially supported by the National Key Research and Development Program of China(no.2022YFC2303100)National Natural Science Foundation of China(nos.T2325010,22305082,52203162,and 22075078)+1 种基金Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism(Shanghai Municipal Education Commission),the Fundamental Research Funds for the Central Universities(nos.JKVD1241029 and JKD01241701)Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry(Changchun Institute of Applied Chemistry,Chinese Academy of Sciences),the Open Project of Engineering Research Center of Dairy Quality and Safety Control Technology(Ministry of Education,no.R202201).
文摘The rising prevalence of drug-resistant Gram-positive pathogens,particularly methicillin-resistant Staphy-lococcus aureus(MRSA)and vancomycin-resistant Enterococci(VRE),poses a substantial clinical challenge.Biofilm-associated infections exacerbate this problem due to their inherent antibiotic resistance and complex structure.Current antibiotic treatments struggle to penetrate biofilms and eradicate persister cells,leading to prolonged antibiotic use and increased resistance.Host defense peptides(HDPs)have shown promise,but their clinical application is limited by factors such as enzymatic degradation and difficulty in largescale preparation.Synthetic HDP mimics,such as poly(2-oxazoline),have emerged as effective alter-natives.Herein,we found that the poly(2-oxazoline),Gly-POX_(20),demonstrated rapid and potent activity against clinically isolated multidrug-resistant Gram-positive strains.Gly-POX_(20) showed greater stability under physiological conditions compared to natural peptides,including resistance to protease degradation.Importantly,Gly-POX_(20) inhibited biofilm formation and eradicated mature biofilm and demonstrated superior in vivo therapeutic efficacy to vancomycin in a MRSA biofilm-associated mouse keratitis model,suggesting its potential as a novel antimicrobial agent against drug-resistant Gram-positive bacteria,especially biofilm-associated infections.
