Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transf...Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transformation into nanomaterials:a hierarchical and multi-level strcture,and a semicrystalline microstructure.Different forms of cellulose nanomaterials,resulting from a top-down deconstructing strategy(cellulose nanocrystals(CNCs),cellulose nanofibrils(CNFs))or bottom-up strategy(bacterial cellulose(BC))can be prepared.Multiple mechanical shearing actions applied to cellulosic fibers release more or less the nanofibrils individually.A controlled strong acid hydrolysis treatment can be applied to cellulosic fibers allowing dissolution of non-crystalline domains.Such cellulose nanomaterials have been the focus of an exponentially increasing number of works or reviews devoted to understand such materials and their applications.They have a high potential for an emerging industry.In the nanoscale,cellulose exhibits specific properties broadening the applications of this naturally occurring polymer.An overview of existing methods for the preparation of cellulose nanomaterials and their specific properties that outperform and contrast with cellulose in the microscale is proposed.展开更多
The poor salt tolerance,thermal stability,and environmental performance of petrochemicals can severely limit their applications in drilling engineering.In this study,cellulose nanofibril(CNF)hydrogels with improved sa...The poor salt tolerance,thermal stability,and environmental performance of petrochemicals can severely limit their applications in drilling engineering.In this study,cellulose nanofibril(CNF)hydrogels with improved salt tolerance and thermal stability were prepared,and their filtration performance was evaluated.The hydrogels were prepared through the simultaneous grafting of 2-acrylamido-2-methylpropane sulfonic acid(AMPS)and butyl acrylate(BA)onto the CNF surface through ceric ammoniumnitrate-induced radical polymerization.The modified and original CNF samples were characterized using Fourier Transform infrared spectroscopy(FT-IR)and rheological measurements.The FT-IR analysis results showed that both AMPS and BA were grafted onto the CNF backbone,affirming the successful preparation of the grafted CNFs.The rheological analysis results showed that the modified CNF hydrogels exhibited significantly improved salt tolerance,thermal stability,and“salt-thickening”effect.Moreover,the results of the fluid loss test showed that the modified CNF hydrogels exhibited a much better fluid loss control than the original CNF hydrogels.In addition,after adding 2%modified CNF hydrogels as a filtrate reducer in the drilling fluids prepared with a 6%combined salt solution,the filtrate loss was significantly reduced even after aging for 72 h at 160℃.展开更多
Cellulose nanofibril(CNF)was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin(PAE)or cationic starch(CS)was used as the cationic component.Their strength...Cellulose nanofibril(CNF)was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin(PAE)or cationic starch(CS)was used as the cationic component.Their strengthening effects were investigated for lowbasis-weight(30 g/m2)paper composed of a mixture of fully bleached softwood and hardwood pulp in a 4:1 mass ratio.Using the PAE/CNF or CS/CNF dual system,it was generally easier to achieve higher wet and dry tensile strengths of paper compared to the paper using the single PAE or CS system.For example,the paper using the PAE(0.4%)/CNF(0.3%)dual system exhibited 89%higher wet tensile strength than the paper using the single PAE(0.4%)system,and the paper using CS(1.3%)/CNF(0.3%)dual treatment showed 21%higher dry strength than that using the single CS(1.3%)system.However,the PAE/CNF system only showed small improvement in the dry strength of paper(11%higher than that of paper using the single PAE system),so did the CS/NFC system on wet strength improvement(only 17%higher than that of paper using the single CS system).展开更多
Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceut...Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.展开更多
With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, ‘‘green" electrically conductive Ag nanowire (Ag NW)/cellulose nanofiber (CNF) hybrid...With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, ‘‘green" electrically conductive Ag nanowire (Ag NW)/cellulose nanofiber (CNF) hybrid nanopaper was fabricated to prepare flexible sensors using the facial solution blending and vacuum filtration technique. The amphiphilic property of cellulose is beneficial for the homogeneous dispersion of Ag NW to construct effective electrically conductive networks. Two different types of strain sensors were designed to study their applications in strain sensing. One was the tensile strain sensor where the hybrid nanopaper was sandwiched between two thermoplastic polyurethane (TPU) films through hot compression, and special micro-crack structure was constructed through the pre-strain process to enhance the sensitivity. Interestingly, typical pre-strain dependent strain sensing behavior was observed due to different crack densities constructed under different pre-strains. As a result, it exhibited an ultralow detection limit as low as 0.2%, good reproducibility under different strains and excellent stability and durability during 500 cycles (1% strain, 0.5 mm/min). The other was the bending strain sensor where the hybrid nanopaper was adhered onto TPU film, showing stable and recoverable linearly sensing behavior towards two different bending modes (tension and compression). Importantly, the bending sensor displayed great potential for human motion and physiological signal detection. Furthermore, the hybrid nanopaper also exhibited stable and reproducible negative temperature sensing behavior when it was served as a temperature sensor. This study provides a guideline for fabricating flexible and biodegradable sensors.展开更多
Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natura...Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natural silk by bionic for the incomplete understanding of silkworm spinning in vivo.Here,we found that amphipol and digitonin stabilized the structure of natural silk fibroin(NSF)by a large-scale screening in vitro,and then studied the close-to-native ultrastructure and hierarchical assembly of NSF in the silk gland lumen.Our study showed that NSF formed reversible flexible nanofibrils mainly composed of random coils with a sedimentation coefficient of 5.8 S and a diameter of about 4 nm,rather than a micellar or rod-like structure assembled by the aggregation of globular NSF molecules.Metal ions were required for NSF nanofibril formation.The successive p H decrease from posterior silk gland(PSG)to anterior silk gland(ASG)resulted in a gradual increase in NSF hydrophobicity,thus inducing the sol-gelation transition of NSF nanofibrils.NSF nanofibrils were randomly dispersed from PSG to ASG-1,and self-assembled into anisotropic herringbone patterns at ASG-2 near the spinneret ready for silkworm spinning.Our findings reveal the controlled self-assembly mechanism of the multi-scale hierarchical architecture of NSF from nanofibrils to herringbone patterns programmed by metal ions and p H gradient,which provides novel insights into the spinning mechanism of silk-secreting animals and bioinspired design of high-performance fibers.展开更多
Surgery remains the standard treatment for spinal metastasis.However,uncontrolled intraoperative bleeding poses a significant challenge for adequate surgical resection and compromises surgical outcomes.In this study,w...Surgery remains the standard treatment for spinal metastasis.However,uncontrolled intraoperative bleeding poses a significant challenge for adequate surgical resection and compromises surgical outcomes.In this study,we develop a thrombin(Thr)-loaded nanorobothydrogel hybrid superstructure by incorporating nanorobots into regenerated silk fibroin nanofibril hydrogels.This superstructure with superior thixotropic properties is injected percutaneously and dispersed into the spinal metastasis of hepatocellular carcinoma(HCC)with easy bleeding characteristics,before spinal surgery in a mouse model.Under near-infrared irradiation,the self-motile nanorobots penetrate into the deep spinal tumor,releasing Thr in a controlled manner.Thr-induced thrombosis effectively blocks the tumor vasculature and reduces bleeding,inhibiting tumor growth and postoperative recurrence with Au nanorod-mediated photothermal therapy.Our minimally invasive treatment platform provides a novel preoperative therapeutic strategy for HCC spinal metastasis effectively controlling intraoperative bleeding and tumor growth,with potentially reduced surgical complications and enhanced operative outcomes.展开更多
Two-dimensional covalent organic framework nanosheets(CONs)with ultrathin thickness and porous crystalline nature show substantial potential as novel membrane materials.However,bringing CONs materials into flexible me...Two-dimensional covalent organic framework nanosheets(CONs)with ultrathin thickness and porous crystalline nature show substantial potential as novel membrane materials.However,bringing CONs materials into flexible membrane form is a monumental challenge due to the limitation of weak interactions among CONs.Herein,one-dimensional silk nanofibrils(SNFs)from silkworm cocoon are designed as the nanobinder to link sulfonated CON(SCON)into robust SCON-based membrane through vacuum-filtration method.Ultrathin and large lateral-sized SCONs are synthesized via bottom-up interface-confined synthesis approach.Benefiting from high length-diameter ratio of SNF and rich functional groups in both SNF and SCON,two-dimensional(2D)SCONs are effectively connected together by physical entanglement and strong H-bond interactions.The resultant SCON/SNF membrane displays dense structure,high mechanical integrity and good stability.Importantly,the rigid porous nanochannels of SCON,high-concentration-SO3H groups insides the pores and H-bonds at SCON-SNF interfaces impart SCON/SNF membrane high-rate proton transfer pathways.Consequently,a superior proton conductivity of 365 mS cm^(-1)is achieved at 80C and 100%RH by SCON/SNF membrane.This work offers a promising approach for connecting 2D CON materials into flexible membrane as high-performance solid electrolyte for hydrogen fuel cell and may be applied in membrane-related other fields.展开更多
