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1.
The self‐assembly of sodium dodecyl benzene sulphonate (SDBS) functionalized graphene sheets (GSs) and horseradish peroxidase (HRP) by electrostatic attraction into novel hierarchical nanostructures in aqueous solution is reported. Data from scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray diffraction demonstrate that the HRP–GSs bionanocomposites feature ordered hierarchical nanostructures with well‐dispersed HRP intercalated between the GSs. UV‐vis and infrared spectra indicate the native structure of HRP is maintained after the assembly, implying good biocompatibility of SDBS‐functionalized GSs. Furthermore, the HRP–GSs composites are utilized for the fabrication of enzyme electrodes (HRP–GSs electrodes). Electrochemical measurements reveal that the resulting HRP–GSs electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, low detection limit, and fast amperometric response. These desirable electrochemical performances are attributed to excellent biocompatibility and superb electron transport efficiency of GSs as well as high HRP loading and synergistic catalytic effect of the HRP–GSs bionanocomposites toward H2O2. As graphene can be readily non‐covalently functionalized by “designer” aromatic molecules with different electrostatic properties, the proposed self‐assembly strategy affords a facile and effective platform for the assembly of various biomolecules into hierarchically ordered bionanocomposites in biosensing and biocatalytic applications.  相似文献   

2.
A new symmetrical sugar‐based perylenediimide derivative PTCDI‐BAG is synthesized and its aggregate morphologies and formation mechanisms are studied in detail in the mixed solvent system water/N,N‐dimethylformamide (H2O/DMF) with changing volume ratios. PTCDI‐BAG molecules self‐assemble into planar ribbons in 20/80 and 40/60 H2O/DMF (v/v), but their chiralities are opposite according to recorded circular dichroism (CD) spectra. With a further increase of the water content, only left‐handed helical nanowires are obtained in 60/40 and 80/20 H2O/DMF (v/v) mixtures. By combining density functional theory (DFT) calculations with the experimental investigations, it is proposed that kinetic and thermodynamic factors play key roles in tuning PTCDI‐BAG structures and helicity. The formation of the ribbon is thermodynamically controlled in the 20/80 H2O/DMF system, but kinetically controlled nucleation followed by thermodynamically controlled self‐assembly plays the governing roles for the formation of nanoribbons in 40/60 H2O/DMF. Devices based on single nanoribbons for hydrazine sensing exhibit better performance than nanofiber bundles obtained in this study and achiral nanostructures reported in previous study. This study not only provides an elaborated route to tuning the structures and helicity of PTCDI molecules, but also provides new possibilities for the construction of high‐performance nanodevices.  相似文献   

3.
A 3‐aminopropyltrimethoxysilane‐derived self‐assembled monolayer (NH2SAM) is investigated as a barrier against copper diffusion for application in back‐end‐of‐line (BEOL) technology. The essential characteristics studied include thermal stability to BEOL processing, inhibition of copper diffusion, and adhesion to both the underlying SiO2 dielectric substrate and the Cu over‐layer. Time‐of‐flight secondary ion mass spectrometry and X‐ray spectroscopy (XPS) analysis reveal that the copper over‐layer closes at 1–2‐nm thickness, comparable with the 1.3‐nm closure of state‐of‐the‐art Ta/TaN Cu diffusion barriers. That the NH2SAM remains intact upon Cu deposition and subsequent annealing is unambiguously revealed by energy‐filtered transmission electron microscopy supported by XPS. The SAM forms a well‐defined carbon‐rich interface with the Cu over‐layer and electron energy loss spectroscopy shows no evidence of Cu penetration into the SAM. Interestingly, the adhesion of the Cu/NH2SAM/SiO2 system increases with annealing temperature up to 7.2 J m?2 at 400 °C, comparable to Ta/TaN (7.5 J m?2 at room temperature). The corresponding fracture analysis shows that when failure does occur it is located at the Cu/SAM interface. Overall, these results demonstrate that NH2SAM is a suitable candidate for subnanometer‐scale diffusion barrier application in a selective coating for copper advanced interconnects.  相似文献   

