Drug-eluting magnesium(Mg)alloy stents have a slower degradation rate and lower restenosis rate compared with uncoated stents,demonstrating good clinical efficacy.However,the release of anti-hyperplasia drugs from coa...Drug-eluting magnesium(Mg)alloy stents have a slower degradation rate and lower restenosis rate compared with uncoated stents,demonstrating good clinical efficacy.However,the release of anti-hyperplasia drugs from coatings delays endothelial tissue repair,thus leading to late stent thrombosis.To address these issues,a dual self-healed coating with various biological properties was fabricated on magnesium fluoride/polydopamine(MgF_(2)/PDA)-treated Mg alloys by spraying-assisted layer-by-layer(LBL)self-assembly of chitosan(CS),gallic acid(GA),and 3-aminobenzeneboronic acid-modified hyaluronic acid(HA-ABBA).The LBL coating,approximately 1.50μm thick,exhibited a uniform morphology with good adhesion strength(~1065 mN).The annual corrosion rate(Pi)of LBL samples was~1400 times slower than that of the Mg substrate,due to the physical barrier function provided by MgF_(2)/PDA layers and the dual self-healed ability of LBL layers.The rapid self-healing ability(with a healing period of~4 h under dynamic/static conditions)resulted from the synergistic interplay between the recombination of diverse chemical bonds within the LBL coating and the coordination of LBL-released GA with Mg2+,as corroborated by computer simulations.Compared with the drug-eluting coatings,the LBL sample demonstrated substantial advantages in anti-oxidation,anti-denaturation of fibrinogen,anti-platelet adhesion,anti-inflammation,anti-hyperplasia,and promoted-endothelialization.These benefits effectively address the limitations associated with drug-eluting coatings.展开更多
The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In...The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.展开更多
In order to develop a facile and precisely controlled approach to synthesize hierarchical mesoporous materials with tailored property, in this work, a novel study was carried out to fabricate montmorillonitechitosan h...In order to develop a facile and precisely controlled approach to synthesize hierarchical mesoporous materials with tailored property, in this work, a novel study was carried out to fabricate montmorillonitechitosan hollow and hierarchical mesoporous spheres(MMTNS@CS-HMPHS) based on single-template layer-by-layer(Lb L) assembly. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), specific surface area analysis and X-ray photoelectron spectroscopy(XPS) analyses were carried out to characterize the morphology and surface properties of MMTNS@CS-HMPHS. Benefitting from the unique lamellar structure of MMTNS, mesoporous channels are formed on the shell of MMTNS@CS hollow spheres, resulting in high surface area. Moreover, the surface functionalization and pore size of MMTNS@CS-HMPHS can be easily tuned, due to the tailored property through Lb L assembly method.Besides the unique microstructure, MMTNS@CS-HMPHS also possesses the active sites generated from both MMT and chitosan, which greatly promotes its performance in fields of adsorption, drug delivery and catalyst supports, etc.展开更多
Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly...Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.展开更多
A simple and controllable layer-by-layer （LBL） assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes （MWNTs） a...A simple and controllable layer-by-layer （LBL） assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes （MWNTs） and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly（allylamine hydrochloride） （PAH） and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue （MB） could mix well with horseradish peroxidase （HRP） to form a biocompatible and negativelycharged HRP-MB biocomposite. A （PAH-MWNTs/HRP-MB）, bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response （2 s） to hydrogen peroxide with a low detection limit of 2.0× 10^-7 mol/L （S/N=3）. This work provided a versatile platform in the further development of reagentless biosensors.展开更多
Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic a...Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.展开更多
An eleetrochromic variable optical attenuator （ECVOA） was fabricated by layer-by-layer （LBL） assembly of disodium N,N-bis（p-sulfonatophenyl）naphthalenedicarboximide （Naph-SO3Na） and common cationic polymer pol...An eleetrochromic variable optical attenuator （ECVOA） was fabricated by layer-by-layer （LBL） assembly of disodium N,N-bis（p-sulfonatophenyl）naphthalenedicarboximide （Naph-SO3Na） and common cationic polymer poly（diallyldimethylammonium） chloride （PDDA）. The UV-Vis absorption spectra of the multilayer films revealed that approximately an equal amount of Naph-SO3Na was assembled in each deposition cycle. Upon one-electron reduction, multilayer films exhibited intense absorption around 452 nm and also a broad absorption band from 1200 nm to 1900 nm. Owing to the improved ionic conductivity, the optical attenuation at 1550 nm of the films showed rapid response time and reached 1.3 dB/μm within 5 s. These results indicate that layer-by-layer assembly could be an effective method for the preparation of ECVOA operating in near infrared region.展开更多
