As the most abundant aromatic bio-based polymer,lignin has great potential as a sustainable feedstock for building crosslinked thermoset polymers as bio-based adhesives.However,the potential of hardwood kraft lignin(H...As the most abundant aromatic bio-based polymer,lignin has great potential as a sustainable feedstock for building crosslinked thermoset polymers as bio-based adhesives.However,the potential of hardwood kraft lignin(HKL)is limited due to its poor crosslinking reactivity.Hence,for the first time,the present study reports the facile oxidation of HKL involving a redox reaction with silver-ammonia complexes([(AgNH3)2]+),primarily focusing on oxidation to produce reactive quinones and promote C-C linkages during reaction.This study aims to increases reactivity of oxidized HKL for effective crosslinking with monoethanolamine(MEA)for the development of bio-based wood adhesives.The characterization,including 13C-nuclear magnetic resonance(NMR)and Fourier transform infrared(FT-IR)spectroscopy,confirms the oxidation reaction,such as the formation of quinones(C=O)and subsequent crosslinking between the oxidized HKL molecules and MEA.Additionally,gel permeation chromatography(GPC)confirms the C-C and C-O linkages with increased molecular weight after oxidation,and is supported by differential scanning calorimetry(DSC)which shows the exothermic reaction due to the crosslinking of the oxidized HKL molecules via condensation to form C-C and C-O linkages.The crosslinked HKL/MEA-based adhesives underwent mild reaction and achieved a maximum dry shear strength of 0.77 MPa,which exceeds the standard requirement of 0.6 MPa.These findings demonstrate not only a one-pot oxidation for improving the reactivity of HKL using silver complexes,but also its facile crosslinking with MEA for sustainable bio-based wood adhesives.展开更多
Reader proteins that bind specific methyllysine are important to biological functions of lysine methylation,but readers of many methyllysine sites are still unknown.Therefore,development of covalent probes is importan...Reader proteins that bind specific methyllysine are important to biological functions of lysine methylation,but readers of many methyllysine sites are still unknown.Therefore,development of covalent probes is important to identify readers from cell samples so as to understand biological roles of lysine methylation.Generally,readers bind methyllysine via aromatic cages that contain tryptophan,tyrosine and phenylalanine,that offer a unique motif for selective crosslinking.We recently reported a site-selective tryptophan crosslinking strategy based on dimethylsulfonium that mimics dimethyllysine to crosslink tryptophan in aromatic cages of readers.Since tyrosine is a key residue for binding affinity to methyllysine,especially some readers that do not contain tryptophan residues in the binding pocket.Here we developed strategies of site-selective crosslinking to tyrosine.Ultraviolet(UV)source was applied to excite tyrosine at neutral pH or phenoxide at basic p H,and subsequent single-electron transfer(SET)from Tyr*to sulfonium inside the binding pocket enables selective crosslinking.In consequence,methyllysine readers with tyrosine-containing aromatic cages could be selectively crosslinked by site-specific sulfonium peptide probes.In addition,we expanded substrates from aromatic cages to tyrosine residues of proximate contact with sulfonium probes.The pair of LgBiT and SmBiT exhibited orthogonal crosslinking in complicated cell samples.As a result,we may expand sulfonium tools to target local tyrosine in future investigations.展开更多
Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and ...Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and stretchability that align with biological tissues.Specifically,their materials should be capable of elastic strain up to 50–80%,while the devices themselves must maintain electric stability under strains that accommodate body movements[1].展开更多
Inorganic CsPbI_(3)perovskite with superior thermal stability and photoelectric properties has developed into a promising candidate for photovoltaic applications.Nevertheless,the power conversion efficiency(PCE)of CsP...Inorganic CsPbI_(3)perovskite with superior thermal stability and photoelectric properties has developed into a promising candidate for photovoltaic applications.Nevertheless,the power conversion efficiency(PCE)of CsPbI_(3)perovskite solar cells(PSCs)still lags far behind that of both organic-inorganic hybrid counterparts and the theoretical PCE limit,primarily restricted by severe fill factor(FF)and opencircuit voltage(VOC)deficits.Herein,an in-situ self-crosslinking strategy is proposed to construct high-performance inverted inorganic PSCs by incorporating acrylate monomers as additives into CsPbI_(3)perovskite precursors.During the thermal annealing process of perovskite films,acrylate monomers can form network structures by breaking the C=C groups through an in-situ polymerization reaction,mainly anchored at the grain boundaries(GBs)and on the surfaces of perovskite.Meanwhile,the C=O groups of acrylate polymers can favorably coordinate with uncoordinated Pb^(2+),thereby decreasing defect density and stabilizing the perovskite phase.Particularly,with multiple crosslinking and passivation sites,the incorporation of dipentaerythritol pentaacrylate(DPHA)can effectively improve the perovskite film quality,suppress nonradiative recombination,and block moisture erosion.Consequently,the DPHAbased PSC achieves a champion PCE of 20.05%with a record-high FF of 85.05%,both of which rank among the top in the performance of inverted CsPbI_(3)PSCs.Moreover,the unencapsulated DPHA-based device exhibits negligible hysteresis,remarkably improved long-term storage,and operational stability.This work offers a facile and useful strategy to simultaneously promote the efficiency and device stability of inverted inorganic PSCs.展开更多