4.
Well defined nanostructured polymeric supramolecular assemblies are formed when an asymmetric perylenebisimide substituted with ethylhexyl chains on one end and functionalized with 3‐pentadecylphenol at the other termini ( PDP‐UPBI ) is complexed with poly(4‐vinylpyridine) (P4VP) via a non‐covalent specific interaction such as hydrogen‐bonding. The resulting P4VP(PDP‐UPBI) n complexes are fully solution processable. The bulk structure and morphologies of the supramolecular film studied using small angle and wide angle X‐ray scattering reveals highly crystalline nature of the complex. Thin film morphology of the 1:1 complex analyzed using transmission electron microscopy shows uniform lamellar structures in the domain range of 5–10 nm. A clear trend of improved electrical parameters in P4VP(PDP‐UPBI) system compared to pristine ( PDP‐UPBI ) is observed from space charge limited current measurements. In short, a simple and facile method to obtain spatially defined organization of n‐type semiconductor perylenebisimide molecules using hydrogen bonding interactions with P4VP as the structural motif is showcased herein.  相似文献   

5.
A mesostructured spinel Li4Ti5O12 (LTO)‐carbon nanocomposite (denoted as Meso‐LTO‐C) with large (>15 nm) and uniform pores is simply synthesized via block copolymer self‐assembly. Exceptionally high rate capability is then demonstrated for Li‐ion battery (LIB) negative electrodes. Polyisoprene‐block‐poly(ethylene oxide) (PI‐b‐PEO) with a sp2‐hybridized carbon‐containing hydrophobic block is employed as a structure‐directing agent. Then the assembled composite material is crystallized at 700 °C enabling conversion to the spinel LTO structure without loss of structural integrity. Part of the PI is converted to a conductive carbon that coats the pores of the Meso‐LTO‐C. The in situ pyrolyzed carbon not only maintains the porous mesostructure as the LTO is crystallized, but also improves the electronic conductivity. A Meso‐LTO‐C/Li cell then cycles stably at 10 C‐rate, corresponding to only 6 min for complete charge and discharge, with a reversible capacity of 115 mA h g?1 with 90% capacity retention after 500 cycles. In sharp contrast, a Bulk‐LTO/Li cell exhibits only 69 mA h g?1 at 10 C‐rate. Electrochemical impedance spectroscopy (EIS) with symmetric LTO/LTO cells prepared from Bulk‐LTO and Meso‐LTO‐C cycled in different potential ranges reveals the factors contributing to the vast difference between the rate‐capabilities. The carbon‐coated mesoporous structure enables highly improved electronic conductivity and significantly reduced charge transfer resistance, and a much smaller overall resistance is observed compared to Bulk‐LTO. Also, the solid electrolyte interphase (SEI)‐free surface due to the limited voltage window (>1 V versus Li/Li+) contributes to dramatically reduced resistance.  相似文献   

6.
Despite advances in the development of silk fibroin (SF)‐based hydrogels, current methods for SF gelation show significant limitations such as lack of reversible crosslinking, use of nonphysiological conditions, and difficulties in controlling gelation time. In the present study, a strategy based on dynamic metal‐ligand coordination chemistry is developed to assemble SF‐based hydrogel under physiological conditions between SF microfibers (mSF) and a polysaccharide binder. The presented SF‐based hydrogel exhibits shear‐thinning and autonomous self‐healing properties, thereby enabling the filling of irregularly shaped tissue defects without gel fragmentation. A biomineralization approach is used to generate calcium phosphate‐coated mSF, which is chelated by bisphosphonate ligands of the binder to form reversible crosslinkages. Robust dually crosslinked (DC) hydrogel is obtained through photopolymerization of acrylamide groups of the binder. DC SF‐based hydrogel supports stem cell proliferation in vitro and accelerates bone regeneration in cranial critical size defects without any additional morphogenes delivered. The developed self‐healing and photopolymerizable SF‐based hydrogel possesses significant potential for bone regeneration application with the advantages of injectability and fit‐to‐shape molding.  相似文献   

