Layer by Layer Self-assembly Fiber-based Flexible Electrochemical Transistor

Poly(3,4-ethylenedioxyethiophene)-polystyrene sulfonic acid(PEDOT:PSS)/polyallyl dimethyl ammonium chloride modified reduced graphene oxide(PDDA-rGO)was layer by layer self-assembled on the cotton fiber.The surface morphology and electric property was investigated.The results confirmed the dense membrane of PEDOT:PSS and the lamellar structure of PDDA-rGO on the fibers.It has excellent electrical conductivity and mechanical properties.The fiber based electrochemical transistor(FECTs)prepared by the composite conductive fiber has a maximum output current of 8.7 mA,a transconductance peak of 10 mS,an on time of 1.37 s,an off time of 1.6 s and excellent switching stability.Most importantly,the devices by layer by layer self-assembly technology opens a path for the true integration of organic electronics with traditional textile technologies and materials,laying the foundation for their later widespread application.

Biomimetic“Nacre-like”Films Prepared via Layer-by-Layer Self-assembly of Mica,Polyvinyl Alcohol and Polymethyl Methacrylate

A film with“brick-and-mortar”structure was prepared by layer-by-layer(LBL)technique using polyvinyl alcohol(PVA)and polymethyl methacrylate(PMMA)as the flexible material or“mortar”and mica as the rigid material or“brick”.The film deposited on a glass slide after self-assembly cycles had a thickness of 3μm thick and an uneven,wavy surface.The film exhibits enhanced mechanical properties,i e,the hardness and indentation modulus values could reach 6.14 and 68.41 GPa,respectively.The hardness and elastic toughness were found to be depended on three factors,i e,the ratio of PVA to mica,the number of self-assembly cycles,and the pretreatment method of the mica suspension.The self-assembly process was driven by formation of the hydrogen bonds between the silanol groups of mica and the hydroxyl groups of PVA and carbonyl groups of PMMA.

Corrosion Inhibition from Thiol Self-assembly Layer: A High Pressure Perspective

Taking dodecanethiol as the representative, we investigated the corrosion inhibition performance of SAL in seawater under pressures from 0.1 to 9 MPa. By using scanning Kelvin probe, the dodecanethiol SAL is confirmed to build on Cu surface, and the modification of SAL has positively shifted the surface potential to realize the inertness. Electrochemical techniques, such as electrochemical impedance spectroscopy and potentiodynamic polarization were used to reveal the corrosion behavior of Cu modified by SAL under the different pressure, i e, 0.1, 3, 6, and 9 MPa. It is indicated that the longer modification time affords better corrosion resistance to Cu. Higher static pressure is easier to deteriorate the corrosion inhibition capability due to the penetration effect. A plausible mechanism is proposed to illustrate the degradation process of SAL in the high pressure seawater environment.

Monodisperse Ultra-Large-Pore Silica Coated Polystyrene Core-Shell Microbeads via Layer-by-Layer Assembly for Nano-Micro Composite

Polystyrene （PS） @SiO2 core-shell microbeads with large pore and large particle size were prepared via layer-by-layer（LBL）assembly technique for potential applications in nano-micro composites. Negative silica nanoparticles synthesized via modified St6ber method and cationic poly （diallyldimethylammonium chloride） were alternately adsorbed on the surface of microbeads. Zeta potential, size, and morphology of the microbeads were monitored during LBL assembly process to ensure the successful deposition of silica nanoparticles. The porous shell was characterized using nitrogen adsorption and desorption analyses, and the surface area, volume and diame- ter of the pores were derived. It is found that the porous shell thickness and the pore size can be tuned by changing the coating times of silica nanoparticles. Finally, PS@SiO2 core-shell microbeads with 5 grn PS solid core and 350 nm mesoporous shell （mean BJH pore diameter is ~27 nm） were used to load CdSe/ZnS quantum dots （QDs）. The fluorescence microscopic image and the optical amplification of the QDs-embedded microbeads （QDBs） indicate that the as-prepared core-shell microbeads can provide adequate space for QDs and may be useful for further application of nano-micro composites.