The layer-by-layer assembly of graphene oxide and diazoresin is carried out via the electrostatic and hydrogen bond interactions on planar substrates and colloidal templates.The successful planar and spherical growth ...The layer-by-layer assembly of graphene oxide and diazoresin is carried out via the electrostatic and hydrogen bond interactions on planar substrates and colloidal templates.The successful planar and spherical growth of multilayer could be investigated by UV-vis spectrophotometry and scanning electron microscopy,respectively.Subsequent UV irradiation or heating would convert the ionic bonds and hydrogen bonds to covalent bands,which significantly improves the stability of the multilayer composite against solvent etching.For the cross-linked core-shell composites,the template cores could be removed by dissolution and hollow microspheres are obtained.展开更多
Metal oxide semiconductor materials such as ZnO have tremendous potential as light absorbers for photocatalysed electrodes in the electrochemical reduction of water. Promoters such as rGO have been added to reduce the...Metal oxide semiconductor materials such as ZnO have tremendous potential as light absorbers for photocatalysed electrodes in the electrochemical reduction of water. Promoters such as rGO have been added to reduce the recombination losses of charge carriers and improve its photoelectrochemical activity. In this study, the effect of layer ordering on the charge transfer properties of rGO-hybridised ZnO sandwich thin films for the photo-catalysed electrochemical reduction of water was investigated. rGO-hybridised ZnO sandwich thin films were prepared via a facile electrode position technique using a layer-by-layer approach. The thin films were analysed using FESEM, XRD, Raman, PL, UV–vis, EIS and CV techniques to investigate its morphological, optical and electrochemical properties. The FESEM images show the formation of distinct layers of rGO and ZnO nanorods/flakes via the layer-by-layer method. XRD confirmed the wurtzite structure of ZnO. PL spectroscopy revealed a reduction of photoemission intensity in the visible region（580 nm） when rGO was incorporated into the ZnO thin film. Among the six thin films prepared, ZnO/rGO showed superior performance compared to the other thin films（0.964 m A/cm） due to the presence of graphene edges which participate as heterogenous electrocatalysts in the photocatalysed electrolysis of water. rGO also acts as electron acceptor, forming an n-p heterojunction which improves the activity of ZnO to oxidise water molecules to O2. EIS revealed that the application of rGO as back contact（rGO/ZnO, rGO/ZnO/rGO） reduces the charge transfer resistance of a semiconductor thin film. Alternatively, rGO as front contact（ZnO/rGO, rGO/ZnO/rGO） improves the photo-catalysed electrolysis of water through the participation of the rGO edges in the chemical activation of water. The findings from this study indicate that the layer ordering significantly affects the thin film＇s electrostatic properties and this understanding can be further advantageous for tunable applications.展开更多
To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnes...To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.展开更多
Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg ...Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.展开更多
A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photo...A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.展开更多
Hollow structure microspheres with composite polymeric-Laponite shells were prepared by electrostatic self-assembly of Laponite on the polymeric hollow microspheres in this work.The multilayer hydrophilic core/hydroph...Hollow structure microspheres with composite polymeric-Laponite shells were prepared by electrostatic self-assembly of Laponite on the polymeric hollow microspheres in this work.The multilayer hydrophilic core/hydrophobic shell polymer latex particles containing carboxyl groups inside were first synthesized via seeded emulsion polymerization,followed by alkali treatment,generating polymeric hollow microspheres.Then,polyethyleneimine（PEI） and Laponite were alternately electrostatic adsorbed on the prepared polymeric hollow microspheres to form polymeric-Laponite composite hollow microspheres.It was indicated that the morphology of alkali-treated microspheres could be tuned through simply altering the dosage of alkali used in the post-treatment process.Along with the increasing of the coating layers,the zeta potential of microspheres absorbed PEI or Laponite approximately tended to be constant respectively,and the thickness of Laponite layer around the hollow microspheres increased clearly,getting more uniform and homogenous.Furthermore,the corresponding polymeric-Laponite hollow microspheres showed high pressure resistance ability compared to the polymeric hollow microspheres.展开更多