Multicellular spheroids,which mimic the natural organ counterparts,allow the prospect of drug screening and regenerative medicine.However,their application is hampered by low processing efficiency or limited scale.Thi...Multicellular spheroids,which mimic the natural organ counterparts,allow the prospect of drug screening and regenerative medicine.However,their application is hampered by low processing efficiency or limited scale.This study introduces an efficient method to drive rapid multicellular spheroid formation by a cellulose nanofibril matrix.This matrix enables the facilitated growth of spheroids(within 48 h)through multiple cell assembly into size-controllable aggregates with well-organized physiological microstructure.The efficiency,dimension,and conformation of the as-formed spheroids depend on the concentration of extracellular nanofibrils,the number of assembled cells,and the heterogeneity of cell types.The above strategy allows the robust formation mechanism of compacted tumoroids and hepatocyte spheroids.展开更多
With increasing emphasis on green chemistry,biomass-based materials have attracted increased attention regarding the development of highly efficient functional materials.Herein,a new pore-rich cellulose nanofibril aer...With increasing emphasis on green chemistry,biomass-based materials have attracted increased attention regarding the development of highly efficient functional materials.Herein,a new pore-rich cellulose nanofibril aerogel is utilized as a substrate to integrate highly conductive polypyrrole and active nanoflower-like nickel-cobalt layered double hydroxide through in situ chemical polymerization and electrodeposition.This ternary composite can act as an effective self-supported electrode for the electrocatalytic oxidation of glucose.With the synergistic effect of three heterogeneous components,the electrode achieves outstanding glucose sensing performance,including a high sensitivity(851.4μA·mmol^(−1)·L·cm^(−2)),a short response time(2.2 s),a wide linear range(two stages:0.001−8.145 and 8.145−35.500 mmol·L^(−1)),strong immunity to interference,outstanding intraelectrode and interelectrode reproducibility,a favorable toxicity resistance(Cl^(‒)),and a good long-term stability(maintaining 86.0%of the original value after 30 d).These data are superior to those of some traditional glucose sensors using nonbiomass substrates.When determining the blood glucose level of a human serum,this electrode realizes a high recovery rate of 97.07%–98.89%,validating the potential for highperformance blood glucose sensing.展开更多
Conductive films have emerged as appealing electrode materials in flexible supercapacitors owing to their conductivity and mechanical flexibility.However,the unsatisfactory electrode structure induced poor output perf...Conductive films have emerged as appealing electrode materials in flexible supercapacitors owing to their conductivity and mechanical flexibility.However,the unsatisfactory electrode structure induced poor output performance and undesirable cycling stability limited their application.Herein,a well-designed film was manufactured by the vacuum filtration and in-situ polymerization method from cellulose nanofibrils(CNFs),molybdenum disulfide(MoS_(2)),and polypyrrole.The electrode presented an outstanding mechanical strength(21.3 MPa)and electrical conductivity(9.70 S cm^(-1)).Meanwhile,the introduce of hydrophilic CNFs induced a desirable increase in diffusion path of electrons and ions,along with the synergistic effect among the three components,further endowed the electrode with excellent specific capacitance(0.734 F·cm^(-2))and good cycling stability(84.50%after 2000 charge/discharge cycles).More importantly,the flexible all-solid-state symmetric supercapacitor delivered a high specific capacitance(1.39 F·cm^(-2)at 1 mA·cm^(-2))and a volumetric energy density(6.36 mW·h·cm^(-3)at the power density of 16.35 mW cm^(-3)).This work provided a method for preparing composite films with desired mechanical and electrochemical performance,which can broaden the high-value applications of nanocellulose.展开更多
傅里叶变换红外(FT-IR)光谱、表面压力-分子面积(π-A)等温线和原子力显微镜(AFM)结果表明,聚乙烯吡咯烷酮(PVP)与胆固醇分子(Chol)在溶液中和气/液界面上可通过氢键作用形成刷状的超分子聚合物PVP-Chol。当表面压力低于2.5 m N?m^(-1)...傅里叶变换红外(FT-IR)光谱、表面压力-分子面积(π-A)等温线和原子力显微镜(AFM)结果表明,聚乙烯吡咯烷酮(PVP)与胆固醇分子(Chol)在溶液中和气/液界面上可通过氢键作用形成刷状的超分子聚合物PVP-Chol。当表面压力低于2.5 m N?m^(-1)时,界面膜主要由富含胆固醇的微区与PVP-Chol纳米纤维构成的微区共存。在相对较低的表面压力下(<2.5 m N?m^(-1)),PVP-Chol微区形貌随界面膜压缩发生有序的变化:从最初的无规结构逐渐变为月牙形、心形和圆形结构;表面压超过2.5 m N?m^(-1)后,圆形的PVP-Chol微区最终消失并转变为少量的纤维聚集体结构。值得注意的是,在1.0 m N?m^(-1)之前,PVP-Chol纳米纤维高度随AFM成像过程中压电陶瓷外加电压的变化在1.8到4.3 nm之间出现了可逆转变,表明扫描探针针尖与样品之间的作用力可诱导超分子聚合物刷PVP-Chol发生从圆柱状到椭柱状的可逆结构转变。展开更多
