The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium...The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.展开更多
In this paper, core–shell quantum dots(QDs) with two polar surface functional groups(ZnSe/ZnS–COOH QDs and ZnSe/ZnS–NH;QDs) are synthesized in an aqueous phase. Photoluminescence(PL) and absorption spectra cl...In this paper, core–shell quantum dots(QDs) with two polar surface functional groups(ZnSe/ZnS–COOH QDs and ZnSe/ZnS–NH;QDs) are synthesized in an aqueous phase. Photoluminescence(PL) and absorption spectra clearly indicate luminescence down-shifting(LDS) properties. On the basis of QDs, surface functional group multilayer LDS films(MLDSs) are fabricated through an electrostatic layer-by-layer(LBL) self-assembly method. The PL intensity increases linearly with the number of bilayers, showing a regular and uniform film growth. When the M-LDS is placed on the surface of a Si-based solar cell as an optical conversion layer for the first time, the external quantum efficiency(EQE) and shortcircuit current density(Jsc) notably increases for the LDS process. The EQE response improves in a wavelength region extending from the UV region to the blue region, and its maximum increase reaches more than 15% between 350 nm and 460 nm.展开更多
The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform as...The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.展开更多
Orthopedic implants for the treatment of bone defects from various causes have been challenged by insufficient osseointegration,bacterial infection,oxidative stress,immune rejection,and insufficient individualized tre...Orthopedic implants for the treatment of bone defects from various causes have been challenged by insufficient osseointegration,bacterial infection,oxidative stress,immune rejection,and insufficient individualized treatment.These challenges not only impact treatment outcomes but also severely impact patients’daily lives.Layer-by-Layer(LbL)serves as a simple surface coating technique,in simple terms,to functionalize implants by sequentially adsorbing oppositely charged materials onto a substrate.In orthopaedics,LbL self-assembly technology solves some of the challenges by loading various drugs or biological agents on the implant surface and controlling their release precisely to the site of bone defects in a personalized way.This review will introduce the basic principle and the development of LbL in orthopaedics,review and analyze the chemical strategy of LbL in the preparation of bone implants to ensure the stability of the implant,and introduce the use of LbL bone implants in orthopaedics in recent years.The application of LbL includes the realization of programmed drug delivery and sustained release,thereby promoting osseointegration and the formation of new blood vessels,antibacterial,antioxidant,etc.This review focuses on the LbL technology,involving the technology selection for the preparation of bone implants,the chemical strategies of the stability guarantee of LbL implants,the pharmacological properties,loading and release mechanisms of loaded drugs,and the molecular mechanisms of osteogenesis and angiogenesis.The aim of this review is to provide an overview of current research advances,and a prospect in this field was also described.展开更多
Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties.Nevertheless,the poor interfacial strength between fib...Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties.Nevertheless,the poor interfacial strength between fibers and the resin matrix limits the performance of composites utilized as tribomaterials.To overcome this drawback,a mild layer-by-layer(LbL)self-assembly method was successfully used to construct hybrid fabric composites in the present work.In addition,this investigation addressed the effect of self-assembly cycles on the friction and wear behaviors of hybrid fabric composites under dry sliding condition.The results demonstrate that fabric composites with three or more self-assembly cycles have significantly enhanced surface activities and anti-wear performances.The results obtained in this work can provide guidance in the preparation of self-lubricating liner composites and highlight how the LbL self-assembly techniques could influence the properties of hybrid fabric composites.展开更多