The development of high-performance non-fullerene acceptors with extended exciton diffusion lengths has positioned the sequential layer-by-layer(LBL)solution processing technique as a promising approach for fabricatin...The development of high-performance non-fullerene acceptors with extended exciton diffusion lengths has positioned the sequential layer-by-layer(LBL)solution processing technique as a promising approach for fabricating high-performance and large-area organic solar cells(OSCs).This method allows for the independent dissolution and deposition of donor and acceptor materials,enabling precise morphology control.In this review,we provide a comprehensive overview of the LBL processing technique,focusing on the morphology of the active layer.The swelling intercalation phase-separation(SIPS)model is introduced as the mainstream theory of morphology evolution,with a detailed discussion on vertical phase separation.We summarize recent strategies for morphology optimization.Additionally,we review the progress in LBL-based large-area device and module fabrication,as well as green processing approaches.Finally,we highlight current challenges and future prospects,paving the way for the commercialization of LBL-processed OSCs.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_2 QDs) are synthesized in an aqueous phase. Photoluminescence(PL) and absorption spectra clearl...In this paper, core–shell quantum dots(QDs) with two polar surface functional groups(ZnSe/ZnS–COOH QDs and ZnSe/ZnS–NH_2 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
Inspired by the birch bark, which has multilayered structures, we fabricated layer-by-layer （LbL） assembled montmorillonite （MMT） and poly（p-aminostyrene） （PPAS） nanocomposites on cotton fiber curved surfaces ...Inspired by the birch bark, which has multilayered structures, we fabricated layer-by-layer （LbL） assembled montmorillonite （MMT） and poly（p-aminostyrene） （PPAS） nanocomposites on cotton fiber curved surfaces to provide protection from atomic oxygen （AO） erosion. The multilayer coated fibers had high flexibility, uniformity, defect free, ease of preparation and low cost. The AO erosion durability has been dramatically enhanced which was evidenced by testing in the ground-based AO effects simulation facility. And the dimension and surface morphologies of the fibers observed by SEM had few changes, indicating excellent AO erosion resistant ability of the coatings. These results provide us a new method to design fibrous materials exposed directly in low earth orbit environment.展开更多
We investigate the power-dependent luminescence of CdSe/ZnS semiconductor quantum dots closely packed layer- by-layer in the proximity of a silver nanorod array cavity. It is found that the emission peak shifts signif...We investigate the power-dependent luminescence of CdSe/ZnS semiconductor quantum dots closely packed layer- by-layer in the proximity of a silver nanorod array cavity. It is found that the emission peak shifts significantly to the longer wavelengths as the excitation power increases, especially when the longitudinal surface plasmon resonance of the Ag nanorod array cavity is adjusted to be close to the emission wavelength. The equivalent gain varies with the coating layer of CdSe/ZnS semiconductor quantum dots and the excitation power is also studied to explain this interesting spectrum-shifting effect. These findings could find applications in the dynamic information processing of active plasmonic and photonic nanodevices.展开更多
Micro/nano texturized oxidized cellulose membranes (MNOCM) were constructed by layer-by-layer (LbL) assembly in which a base cellulose film was modified by covalent linkages to amino-functionalized silica nanoparticle...Micro/nano texturized oxidized cellulose membranes (MNOCM) were constructed by layer-by-layer (LbL) assembly in which a base cellulose film was modified by covalent linkages to amino-functionalized silica nanoparticles (amino-SiO2 NPs, 260 nm diameter) and epoxy-functionalized silica nanoparticles (epoxy-SiO2 NPs, 30 nm diameter). The amino-SiO2 NPs grafted onto the MNOCM surface through a standard amidation reaction between the amino groups of the SiO2 NPs and the carboxyl groups of the MNOCM surface in the presence of EDC and NHS consequently forming a first layer of large (260 nm) nanoparticles;subsequently, it was reacted with smaller (30 nm) epoxy-SiO2 NPs. Continuous repetitions of these alternating sized silica NPs through a standard LbL approach lead to a highly micro/nano-texturized MNOCM film as shown by SEM, which was ultimately sealed with a layer of hydrophobic PFOTES (1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane). Although the wettability of MNOCM was no longer hydrophilic, it was found that at five layers deep of NPs, it became superhydrophobic as evidenced by a water contact angle of 151° ± 2° and slide angle of 4°. The change in wettability was attributed to increases in final LbL layer surface roughness induced by the sufficient LbL layering of alternating sizes of NPs akin to what is observed in a lotus leaf surface. It was also noted that these superhydrophobic-MNOCM materials displayed good self-cleaning.展开更多
Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon...Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-_3 and NO-_2 were comparatively studied.展开更多