All-safe liquid-state lithium-ion batteries(ASLS-LIBs) is of great interest as they can potentially combine the safety of all-solid-state batteries with the high performance and low manufacturing cost of traditional l...All-safe liquid-state lithium-ion batteries(ASLS-LIBs) is of great interest as they can potentially combine the safety of all-solid-state batteries with the high performance and low manufacturing cost of traditional liquid-state LIBs. However, the practical success of ASLS-LIBs is bottlenecked by the lack of advanced separator technology that can simultaneously realize high performances in puncturing-tolerability,fire-resistance, and importantly, wetting-capability with non-flammable liquid-electrolytes. Here, we propose a concept of inorganic in-situ separator(IISS) by hybrid-sol physical crosslinking directly onto the electrode surface to address the above challenges. Particularly, the hybrid-sol is designed with silica nanoparticles as the building block and poly(vinylidene difluoride) nanoparticles as the crosslinking agent. The critical factors for controlling the IISS microstructures and properties have been systematically investigated. The advantages of the IISS have been confirmed by its fast wetting with various fireresistant liquid-electrolytes, customizable thickness and porous structures, robust interface with planar or three-dimensional(3D)-structured electrodes, and importantly, unexpected self-adaptability against puncturing. Enabled by the above merits, a fire-resistant ASLS-LIB is successfully assembled and demonstrated with stable electrochemical performance. This sol-crosslinked IISS may open an avenue for the studies on the next-generation separator technology, cell assembling, solid electrolyte processing as well as non-flammable secondary batteries.展开更多
AIM:To assess the visual outcomes and corneal biomechanical properties of myopia patients between laser in situ keratomileusis(LASIK)and LASIK combined with accelerated corneal crosslinking(LASIK Xtra).METHODS:This pr...AIM:To assess the visual outcomes and corneal biomechanical properties of myopia patients between laser in situ keratomileusis(LASIK)and LASIK combined with accelerated corneal crosslinking(LASIK Xtra).METHODS:This prospective study analyzed 52 consecutive myopia patients treated with LASIK Xtra and 45 consecutive myopia patients treated with LASIK.Only the right eyes in the two groups were analyzed.The uncorrected distance visual acuity(UDVA),keratometry values,postoperative central corneal thickness(CCT),corneal demarcation line depth,the corneal compensated intraocular pressure(IOPcc),Goldmann-correlated IOP(IOPg),corneal resistance factor(CRF)and corneal hysteresis(CH)from Ocular Response Analyzer(ORA)were analyzed.Further,the correlation between the demarcation line depth and ORA-related biomechanical parameters were analyzed.RESULTS:No significant differences in UDVA,postoperative CCT,or mean K values were found between the 2 groups at 1 to 12mo postoperative follow-up(all P>0.05).The changes of CRF was significantly lower in the LASIK Xtra group compared to the LASIK group(all P<0.05)at all the postoperative visits.The changes of CH were significantly higher in the LASIK Xtra group(all P<0.05).No significant differences were discovered regarding the changes of IOPcc and IOPg posperatively(all P>0.05).Out of 52 cases in the LASIK Xtra group,the demarcation line was present in 40 eyes(77%).The average depth of the demarcation was 220.73±42.70μm(136 to 288μm).No significant correlation was observed between the depth of the demarcation line and any of the ORA-related biomechanical parameters such as IOPcc,IOPg,CRF and CH at 12mo(all P>0.05).CONCLUSION:Both procedures demonstrate comparable outcomes in terms of visual acuity,refraction and ablation predictability.This study confirms that corneal biomechanical properties of the included patients weakened after both procedures,but the cornea after LASIK Xtra are stiffer than conventional LASIK.展开更多
A yellow crosslinking polymeric dye was prepared by grafting the flavone moiety containing azo chromophore onto polyvinylamine backbone.The λ max of this polymeric dye in water is 382 nm.The polymeric dye is fixed to...A yellow crosslinking polymeric dye was prepared by grafting the flavone moiety containing azo chromophore onto polyvinylamine backbone.The λ max of this polymeric dye in water is 382 nm.The polymeric dye is fixed to silk and cotton with a crosslinking agent,2-chloro-4,6-di(aminobenzene-4'-β-sulphatoethylsulphone)-1,3,5-s-triazine,which acts as a bridge between the fiber and dye molecules.The fixation of this polymeric dye reaches 99% and the dyed samples exhibit excellent rubbing and washing fastness.展开更多
AIM:To compare the safety and efficacy of conventional versus accelerated(9 mW/cm^2)corneal collagen crosslinking(CXL)in progressive keratoconus at the 2-year follow-up.METHODS:In this prospective study,consecutive pr...AIM:To compare the safety and efficacy of conventional versus accelerated(9 mW/cm^2)corneal collagen crosslinking(CXL)in progressive keratoconus at the 2-year follow-up.METHODS:In this prospective study,consecutive progressive keratoconus patients were randomized to receive either conventional CXL(CCXL)or accelerated CXL(ACXL;using hydroxypropyl methylcellulose-assisted riboflavin imbibition for 10 min at 9 mW/cm^2).Visual,refractive,keratometric,topographic,and aberrometric outcomes and stromal demarcation line depth(DLD)measurements were compared at the end of a 2-year follow-up.RESULTS:Thirty-two eyes from 32 patients in the CCXL and 27 eyes from 27 patients in the ACXL groups completed 2-year follow-up.At 2y post-CXL,both uncorrected and corrected visual acuities improved significantly in both groups.The improvements in keratometric readings,flattening rate(flattening of the maximum keratometry more than 1 D),3 topographic indices,and vertical coma were significantly better in the CCXL group compared to the ACXL group(P<0.05).The DLD as measured by anterior segment optical coherence tomography or in vivo confocal microscopy was better detectable and significantly deeper in the CCXL group compared to the ACXL group.The deeper DLD was found to be significantly correlated with improvements in the mean keratometry measurements.Progression was noted in 11.1%of eyes in the ACXL group,whereas progression was not observed in any patient eye in the CCXL group.CONCLUSION:In this prospective randomized study,ACXL is less effective in halting the progression of keratoconus at a 2-year follow-up compared to CCXL.展开更多
Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation ...Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.展开更多