Spherical polyelectrolyte brushes (SPBs) consisting of polystyrene (PS) core and poly(2-aminoethyl methacrylate hydrochloride) (PAEMH) shell were prepared by photo-emulsion polymerization. Au nanoparticles (A...Spherical polyelectrolyte brushes (SPBs) consisting of polystyrene (PS) core and poly(2-aminoethyl methacrylate hydrochloride) (PAEMH) shell were prepared by photo-emulsion polymerization. Au nanoparticles (Au-NPs) with controlled size and size distribution were synthesized in situ using SPBs as nanoreactors. Via layer-by-layer deposition technique on the surface of SPBs, nano-composite particles with Au/Ag-NPs bilayer and Au/Ag/Au-NPs trilayer were prepared. The structures of the as-prepared Au/Ag multilayer SPBs were characterized by UV-Vis spectroscopy, TEM, ICP-AES and DLS. The charge reversal of the nano-composite particles observed by zeta potential confirmed the success of layer-by-layer assembly. The Au/Ag-NPs bilayer nano-composite particles showed high catalytic efficiency with an apparent activation energy of about 41.2 kJ/mol in the reduction reaction of 4-nitrophenol to 4-aminophenol in the existence of sodium borohydride monitored. The catalytic activity ofAu/Ag-NPs multilayer SPBs close to that of Au-NPs SPBs and much higher than that of Ag-NPs SPBs reveals its potential applications in cost-effective catalysts with high-performance.展开更多
Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler,owing to the excellent electrochemical inertness and barrier property.However,as the arrangement of graphene nanosheets is difficult to...Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler,owing to the excellent electrochemical inertness and barrier property.However,as the arrangement of graphene nanosheets is difficult to form a perfect layered structure,polymeric coating with graphene nanosheets usually needs micron-scale thickness to ensure the enhancement of corrosion protection.In this work,layer-by-layer stacked graphene nanocoatings were fabricated on stainless steel by self-assembly based on Marangoni effect.The anti-corrosion property of graphene coatings were studied through Tafel polarization curves,electrochemical impedance spectroscopy and accelerated corrosion test with extra applied voltage.The self corrosion current density of optimized three-layered graphene coated sample was one quarter of that of bare stainless steel.And the self corrosion potential of optimized sample is increased to-0.045 V.According to the results,graphene nanocoatings composed of layered nanosheets exhibits good anticorrosion property.Besides,the self-assembly method provide a promising approach to make layeredstructure coating for other researches about 2 D material nanosheets.展开更多
Ultrathin multilayer films of a rare-earth-containing polyoxo-metalateNa_9[Eu(W_5O_(18))_] (EW) and poly ( allylamine hydrochloride) (PAH) have been prepared bylayer-by-layer self-assembly from dilute aqueous solution...Ultrathin multilayer films of a rare-earth-containing polyoxo-metalateNa_9[Eu(W_5O_(18))_] (EW) and poly ( allylamine hydrochloride) (PAH) have been prepared bylayer-by-layer self-assembly from dilute aqueous solutions. The fabrication process of the EW/PAHmultilayer films was followed by UV-vis spec-troscopy and ellipsometry, which show that thedeposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayerthickness of ca. 2.1 nm was determined by ellipsometry. In addition, the scanning electronmicroscopy (SEM) image of the EW/PAH film indicates that the film surface is relatively uniform andsmooth. The photolumi-nescent properties of these films were also investigated by fluorescencespectroscopy.展开更多
The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes (MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon ele...The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes (MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase (ACHE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected by using i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrode with 0.01U activity value and the detection limit of carbaryl is 10^- 12 g L ^-1 so the enzyme biosensor showed good properties for pesticides residue detection.展开更多
An efficient and safe gene delivery system remains a challenge in the development of gene therapy.Polycation-based gene nanoparticles are a typical non-viral gene delivery system,which are able to transfect cells in v...An efficient and safe gene delivery system remains a challenge in the development of gene therapy.Polycation-based gene nanoparticles are a typical non-viral gene delivery system,which are able to transfect cells in vitro and in vivo.This paper reported a facile method for constructing biodegradable multilayers via layer-by-layer self-assembly,in which the polycation-based gene nanoparticles were loaded.Through this surface-mediated delivery system,adherent cells on the multilayer could be transfected in situ.Gene nanoparticles-loaded multilayers transfect cells with higher efficiency than naked DNA-loaded multilayers because of the complex configuration of the DNA.DNA nanoparticles/PGA multilayers constructed on the scaffold surface could also realize in situ transfection on the adherent cells.The well-structured,easy-processed multilayers may provide a novel approach to precisely controlled delivery of gene nanoparticles,which may have potential applications for gene therapy in tissue engineering and medical implants.展开更多