Low friction under ultrahigh contact pressure enabled by self-assembled fluorinated azobenzene layers

Extensive efforts have been made to pursue a low-friction state with promising applications in many fields,such as mechanical and biomedical engineering.Among which,the load capacity of the low-friction state has been considered to be crucial for industrial applications.Here,we report a low friction under ultrahigh contact pressure by building a novel self-assembled fluorinated azobenzene layer on an atomically smooth highly-oriented pyrolytic graphite(HOPG)surface.Sliding friction coefficients could be as low as 0.0005 or even lower under a contact pressure of up to 4 GPa.It demonstrates that the low friction under ultrahigh contact pressure is attributed to molecular fluorination.The fluorination leads to effective and robust lubrication between the tip and the self-assembled layer and enhances tighter rigidity which can reduce the stress concentration in the substrate,which was verified by density functional theory(DFT)and molecular dynamics(MD)simulation.This work provides a new approach to avoid the failure of ultralow friction coefficient under relatively high contact pressure,which has promising potential application value in the future.

Bacterial Surface Layer Proteins: A Promising Nano-Technological Tool for Bio-Sensing Applications

The phenomenal rise in the demand of biosensors accelerated their rapid development and immersive applications in the myriads of fields. The essential requirement of developing efficient bio-sensing platform is to find stable well organized interfacial architecture that can serve as an excellent matrix for binding and recognizing biomolecules. In this context, the enormous potential has been envisaged in surface layer proteins that represented themselves as most primitive and simplest self-assembled system with repetitive physicochemical properties for the molecular functionalization of surfaces and various interfaces. The prominence of S-layer proteins has been broadened by integrating genetic engineering approaches for the fine tuning of functional groups and protein domains in geometrically well-defined manner. The efficient and stable binding of various nanomaterials with S-layers in regular arrays has led to paradigmatic shift in their nano-biotechnological sensing applications. More recently, functional S-layer supported lipid membranes have been generated through covalent binding of lipid molecules either with native or recombinant S-layer proteins at nano-scale dimensions serving as “proof of concept” for the development of bio-sensing platform. Thus, in the light of benefits conferred by surface layer proteins for the development of highly efficient biosensors, an exciting path has been opened for broadening their translational applications in drug delivery, disease diagnosis, vaccines development, lab-on-chip devices etc. Therefore, this review intends to describe about the importance of surface layer proteins in the development of biosensors.

Bacterial Surface Layer Proteins: From Moonlighting to Biomimetics: A New Horizonto Lead

The landmark discovery of moonlighting proteins embarks the significant progress in understanding the biological complexity and their closed-circuit analysis. The growing continuum in the variety of moonlighting functions paved the way for further elucidation of structural-functional aspects of protein evolution and design of proteins with novel functions. Currently, the moonlighting functions in various adhesive properties of surface layer proteins, an essential component of cell surface architecture of archaea and all phylogenetic groups of eubacteria become more prominently recognized. The remarkable credentials of surface layer proteins to self-assemble into supramolecular structures at nano-scale dimension have been exploited for the production of smart biomaterials in the form of biomimetics has been thrust area of research. The finely tuned topological features in terms of shape, size, geometry and surface chemistry of surface layer proteins are crucial for the production of biomimetics. The current developments of biomimetic lipid bilayers and composite membranes find applicability in understanding the functional dynamism of evolutionary relationship of bacterial cell envelopes and vaccine development, drug development and drug delivery. Though the development of biomimetics embraces fascination but faces with technological challenges. The plethora of literature has been available for the moonlighting aspects and nano-technological applications separately but none of the review describes towards the rhythmic transition from moonlighting functions of surface layer proteins of bacteria to biomimetics development and applications. Therefore, this review describes certain basic aspects of moonlighting functions and their mechanism of action, surface layer proteins and their moonlighting functions of commensal bacteria and their transition towards biomimetics. The recent developments of biomimetics based on surface layer proteins have been summarized and also posited different challenges and future prospects.

Tunable Self-assembled Weak Polyelectrolyte Brushes

The authors have investigated the pH and ionic strength response of self-assembled layers formed by adsorption of amphiphilic weak polyelectrolytes. Using the SFA （Surface Forces Apparatus） the authors measured force-distance profiles of poly （isoprene）-poly （acrylic acid） block copolymers adsorbed on mica. Also by Atomic Force Microscopy the authors captured single polyelectrolyte molecule adsorbed on a surface. The effect of salt concentration （Cs） and pH upon the height of the brush layers was explored mainly by measuring the forces between two adsorbed polyelectrolyte brushes. At pH = 4 our results are in good agreement with the scaling prediction L0 ∝Cs-1/3 Changing the pH from 4 to 10 causes a remarkable swelling of the polymer layer, but only a weak dependence on salt concentration was detected at the higher pH. This can be attributed to the degree of dissociation, which depends on the local pH value. At low pH the polyelectrolyte chains have a low charge density, while on increasing the pH the degree of dissociation rises, and the increased charge density is followed by swelling of the adsorbed layer. The local concentration of ions in the brush is now greater than that of pH = 4 and approximately equivalent to 0.3 M. So the swelling is only weakly dependent on salt concentration in the range 0.01-1.0 M. The results demonstrate the tunable nature of such self-assembled polyelectroiyte brushes whose height and range of interactions, can be systematically controlled by adjusting the pH and ionic strength of the medium.