Crosslinking reactions of high density polyethylene with low peroxide concentrations ranging from 0.1 wt% to 1.0 wt% at temperatures of 170, 180 and 190 ℃ were monitored by rheological measurements. A critical gel fo...Crosslinking reactions of high density polyethylene with low peroxide concentrations ranging from 0.1 wt% to 1.0 wt% at temperatures of 170, 180 and 190 ℃ were monitored by rheological measurements. A critical gel forms at the peroxide concentration of 0.2 wt%, where the transition from long chain branching generation to crosslinking network formation could occur. Rheokinetics of crosslinking can be fitted well by Ding-Leonov＇s model. The curing rate k2 at the earlier stage exhibits about 3 times acceleration per 10 ~C with increasing temperature, while the equilibrium modulus G＇ at the fully cured stage is almost independent of temperature. Influences of crosslinking on the subsequent crystallization behaviors were detected by DSC measurements. Above the critical gel concentration, crystallization is largely retarded as evidenced by the lower crystallization temperature Tc and crystallinity Xc due to the network formation. The secondary crystallization valley located at the temperature near 80 ℃ can be observed above the critical concentration, which becomes more evident with the increasing peroxide concentration and curing temperature. This phenomenon provides another evidence of crystallization retardation by the crosslinking network.展开更多
Objective： Procyanidins （PC） are widely available natural polyphenols. The present study is designed to investigate if PC can inhibit angiogenesis in lung adenocarcinoma xenografts through crosslinking vascular ext...Objective： Procyanidins （PC） are widely available natural polyphenols. The present study is designed to investigate if PC can inhibit angiogenesis in lung adenocarcinoma xenografts through crosslinking vascular extracellular matrix （ECM） and preventing proteolysis by matrix metalloproteinases （MMPs）. Methods： Using the in vitro MMP-2 proteolysis and in vivo subcutaneous implantation models, we investigated if PC crosslinking inhibits MMP-mediated proteolysis. Using a cultured cell detachment assay, an in vitro angiogenesis assay, and a cell proliferation assay, we investigated if PC inhibits MMP-2-mediated endothelial cell detachment, angiogenesis, and cell proliferation, respectively. Using tumor xenografts, we evaluated if PC can inhibit growth of lung adenocarcinoma. Results： PC crosslink vascular ECM proteins, protecting them against proteolysis by MMPs in vitro and in vivo, protecting cultured human umbilical vein endothelial cells from detachment by MMP-2, and inhibiting in vitro angiogenesis. However, PC （0.75-100 μg/mL） did not inhibit vascular and tumor cells proliferation. PC injections （30 mg PC/kg bodyweight） in situ had anticancer effects on xenografts of lung adenocarcinoma, most likely by inhibiting angiogenesis during ECM proteolysis by MMPs. Conclusion： The results suggest that PC may be important MMP inhibitors that can be used as therapeutic anticancer agents.展开更多
Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism...Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.展开更多
AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-...AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-centre study, CXL was performed in 20 eyes of 11 patients who had LASIK for myopic astigmatism and subsequently developed keratectasia. The procedure included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation. The eyes were evaluated preoperatively and at 1-, 3-, 6-, and 12-month intervals. The complete ophthalmologic examination comprised uncorrected visual acuity, best spectacle-corrected visual acuity, endothelial cell count, ultrasound pachymetry, corneal topography, and in vivo confocal microscopy. RESULTS: CXL appeared to stabilise or partially reverse the progression of post-LASIK corneal ectasia without apparent complication in our cohort. UCVA and BCVA improvements were statistically significant (P<0.05)beyond 12 months after surgery (improvement of 0.07 and 0.13 logMAR at 1 year, respectively). Mean baseline flattest meridian keratometry and mean steepest meridian keratometry reduction (improvement of 2.00 and 1.50 diopters (D), respectively) were statistically significant (P < 0.05) at 12 months postoperatively. At 1 year after 01, mean endothelial cell count did not deteriorate. Mean thinnest cornea pachymetry increased significantly. CONCLUSION: The results of the study showed a long-term stability of post-LASIK corneal ectasia after crosslinking without relevant side effects. It seems to be a safe and promising procedure to stop the progression of post-LASIK keratectasia, thereby avoiding or delaying keratoplasty.展开更多
Carcinoma-associated fibroblasts(CAFs)are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix(ECM).The tumor-associated ECM is characterized ...Carcinoma-associated fibroblasts(CAFs)are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix(ECM).The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase(LOX).Small extracellular vesicles(sEVs)mediate cell-cell communication.However,the interactions between sEVs and the ECM remain unclear.Here,we demonstrated that sEVs released from oral squamous cell carcinoma(OSCC)-derived CAFs induce collagen crosslinking,thereby promoting epithelial-mesenchymal transition(EMT).CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking,and a LOX inhibitor or blocking antibody suppressed this effect.Active LOX(αLOX),but not the LOX precursor,was enriched in CAF sEVs and interacted with periostin,fibronectin,and bone morphogenetic protein-1 on the surface of sEVs.CAF sEV-associated integrinα2β1 mediated the binding of CAF sEVs to collagen I,and blocking integrinα2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I.CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway.Taken together,these findings reveal a novel role of CAF sEVs in tumor ECM remodeling,suggesting a critical mechanism for CAF-induced EMT of cancer cells.展开更多