Layer-by-layer (LbL) strategy has been developed to form bulk heterojunction (BHJ) structure for processing efficient organic solar cells (OSCs). Herein, LbL slot-die coating with twin boiling point solvents (TBPS) st...Layer-by-layer (LbL) strategy has been developed to form bulk heterojunction (BHJ) structure for processing efficient organic solar cells (OSCs). Herein, LbL slot-die coating with twin boiling point solvents (TBPS) strategy was developed to fabricate highly efficient OSCs, which matches with large-scale, high throughput roll-to-roll (R2R) industrialized mass process. The TBPS strategy could produce high-quality thin film without any additive, leading to the optimized vertical phase separation with interpenetrating nanostructures, as well as the enhanced charge transport and extraction. Thus, the power conversion efficiency up to 14.42% was achieved for [(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo [1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)]:2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4″,5″]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene)) bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (PM6:Y6) OSCs fabricated via sequentially LbL slot-die coating using the TBPS strategy under ambient condition. The research provides a potential route for industrialized production of high-efficiency and large-area OSC devices.展开更多
Electrochemical sensing of carcinoembryonic antigen(CEA)on a gold electrode modified by the se- quential incorporation of the mediator,thionine(Thi),and gold nanoparticles(nano-Au),through co- valent linkage and elect...Electrochemical sensing of carcinoembryonic antigen(CEA)on a gold electrode modified by the se- quential incorporation of the mediator,thionine(Thi),and gold nanoparticles(nano-Au),through co- valent linkage and electrostatic interactions onto a self-assembled monolayer configuration is de- scribed in this paper.The enzyme,horseradish peroxidase(HRP),was employed to block the possible remaining active sites of the nano-Au monolayer,avoid the non-specific adsorption,instead of bovine serum albumin(BSA),and amplify the response of the antigen-antibody reaction.Electrochemical ex- periments indicated highly efficient electron transfer by the imbedded Thi mediator and adsorbed nano-Au.The HRP kept its activity after immobilization,and the studied electrode showed sensitive response to CEA and high stability during a long period of storage.The working range for the system was 2.5 to 80.0 ng/mL with a detection limit of 0.90 ng/mL.The model membrane system in this work is a potential biosensor for mimicking the other immunosensor and enzyme sensor.展开更多
A post-photochemical cross-linking strategy was successfully demonstrated to enhance the stability of polyelectrolyte poly(allylamine hydrochloride)(PAH)/poly(vinylsulfonic acid sodium salt)(PVS) multilayers. ...A post-photochemical cross-linking strategy was successfully demonstrated to enhance the stability of polyelectrolyte poly(allylamine hydrochloride)(PAH)/poly(vinylsulfonic acid sodium salt)(PVS) multilayers. Con- ventional polyelectrolyte multilayers of PAH/PVS are usually fabricated through electrostatic layer-by-layer(LbL) assembly, resulting in poor stability, especially in basic solutions, which leads to the urgent demand for converting weak electrostatic interactions into covalent bonds to enhance the stability of the multilayers. This stability problem has been ultimately addressed by post-infiltrating a photosensitive cross-linking agent, 4,4'-diazostilbene-2,2'- disulfonie acid disodium salt(DAS), into the LbL assembled films to initiate the photochemical reaction to cross-link the multilayers. The obviously improved stability of the photo-cross-linked multilayers was demonstrated through experiments with basic solution treatments. Compared to the complete decomposition of uncross-linked multilayers in basic solution, over 74.4% of the covalently cross-linked multilayers were retained under the same conditions, even after a longer duration of basic solution treatment.展开更多
Silver halide (AgX) microcrystal was used as template to synthesize hollow polyelectrolyte capsules. These hollow capsules were characterized by laser light scattering (LLS) used to measure the size of the capsules in...Silver halide (AgX) microcrystal was used as template to synthesize hollow polyelectrolyte capsules. These hollow capsules were characterized by laser light scattering (LLS) used to measure the size of the capsules in solution. The ratio of hydrodynamic radius (R h ) from dynamic LLS to the radius of gyration (Rg) from static LLS is almost unity, revealing that the entities are hollow in solution. The results suggest that the LLS method can be regarded as a good complement to the confocal laser scanning microscopy (CLSM) method for the characterization of small hollow capsules, and it possesses the advantage of not needing fluorescence labeling.展开更多