7.
A new mechanism is proposed for the generation of self‐assembled nanodots at the surface of a film based on spontaneous outcropping of the secondary phase of a nanocomposite epitaxial film. Epitaxial self‐assembled Sr–La oxide insulating nanodots are formed through this mechanism at the surface of an epitaxial metallic ferromagnetic La0.7Sr0.3MnO3 (LSMO) film grown on SrTiO3 from chemical solutions. TEM analysis reveals that, underneath the La–Sr oxide (LSO) nanodots, the film switches from the compressive out‐of‐plane stress component to a tensile one. It is shown that the size and concentration of the nanodots can be tuned by means of growth kinetics and through modification of the La excess in the precursor chemical solution. The driving force for the nanodot formation can be attributed to a cooperative effect involving the minimization of the elastic strain energy and a thermodynamic instability of the LSMO phase against the formation of a Ruddelsden–Popper phase Sr3Mn4O7 embedded in the film, and LSO surface nanodots. The mechanism can be described as a generalization of the classical Stranski–Krastanov growth mode involving phase separation. LSO islands induce an isotropic strain to the LSMO film underneath the island which decreases the magnetoelastic contribution to the magnetic anisotropy.  相似文献   

8.
Despite tremendous efforts, tissue engineered constructs are restricted to thin, simple tissues sustained only by diffusion. The most significant barrier in tissue engineering is insufficient vascularization to deliver nutrients and metabolites during development in vitro and to facilitate rapid vascular integration in vivo. Tissue engineered constructs can be greatly improved by developing perfusable microvascular networks in vitro in order to provide transport that mimics native vascular organization and function. Here a microfluidic hydrogel is integrated with a self‐assembling pro‐vasculogenic co‐culture in a strategy to perfuse microvascular networks in vitro. This approach allows for control over microvascular network self‐assembly and employs an anastomotic interface for integration of self‐assembled microvascular networks with fabricated microchannels. As a result, transport within the system shifts from simple diffusion to vessel supported convective transport and extra‐vessel diffusion, thus improving overall mass transport properties. This work impacts the development of perfusable prevascularized tissues in vitro and ultimately tissue engineering applications in vivo.  相似文献   

9.
Rational assembly of carbon nanostructures into large‐area films is a key step to realize their applications in ubiquitous electronics and energy devices. Here, a self‐assembly methodology is devised to organize diverse carbon nanostructures (nanotubes, dots, microspheres, etc.) into homogeneous films with potentially infinite lateral dimensions. On the basis of studies of the redox reactions in the systems and the structures of films, the spontaneous deposition of carbon nanostructures onto the surface of the copper substrate is found to be driven by the electrical double layer between copper and solution. As a notable example, the as‐assembled multiwalled carbon nanotube (MWCNT) films display exceptional properties. They are a promising material for flexible electronics with superior electrical and mechanical compliance characteristics. Finally, two kinds of all‐solid‐state supercapacitors based on the self‐assembled MWCNT films are fabricated. The supercapacitor using carbon cloth as the current collector delivers an energy density of 3.5 Wh kg?1 and a power density of 28.1 kW kg?1, which are comparable with the state‐of‐the‐art supercapacitors fabricated by the costly single‐walled carbon nanotubes and arrays. The supercapacitor free of foreign current collector is ultrathin and shows impressive volumetric energy density (0.58 mWh cm?3) and power density (0.39 W cm?3) too.  相似文献   

10.
The performance of bottom‐contact thin‐film transistor (TFT) structures lags behind that of top‐contact structures owing to the far greater contact resistance. The major sources of the contact resistance in bottom‐contact TFTs are believed to reflect a combination of non‐optimal semiconductor growth morphology on the metallic contact surface and the limited available charge injection area versus top‐contact geometries. As a part of an effort to understand the sources of high charge injection barriers in n‐channel TFTs, the influence of thiol metal contact treatment on the molecular‐level structures of such interfaces is investigated using hexamethyldisilazane (HMDS)‐treated SiO2 gate dielectrics. The focus is on the self‐assembled monolayer (SAM) contact surface treatment methods for bottom‐contact TFTs based on two archetypical n‐type semiconductors, α,ω‐diperfluorohexylquarterthiophene (DFH‐4T) and N,N′bis(n‐octyl)‐dicyanoperylene‐3,4:9,10‐bis(dicarboximide) (PDI‐8CN2). TFT performance can be greatly enhanced, to the level of the top contact device performance in terms of mobility, on/off ratio, and contact resistance. To analyze the molecular‐level film structural changes arising from the contact surface treatment, surface morphologies are characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The high‐resolution STM images show that the growth orientation of the semiconductor molecules at the gold/SAM/semiconductor interface preserves the molecular long axis orientation along the substrate normal. As a result, the film microstructure is well‐organized for charge transport in the interfacial region.  相似文献   