It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer...It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer(MSMEV),which exhibits high mechanical properties,multi-shape memory property and malleability.The triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F(DGEBF)with 4-aminophenyl disulfide,γ-aminopropyltriethoxysilane(APTS)and poly(propylene glycol)bis(2-aminopropyl ether)(D2000).The triple crosslinking manifests triple functions:the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network;the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region,leading to multi-shape memory property;a small amount of D2000 increases the modulus difference between the glassy and rubbery states,thereby improving the shape fixity ratio.Meanwhile,the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s modulus.Moreover,integrating carbon fibers and MSMEV results in shape memory composites.The superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.展开更多
Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,ad...Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,adipoyl dichloride and hexamethylene diisocyanate ester with long flexible aliphatic chains and high reactivity with N-H groups were used in the experiments.Attenuated total reflective Fourier transform infrared spectra verified the successful preparation of highly crosslinked membranes by crosslinking treatments.It was suggested that the crosslinking agents were connected to membrane surface through the reactions with amine and amide Ⅱ groups,which is confirmed by surface charge measurements.Based on contact angle measurements,crosslinking treatments decreased membrane hydrophilicity by introducing methylene groups to membrane surface.With increasing amount of crosslinking agent molecules connected to membrane surface,the hydrolysis of unconnected functional groups of crosslinking agent produced polar groups and increased membrane hydrophilicity.The highly crosslinked membranes showed higher salt rejections and lower water fluxes as compared with the raw membrane.Since the active sites(N-H groups) vulnerable to free chlorine on membrane surface were eliminated by crosslinking treatments,the chlorine resistances of the highly crosslinked membranes were significantly improved by slighter changes in both water fluxes and salt rejections after chlorination.展开更多
With the discovery of the two-dimensional(2D) MXene, it shows a great application potential in the field of electromagnetic interference(EMI) shielding, but the mechanical brittleness and easy oxidation of MXene limit...With the discovery of the two-dimensional(2D) MXene, it shows a great application potential in the field of electromagnetic interference(EMI) shielding, but the mechanical brittleness and easy oxidation of MXene limit its wide application. For this reason, a double crosslinking strategy is provided to solve the above problems in a nacre-like “brick-mortar” layered MXene/cellulose nanofiber(MXene/CNF) film.Typically, the film was firstly suffered by dopamine modification, then was further reinforced by secondary Ca^(2+)bridging, so as to obtain excellent mechanical properties and antioxidative EMI shielding performance. Comparing with the single crosslinking, the double crosslinking strategy reveals a higher efficiency in improving the mechanical property. The mechanical strength and toughness of the double crosslinking MXene/CNF film can increase to 142.2 MPa and 9.48 MJ/m^(3), respectively. More importantly, while achieving good mechanical properties, the MXene composite film still holds a very stable EMI shielding performance of more than 44.6 dB when suffering from the oxidation treatment of hightemperature annealing, showing excellent anti-oxidation ability and environment tolerance. Therefore,this work provides a universal but effective double crosslinking strategy to solve the mechanical brittleness and easy oxidation of MXene-based composites, thus showing a huge potential in flexible EMI shielding applications.展开更多
Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite t...Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite their widespread utilization and numerous advantages,the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment,proliferation,and vascularization remains a challenge.Multi-material composite hydrogels present incredible potential in this field.Thus,in this work,a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed,which provides good printability and shape fidelity.In addition,a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate(TPP),genipin(GP),and glutaraldehyde(GTA)were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds.All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering,especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.展开更多
A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl...A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.展开更多
In this report, bienzymatic crosslinking approach was applied to prepare biopolymer hydrogel fibers composed of gelatin and chitosan with an interpenetrating polymer network （IPN） structure. The IPN biopolymer hydro...In this report, bienzymatic crosslinking approach was applied to prepare biopolymer hydrogel fibers composed of gelatin and chitosan with an interpenetrating polymer network （IPN） structure. The IPN biopolymer hydrogel fibers were prepared by wet spinning while microbial transglutaminase （mTG） catalyzed the formation of one network of gelatin and horseradish peroxidase （HRP） in the presence of H202 induced another network of chitosan grafted with phloretic acid （chitosan-PA） intertwining with the former. The mechanical performances of the hydrogel fibers were measured by an electronic single fiber strength tester. It was found that the mechanical properties of the gelatin/chitosan IPN hydrogel fibers had a significant improvement with the increase of the concentration of gelatin and chitosan, and the IPN fiber has the highest tension of 38.6 cN and elongation of 387.2%. Accelerated degradation in the presence of papin indicated that the gelatin/chitosan-PA IPN hydrogel fibers own controllable degradability. In addition, biological evaluation indicated the IPN hydrogel fibers can support cell adhesion and proliferation. Moreover, hand weaving trail showed the knittablity of the IPN hydrogel fibers. Therefore, the gelatin/chitosan IPN hydrogel fibers prepared by bienzymatic crosslinking approach possess excellent biocompatibility and mechanical strength, which may be desirable candidates for engineering tissue scaffolds.展开更多
基金supported by the National Research Foundation(NRF)of Korea,funded by the Korean Government(MSIT)(Grant No.RS-2023-00240043).