The integration of multiscale and multicomponent of molecules and nanoparticles into thin films for applications requires the abilities of controlled their processing and assembly,which has been an great challenge bec...The integration of multiscale and multicomponent of molecules and nanoparticles into thin films for applications requires the abilities of controlled their processing and assembly,which has been an great challenge because of the difficulty in manipulating the various materials such as small molecules,complexes,polymers,and inorganic nanomaterials through synergetic combinations of chemical or physical fabrications.Eletropolymerization is of great significance to fabricate polymeric film materials straight on the conductive substrates with tunable morphologies and thicknesses.However,unlimited electrochemical reactions（polymerization）have been usually leading to disadvantageous in ill-defined structure and highly doped state.Thanks to finding of exceptional electrochemical reaction（oligomerization）of N-alkylcarbazole,electrochemical layer by layer assembly has emerged as a promising strategy for a wide library of applications.The capability of this strategy can manipulate various molecules and nanoparticles into the scale and component controllable thin films.Unlike other electropolymerizable precursors such as aniline and thiophene,the resulting di-N-alkylcarbazole is transparent in the visible light region and thus does not impair the intrinsic properties of the components in the film.This account highlights of the typical findings in investigating both single-and multi-components thin films as a forum for discussing new opportunities in exploiting novel designs and applications of optical thin films.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFC2400703)the Key Scientific and Technological Research Projects in Henan Province(Nos.232102311155 and 232102230106)Zhengzhou University Major Project Cultivation Special Project(No.125-32214076).
文摘Drug-eluting magnesium(Mg)alloy stents have a slower degradation rate and lower restenosis rate compared with uncoated stents,demonstrating good clinical efficacy.However,the release of anti-hyperplasia drugs from coatings delays endothelial tissue repair,thus leading to late stent thrombosis.To address these issues,a dual self-healed coating with various biological properties was fabricated on magnesium fluoride/polydopamine(MgF_(2)/PDA)-treated Mg alloys by spraying-assisted layer-by-layer(LBL)self-assembly of chitosan(CS),gallic acid(GA),and 3-aminobenzeneboronic acid-modified hyaluronic acid(HA-ABBA).The LBL coating,approximately 1.50μm thick,exhibited a uniform morphology with good adhesion strength(~1065 mN).The annual corrosion rate(Pi)of LBL samples was~1400 times slower than that of the Mg substrate,due to the physical barrier function provided by MgF_(2)/PDA layers and the dual self-healed ability of LBL layers.The rapid self-healing ability(with a healing period of~4 h under dynamic/static conditions)resulted from the synergistic interplay between the recombination of diverse chemical bonds within the LBL coating and the coordination of LBL-released GA with Mg2+,as corroborated by computer simulations.Compared with the drug-eluting coatings,the LBL sample demonstrated substantial advantages in anti-oxidation,anti-denaturation of fibrinogen,anti-platelet adhesion,anti-inflammation,anti-hyperplasia,and promoted-endothelialization.These benefits effectively address the limitations associated with drug-eluting coatings.
基金supported by the Italian Ministry of University(MIUR)call PRIN 2017 with the project“PANACEA:A technology Platform for the sustainable recovery and advanced use of NAnostructured CEllulose from Agro-food residues”(grant No.2017LEPH3M).
文摘The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.
基金supported financially by the National Natural Science Foundation of China (Nos. 51874220 and 51674183)the Natural Science Foundation of Hubei Province of China (No. 2018CFB468)the Excellent Dissertation Cultivation Funds of Wuhan University of Technology (No. 2018-YS-050)
文摘In order to develop a facile and precisely controlled approach to synthesize hierarchical mesoporous materials with tailored property, in this work, a novel study was carried out to fabricate montmorillonitechitosan hollow and hierarchical mesoporous spheres(MMTNS@CS-HMPHS) based on single-template layer-by-layer(Lb L) assembly. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), specific surface area analysis and X-ray photoelectron spectroscopy(XPS) analyses were carried out to characterize the morphology and surface properties of MMTNS@CS-HMPHS. Benefitting from the unique lamellar structure of MMTNS, mesoporous channels are formed on the shell of MMTNS@CS hollow spheres, resulting in high surface area. Moreover, the surface functionalization and pore size of MMTNS@CS-HMPHS can be easily tuned, due to the tailored property through Lb L assembly method.Besides the unique microstructure, MMTNS@CS-HMPHS also possesses the active sites generated from both MMT and chitosan, which greatly promotes its performance in fields of adsorption, drug delivery and catalyst supports, etc.