To prepare layer-by-layer(LbL) multilayers in time-efficient manners by the dipping method is highly ap- pealing. However, the fast LbL assembly produces multilayers with high surface roughness. In our attempt to sm...To prepare layer-by-layer(LbL) multilayers in time-efficient manners by the dipping method is highly ap- pealing. However, the fast LbL assembly produces multilayers with high surface roughness. In our attempt to smooth the surface morphologies of LbL multilayers obtained by fast assembly(5 s dipping), we studied the influence of the assembly conditions on the surface morphologies. The study shows that by properly adjusting the assembly condi- tions, such as washing duration, water annealing period, and drying with nitrogen flow, LbL multilayers with en- hanced surface smoothness could be obtained through fast LbL assembly.展开更多
Active sites of two-dimensional(2D)electrocatalysts are often partially blocked owing to their inevitable stacking and hydrophobic polymeric binders in macroscale electrodes,therefore impeding their applications in ef...Active sites of two-dimensional(2D)electrocatalysts are often partially blocked owing to their inevitable stacking and hydrophobic polymeric binders in macroscale electrodes,therefore impeding their applications in efficient electrolyzers.Here,using layered double hydroxide(LDH)nanosheets as a model 2D electrocatalyst,we demonstrate that their performance toward water splitting can be boosted when they are electrostatically assembled into an organized structure pillared by hydrophilic polyelectrolytes or nanoparticles in a layer-by-layer(LbL)fashion.In particular,their mass activity on a planar electrode can be as large as 2.267 mA·μg^(-1) toward oxygen evolution reaction(OER),when NiFe-LDH nanosheets are electrostatically connected by poly(sodium 4-styrenesulfonate)(PSS),while drop-casted NiFe-LDH nanosheets only have a mass activity of 0.116 mA·μg^(-1).In addition,these homogeneous NiFe-LDH nanofilms can be easily deposited on three-dimensional(3D)surfaces with high areas,such as carbon cloths,to serve as practical electrodes with overpotentials of 328 mV at a current density of 100 mA·cm^(-2),and stability for 40 h.Furthermore,Pt nanoparticles can be LbL assembled with NiFe-LDH as bifunctional electrodes for synergistically boosted oxygen and hydrogen evolution reactions(HER),leading to successful overall water splitting powered by a 1.5 V battery.This study heralds the spatial control of 2D nanomaterials in nanoscale precision as an efficient strategy for the design of advanced electrocatalysts.展开更多
Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes,where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance.In this work,an ion...Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes,where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance.In this work,an ionic strength directed self-assembly procedure is described for the preparation of nanofiltration membranes consisting of only a single bilayer of poly(diallyldimethylammoniumchloride)and poly(sodium-4-styrenesulfoate).The influence of background ionic strength as well as membrane substrate properties on the formation of singlebilayer membranes are systematically evaluated.Such a simplified polyelectrolyte deposition procedure results in membranes having outstanding separation performance with permeating flux of 14.21.5 L∙m^(–2)∙h^(-1)∙bar^(–1) and Na2SO4 rejection of 97.1%0.8%under a low applied pressure of 1 bar.These results surpass the ones for conventional multilayered polyelectrolyte membranes.This work encompasses an investigation of ionic strength induced coiling of the polyelectrolyte chains and emphasizes the interplay between-polyelectrolyte chain configuration and substrate pore profile.It thus introduces a new concept on the control of membrane fabrication process toward high performance nanofiltration.展开更多
Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strateg...Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strategy of efficient utilization of CNT in producing CNT incorporated aramid papers is demonstrated.The layer-by-layer self-assembly technique is used to coat the surfaces of meta-aramid fibers and fibrils with CNT,providing novel raw materials available for the large-scale papermaking.The hierarchical construction of CNT networks resolves the dilemma of increasing CNT content and avoiding the agglomeration of CNT,which is a frequent challenge for CNT incorporated polymeric composites.The composite paper,which contains abundant heterogeneous interfaces and long-range conductive networks,is capable of reaching a high permittivity and dielectric loss tangent at a low CNT loading,its complex permittivity is,so far,adjustable in the range of(1.20−j0.05)to(25.17−j18.89)at 10 GHz.Some papers with optimal matching thicknesses achieve a high-efficiency microwave absorption with a reflection loss lower than−10 dB in the entire X-band.展开更多
基金National Undergraduate Training Program for Innovation and Entrepreneurship of China (Grant No.202210288027).