Carboxymethylated cellulose nanofibril(CMCNF)is an effective green dispersant to prepare well-dispersed monolayer montmorillonites(MMTs)in water,thereby facilitating the preparation of a high-performance MMT/polymer n...Carboxymethylated cellulose nanofibril(CMCNF)is an effective green dispersant to prepare well-dispersed monolayer montmorillonites(MMTs)in water,thereby facilitating the preparation of a high-performance MMT/polymer nanocomposite film.However,not enough attention has been paid to correlating the degree of substitution(DS)of CMCNFs with the mechanical and optical properties of the final nanocomposite films.In this study,a series of homogeneous monolayer MMT nanoplatelet dispersions was prepared initially using CMCNFs with different DS as a dispersant,and the as-prepared CMCNF-dispersed MMT dispersions were then mixed with sodium carboxymethyl cellulose(CMC-Na)to fabricate nacre-like nanocomposite films with different contents of MMTs through self-assembly.The layered nanostructure and optical and mechanical properties of the asprepared CMCNF-dispersed MMT/CMC-Na nanocomposite films were investigated,which demonstrated that CMCNFs with lower DS have a positive effect on their optical and mechanical properties.This study sheds light on the preparation of MMT-based nanocomposite films with superior optical and mechanical properties.展开更多
Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are en...Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are energy intensive because heating and mechanical disintegration are required to produce cellulose fibers below 100 nm in size.In this study,CNFs were prepared through the multi-site regioselective oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)and periodate at room temperature(20–25°C),without any mechanical-disintegration treatment.Transmission electron microscopy(TEM)revealed that the CNFs had the average widths of 14.1,55.4,and 81.9 nm for three different treatments.Fourier-transform infrared spectroscopy revealed that carboxyl groups were created on the surfaces of the microfibrils,while X-ray diffraction studies showed that the cellulose I structure was maintained after oxidation,and that the cellulose nanofibril crystallinity index exceeded 70%.These results demonstrate that CNFs can be prepared by multi-site regioselective oxidation at room temperature in the absence of mechanical disintegration.In addition,a model was developed to calculate the total content of carboxylate and aldehyde groups of CNFs prepared by the TEMPO mediate oxidation,the periodate oxidation,and the multi-site regioselective oxidation methods based on the particle width determined by TEM.The calculated values of the model were in good agreement with the total content(experimental value)of carboxylate and aldehyde groups of CNFs prepared by the TEMPO-mediated oxidation and the multi-site regioselective oxidation methods.However,the model was not valid for CNFs prepared by the periodate oxidation method.展开更多
The spider dragline silk has excellent mechanical properties. The stress- strain curves of dragline silk fibers have intraspecific and intraindividual variability because of the spider’s active control during spinnin...The spider dragline silk has excellent mechanical properties. The stress- strain curves of dragline silk fibers have intraspecific and intraindividual variability because of the spider’s active control during spinning process. To investigate the relationship between the morphology of dragline silk fibers and spinning conditions, four samples were made at the reeling rates of 1 mm/s, 20 mm/s, 43.5 mm/s and 110 mm/s from the major ampullate glands of Araneus Ventricosus and the other two of dragline silks were prepared from a crawling or dropping spider. The surface microstructure and nanofibril characteristic were analyzed with atomic force microscopy (AFM). AFM images of 2 000 nm *2 000 nm and 500 nm*500 nm of these samples showed that the spinning condition influenced the surface roughness and fibril size, while AFM images of 200 nm*200 nm clearly displayed that dragline silk of Araneus Ventricosus included sheet macro-conformation structure. These results can facilitate the further investigation of the spinning mechanism of a spider in order to understand mechanical properties and macromolecular structures of dragline silk.展开更多
基金LGP2 is part of the LabEx Tec 21(Investissements d’Avenir-grant agreement n°ANR-11-LABX-0030)of the PolyNat Carnot Institut(Investissements d’Avenir-grant agreement n°ANR-11-CARN-030-01).
文摘Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transformation into nanomaterials:a hierarchical and multi-level strcture,and a semicrystalline microstructure.Different forms of cellulose nanomaterials,resulting from a top-down deconstructing strategy(cellulose nanocrystals(CNCs),cellulose nanofibrils(CNFs))or bottom-up strategy(bacterial cellulose(BC))can be prepared.Multiple mechanical shearing actions applied to cellulosic fibers release more or less the nanofibrils individually.A controlled strong acid hydrolysis treatment can be applied to cellulosic fibers allowing dissolution of non-crystalline domains.Such cellulose nanomaterials have been the focus of an exponentially increasing number of works or reviews devoted to understand such materials and their applications.They have a high potential for an emerging industry.In the nanoscale,cellulose exhibits specific properties broadening the applications of this naturally occurring polymer.An overview of existing methods for the preparation of cellulose nanomaterials and their specific properties that outperform and contrast with cellulose in the microscale is proposed.
