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
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
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
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
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
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
Implant failure,which is commonly associated with failure of osseointegration and peri-implant infection,is a severe complication of orthopedic surgery.In particular,the survival rate of implants is significantly decr...Implant failure,which is commonly associated with failure of osseointegration and peri-implant infection,is a severe complication of orthopedic surgery.In particular,the survival rate of implants is significantly decreased in patients using long-term glucocorticoids(GCs).However,the exact molecular mechanism underlying GCs-induced implant loosening,as well as preventive strategies for these patients,is unclear.To address this problem,we performed RNA-sequencing and found that WNT16 was correlated with GCs-induced osteopenia(LogFC=-5.17,p<0.01).Inspired by the concept of“organic-inorganic”hybrid,we theorized to introduce a bioactive two-dimensional nanosheet into a layer-by-layer(LbL)self-assembly coating to construct a customized implant that targets WNT16.After screening commercially available nanosheets,laponite(LAP)was identified as a cost-effective rescuer for GCs-induced WNT16 inhibition,which was then intercalated into LbL deposition system consisting of quaternized chitosan(QCS)and hyaluronic acid(HA).The hybrid coating(QCS/HA/LAP)showed micrometer thickness and improved hydrophilicity and interface roughness.Furthermore,QCS/HA/LAP coated polyetheretherketone(PEEK)implant enhanced cell viability,adhesion,and osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs),and promoted osteointegration of PEEK in GCs-treated rats by targeting the WNT16/β-catenin axis.The assembled QCS has proven antibacterial properties,and the hybrid coating exerted potent detrimental effects against methicillin-resistant Staphylococcus aureus(MRSA)and Escherichia coli(E.coli),both in vitro and in vivo.Taken together,these results suggest that QCS/HA/LAP coating has great potential for use in implants customization,and has synergistic pro-osteogenic and antibacterial effects that help prevent implant failure in GCs-treated patients.展开更多
Owing to their high-specific binding toward targets as well as fast and convenient separation operations,immunomagnetic beads(IMBs)are widely used in the capture and detection of circulating tumor cells(CTCs).To const...Owing to their high-specific binding toward targets as well as fast and convenient separation operations,immunomagnetic beads(IMBs)are widely used in the capture and detection of circulating tumor cells(CTCs).To construct the IMBs,surface modifications are generally performed to functionalize the magnetic cores(e.g.Fe_(3)O_(4)nanoparticles),and the employed surface modification strategies normally influence the structure and functions of the prepared IMBs in return.Different from the existing work,we proposed the use of supramolecular layer-by-layer(LBL)self-assembly strategy to construct the IMBs.In general,owing to theπ-πstacking interactions,the polydopamine,graphene oxide and‘molecular glue’γ-oxo-1-pyrenebutyric acid were self-assembled on Fe_(3)O_(4)nanoparticles sequentially,thereby accomplishing the integration of different functional components onto magnetic cores to prepare the self-assembled supramolecular immunomagnetic beads(ASIMBs).The ASIMBs showed high sensitivity,specificity and good biocompatibility to the model CTCs and low nonspecific adsorption to the negative cells(∼93%for MCF-7 cells and 17%for Jurkat cells).Meanwhile,ASIMBs possessed a remarkable potential to screen the rare MCF-7 cells out of large amounts of interfering Jurkat cells with the capture efficiency of 75-100%or out of mouse whole blood with the capture efficiency of 20-90%.The captured cells can be further recultured directly without any more treatment,which showed huge applicability of the ASIMBs for in vitro detection in clinical practices.展开更多
In this study, macroscopic graphene-wrapped melamine foams (MF-G) were fabricated by an MF-templated layer-by-layer (LBL) assembly using graphene oxide as building blocks, followed by solution-processed reduction....In this study, macroscopic graphene-wrapped melamine foams (MF-G) were fabricated by an MF-templated layer-by-layer (LBL) assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole (PPy) was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.展开更多
Coronary atherosclerotic lesions exhibit a low-pH chronic inflammatory response.Due to insufficient drug release control,drug-eluting stent intervention can lead to delayed endothelialization,advanced thrombosis,and u...Coronary atherosclerotic lesions exhibit a low-pH chronic inflammatory response.Due to insufficient drug release control,drug-eluting stent intervention can lead to delayed endothelialization,advanced thrombosis,and unprecise treatment.In this study,hyaluronic acid and chitosan were used to prepare pH-responsive self-assembling films.The hydrogen sulfide(H2S)releasing aspirin derivative ACS14 was used as drug in the film.The film regulates the release of the drug adjusted to the microenvironment of the lesion,and the drug balances the vascular function by releasing the regulating gas H2S,which comparably to NO promotes the self-healing capacity of blood vessels.Drug releasing profiles of the films at different pH,and other biological effects on blood vessels were evaluated through blood compatibility,cellular,and implantation experiments.This novel method of self-assembled films which H2S in an amount,which is adjusted to the condition of the lesion provides a new concept for the treatment of cardiovascular diseases.展开更多
In recent years, there has been a considerable research interest in moving-bed biofilm reactor(MBBR) for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam...In recent years, there has been a considerable research interest in moving-bed biofilm reactor(MBBR) for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam(PU) carriers via the layer-by-layer self-assembly of hyperbranched polymeric diazonium salt(M-HB-DAS) and poly(sodium-p-styrenesulfonate)(PSS). Modified carriers showed very good adsorption for microbes according to the results of scanning electron microscope(SEM). Biochemical experiments on wastewater treatment confirm that the modified PU carriers can improve the removal rate of chemical oxygen demand(COD).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 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.