11.
Ionic self‐assembled (ISA) surfactant complexes present a facile concept for self‐assembly of various functional materials. However, no general scheme has been shown to allow their overall alignment beyond local polydomain‐like order. Here we demonstrate that ionic complexes forming a columnar liquid‐crystalline phase in bulk can be aligned within polymer blends upon shearing, taken that the matrix polymers have sufficiently high molecular weight. We use an ISA complex of N,N′‐bis(ethylenetrimethylammonium)perylenediimide/bis(2‐ethylhexyl) phosphate (Pery‐BEHP) blended with different molecular weight polystyrenes (PS). Based on X‐ray scattering studies and transmission electron microscopy the pure Pery‐BEHP complex was found to form a two‐dimensional oblique columnar phase where the perylene units stack within the columns. Blending the complex with PS lead to high aspect ratio Pery‐BEHP aggregates with lateral dimension in the mesoscale, having internal columnar liquid‐crystalline order similar to the pure Pery‐BEHP complex. When the Pery‐BEHP/PS blend was subjected to a shear flow field, the alignment of perylenes can be achieved but requires sufficiently high molecular weight of the polystyrene matrix. The concept also suggests a simple route for macroscopically aligned nanocomposites with conjugated columnar liquid‐crystalline functional additives.  相似文献   

12.
A novel strategy to prepare a surface confined molecularly imprinted polymer (MIP) film directly on a transducer surface for protein sensing is achieved by combining interaction with a natural binding receptor and binding to a fully synthetic MIP. A thiolated oligoethyleneglycol (OEG)/mannose conjugate is first self‐assembled on the transducer surface. Then the carbohydrate binding protein, concanavalin A (ConA), is “vectorially” immobilized as a submonolayer on the underlying mannose modified surface. Afterwards, an ultrathin polyscopoletin film with the thickness comparable to that of the protein is electrodeposited on the top. This architecture ensures that the target is confined to the film surface. The resulting functional material shows an approximately 20‐fold higher affinity than that obtained from the mannose self‐assembled monolayer. This result shows a synergism between multivalent binding of the natural sugar ligand and the non‐covalent interactions of the target within the MIP cavities. Recognition capability of the film is characterized by a real‐time measurement using quartz crystal microbalance. In comparison to the non‐imprinted film, the imprinted film reveals 8.6 times higher binding capacity towards ConA. High discrimination towards the target protein's homologues shows size and shape specificity of the imprint.  相似文献   

13.
A comparative study of the self‐assembly at a variety of surfaces of a dithiophene rotaxane 1 ?β‐CD and its corresponding dumbbell, 1, by means of atomic force microscopy (AFM) imaging and scanning tunneling microscopy (STM) imaging on the micrometer and nanometer scale, respectively. The dumbbell is found to have a greater propensity to form ordered supramolecular assemblies, as a result of π–π interactions between dithiophenes belonging to adjacent molecules, which are hindered in the rotaxane. The fine molecular structure determined by STM was compared to that obtained by molecular modelling. The optical properties of both rotaxane and dumbbell in the solid state were investigated by steady‐state and time‐resolved photoluminescence (PL) experiments on spin‐cast films and diluted solutions. The comparison between the optical features of the threaded and unthreaded systems reveals an effective role of encapsulation in reducing aggregation and exciton migration for the rotaxanes with respect to the dumbbells, thus leading to higher PL quantum efficiency and preserved single‐molecule photophysics for longer times after excitation in the threaded oligomers.  相似文献   