文摘As the most abundant aromatic bio-based polymer,lignin has great potential as a sustainable feedstock for building crosslinked thermoset polymers as bio-based adhesives.However,the potential of hardwood kraft lignin(HKL)is limited due to its poor crosslinking reactivity.Hence,for the first time,the present study reports the facile oxidation of HKL involving a redox reaction with silver-ammonia complexes([(AgNH3)2]+),primarily focusing on oxidation to produce reactive quinones and promote C-C linkages during reaction.This study aims to increases reactivity of oxidized HKL for effective crosslinking with monoethanolamine(MEA)for the development of bio-based wood adhesives.The characterization,including 13C-nuclear magnetic resonance(NMR)and Fourier transform infrared(FT-IR)spectroscopy,confirms the oxidation reaction,such as the formation of quinones(C=O)and subsequent crosslinking between the oxidized HKL molecules and MEA.Additionally,gel permeation chromatography(GPC)confirms the C-C and C-O linkages with increased molecular weight after oxidation,and is supported by differential scanning calorimetry(DSC)which shows the exothermic reaction due to the crosslinking of the oxidized HKL molecules via condensation to form C-C and C-O linkages.The crosslinked HKL/MEA-based adhesives underwent mild reaction and achieved a maximum dry shear strength of 0.77 MPa,which exceeds the standard requirement of 0.6 MPa.These findings demonstrate not only a one-pot oxidation for improving the reactivity of HKL using silver complexes,but also its facile crosslinking with MEA for sustainable bio-based wood adhesives.
基金the support from National Natural Science Foundation of China(No.22161132006)Key R&D Program of Zhejiang(No.2024SSYS0036)Westlake University Startup。
文摘Reader proteins that bind specific methyllysine are important to biological functions of lysine methylation,but readers of many methyllysine sites are still unknown.Therefore,development of covalent probes is important to identify readers from cell samples so as to understand biological roles of lysine methylation.Generally,readers bind methyllysine via aromatic cages that contain tryptophan,tyrosine and phenylalanine,that offer a unique motif for selective crosslinking.We recently reported a site-selective tryptophan crosslinking strategy based on dimethylsulfonium that mimics dimethyllysine to crosslink tryptophan in aromatic cages of readers.Since tyrosine is a key residue for binding affinity to methyllysine,especially some readers that do not contain tryptophan residues in the binding pocket.Here we developed strategies of site-selective crosslinking to tyrosine.Ultraviolet(UV)source was applied to excite tyrosine at neutral pH or phenoxide at basic p H,and subsequent single-electron transfer(SET)from Tyr*to sulfonium inside the binding pocket enables selective crosslinking.In consequence,methyllysine readers with tyrosine-containing aromatic cages could be selectively crosslinked by site-specific sulfonium peptide probes.In addition,we expanded substrates from aromatic cages to tyrosine residues of proximate contact with sulfonium probes.The pair of LgBiT and SmBiT exhibited orthogonal crosslinking in complicated cell samples.As a result,we may expand sulfonium tools to target local tyrosine in future investigations.
基金supported by generous grants from the Natural Science Foundation of Zhejiang Province(LR24E030003)Zhejiang Province Qianjiang Talent Program(ZJ-QJRC-2020-32).
文摘Elastic electronics are increasingly prevalent in information storage,smart sensing and health monitoring due to their softness,stretchability and portability.Wearable electronic devices should possess elasticity and stretchability that align with biological tissues.Specifically,their materials should be capable of elastic strain up to 50–80%,while the devices themselves must maintain electric stability under strains that accommodate body movements[1].
基金supported by the Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)the Natural Science Foundation of Ningbo City(No.2023J119)+1 种基金the Ningbo Youth Science and Technology Innovation Leading Talent Project(2023QL029)K.C.Wong Magna Fund in Ningbo University,China。
文摘Inorganic CsPbI_(3)perovskite with superior thermal stability and photoelectric properties has developed into a promising candidate for photovoltaic applications.Nevertheless,the power conversion efficiency(PCE)of CsPbI_(3)perovskite solar cells(PSCs)still lags far behind that of both organic-inorganic hybrid counterparts and the theoretical PCE limit,primarily restricted by severe fill factor(FF)and opencircuit voltage(VOC)deficits.Herein,an in-situ self-crosslinking strategy is proposed to construct high-performance inverted inorganic PSCs by incorporating acrylate monomers as additives into CsPbI_(3)perovskite precursors.During the thermal annealing process of perovskite films,acrylate monomers can form network structures by breaking the C=C groups through an in-situ polymerization reaction,mainly anchored at the grain boundaries(GBs)and on the surfaces of perovskite.Meanwhile,the C=O groups of acrylate polymers can favorably coordinate with uncoordinated Pb^(2+),thereby decreasing defect density and stabilizing the perovskite phase.Particularly,with multiple crosslinking and passivation sites,the incorporation of dipentaerythritol pentaacrylate(DPHA)can effectively improve the perovskite film quality,suppress nonradiative recombination,and block moisture erosion.Consequently,the DPHAbased PSC achieves a champion PCE of 20.05%with a record-high FF of 85.05%,both of which rank among the top in the performance of inverted CsPbI_(3)PSCs.Moreover,the unencapsulated DPHA-based device exhibits negligible hysteresis,remarkably improved long-term storage,and operational stability.This work offers a facile and useful strategy to simultaneously promote the efficiency and device stability of inverted inorganic PSCs.