文摘The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2017PF011)the National Natural Science Foundation of China(Grant No.E020701)the Doctoral Scientific Research Foundation of Binzhou University,China(Grant No.2014Y10)
文摘In this paper, core–shell quantum dots(QDs) with two polar surface functional groups(ZnSe/ZnS–COOH QDs and ZnSe/ZnS–NH;QDs) are synthesized in an aqueous phase. Photoluminescence(PL) and absorption spectra clearly indicate luminescence down-shifting(LDS) properties. On the basis of QDs, surface functional group multilayer LDS films(MLDSs) are fabricated through an electrostatic layer-by-layer(LBL) self-assembly method. The PL intensity increases linearly with the number of bilayers, showing a regular and uniform film growth. When the M-LDS is placed on the surface of a Si-based solar cell as an optical conversion layer for the first time, the external quantum efficiency(EQE) and shortcircuit current density(Jsc) notably increases for the LDS process. The EQE response improves in a wavelength region extending from the UV region to the blue region, and its maximum increase reaches more than 15% between 350 nm and 460 nm.
基金supported by the Starting Foundation of Renmin University of China and the National Natural Science Foundation of China(No.20703066).
文摘The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.
文摘Orthopedic implants for the treatment of bone defects from various causes have been challenged by insufficient osseointegration,bacterial infection,oxidative stress,immune rejection,and insufficient individualized treatment.These challenges not only impact treatment outcomes but also severely impact patients’daily lives.Layer-by-Layer(LbL)serves as a simple surface coating technique,in simple terms,to functionalize implants by sequentially adsorbing oppositely charged materials onto a substrate.In orthopaedics,LbL self-assembly technology solves some of the challenges by loading various drugs or biological agents on the implant surface and controlling their release precisely to the site of bone defects in a personalized way.This review will introduce the basic principle and the development of LbL in orthopaedics,review and analyze the chemical strategy of LbL in the preparation of bone implants to ensure the stability of the implant,and introduce the use of LbL bone implants in orthopaedics in recent years.The application of LbL includes the realization of programmed drug delivery and sustained release,thereby promoting osseointegration and the formation of new blood vessels,antibacterial,antioxidant,etc.This review focuses on the LbL technology,involving the technology selection for the preparation of bone implants,the chemical strategies of the stability guarantee of LbL implants,the pharmacological properties,loading and release mechanisms of loaded drugs,and the molecular mechanisms of osteogenesis and angiogenesis.The aim of this review is to provide an overview of current research advances,and a prospect in this field was also described.
基金National Nature Science Foundation of China(Nos.51805516 and 51675252).
文摘Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties.Nevertheless,the poor interfacial strength between fibers and the resin matrix limits the performance of composites utilized as tribomaterials.To overcome this drawback,a mild layer-by-layer(LbL)self-assembly method was successfully used to construct hybrid fabric composites in the present work.In addition,this investigation addressed the effect of self-assembly cycles on the friction and wear behaviors of hybrid fabric composites under dry sliding condition.The results demonstrate that fabric composites with three or more self-assembly cycles have significantly enhanced surface activities and anti-wear performances.The results obtained in this work can provide guidance in the preparation of self-lubricating liner composites and highlight how the LbL self-assembly techniques could influence the properties of hybrid fabric composites.
基金financially supported by the National Natural Science Foundation of China(No.51273063 and 51003028)the Fundamental Research Funds for the Central Universities+1 种基金the Higher School Specialized Research Fund for the Doctoral Program(No.20110074110003)111 Project Grant(No.B08021)
文摘Spherical polyelectrolyte brushes (SPBs) consisting of polystyrene (PS) core and poly(2-aminoethyl methacrylate hydrochloride) (PAEMH) shell were prepared by photo-emulsion polymerization. Au nanoparticles (Au-NPs) with controlled size and size distribution were synthesized in situ using SPBs as nanoreactors. Via layer-by-layer deposition technique on the surface of SPBs, nano-composite particles with Au/Ag-NPs bilayer and Au/Ag/Au-NPs trilayer were prepared. The structures of the as-prepared Au/Ag multilayer SPBs were characterized by UV-Vis spectroscopy, TEM, ICP-AES and DLS. The charge reversal of the nano-composite particles observed by zeta potential confirmed the success of layer-by-layer assembly. The Au/Ag-NPs bilayer nano-composite particles showed high catalytic efficiency with an apparent activation energy of about 41.2 kJ/mol in the reduction reaction of 4-nitrophenol to 4-aminophenol in the existence of sodium borohydride monitored. The catalytic activity ofAu/Ag-NPs multilayer SPBs close to that of Au-NPs SPBs and much higher than that of Ag-NPs SPBs reveals its potential applications in cost-effective catalysts with high-performance.