基金Supported by the National Basic Research Program of China(2015CB655301)the Natural Science Foundation of China(21825803)+2 种基金and the Natural Science Foundation of Jiangsu Province(BK20150063)the Program of Excellent Innovation Teams of Jiangsu Higher Education Institutionsthe Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.
基金Project (Nos.20805043 and 30800247) supported by the National Natural Science Foundation of China
文摘A simple and controllable layer-by-layer （LBL） assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes （MWNTs） and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly（allylamine hydrochloride） （PAH） and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue （MB） could mix well with horseradish peroxidase （HRP） to form a biocompatible and negativelycharged HRP-MB biocomposite. A （PAH-MWNTs/HRP-MB）, bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response （2 s） to hydrogen peroxide with a low detection limit of 2.0× 10^-7 mol/L （S/N=3）. This work provided a versatile platform in the further development of reagentless biosensors.
基金supported by Rachadapisek Sompote Fund for Postdoctoral Fellowship, Chulalongkorn University, Thailandthe Nanotechnology Center (NANOTEC), NSTDA Ministry of Science and Technology, Thailand, through its program of Center of Excellence Network+1 种基金National Research University Project of CHEthe Rachadapisek Sompote Endowment Fund (No. AM1041A)
文摘Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.
基金supported by the National Natural Science Foundation of China(Nos.20674001,20325415, 20834001)the Research Fund for Doctoral Program of Higher Education of MOE of China(No.20060001029)
文摘An eleetrochromic variable optical attenuator （ECVOA） was fabricated by layer-by-layer （LBL） assembly of disodium N,N-bis（p-sulfonatophenyl）naphthalenedicarboximide （Naph-SO3Na） and common cationic polymer poly（diallyldimethylammonium） chloride （PDDA）. The UV-Vis absorption spectra of the multilayer films revealed that approximately an equal amount of Naph-SO3Na was assembled in each deposition cycle. Upon one-electron reduction, multilayer films exhibited intense absorption around 452 nm and also a broad absorption band from 1200 nm to 1900 nm. Owing to the improved ionic conductivity, the optical attenuation at 1550 nm of the films showed rapid response time and reached 1.3 dB/μm within 5 s. These results indicate that layer-by-layer assembly could be an effective method for the preparation of ECVOA operating in near infrared region.
基金supported by the Natural Science Foundation of China(Nos.21173266 and 21473250)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(No.11XNJ021)
文摘The layer-by-layer assembly of graphene oxide and diazoresin is carried out via the electrostatic and hydrogen bond interactions on planar substrates and colloidal templates.The successful planar and spherical growth of multilayer could be investigated by UV-vis spectrophotometry and scanning electron microscopy,respectively.Subsequent UV irradiation or heating would convert the ionic bonds and hydrogen bonds to covalent bands,which significantly improves the stability of the multilayer composite against solvent etching.For the cross-linked core-shell composites,the template cores could be removed by dissolution and hollow microspheres are obtained.