基金National Natural Science Foundation of China (52203123)Sichuan Science and Technology Program (2023NSFSC0991)+2 种基金State Key Laboratory of Polymer Materials Engineering (sklpme-2023-1-05 and sklpme-2024-2-04)Fundamental Research Funds for the Central UniversitiesThis research was also partially sponsored by the Double First-Class Construction Funds of Sichuan University。
文摘All-safe liquid-state lithium-ion batteries(ASLS-LIBs) is of great interest as they can potentially combine the safety of all-solid-state batteries with the high performance and low manufacturing cost of traditional liquid-state LIBs. However, the practical success of ASLS-LIBs is bottlenecked by the lack of advanced separator technology that can simultaneously realize high performances in puncturing-tolerability,fire-resistance, and importantly, wetting-capability with non-flammable liquid-electrolytes. Here, we propose a concept of inorganic in-situ separator(IISS) by hybrid-sol physical crosslinking directly onto the electrode surface to address the above challenges. Particularly, the hybrid-sol is designed with silica nanoparticles as the building block and poly(vinylidene difluoride) nanoparticles as the crosslinking agent. The critical factors for controlling the IISS microstructures and properties have been systematically investigated. The advantages of the IISS have been confirmed by its fast wetting with various fireresistant liquid-electrolytes, customizable thickness and porous structures, robust interface with planar or three-dimensional(3D)-structured electrodes, and importantly, unexpected self-adaptability against puncturing. Enabled by the above merits, a fire-resistant ASLS-LIB is successfully assembled and demonstrated with stable electrochemical performance. This sol-crosslinked IISS may open an avenue for the studies on the next-generation separator technology, cell assembling, solid electrolyte processing as well as non-flammable secondary batteries.
基金Supported by Wu Jieping Medical Foundation(No.320.6750.2021-04-15).
文摘AIM:To assess the visual outcomes and corneal biomechanical properties of myopia patients between laser in situ keratomileusis(LASIK)and LASIK combined with accelerated corneal crosslinking(LASIK Xtra).METHODS:This prospective study analyzed 52 consecutive myopia patients treated with LASIK Xtra and 45 consecutive myopia patients treated with LASIK.Only the right eyes in the two groups were analyzed.The uncorrected distance visual acuity(UDVA),keratometry values,postoperative central corneal thickness(CCT),corneal demarcation line depth,the corneal compensated intraocular pressure(IOPcc),Goldmann-correlated IOP(IOPg),corneal resistance factor(CRF)and corneal hysteresis(CH)from Ocular Response Analyzer(ORA)were analyzed.Further,the correlation between the demarcation line depth and ORA-related biomechanical parameters were analyzed.RESULTS:No significant differences in UDVA,postoperative CCT,or mean K values were found between the 2 groups at 1 to 12mo postoperative follow-up(all P>0.05).The changes of CRF was significantly lower in the LASIK Xtra group compared to the LASIK group(all P<0.05)at all the postoperative visits.The changes of CH were significantly higher in the LASIK Xtra group(all P<0.05).No significant differences were discovered regarding the changes of IOPcc and IOPg posperatively(all P>0.05).Out of 52 cases in the LASIK Xtra group,the demarcation line was present in 40 eyes(77%).The average depth of the demarcation was 220.73±42.70μm(136 to 288μm).No significant correlation was observed between the depth of the demarcation line and any of the ORA-related biomechanical parameters such as IOPcc,IOPg,CRF and CH at 12mo(all P>0.05).CONCLUSION:Both procedures demonstrate comparable outcomes in terms of visual acuity,refraction and ablation predictability.This study confirms that corneal biomechanical properties of the included patients weakened after both procedures,but the cornea after LASIK Xtra are stiffer than conventional LASIK.
基金Supported by the National Natural Science Foundation of China （20804007） the State Key Laboratory of Fine Chemicals（KF1014）
文摘A yellow crosslinking polymeric dye was prepared by grafting the flavone moiety containing azo chromophore onto polyvinylamine backbone.The λ max of this polymeric dye in water is 382 nm.The polymeric dye is fixed to silk and cotton with a crosslinking agent,2-chloro-4,6-di(aminobenzene-4'-β-sulphatoethylsulphone)-1,3,5-s-triazine,which acts as a bridge between the fiber and dye molecules.The fixation of this polymeric dye reaches 99% and the dyed samples exhibit excellent rubbing and washing fastness.
文摘AIM:To compare the safety and efficacy of conventional versus accelerated(9 mW/cm^2)corneal collagen crosslinking(CXL)in progressive keratoconus at the 2-year follow-up.METHODS:In this prospective study,consecutive progressive keratoconus patients were randomized to receive either conventional CXL(CCXL)or accelerated CXL(ACXL;using hydroxypropyl methylcellulose-assisted riboflavin imbibition for 10 min at 9 mW/cm^2).Visual,refractive,keratometric,topographic,and aberrometric outcomes and stromal demarcation line depth(DLD)measurements were compared at the end of a 2-year follow-up.RESULTS:Thirty-two eyes from 32 patients in the CCXL and 27 eyes from 27 patients in the ACXL groups completed 2-year follow-up.At 2y post-CXL,both uncorrected and corrected visual acuities improved significantly in both groups.The improvements in keratometric readings,flattening rate(flattening of the maximum keratometry more than 1 D),3 topographic indices,and vertical coma were significantly better in the CCXL group compared to the ACXL group(P<0.05).The DLD as measured by anterior segment optical coherence tomography or in vivo confocal microscopy was better detectable and significantly deeper in the CCXL group compared to the ACXL group.The deeper DLD was found to be significantly correlated with improvements in the mean keratometry measurements.Progression was noted in 11.1%of eyes in the ACXL group,whereas progression was not observed in any patient eye in the CCXL group.CONCLUSION:In this prospective randomized study,ACXL is less effective in halting the progression of keratoconus at a 2-year follow-up compared to CCXL.
基金supported by the National Natural Science Foundation of China (Grant No. 50575106)High Technology Project of Jiangsu Province, P. R. China (Grant No. BG2007046)
文摘Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.