基金the National Natural Science Foundation of China(Grant No.31700514)the Natural Science Foundation of Tianjin,China(Grant No.18JCYBJC86500)for their financial supports
文摘The poor salt tolerance,thermal stability,and environmental performance of petrochemicals can severely limit their applications in drilling engineering.In this study,cellulose nanofibril(CNF)hydrogels with improved salt tolerance and thermal stability were prepared,and their filtration performance was evaluated.The hydrogels were prepared through the simultaneous grafting of 2-acrylamido-2-methylpropane sulfonic acid(AMPS)and butyl acrylate(BA)onto the CNF surface through ceric ammoniumnitrate-induced radical polymerization.The modified and original CNF samples were characterized using Fourier Transform infrared spectroscopy(FT-IR)and rheological measurements.The FT-IR analysis results showed that both AMPS and BA were grafted onto the CNF backbone,affirming the successful preparation of the grafted CNFs.The rheological analysis results showed that the modified CNF hydrogels exhibited significantly improved salt tolerance,thermal stability,and“salt-thickening”effect.Moreover,the results of the fluid loss test showed that the modified CNF hydrogels exhibited a much better fluid loss control than the original CNF hydrogels.In addition,after adding 2%modified CNF hydrogels as a filtrate reducer in the drilling fluids prepared with a 6%combined salt solution,the filtrate loss was significantly reduced even after aging for 72 h at 160℃.
基金supported by the National Program on Key Research & Development Project of China (Grant No. 2017YFB0307902)
文摘Cellulose nanofibril(CNF)was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin(PAE)or cationic starch(CS)was used as the cationic component.Their strengthening effects were investigated for lowbasis-weight(30 g/m2)paper composed of a mixture of fully bleached softwood and hardwood pulp in a 4:1 mass ratio.Using the PAE/CNF or CS/CNF dual system,it was generally easier to achieve higher wet and dry tensile strengths of paper compared to the paper using the single PAE or CS system.For example,the paper using the PAE(0.4%)/CNF(0.3%)dual system exhibited 89%higher wet tensile strength than the paper using the single PAE(0.4%)system,and the paper using CS(1.3%)/CNF(0.3%)dual treatment showed 21%higher dry strength than that using the single CS(1.3%)system.However,the PAE/CNF system only showed small improvement in the dry strength of paper(11%higher than that of paper using the single PAE system),so did the CS/NFC system on wet strength improvement(only 17%higher than that of paper using the single CS system).
基金grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.31770628 and 31901267)the Taishan Scholars Program+3 种基金the Provincial Key Research and Development Program of Shandong(Grant Nos.2019JZZY010326 and 2019JZZY010328)a projectu(Grant No.ZR2019BC042)supported by the Shandong Provincial Natural Science Foundationa project of the Shandong Province Higher Educational Science and Technology Program(J18KA111).
文摘Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.
基金supported by the National Natural Science Foundation of China(51803191)the China Postdoctoral Science Foundation(2018M642782)the 111 project(D18023)
文摘With the rapid development of smart wearable devices, flexible and biodegradable sensors are in urgent needs. In this study, ‘‘green" electrically conductive Ag nanowire (Ag NW)/cellulose nanofiber (CNF) hybrid nanopaper was fabricated to prepare flexible sensors using the facial solution blending and vacuum filtration technique. The amphiphilic property of cellulose is beneficial for the homogeneous dispersion of Ag NW to construct effective electrically conductive networks. Two different types of strain sensors were designed to study their applications in strain sensing. One was the tensile strain sensor where the hybrid nanopaper was sandwiched between two thermoplastic polyurethane (TPU) films through hot compression, and special micro-crack structure was constructed through the pre-strain process to enhance the sensitivity. Interestingly, typical pre-strain dependent strain sensing behavior was observed due to different crack densities constructed under different pre-strains. As a result, it exhibited an ultralow detection limit as low as 0.2%, good reproducibility under different strains and excellent stability and durability during 500 cycles (1% strain, 0.5 mm/min). The other was the bending strain sensor where the hybrid nanopaper was adhered onto TPU film, showing stable and recoverable linearly sensing behavior towards two different bending modes (tension and compression). Importantly, the bending sensor displayed great potential for human motion and physiological signal detection. Furthermore, the hybrid nanopaper also exhibited stable and reproducible negative temperature sensing behavior when it was served as a temperature sensor. This study provides a guideline for fabricating flexible and biodegradable sensors.