基金the Ministry of Higher Education High Impact Research (HIR F000032)the University of Malaya (RP022-2012A)for their generous financial support, and the Nanotechnology and Catalysis Research Centre (NANOCAT) for their analytical services
文摘Metal oxide semiconductor materials such as ZnO have tremendous potential as light absorbers for photocatalysed electrodes in the electrochemical reduction of water. Promoters such as rGO have been added to reduce the recombination losses of charge carriers and improve its photoelectrochemical activity. In this study, the effect of layer ordering on the charge transfer properties of rGO-hybridised ZnO sandwich thin films for the photo-catalysed electrochemical reduction of water was investigated. rGO-hybridised ZnO sandwich thin films were prepared via a facile electrode position technique using a layer-by-layer approach. The thin films were analysed using FESEM, XRD, Raman, PL, UV–vis, EIS and CV techniques to investigate its morphological, optical and electrochemical properties. The FESEM images show the formation of distinct layers of rGO and ZnO nanorods/flakes via the layer-by-layer method. XRD confirmed the wurtzite structure of ZnO. PL spectroscopy revealed a reduction of photoemission intensity in the visible region（580 nm） when rGO was incorporated into the ZnO thin film. Among the six thin films prepared, ZnO/rGO showed superior performance compared to the other thin films（0.964 m A/cm） due to the presence of graphene edges which participate as heterogenous electrocatalysts in the photocatalysed electrolysis of water. rGO also acts as electron acceptor, forming an n-p heterojunction which improves the activity of ZnO to oxidise water molecules to O2. EIS revealed that the application of rGO as back contact（rGO/ZnO, rGO/ZnO/rGO） reduces the charge transfer resistance of a semiconductor thin film. Alternatively, rGO as front contact（ZnO/rGO, rGO/ZnO/rGO） improves the photo-catalysed electrolysis of water through the participation of the rGO edges in the chemical activation of water. The findings from this study indicate that the layer ordering significantly affects the thin film＇s electrostatic properties and this understanding can be further advantageous for tunable applications.
基金Project(2014TDJH104)supported by Shandong University of Science and Technology(SDUST)Research FundChina+3 种基金Project(2013RCJJ006)supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited TalentsChinaProject(BS2013CL009)supported by Scientific Research Foundation of Shandong for Outstanding Young ScientistChina
文摘To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.
基金Projects(51571134,51601108)supported by the National Natural Science Foundation of ChinaProject(2013RCJJ006)supported by the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents,China+1 种基金Project(2016ZRB01A62)supported by the Natural Science Foundation of Shandong Province,ChinaProject(2014TDJH104)supported by Shandong University of Science and Technology Research Fund,China
文摘Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.
基金This work was supported by the National Natural Sci-ence Foundation of China(51571134)Shandong Provincial Natural Science Foundation(ZR2017BEM002)Shan-dong University of Science and Technology Research Fund(2014TDJH104).
文摘A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.
基金supported by Heilongjiang Provincial Natural Science Foundation for Youth, China (No. QC2014C052)Fund of Key Laboratory of Advanced materials of Ministry of Education (No. 2016AML06)the training project for innovation and entrepreneurship of the Harbin University of Science and Technology, China (2016)
文摘Hollow structure microspheres with composite polymeric-Laponite shells were prepared by electrostatic self-assembly of Laponite on the polymeric hollow microspheres in this work.The multilayer hydrophilic core/hydrophobic shell polymer latex particles containing carboxyl groups inside were first synthesized via seeded emulsion polymerization,followed by alkali treatment,generating polymeric hollow microspheres.Then,polyethyleneimine（PEI） and Laponite were alternately electrostatic adsorbed on the prepared polymeric hollow microspheres to form polymeric-Laponite composite hollow microspheres.It was indicated that the morphology of alkali-treated microspheres could be tuned through simply altering the dosage of alkali used in the post-treatment process.Along with the increasing of the coating layers,the zeta potential of microspheres absorbed PEI or Laponite approximately tended to be constant respectively,and the thickness of Laponite layer around the hollow microspheres increased clearly,getting more uniform and homogenous.Furthermore,the corresponding polymeric-Laponite hollow microspheres showed high pressure resistance ability compared to the polymeric hollow microspheres.
基金Project(22408404)supported by the National Natural Science Foundation of China。
文摘The development of high-performance non-fullerene acceptors with extended exciton diffusion lengths has positioned the sequential layer-by-layer(LBL)solution processing technique as a promising approach for fabricating high-performance and large-area organic solar cells(OSCs).This method allows for the independent dissolution and deposition of donor and acceptor materials,enabling precise morphology control.In this review,we provide a comprehensive overview of the LBL processing technique,focusing on the morphology of the active layer.The swelling intercalation phase-separation(SIPS)model is introduced as the mainstream theory of morphology evolution,with a detailed discussion on vertical phase separation.We summarize recent strategies for morphology optimization.Additionally,we review the progress in LBL-based large-area device and module fabrication,as well as green processing approaches.Finally,we highlight current challenges and future prospects,paving the way for the commercialization of LBL-processed OSCs.