14.
A Pt(II) complex, bearing an oligo‐ethyleneoxide pendant, is able to self‐assemble in ultralong ribbons that display mechanochromism upon nanoscale mechanical stimuli, delivered through atomic force microscopy (AFM). Such observation paves the way to fine understanding and manipulation of the mechanochromic properties of such material at the nanoscale. AFM allows quantitative assessment of nanoscale mechanochromism as arising from static pressure (piezochromism) and from shear‐based mechanical stimuli (tribochromism), and to compare them with bulk pressure‐dependent luminescence observed with diamond‐anvil cell (DAC) technique. Confocal spectral imaging reveals that mechanochromism only takes place within short distance from the localized mechanical stimulation, which allows to design high‐density information writing with AFM nanolithography applied on individual self‐assembled ribbons. Each ribbon hence serves as an individual microsystem for data storage. The orange luminescence of written information displays high contrast compared to cyan native luminescence; moreover, it can be selectively excited with visible light. In addition, ribbons show photochromism, i.e., the emission spectrum changes upon exposure to light, in a similar way as upon mechanical stress. Photochromism is here conveniently used to conceal and eventually erase information previously written with nanolithography by irradiation.  相似文献   

15.
A novel Self‐assembled Monolayer (SAM) forming molecule bisjulolidyldisulfide (9,9'‐disulfanediylbis(2,3,6,7‐tetrahydro‐1H,5H‐pyrido[3,2,1‐ij]quinoline)) is demonstrated which lowers the work function of metal surfaces by ≈1.2 eV and can be deposited in a 1 min process. Bisjulolidyldisulfide exists in a stable disulfide configuration prior to surface exposure and can therefore be stored, handled, and processed in ambient conditions. SAM from bisjulolidyldisulfide are deposited on metal surfaces (Au and Ag), including inkjet printed Ag on polyethylene terephthalate substrates, investigated by photoelectron and infrared spectroscopy, and used as electrodes in n‐type organic field effect transistor (OFET). Treatment of electrodes in OFET devices with with bisjulolidyldisulfide‐SAMs reduces the contact resistance by two orders of magnitude and improves shelf life with respect to pristine metal electrodes. The presented treatment also increases the surfaces wettability and thereby facilitates solution processing of a subsequent layer. These beneficial properties for device performance, processing, and stability, combined with ease of preparation and handling, render this SAM‐forming molecule an excellent candidate for the high‐throughput production of flexible electronic devices.  相似文献   

16.
A new type of efficient CO2 absorbent with improved thermal stability is synthesized via self‐assembly between 2D inorganic nanosheets and two kinds of 0D inorganic nanoclusters. In these self‐assembled nanohybrids, the nanoclusters of CdO and Cr2O3 are commonly interstratified with layered titanate nanosheets, leading to the formation of highly microporous pillared structure with increased basicity of pore wall. The co‐pillaring of basic CdO with Cr2O3 is fairly effective at increasing a proportion of micropores and reactivity for CO2 molecules and at improving the thermal stability of the resulting porous structure. Of prime importance is that the present inorganic‐pillared nanohybrids show highly efficient CO2 adsorption capacity, which is much superior to those of many other absorbents and compatible to those of CO2 adsorbing metal?organic framework (MOF) compounds. Taking into account an excellent thermal stability of the present nanohybrids, these materials are very promising CO2 adsorbents usable at elevated temperature. This is the first example of efficient CO2 adsorbent from pillared materials. The co‐pillaring of basic metal oxide nanoclusters employed in this study can provide a very powerful way of developing thermally stable CO2 adsorbents from many known pillared systems.  相似文献   