Synthesis ofα-Li FeO_(2)/Graphene nanocomposite via layer by layer self-assembly strategy for lithium-ion batteries with excellent electrochemical performance

As a potential alternative cathode material,α-LiFeO2 suffers a realization handicap,mainly due to its poor electrical conductivity and low lithium ion diffusion rate.In this work,we have successfully synthesized α-LiFeO2/rGO nanocomposite through a layer by layer self-assembly modification process and annealing treatment.Due to the strong electrostatic attraction between opposite cha rged spices,α-LiFeO2 nanoparticles were homogeneously dispersed on the graphene sheet to form a typical interconnected conducting network which was bene ficial for electronic conductivity and ionic diffu sivity.In comparison to pristine α-LiFeO2,the α-LiFeO2/rGO displayed an excellent electrochemical perfo rmance with average discharge capacities of 238.9,187.2,178.4,121.8 and 99.5 mA hg^-1 at 0.1,0.2,0.5,1 and 2 C,respectively.Besides,the specific capacity retained 164.9 mA h g^-1 and 107.98 mA h g^-1 after 50 cycles at 0.5 C and 1 C,respectively.The remarkable progress in rate capability and cycling ability of this new nanocomposite developed a new approach to improve the electrochemical performance of α-LiFeO2.

Self-assembly of Ophiopogonis polysaccharide-iron(Ⅲ) complex in aqueous solution and solid state

Ophiopogonis polysaccharide-iron(Ⅲ)(OPI)was prepared and characterized in the present study.The optimum condition for preparing OPI was as follows:OP and trisodium citrate were mixed at a weight ratio of 4:1 and reacted in a water bath at 70°C for 3 h within the pH range of 8.0–8.5.Aggregation morphology or structure of OPI in aqueous solution and solid state was studied by scanning electron microscopy,transmission electron microscopy and small-angle X-ray diffraction.In aqueous solution,OPI could self-assemble into micron vesicles with flower-shaped morphology.Results of X-ray diffraction showed OPI with layered structure.A core-shell model was proposed for OPI.

Properties of a water layer on hydrophilic and hydrophobic self-assembled monolayer surfaces: A molecular dynamics study

The microscopic behaviors of a water layer on different monolayers （SAMs） are studied by molecular dynamics hydrophilic and hydrophobic surfaces of well ordered self-assembled simulations. The SAMs consist of 18-carbon alkyl chains bound to a silicon（111） substrate, and the characteristic of its surface is tuned from hydrophobic to hydrophilic by using different terminal functional groups （-CH3, -COOH）. In the simulation, the properties of water membranes adjacent to the surfaces of SAMs were reported by comparing pure water in mobility, structure, and orientational ordering of water molecules. The results sug- gest that the mobility of water molecules adjacent to hydrophilic surface becomes weaker and the molecules have a better or- dering. The distribution of hydrogen bonds indicates that the number of water-water hydrogen bonds per water molecule tends to be lower. However, the mobility of water molecules and distribution of hydrogen bonds of a water membrane in hydropho- bic system are nearly the same as those in pure water system. In addition, hydrogen bonds are mainly formed between the hy- droxyl of the COOH group and water molecules in a hydrophilic system, which is helpful in understanding the structure of in- terfacial water.

Application of a Nanostructured Composite Material Constructed by Self-Assembly of Titanoniobate Nanosheets and Cobalt Porphyrin to Electrocatalytic Reduction of Oxygen

A novel layered nanocomposite was fabricated by the self-assembly of TiNbOs-nanosheets and 5,10,15,20- tetrakis（N-methylpyridinium-4-yl）porphyrinatocobalt（III） （CoTMPyP）. The product was characterized by a variety of analytical techniques such as XRD, EDX, Zeta potential, AFM, UV-vis, IR and SEM, the guest species were intercalated into the interlayer gallery of KTiNbO5 successfully. The electrochemical property of TiNbO5-CoTMPyP as an electrode modifying material was examined by cyclic voltammetry test in PBS solution （pH = 7）, and the hybrid exhibited excellent electrocatalytical property towards oxygen reduction with the peak potential shifting from -0.703 V （bare GCE） to -0.278 V （modified electrode）. The result also indicated that the oxygen molecule was reduced to H2O2 by a two-electron process.