基金This work was supported by Shanghai Sailing Program(22YF1433200)the National Natural Science Foundation of China(82172400).
文摘Implant failure,which is commonly associated with failure of osseointegration and peri-implant infection,is a severe complication of orthopedic surgery.In particular,the survival rate of implants is significantly decreased in patients using long-term glucocorticoids(GCs).However,the exact molecular mechanism underlying GCs-induced implant loosening,as well as preventive strategies for these patients,is unclear.To address this problem,we performed RNA-sequencing and found that WNT16 was correlated with GCs-induced osteopenia(LogFC=-5.17,p<0.01).Inspired by the concept of“organic-inorganic”hybrid,we theorized to introduce a bioactive two-dimensional nanosheet into a layer-by-layer(LbL)self-assembly coating to construct a customized implant that targets WNT16.After screening commercially available nanosheets,laponite(LAP)was identified as a cost-effective rescuer for GCs-induced WNT16 inhibition,which was then intercalated into LbL deposition system consisting of quaternized chitosan(QCS)and hyaluronic acid(HA).The hybrid coating(QCS/HA/LAP)showed micrometer thickness and improved hydrophilicity and interface roughness.Furthermore,QCS/HA/LAP coated polyetheretherketone(PEEK)implant enhanced cell viability,adhesion,and osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs),and promoted osteointegration of PEEK in GCs-treated rats by targeting the WNT16/β-catenin axis.The assembled QCS has proven antibacterial properties,and the hybrid coating exerted potent detrimental effects against methicillin-resistant Staphylococcus aureus(MRSA)and Escherichia coli(E.coli),both in vitro and in vivo.Taken together,these results suggest that QCS/HA/LAP coating has great potential for use in implants customization,and has synergistic pro-osteogenic and antibacterial effects that help prevent implant failure in GCs-treated patients.
基金supports by the National Natural Science Foundation of China(32071438,31971265)the Hui-min Project of the Chengdu Science and Technology Bureau(2021-YF05-01578-SN)Dr Lingzhu Yu is appreciated(National Engineering Research Center for Biomaterials,Sichuan University)for SEM measurement.
文摘Owing to their high-specific binding toward targets as well as fast and convenient separation operations,immunomagnetic beads(IMBs)are widely used in the capture and detection of circulating tumor cells(CTCs).To construct the IMBs,surface modifications are generally performed to functionalize the magnetic cores(e.g.Fe_(3)O_(4)nanoparticles),and the employed surface modification strategies normally influence the structure and functions of the prepared IMBs in return.Different from the existing work,we proposed the use of supramolecular layer-by-layer(LBL)self-assembly strategy to construct the IMBs.In general,owing to theπ-πstacking interactions,the polydopamine,graphene oxide and‘molecular glue’γ-oxo-1-pyrenebutyric acid were self-assembled on Fe_(3)O_(4)nanoparticles sequentially,thereby accomplishing the integration of different functional components onto magnetic cores to prepare the self-assembled supramolecular immunomagnetic beads(ASIMBs).The ASIMBs showed high sensitivity,specificity and good biocompatibility to the model CTCs and low nonspecific adsorption to the negative cells(∼93%for MCF-7 cells and 17%for Jurkat cells).Meanwhile,ASIMBs possessed a remarkable potential to screen the rare MCF-7 cells out of large amounts of interfering Jurkat cells with the capture efficiency of 75-100%or out of mouse whole blood with the capture efficiency of 20-90%.The captured cells can be further recultured directly without any more treatment,which showed huge applicability of the ASIMBs for in vitro detection in clinical practices.
基金The authors gratefully acknowledge the National Natural Science Foundation of China (No. 21504012, 51125011 and 51433001) and the Fundamental Research Funds for the Central Universities of China (No. 16D110617).
文摘In this study, macroscopic graphene-wrapped melamine foams (MF-G) were fabricated by an MF-templated layer-by-layer (LBL) assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole (PPy) was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.
基金the National Natural Science Foundation of China(NSFC 81771988)Sichuan Science and Technology Program(No.20GJHZ0268).
文摘Coronary atherosclerotic lesions exhibit a low-pH chronic inflammatory response.Due to insufficient drug release control,drug-eluting stent intervention can lead to delayed endothelialization,advanced thrombosis,and unprecise treatment.In this study,hyaluronic acid and chitosan were used to prepare pH-responsive self-assembling films.The hydrogen sulfide(H2S)releasing aspirin derivative ACS14 was used as drug in the film.The film regulates the release of the drug adjusted to the microenvironment of the lesion,and the drug balances the vascular function by releasing the regulating gas H2S,which comparably to NO promotes the self-healing capacity of blood vessels.Drug releasing profiles of the films at different pH,and other biological effects on blood vessels were evaluated through blood compatibility,cellular,and implantation experiments.This novel method of self-assembled films which H2S in an amount,which is adjusted to the condition of the lesion provides a new concept for the treatment of cardiovascular diseases.
基金Supported by the National Natural Science Foundation of China(Nos.21474056, 21674058).
文摘In recent years, there has been a considerable research interest in moving-bed biofilm reactor(MBBR) for its efficiency and stability. This work proposes a new way to modify the hydrophilicity of polyurethane foam(PU) carriers via the layer-by-layer self-assembly of hyperbranched polymeric diazonium salt(M-HB-DAS) and poly(sodium-p-styrenesulfonate)(PSS). Modified carriers showed very good adsorption for microbes according to the results of scanning electron microscope(SEM). Biochemical experiments on wastewater treatment confirm that the modified PU carriers can improve the removal rate of chemical oxygen demand(COD).