基金financially supported by the Technical Innovation Project of National Institute of Clean and Low-Carbon Energy(No.15H0543)the Open Project of State Key Laboratory of Polymer Materials Engineering of China(Sichuan University)(No.sklpme2015-4-11)
文摘Crosslinking reactions of high density polyethylene with low peroxide concentrations ranging from 0.1 wt% to 1.0 wt% at temperatures of 170, 180 and 190 ℃ were monitored by rheological measurements. A critical gel forms at the peroxide concentration of 0.2 wt%, where the transition from long chain branching generation to crosslinking network formation could occur. Rheokinetics of crosslinking can be fitted well by Ding-Leonov＇s model. The curing rate k2 at the earlier stage exhibits about 3 times acceleration per 10 ~C with increasing temperature, while the equilibrium modulus G＇ at the fully cured stage is almost independent of temperature. Influences of crosslinking on the subsequent crystallization behaviors were detected by DSC measurements. Above the critical gel concentration, crystallization is largely retarded as evidenced by the lower crystallization temperature Tc and crystallinity Xc due to the network formation. The secondary crystallization valley located at the temperature near 80 ℃ can be observed above the critical concentration, which becomes more evident with the increasing peroxide concentration and curing temperature. This phenomenon provides another evidence of crystallization retardation by the crosslinking network.
基金supported by National "863" High-tech R & D Program of China(No. 2007AA03Z317)the National Natural Science Foundation of China(No.31070870)+1 种基金"973" Program of the Ministry of Science and Technology of China (No.2007CB714502, 2007CB936000)Shanghai Municipal Committee of Science and Techology (No. 08520740300, 1052nm06100 and 09JC1416500)
文摘Objective： Procyanidins （PC） are widely available natural polyphenols. The present study is designed to investigate if PC can inhibit angiogenesis in lung adenocarcinoma xenografts through crosslinking vascular extracellular matrix （ECM） and preventing proteolysis by matrix metalloproteinases （MMPs）. Methods： Using the in vitro MMP-2 proteolysis and in vivo subcutaneous implantation models, we investigated if PC crosslinking inhibits MMP-mediated proteolysis. Using a cultured cell detachment assay, an in vitro angiogenesis assay, and a cell proliferation assay, we investigated if PC inhibits MMP-2-mediated endothelial cell detachment, angiogenesis, and cell proliferation, respectively. Using tumor xenografts, we evaluated if PC can inhibit growth of lung adenocarcinoma. Results： PC crosslink vascular ECM proteins, protecting them against proteolysis by MMPs in vitro and in vivo, protecting cultured human umbilical vein endothelial cells from detachment by MMP-2, and inhibiting in vitro angiogenesis. However, PC （0.75-100 μg/mL） did not inhibit vascular and tumor cells proliferation. PC injections （30 mg PC/kg bodyweight） in situ had anticancer effects on xenografts of lung adenocarcinoma, most likely by inhibiting angiogenesis during ECM proteolysis by MMPs. Conclusion： The results suggest that PC may be important MMP inhibitors that can be used as therapeutic anticancer agents.
基金Funded by the Science and Technology Department Program of Guizhou Province (ZK[2021]162 and [2019]2325)the Special Project of"Doctor Professor Service Group of Kaili University (BJFWT201906)+1 种基金the Cultivation Project of Guizhou University of China ([2019]37)the Camellia Engineering Technology Research Center of Guizhou Province ([2018]5252)。
文摘Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.
文摘AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-centre study, CXL was performed in 20 eyes of 11 patients who had LASIK for myopic astigmatism and subsequently developed keratectasia. The procedure included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation. The eyes were evaluated preoperatively and at 1-, 3-, 6-, and 12-month intervals. The complete ophthalmologic examination comprised uncorrected visual acuity, best spectacle-corrected visual acuity, endothelial cell count, ultrasound pachymetry, corneal topography, and in vivo confocal microscopy. RESULTS: CXL appeared to stabilise or partially reverse the progression of post-LASIK corneal ectasia without apparent complication in our cohort. UCVA and BCVA improvements were statistically significant (P<0.05)beyond 12 months after surgery (improvement of 0.07 and 0.13 logMAR at 1 year, respectively). Mean baseline flattest meridian keratometry and mean steepest meridian keratometry reduction (improvement of 2.00 and 1.50 diopters (D), respectively) were statistically significant (P < 0.05) at 12 months postoperatively. At 1 year after 01, mean endothelial cell count did not deteriorate. Mean thinnest cornea pachymetry increased significantly. CONCLUSION: The results of the study showed a long-term stability of post-LASIK corneal ectasia after crosslinking without relevant side effects. It seems to be a safe and promising procedure to stop the progression of post-LASIK keratectasia, thereby avoiding or delaying keratoplasty.
基金supported by the National Natural Science Foundation of China(82073001 and 82103423)Shanghai Natural Science Foundation(23ZR1454800)Scientific Research Foundation for the Introduction of Talent in Shanghai Stomatological Hospital(SSDC-2021-RC01).
文摘Carcinoma-associated fibroblasts(CAFs)are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix(ECM).The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase(LOX).Small extracellular vesicles(sEVs)mediate cell-cell communication.However,the interactions between sEVs and the ECM remain unclear.Here,we demonstrated that sEVs released from oral squamous cell carcinoma(OSCC)-derived CAFs induce collagen crosslinking,thereby promoting epithelial-mesenchymal transition(EMT).CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking,and a LOX inhibitor or blocking antibody suppressed this effect.Active LOX(αLOX),but not the LOX precursor,was enriched in CAF sEVs and interacted with periostin,fibronectin,and bone morphogenetic protein-1 on the surface of sEVs.CAF sEV-associated integrinα2β1 mediated the binding of CAF sEVs to collagen I,and blocking integrinα2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I.CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway.Taken together,these findings reveal a novel role of CAF sEVs in tumor ECM remodeling,suggesting a critical mechanism for CAF-induced EMT of cancer cells.