Hole-Selective Contact with Molecularly Tailorable Reactivity for Passivating High-Performing Inverted Perovskite Solar Cells

The precisely customizable attributes of self-assembled monolayers(SAMs)molecules at the atomic level hold the potential to facilitate efficient hole selection and interface passivation simultaneously.However,the correlation between the exposure of passivating groups on the surface and device performance remains unexplored.Herein,we introduce two newly designed SAM molecules,Cbz2S and Cbz2SMe,incorporating cyclic disulfide or two flanking thiomethyls by modifying the 4,5-position of carbazole to adjust the Lewis basicity of the SAM-modified surface.Despite possessing suitable energetic alignment,Cbz2S with more-exposed sulfur atoms exhibited inferior device performance due to excessive reactivity,leading to an overpopulation of PbI2 crystallites at the buried perovskite interface.In contrast,the screening effect from the methyl groups of Cbz2SMe optimized SAM reactivity,exquisitely integrating buried interface passivation and hole selection together.Consequently,the champion inverted perovskite solar cell(PSC)employing Cbz2SMe achieved an impressive power conversion efficiency of 24.42%,accompanied by prolonged stability.This work demonstrates the feasibility of incorporating Lewis-basic passivation groups into SAM molecules and elucidates the relationship between the reactivity of SAM passivation groups and device performance.These findings provide valuable insights for the design of novel multifunctional SAM molecules,further advancing the performance of PSCs.

Magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres derived from FeNi-LDH precursor anchoring on rGO nanosheets for enhanced electromagnetic wave absorption

Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it’s an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt%and a low density of 4.4 mg/cm^(3).In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell struc-ture nanospheres.

Amine-functionalized SiO2 nanodot-coated layered double hydroxide nanocomposites for enhanced gene delivery

In this work a novel strategy has been developed to prepare well-dispersed amine-functionalized SiO2 nanodot-coated layered double hydroxide nano- composite （NH2-SiO2@LDH） via electrostatic interactions and condensation of （3-aminopropyl）triethoxysilane （APTES）. This nanocomposite system is well dispersed in culture media and phosphate buffered saline, and exhibits low cytotoxicity and good biocompatibility. The fluorescence microscopy images and flow cytometry data indicate that such an NH2-SiO2@LDH nanocomposite is able to efficiently deliver small interfering RNA （siRNA） into the U2OS cell line to inhibit cell proliferation. Thus, NH2-SiOR@LDH nanocomposite has a great potential as a nanocarrier for efficient gene delivery.

Self-Assembled Materials for Catalysis

The purpose of this review is to highlight developments in self-assembled nanostructured materials(i.e.,mesoporous and nanoparticle-based materials)and their catalytic applications.Since there are many available reviews of metal-based nanoparticles as catalysts,this review will mainly focus on self-assembled oxide-based catalytic materials.The content includes:(1)design and synthetic strategies for self-assembled mesoporous catalysts,(2)polyoxometalate(POM)-based nanocatalysts,(3)dendrimer-based nanocatalysts,and(4)shaped nanomaterials and catalytic applications.We show that controlled assembly of molecules,crystalline seeds,and nano building blocks into organized mesoscopic structures or controlled morphologies is an effective approach for tailoring porosities of heterogeneous catalysts and controlling their catalytic activities.

Interaction of straight chain alcohol vapors with self-assembled MOF film by surface plasmon resonance sensing and imaging

Interaction of straight chain alcohol vapors with MOF-199-functionalized films was studied by SPR. The signals had linear relationships with the concentration of alcohols over a wide range from 0 to 70% （v/v） and were reversible in proportional to the chain length, with R2 all above 0.99.

Superlattice Structure from Re-stacked NiFe Layer Double Hydroxides for Oxygen Evolution Reaction

Layer double hydroxides(LDHs)have drawn significant amount of rescarch attentions as a typical category of inorganic 2D materials,with facile synthetic methodologies and a wide range of applications in catalysis and energy storage[1,2].LDHs consist of positively charged brucite-like host layers containing M(OH),octahedra,while anions and solvation molecules filled the interlayer for charge compensation.Generally.