基金the financial support by the National Natural Science Foundation of China(Nos.51573201,51501209,201675165 and 61901460)NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(No.U1709205)+7 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22000000)Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201640)Science and Technology Major Project of Ningbo(Nos.2016S1002 and 2016B10038)International S&T Cooperation Program of Ningbo(No.2017D10016)China Postdoctoral Science Foundation(No.2019M653125)for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbo。
文摘Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler,owing to the excellent electrochemical inertness and barrier property.However,as the arrangement of graphene nanosheets is difficult to form a perfect layered structure,polymeric coating with graphene nanosheets usually needs micron-scale thickness to ensure the enhancement of corrosion protection.In this work,layer-by-layer stacked graphene nanocoatings were fabricated on stainless steel by self-assembly based on Marangoni effect.The anti-corrosion property of graphene coatings were studied through Tafel polarization curves,electrochemical impedance spectroscopy and accelerated corrosion test with extra applied voltage.The self corrosion current density of optimized three-layered graphene coated sample was one quarter of that of bare stainless steel.And the self corrosion potential of optimized sample is increased to-0.045 V.According to the results,graphene nanocoatings composed of layered nanosheets exhibits good anticorrosion property.Besides,the self-assembly method provide a promising approach to make layeredstructure coating for other researches about 2 D material nanosheets.
基金theNationalNaturalScienceFoundationofChina (No .2 0 0 710 0 7)andtheFoundationforUniversityKeyTeacherbytheMinistryofEducationofChina
文摘Ultrathin multilayer films of a rare-earth-containing polyoxo-metalateNa_9[Eu(W_5O_(18))_] (EW) and poly ( allylamine hydrochloride) (PAH) have been prepared bylayer-by-layer self-assembly from dilute aqueous solutions. The fabrication process of the EW/PAHmultilayer films was followed by UV-vis spec-troscopy and ellipsometry, which show that thedeposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayerthickness of ca. 2.1 nm was determined by ellipsometry. In addition, the scanning electronmicroscopy (SEM) image of the EW/PAH film indicates that the film surface is relatively uniform andsmooth. The photolumi-nescent properties of these films were also investigated by fluorescencespectroscopy.
文摘The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes (MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase (ACHE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected by using i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrode with 0.01U activity value and the detection limit of carbaryl is 10^- 12 g L ^-1 so the enzyme biosensor showed good properties for pesticides residue detection.
基金supported by the National Natural Science Foundation of China (Grant No 50830106)the 863 Programm (Grant No 2006AA03Z329)Science and Technology Plan of Zhejiang Province of China (Grant No 2007C24008)
文摘An efficient and safe gene delivery system remains a challenge in the development of gene therapy.Polycation-based gene nanoparticles are a typical non-viral gene delivery system,which are able to transfect cells in vitro and in vivo.This paper reported a facile method for constructing biodegradable multilayers via layer-by-layer self-assembly,in which the polycation-based gene nanoparticles were loaded.Through this surface-mediated delivery system,adherent cells on the multilayer could be transfected in situ.Gene nanoparticles-loaded multilayers transfect cells with higher efficiency than naked DNA-loaded multilayers because of the complex configuration of the DNA.DNA nanoparticles/PGA multilayers constructed on the scaffold surface could also realize in situ transfection on the adherent cells.The well-structured,easy-processed multilayers may provide a novel approach to precisely controlled delivery of gene nanoparticles,which may have potential applications for gene therapy in tissue engineering and medical implants.
基金This work was supported by the National Key Research and Development Program of China(No.2017YFA0206600)the Science and Technology Innovation Program of Hunan Province(No.2020RC4004)the Special Funding for the Construction of Innovative Provinces in Hunan Province(No.2020GK2024).
文摘Layer-by-layer (LbL) strategy has been developed to form bulk heterojunction (BHJ) structure for processing efficient organic solar cells (OSCs). Herein, LbL slot-die coating with twin boiling point solvents (TBPS) strategy was developed to fabricate highly efficient OSCs, which matches with large-scale, high throughput roll-to-roll (R2R) industrialized mass process. The TBPS strategy could produce high-quality thin film without any additive, leading to the optimized vertical phase separation with interpenetrating nanostructures, as well as the enhanced charge transport and extraction. Thus, the power conversion efficiency up to 14.42% was achieved for [(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo [1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)]:2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4″,5″]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene)) bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (PM6:Y6) OSCs fabricated via sequentially LbL slot-die coating using the TBPS strategy under ambient condition. The research provides a potential route for industrialized production of high-efficiency and large-area OSC devices.