17.
Artificial photonic nanomaterials made from densely packed scatterers are frequently realized either by top‐down or bottom‐up techniques. While top‐down techniques offer unprecedented control over achievable geometries for the scatterers, by trend they suffer from being limited to planar and periodic structures. In contrast, materials fabricated with bottom‐up techniques do not suffer from such disadvantages but, unfortunately, they offer only little control on achievable geometries for the scatterers. To overcome these limitations, a nanofabrication strategy is introduced that merges both approaches. A large number of scatterers are fabricated with a tailored optical response by fast character projection electron‐beam lithography and are embedded into a membrane. By peeling‐off this membrane from the substrate, scrambling, and densifying it, a bulk material comprising densely packed and randomly arranged scatterers is obtained. The fabrication of an isotropic material from these scatterers with a strong electric and magnetic response is demonstrated. The approach of this study unlocks novel opportunities to fabricate nanomaterials with a complex optical response in the bulk but also on top of arbitrarily shaped surfaces.  相似文献   

18.
Ordered nanostructured crystals of thin organic–inorganic metal halide perovskites (OIHPs) are of great interest to researchers because of the dimensional‐dependence of their photoelectronic properties for developing OIHPs with novel properties. Top‐down routes such as nanoimprinting and electron beam lithography are extensively used for nanopatterning OIHPs, while bottom‐up approaches are seldom used. Herein, developed is a simple and robust route, involving the controlled crystallization of the OIHPs templated with a self‐assembled block copolymer (BCP), for fabricating nanopatterned OIHP films with various shapes and nanodomain sizes. When the precursor solution consisting of methylammonium lead halide (MAPbX3, X = Br?, I?) perovskite and poly(styrene)‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) is spin‐coated on the substrate, a nanostructured BCP is developed by microphase separation. Spontaneous crystallization of the precursor ions preferentially coordinated with the P2VP domains yields ordered nanocrystals with various nanostructures (cylinders, lamellae, and cylindrical mesh) with controlled domain size (≈40–72 nm). The nanopatterned OIHPs show significantly enhanced photoluminescence (PL) with high resistance to both humidity and heat due to geometrically confining OIHPs in and passivation with the P2VP chains. The self‐assembled OIHP films with high PL performance provide a facile control of color coordinates by color conversion layers in blue‐emitting devices for cool‐white emission.  相似文献   

19.
Three water‐soluble dipeptides containing N‐terminally located β‐alanine residue and C‐terminally located α‐amino acid residues (β‐Ala‐L ‐Xaa, Xaa = Val/Ile/Phe) form robust crystalline nanotubes. These dipeptide nanotubes contain a common motif, a hybrid of β,α‐amino acids, which are stable against heat up to 80 °C, a wide range of pH (2–10), and proteolytic degradation. These robust crystalline dipeptide nanotubes are used as a template for fabricating dipeptide‐capped gold nanoparticles on their outer surfaces. This is an easy way to develop nanotube/nanoparticle hybrid materials under mild conditions.  相似文献   

20.
In the work, a facile yet efficient self‐sacrifice strategy is smartly developed to scalably fabricate hierarchical mesoporous bi‐component‐active ZnO/ZnFe2O4 (ZZFO) sub‐microcubes (SMCs) by calcination of single‐resource Prussian blue analogue of Zn3[Fe(CN)6]2 cubes. The hybrid ZZFO SCMs are homogeneously constructed from well‐dispersed nanocrstalline ZnO and ZnFe2O4 (ZFO) subunites at the nanoscale. After selectively etching of ZnO nanodomains from the hybrid, porously assembled ZFO SMCs with integrate architecture are obtained accordingly. When evaluated as anodes for LIBs, both hybrid ZZFO and ZFO samples exhibit appealing electrochemical performance. However, the as‐synthesized ZZFO SMCs demonstrate even better electrochemical Li‐storage performance, including even larger initial discharge capacity and reversible capacity, higher rate behavior and better cycling performance, particularly at high rates, compared with the single ZFO, which should be attributed to its unique microstructure characteristics and striking synergistic effect between the bi‐component‐active, well‐dispersed ZnO and ZFO nanophases. Of great significance, light is shed upon the insights into the correlation between the electrochemical Li‐storage property and the structure/component of the hybrid ZZFO SMCs, thus, it is strongly envisioned that the elegant design concept of the hybrid holds great promise for the efficient synthesis of advanced yet low‐cost anodes for next‐generation rechargeable Li‐ion batteries.  相似文献   

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