基金by the State Key Scientific Special Project of China(No.2016ZX05017-002)the National Natural Science Foundation of China(No.51873110).
文摘It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer(MSMEV),which exhibits high mechanical properties,multi-shape memory property and malleability.The triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F(DGEBF)with 4-aminophenyl disulfide,γ-aminopropyltriethoxysilane(APTS)and poly(propylene glycol)bis(2-aminopropyl ether)(D2000).The triple crosslinking manifests triple functions:the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network;the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region,leading to multi-shape memory property;a small amount of D2000 increases the modulus difference between the glassy and rubbery states,thereby improving the shape fixity ratio.Meanwhile,the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s modulus.Moreover,integrating carbon fibers and MSMEV results in shape memory composites.The superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.
基金Supported by the National Natural Science Foundation of China （20676095）the Program of Introducing Talents of Discipline to Universities （B06006）
文摘Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,adipoyl dichloride and hexamethylene diisocyanate ester with long flexible aliphatic chains and high reactivity with N-H groups were used in the experiments.Attenuated total reflective Fourier transform infrared spectra verified the successful preparation of highly crosslinked membranes by crosslinking treatments.It was suggested that the crosslinking agents were connected to membrane surface through the reactions with amine and amide Ⅱ groups,which is confirmed by surface charge measurements.Based on contact angle measurements,crosslinking treatments decreased membrane hydrophilicity by introducing methylene groups to membrane surface.With increasing amount of crosslinking agent molecules connected to membrane surface,the hydrolysis of unconnected functional groups of crosslinking agent produced polar groups and increased membrane hydrophilicity.The highly crosslinked membranes showed higher salt rejections and lower water fluxes as compared with the raw membrane.Since the active sites(N-H groups) vulnerable to free chlorine on membrane surface were eliminated by crosslinking treatments,the chlorine resistances of the highly crosslinked membranes were significantly improved by slighter changes in both water fluxes and salt rejections after chlorination.
基金financially supported by the National Key R&D Program of China(No.2019YFA0706802)the National Natural Science Foundation of China(Nos.51903223 and 12072325)the Key Technologies R&D Program of Henan Province(No.212102210302)。
文摘With the discovery of the two-dimensional(2D) MXene, it shows a great application potential in the field of electromagnetic interference(EMI) shielding, but the mechanical brittleness and easy oxidation of MXene limit its wide application. For this reason, a double crosslinking strategy is provided to solve the above problems in a nacre-like “brick-mortar” layered MXene/cellulose nanofiber(MXene/CNF) film.Typically, the film was firstly suffered by dopamine modification, then was further reinforced by secondary Ca^(2+)bridging, so as to obtain excellent mechanical properties and antioxidative EMI shielding performance. Comparing with the single crosslinking, the double crosslinking strategy reveals a higher efficiency in improving the mechanical property. The mechanical strength and toughness of the double crosslinking MXene/CNF film can increase to 142.2 MPa and 9.48 MJ/m^(3), respectively. More importantly, while achieving good mechanical properties, the MXene composite film still holds a very stable EMI shielding performance of more than 44.6 dB when suffering from the oxidation treatment of hightemperature annealing, showing excellent anti-oxidation ability and environment tolerance. Therefore,this work provides a universal but effective double crosslinking strategy to solve the mechanical brittleness and easy oxidation of MXene-based composites, thus showing a huge potential in flexible EMI shielding applications.
基金The authors acknowledge the funding support from the National Natural Science Foundation of China(Nos.52175474 and 51775324)the China Scholarship Council(No.202006890054).
文摘Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite their widespread utilization and numerous advantages,the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment,proliferation,and vascularization remains a challenge.Multi-material composite hydrogels present incredible potential in this field.Thus,in this work,a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed,which provides good printability and shape fidelity.In addition,a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate(TPP),genipin(GP),and glutaraldehyde(GTA)were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds.All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering,especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.
基金financially supported by the National Natural Science Foundation of China(Nos.21474058 and 51633003)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(No.LK1404)+1 种基金Tsinghua University Scientific Research Project(No.2014Z22069)State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology(No.OIC-201601006)
文摘A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.
基金financially supported by the National Natural Science Foundation of China(Nos.51373034 and 51073036)
文摘In this report, bienzymatic crosslinking approach was applied to prepare biopolymer hydrogel fibers composed of gelatin and chitosan with an interpenetrating polymer network （IPN） structure. The IPN biopolymer hydrogel fibers were prepared by wet spinning while microbial transglutaminase （mTG） catalyzed the formation of one network of gelatin and horseradish peroxidase （HRP） in the presence of H202 induced another network of chitosan grafted with phloretic acid （chitosan-PA） intertwining with the former. The mechanical performances of the hydrogel fibers were measured by an electronic single fiber strength tester. It was found that the mechanical properties of the gelatin/chitosan IPN hydrogel fibers had a significant improvement with the increase of the concentration of gelatin and chitosan, and the IPN fiber has the highest tension of 38.6 cN and elongation of 387.2%. Accelerated degradation in the presence of papin indicated that the gelatin/chitosan-PA IPN hydrogel fibers own controllable degradability. In addition, biological evaluation indicated the IPN hydrogel fibers can support cell adhesion and proliferation. Moreover, hand weaving trail showed the knittablity of the IPN hydrogel fibers. Therefore, the gelatin/chitosan IPN hydrogel fibers prepared by bienzymatic crosslinking approach possess excellent biocompatibility and mechanical strength, which may be desirable candidates for engineering tissue scaffolds.