基金supported by the National Key Research and Development Program of China(2022YFD1201600,2021YFA1300100,and 2018YFE0203300)the National Natural Science Foundation of China(31972622 and 32241029)+6 种基金the State Key Program of National Natural Science Foundation of China(32030103)the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-LZX0302,CSTB2022NSCQ-MSX0761,and cstc2020jcyj-cxtt X0001)the Fundamental Research Funds for the Central Universities(XDJK2020TJ001)the Key Project of Science and Technology Research Program of Chongqing Municipal Education Commission,China(KJZD-K202200205)the Chinese Academy of Sciences(CAS)Strategic Priority Research Program(XDB37010100)the Shennong Youth Talent Program(Ministry of Agriculture and Rural Affairs,China)the Chongqing Innovation Supporting Program for Oversea Returned Talents(CX2023069)。
文摘Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent.It is a great challenge to reproduce high-performance artificial fibers comparable to natural silk by bionic for the incomplete understanding of silkworm spinning in vivo.Here,we found that amphipol and digitonin stabilized the structure of natural silk fibroin(NSF)by a large-scale screening in vitro,and then studied the close-to-native ultrastructure and hierarchical assembly of NSF in the silk gland lumen.Our study showed that NSF formed reversible flexible nanofibrils mainly composed of random coils with a sedimentation coefficient of 5.8 S and a diameter of about 4 nm,rather than a micellar or rod-like structure assembled by the aggregation of globular NSF molecules.Metal ions were required for NSF nanofibril formation.The successive p H decrease from posterior silk gland(PSG)to anterior silk gland(ASG)resulted in a gradual increase in NSF hydrophobicity,thus inducing the sol-gelation transition of NSF nanofibrils.NSF nanofibrils were randomly dispersed from PSG to ASG-1,and self-assembled into anisotropic herringbone patterns at ASG-2 near the spinneret ready for silkworm spinning.Our findings reveal the controlled self-assembly mechanism of the multi-scale hierarchical architecture of NSF from nanofibrils to herringbone patterns programmed by metal ions and p H gradient,which provides novel insights into the spinning mechanism of silk-secreting animals and bioinspired design of high-performance fibers.
基金supported by the National Natural Science Foundation of China(No.52103171,82172738,82272457,22305044)China Postdoctoral Science Foundation(2023M730638)+3 种基金“Technology Innovation Action Plan”of Science and Technology Commission of Shanghai Municipality(21S11902700)Natural Science Foundation of Shanghai(21ZR1412300),Shanghai Science and Technology program(23Y31900202,23010502600)Shanghai“Rising Stars of Medical Talent”Youth Development Program(Youth Medical Talents-Specialist Program,[2020]087)Medical Engineering fund of Fudan University(yg2023-27).
文摘Surgery remains the standard treatment for spinal metastasis.However,uncontrolled intraoperative bleeding poses a significant challenge for adequate surgical resection and compromises surgical outcomes.In this study,we develop a thrombin(Thr)-loaded nanorobothydrogel hybrid superstructure by incorporating nanorobots into regenerated silk fibroin nanofibril hydrogels.This superstructure with superior thixotropic properties is injected percutaneously and dispersed into the spinal metastasis of hepatocellular carcinoma(HCC)with easy bleeding characteristics,before spinal surgery in a mouse model.Under near-infrared irradiation,the self-motile nanorobots penetrate into the deep spinal tumor,releasing Thr in a controlled manner.Thr-induced thrombosis effectively blocks the tumor vasculature and reduces bleeding,inhibiting tumor growth and postoperative recurrence with Au nanorod-mediated photothermal therapy.Our minimally invasive treatment platform provides a novel preoperative therapeutic strategy for HCC spinal metastasis effectively controlling intraoperative bleeding and tumor growth,with potentially reduced surgical complications and enhanced operative outcomes.
文摘Two-dimensional covalent organic framework nanosheets(CONs)with ultrathin thickness and porous crystalline nature show substantial potential as novel membrane materials.However,bringing CONs materials into flexible membrane form is a monumental challenge due to the limitation of weak interactions among CONs.Herein,one-dimensional silk nanofibrils(SNFs)from silkworm cocoon are designed as the nanobinder to link sulfonated CON(SCON)into robust SCON-based membrane through vacuum-filtration method.Ultrathin and large lateral-sized SCONs are synthesized via bottom-up interface-confined synthesis approach.Benefiting from high length-diameter ratio of SNF and rich functional groups in both SNF and SCON,two-dimensional(2D)SCONs are effectively connected together by physical entanglement and strong H-bond interactions.The resultant SCON/SNF membrane displays dense structure,high mechanical integrity and good stability.Importantly,the rigid porous nanochannels of SCON,high-concentration-SO3H groups insides the pores and H-bonds at SCON-SNF interfaces impart SCON/SNF membrane high-rate proton transfer pathways.Consequently,a superior proton conductivity of 365 mS cm^(-1)is achieved at 80C and 100%RH by SCON/SNF membrane.This work offers a promising approach for connecting 2D CON materials into flexible membrane as high-performance solid electrolyte for hydrogen fuel cell and may be applied in membrane-related other fields.