基金the National Natural Science Foundation of China(Grant No.20675064)Natural Science Foundation of Chongqing City(Grant Nos.CSTC-2004BB4149 and 2005BB4100)the High Technology Project Foundation ofSouthwest University(XSGX02),China
文摘Electrochemical sensing of carcinoembryonic antigen(CEA)on a gold electrode modified by the se- quential incorporation of the mediator,thionine(Thi),and gold nanoparticles(nano-Au),through co- valent linkage and electrostatic interactions onto a self-assembled monolayer configuration is de- scribed in this paper.The enzyme,horseradish peroxidase(HRP),was employed to block the possible remaining active sites of the nano-Au monolayer,avoid the non-specific adsorption,instead of bovine serum albumin(BSA),and amplify the response of the antigen-antibody reaction.Electrochemical ex- periments indicated highly efficient electron transfer by the imbedded Thi mediator and adsorbed nano-Au.The HRP kept its activity after immobilization,and the studied electrode showed sensitive response to CEA and high stability during a long period of storage.The working range for the system was 2.5 to 80.0 ng/mL with a detection limit of 0.90 ng/mL.The model membrane system in this work is a potential biosensor for mimicking the other immunosensor and enzyme sensor.
基金Supported by the National Natural Science Foundation of China(Nos.51372125, 51302010) and the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20130010120009).
文摘A post-photochemical cross-linking strategy was successfully demonstrated to enhance the stability of polyelectrolyte poly(allylamine hydrochloride)(PAH)/poly(vinylsulfonic acid sodium salt)(PVS) multilayers. Con- ventional polyelectrolyte multilayers of PAH/PVS are usually fabricated through electrostatic layer-by-layer(LbL) assembly, resulting in poor stability, especially in basic solutions, which leads to the urgent demand for converting weak electrostatic interactions into covalent bonds to enhance the stability of the multilayers. This stability problem has been ultimately addressed by post-infiltrating a photosensitive cross-linking agent, 4,4'-diazostilbene-2,2'- disulfonie acid disodium salt(DAS), into the LbL assembled films to initiate the photochemical reaction to cross-link the multilayers. The obviously improved stability of the photo-cross-linked multilayers was demonstrated through experiments with basic solution treatments. Compared to the complete decomposition of uncross-linked multilayers in basic solution, over 74.4% of the covalently cross-linked multilayers were retained under the same conditions, even after a longer duration of basic solution treatment.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 20204017 and 50373049) and theChinese Academy of Sciences (CMS-CX200308).
文摘Silver halide (AgX) microcrystal was used as template to synthesize hollow polyelectrolyte capsules. These hollow capsules were characterized by laser light scattering (LLS) used to measure the size of the capsules in solution. The ratio of hydrodynamic radius (R h ) from dynamic LLS to the radius of gyration (Rg) from static LLS is almost unity, revealing that the entities are hollow in solution. The results suggest that the LLS method can be regarded as a good complement to the confocal laser scanning microscopy (CLSM) method for the characterization of small hollow capsules, and it possesses the advantage of not needing fluorescence labeling.
基金Supported by the National Natural Science Foundation of China(No.21303169), the Fundamental Research Funds for the Central Universities, China(No.2652013115), the Beijing Nova Program, China(No.Z141103001814064), the Beijing Specific Project to Foster Elitist, China(No.2013D009015000001), the Open Project of State Key Laboratory of Chemical Resource Engi- neering, China(No.CRE-2013-C-201), the National High Technology Research and Development Program of China (No.2012AA06A109) and the Special co-Construction Project of Beijing City Education Committee, China.
文摘To prepare layer-by-layer(LbL) multilayers in time-efficient manners by the dipping method is highly ap- pealing. However, the fast LbL assembly produces multilayers with high surface roughness. In our attempt to smooth the surface morphologies of LbL multilayers obtained by fast assembly(5 s dipping), we studied the influence of the assembly conditions on the surface morphologies. The study shows that by properly adjusting the assembly condi- tions, such as washing duration, water annealing period, and drying with nitrogen flow, LbL multilayers with en- hanced surface smoothness could be obtained through fast LbL assembly.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52273076,52111540268,and 12004195)the 111 Project(No.B18030)in China+1 种基金The authors also acknowledge the financial support by Haihe Laboratory of Sustainable Chemical Transformations(No.YYJC202101)Open Research Fund Program of the State Key Laboratory of Low Dimensional Quantum Physics(No.KF202113).