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_2 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 Specialized Research Fund for the Doctoral Program of High Education(Nos. 20111102120050 and 20101102110035)National Basic Research Program of China (No. 2010CB934700)
文摘Inspired by the birch bark, which has multilayered structures, we fabricated layer-by-layer （LbL） assembled montmorillonite （MMT） and poly（p-aminostyrene） （PPAS） nanocomposites on cotton fiber curved surfaces to provide protection from atomic oxygen （AO） erosion. The multilayer coated fibers had high flexibility, uniformity, defect free, ease of preparation and low cost. The AO erosion durability has been dramatically enhanced which was evidenced by testing in the ground-based AO effects simulation facility. And the dimension and surface morphologies of the fibers observed by SEM had few changes, indicating excellent AO erosion resistant ability of the coatings. These results provide us a new method to design fibrous materials exposed directly in low earth orbit environment.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174229,11374236 and 11204221the National Basic Research Program of China under Grant No 2011CB922201
文摘We investigate the power-dependent luminescence of CdSe/ZnS semiconductor quantum dots closely packed layer- by-layer in the proximity of a silver nanorod array cavity. It is found that the emission peak shifts significantly to the longer wavelengths as the excitation power increases, especially when the longitudinal surface plasmon resonance of the Ag nanorod array cavity is adjusted to be close to the emission wavelength. The equivalent gain varies with the coating layer of CdSe/ZnS semiconductor quantum dots and the excitation power is also studied to explain this interesting spectrum-shifting effect. These findings could find applications in the dynamic information processing of active plasmonic and photonic nanodevices.
文摘Micro/nano texturized oxidized cellulose membranes (MNOCM) were constructed by layer-by-layer (LbL) assembly in which a base cellulose film was modified by covalent linkages to amino-functionalized silica nanoparticles (amino-SiO2 NPs, 260 nm diameter) and epoxy-functionalized silica nanoparticles (epoxy-SiO2 NPs, 30 nm diameter). The amino-SiO2 NPs grafted onto the MNOCM surface through a standard amidation reaction between the amino groups of the SiO2 NPs and the carboxyl groups of the MNOCM surface in the presence of EDC and NHS consequently forming a first layer of large (260 nm) nanoparticles;subsequently, it was reacted with smaller (30 nm) epoxy-SiO2 NPs. Continuous repetitions of these alternating sized silica NPs through a standard LbL approach lead to a highly micro/nano-texturized MNOCM film as shown by SEM, which was ultimately sealed with a layer of hydrophobic PFOTES (1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane). Although the wettability of MNOCM was no longer hydrophilic, it was found that at five layers deep of NPs, it became superhydrophobic as evidenced by a water contact angle of 151° ± 2° and slide angle of 4°. The change in wettability was attributed to increases in final LbL layer surface roughness induced by the sufficient LbL layering of alternating sizes of NPs akin to what is observed in a lotus leaf surface. It was also noted that these superhydrophobic-MNOCM materials displayed good self-cleaning.
文摘Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-_3 and NO-_2 were comparatively studied.
基金supported by the National Natural Science Foundation of China (Nos. 21374115, 51573181, and 21504088)the Hundred Talents Program, CAS, China
文摘The integration of multiscale and multicomponent of molecules and nanoparticles into thin films for applications requires the abilities of controlled their processing and assembly,which has been an great challenge because of the difficulty in manipulating the various materials such as small molecules,complexes,polymers,and inorganic nanomaterials through synergetic combinations of chemical or physical fabrications.Eletropolymerization is of great significance to fabricate polymeric film materials straight on the conductive substrates with tunable morphologies and thicknesses.However,unlimited electrochemical reactions（polymerization）have been usually leading to disadvantageous in ill-defined structure and highly doped state.Thanks to finding of exceptional electrochemical reaction（oligomerization）of N-alkylcarbazole,electrochemical layer by layer assembly has emerged as a promising strategy for a wide library of applications.The capability of this strategy can manipulate various molecules and nanoparticles into the scale and component controllable thin films.Unlike other electropolymerizable precursors such as aniline and thiophene,the resulting di-N-alkylcarbazole is transparent in the visible light region and thus does not impair the intrinsic properties of the components in the film.This account highlights of the typical findings in investigating both single-and multi-components thin films as a forum for discussing new opportunities in exploiting novel designs and applications of optical thin films.