基金supported by the National Natural Science Foundation of China(No.32071347)the ZJU-Hangzhou Global Scientific and Technological Innovation Center,Zhejiang University(No.02020200-K02013008)the Joint Laboratory Grant from Jiangsu Wuzhong Aesthetics Biotech Co.,Ltd.,and the Starting Grant of ShanghaiTech University.
文摘Multicellular spheroids,which mimic the natural organ counterparts,allow the prospect of drug screening and regenerative medicine.However,their application is hampered by low processing efficiency or limited scale.This study introduces an efficient method to drive rapid multicellular spheroid formation by a cellulose nanofibril matrix.This matrix enables the facilitated growth of spheroids(within 48 h)through multiple cell assembly into size-controllable aggregates with well-organized physiological microstructure.The efficiency,dimension,and conformation of the as-formed spheroids depend on the concentration of extracellular nanofibrils,the number of assembled cells,and the heterogeneity of cell types.The above strategy allows the robust formation mechanism of compacted tumoroids and hepatocyte spheroids.
基金supported by the National Natural Science Foundation of China(Grant No.31901249),the Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ30079)the Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology(Grant No.2020RC3041)the Training Program for Excellent Young Innovators of Changsha(Grant No.kq2106056).
文摘With increasing emphasis on green chemistry,biomass-based materials have attracted increased attention regarding the development of highly efficient functional materials.Herein,a new pore-rich cellulose nanofibril aerogel is utilized as a substrate to integrate highly conductive polypyrrole and active nanoflower-like nickel-cobalt layered double hydroxide through in situ chemical polymerization and electrodeposition.This ternary composite can act as an effective self-supported electrode for the electrocatalytic oxidation of glucose.With the synergistic effect of three heterogeneous components,the electrode achieves outstanding glucose sensing performance,including a high sensitivity(851.4μA·mmol^(−1)·L·cm^(−2)),a short response time(2.2 s),a wide linear range(two stages:0.001−8.145 and 8.145−35.500 mmol·L^(−1)),strong immunity to interference,outstanding intraelectrode and interelectrode reproducibility,a favorable toxicity resistance(Cl^(‒)),and a good long-term stability(maintaining 86.0%of the original value after 30 d).These data are superior to those of some traditional glucose sensors using nonbiomass substrates.When determining the blood glucose level of a human serum,this electrode realizes a high recovery rate of 97.07%–98.89%,validating the potential for highperformance blood glucose sensing.
基金supports from the National Key R&D Program of China(2019YFC1905901)the Beijing Forestry University Outstanding Young Talent Cultivation Project(2019JQ03014)the Key Production Innovative Development Plan of the Southern Bingtuan(2019DB007)are gratefully acknowledged.
文摘Conductive films have emerged as appealing electrode materials in flexible supercapacitors owing to their conductivity and mechanical flexibility.However,the unsatisfactory electrode structure induced poor output performance and undesirable cycling stability limited their application.Herein,a well-designed film was manufactured by the vacuum filtration and in-situ polymerization method from cellulose nanofibrils(CNFs),molybdenum disulfide(MoS_(2)),and polypyrrole.The electrode presented an outstanding mechanical strength(21.3 MPa)and electrical conductivity(9.70 S cm^(-1)).Meanwhile,the introduce of hydrophilic CNFs induced a desirable increase in diffusion path of electrons and ions,along with the synergistic effect among the three components,further endowed the electrode with excellent specific capacitance(0.734 F·cm^(-2))and good cycling stability(84.50%after 2000 charge/discharge cycles).More importantly,the flexible all-solid-state symmetric supercapacitor delivered a high specific capacitance(1.39 F·cm^(-2)at 1 mA·cm^(-2))and a volumetric energy density(6.36 mW·h·cm^(-3)at the power density of 16.35 mW cm^(-3)).This work provided a method for preparing composite films with desired mechanical and electrochemical performance,which can broaden the high-value applications of nanocellulose.