文摘Active sites of two-dimensional(2D)electrocatalysts are often partially blocked owing to their inevitable stacking and hydrophobic polymeric binders in macroscale electrodes,therefore impeding their applications in efficient electrolyzers.Here,using layered double hydroxide(LDH)nanosheets as a model 2D electrocatalyst,we demonstrate that their performance toward water splitting can be boosted when they are electrostatically assembled into an organized structure pillared by hydrophilic polyelectrolytes or nanoparticles in a layer-by-layer(LbL)fashion.In particular,their mass activity on a planar electrode can be as large as 2.267 mA·μg^(-1) toward oxygen evolution reaction(OER),when NiFe-LDH nanosheets are electrostatically connected by poly(sodium 4-styrenesulfonate)(PSS),while drop-casted NiFe-LDH nanosheets only have a mass activity of 0.116 mA·μg^(-1).In addition,these homogeneous NiFe-LDH nanofilms can be easily deposited on three-dimensional(3D)surfaces with high areas,such as carbon cloths,to serve as practical electrodes with overpotentials of 328 mV at a current density of 100 mA·cm^(-2),and stability for 40 h.Furthermore,Pt nanoparticles can be LbL assembled with NiFe-LDH as bifunctional electrodes for synergistically boosted oxygen and hydrogen evolution reactions(HER),leading to successful overall water splitting powered by a 1.5 V battery.This study heralds the spatial control of 2D nanomaterials in nanoscale precision as an efficient strategy for the design of advanced electrocatalysts.
基金supported by the National Key Research and Development Project(Grant Nos.2019YFC1711300 and 2019YFA0705800)the National Natural Science Funds for Distinguished Young Scholar(Grant No.51625306)+1 种基金the National Natural Science Foundation of China(Grant Nos.21988102 and 51873230)the Social Development Program of Jiangsu Province(Grant No.BE2019678).
文摘Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes,where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance.In this work,an ionic strength directed self-assembly procedure is described for the preparation of nanofiltration membranes consisting of only a single bilayer of poly(diallyldimethylammoniumchloride)and poly(sodium-4-styrenesulfoate).The influence of background ionic strength as well as membrane substrate properties on the formation of singlebilayer membranes are systematically evaluated.Such a simplified polyelectrolyte deposition procedure results in membranes having outstanding separation performance with permeating flux of 14.21.5 L∙m^(–2)∙h^(-1)∙bar^(–1) and Na2SO4 rejection of 97.1%0.8%under a low applied pressure of 1 bar.These results surpass the ones for conventional multilayered polyelectrolyte membranes.This work encompasses an investigation of ionic strength induced coiling of the polyelectrolyte chains and emphasizes the interplay between-polyelectrolyte chain configuration and substrate pore profile.It thus introduces a new concept on the control of membrane fabrication process toward high performance nanofiltration.
基金the National Natural Science Foundation of China(No.U21A2093).
文摘Carbon nanotubes(CNTs)incorporated polymeric composites have been extensively investigated for microwave absorption at target frequencies to meet the requirement of radar cross-section reduction.In this work,a strategy of efficient utilization of CNT in producing CNT incorporated aramid papers is demonstrated.The layer-by-layer self-assembly technique is used to coat the surfaces of meta-aramid fibers and fibrils with CNT,providing novel raw materials available for the large-scale papermaking.The hierarchical construction of CNT networks resolves the dilemma of increasing CNT content and avoiding the agglomeration of CNT,which is a frequent challenge for CNT incorporated polymeric composites.The composite paper,which contains abundant heterogeneous interfaces and long-range conductive networks,is capable of reaching a high permittivity and dielectric loss tangent at a low CNT loading,its complex permittivity is,so far,adjustable in the range of(1.20−j0.05)to(25.17−j18.89)at 10 GHz.Some papers with optimal matching thicknesses achieve a high-efficiency microwave absorption with a reflection loss lower than−10 dB in the entire X-band.