基金supported by the National Natural Science Foundation of China(21273074,21576079,91334203,21476070)the 111 Project of Ministry of Education of China(B08021)~~
文摘傅里叶变换红外(FT-IR)光谱、表面压力-分子面积(π-A)等温线和原子力显微镜(AFM)结果表明,聚乙烯吡咯烷酮(PVP)与胆固醇分子(Chol)在溶液中和气/液界面上可通过氢键作用形成刷状的超分子聚合物PVP-Chol。当表面压力低于2.5 m N?m^(-1)时,界面膜主要由富含胆固醇的微区与PVP-Chol纳米纤维构成的微区共存。在相对较低的表面压力下(<2.5 m N?m^(-1)),PVP-Chol微区形貌随界面膜压缩发生有序的变化:从最初的无规结构逐渐变为月牙形、心形和圆形结构;表面压超过2.5 m N?m^(-1)后,圆形的PVP-Chol微区最终消失并转变为少量的纤维聚集体结构。值得注意的是,在1.0 m N?m^(-1)之前,PVP-Chol纳米纤维高度随AFM成像过程中压电陶瓷外加电压的变化在1.8到4.3 nm之间出现了可逆转变,表明扫描探针针尖与样品之间的作用力可诱导超分子聚合物刷PVP-Chol发生从圆柱状到椭柱状的可逆结构转变。
基金We would like to thank for the financial support from the National Natural Science Foundation of China(21978103)the Natural Science Foundation of Guangdong Province(2020B1515020021)+2 种基金the Pearl River S&T Nova Program of Guangzhou(201806010141)the Foundation of Key Laboratory of Pulp and Paper Science and Technology of Ministry of Education/Shandong Province of China(KF201812)the Fundamental Research Funds for the Central Universities(2019MS083).
文摘Carboxymethylated cellulose nanofibril(CMCNF)is an effective green dispersant to prepare well-dispersed monolayer montmorillonites(MMTs)in water,thereby facilitating the preparation of a high-performance MMT/polymer nanocomposite film.However,not enough attention has been paid to correlating the degree of substitution(DS)of CMCNFs with the mechanical and optical properties of the final nanocomposite films.In this study,a series of homogeneous monolayer MMT nanoplatelet dispersions was prepared initially using CMCNFs with different DS as a dispersant,and the as-prepared CMCNF-dispersed MMT dispersions were then mixed with sodium carboxymethyl cellulose(CMC-Na)to fabricate nacre-like nanocomposite films with different contents of MMTs through self-assembly.The layered nanostructure and optical and mechanical properties of the asprepared CMCNF-dispersed MMT/CMC-Na nanocomposite films were investigated,which demonstrated that CMCNFs with lower DS have a positive effect on their optical and mechanical properties.This study sheds light on the preparation of MMT-based nanocomposite films with superior optical and mechanical properties.
基金This research was funded by The Talents Project for Harbin Science and Technology Innovation,grant number 2016RAXXJ006China Postdoctoral Science Foundation,grant number 2017M611341.
文摘Cellulose nanofibrils(CNFs)are promising sustainable materials that can be applied to nanocomposites,as well as medical and life-sciences devices.However,methods for the preparation of these important materials are energy intensive because heating and mechanical disintegration are required to produce cellulose fibers below 100 nm in size.In this study,CNFs were prepared through the multi-site regioselective oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)and periodate at room temperature(20–25°C),without any mechanical-disintegration treatment.Transmission electron microscopy(TEM)revealed that the CNFs had the average widths of 14.1,55.4,and 81.9 nm for three different treatments.Fourier-transform infrared spectroscopy revealed that carboxyl groups were created on the surfaces of the microfibrils,while X-ray diffraction studies showed that the cellulose I structure was maintained after oxidation,and that the cellulose nanofibril crystallinity index exceeded 70%.These results demonstrate that CNFs can be prepared by multi-site regioselective oxidation at room temperature in the absence of mechanical disintegration.In addition,a model was developed to calculate the total content of carboxylate and aldehyde groups of CNFs prepared by the TEMPO mediate oxidation,the periodate oxidation,and the multi-site regioselective oxidation methods based on the particle width determined by TEM.The calculated values of the model were in good agreement with the total content(experimental value)of carboxylate and aldehyde groups of CNFs prepared by the TEMPO-mediated oxidation and the multi-site regioselective oxidation methods.However,the model was not valid for CNFs prepared by the periodate oxidation method.
基金science and technology office of Jiangsu province
文摘The spider dragline silk has excellent mechanical properties. The stress- strain curves of dragline silk fibers have intraspecific and intraindividual variability because of the spider’s active control during spinning process. To investigate the relationship between the morphology of dragline silk fibers and spinning conditions, four samples were made at the reeling rates of 1 mm/s, 20 mm/s, 43.5 mm/s and 110 mm/s from the major ampullate glands of Araneus Ventricosus and the other two of dragline silks were prepared from a crawling or dropping spider. The surface microstructure and nanofibril characteristic were analyzed with atomic force microscopy (AFM). AFM images of 2 000 nm *2 000 nm and 500 nm*500 nm of these samples showed that the spinning condition influenced the surface roughness and fibril size, while AFM images of 200 nm*200 nm clearly displayed that dragline silk of Araneus Ventricosus included sheet macro-conformation structure. These results can facilitate the further investigation of the spinning mechanism of a spider in order to understand mechanical properties and macromolecular structures of dragline silk.