D4(H)/D4(V) silicone: a replica material with several advantages for nanoimprint lithography and capillary force lithography

Reported are demonstrations that D(4)(H)/D(4)(V) silicone (the product of the platinum-catalyzed hydrosilylation reaction between tetramethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane) is useful and practical as a replica material for both nanoimprint lithography (NIL) and capillary force lithography (CFL). The multiple advantageous properties of this extremely cross-linked material include UV transparency (for photo NIL and photo CFL), thermal stability (for high printing temperatures), high modulus (for high printing pressures), low surface energy (for easy demolding), and low viscosity precursors (for replicating small scale features). The replication performance of this material was tested using Blu-ray discs with sub-25 nm features and anodized aluminum foil with sub-10 nm features. Structures of ～5 nm length scale on the surface of the anodized Al were replicated using D(4)(H)/D(4)(V) silicone as a mold material for CFL with a photocurable epoxy resin and for NIL with poly(methyl methacrylate) (PMMA). Features (holes in the anodized aluminum) with aspect ratios of greater than 9 were replicated.     

Top-down approaches to the formation of silica nanoparticle patterns

This article reports a simple, versatile approach to the fabrication of lithographically defined mesoscopic colloidal silica nanoparticle patterns over large areas using spin-coating, interferometric lithography, and reactive-ion etching. One-dimensional nanoparticle films (bands) and 2D discs, diamonds, and holes with sub-micrometer periodicity, high quality, and excellent uniformity were successfully fabricated over large areas. The well-defined shape and period of the patterned nanoparticle film were controlled in the interferometric lithography step, while the thickness of nanoparticle film was easily tuned in the spin-coating step. This approach can extend to other deposition methods such as convective self-assembly, electrostatic self-assembly, and other materials such as metallic and ferromagnetic nanoparticles. We have also been able to generate sparse, random, isolated particle patterns, using a combination of interferometric lithography and layer-by-layer deposition as an extension of this approach to another deposition method, and to generate disc nanoparticle patterns using colloidal lithography as an extension of this approach to another lithography technique. These patterned films will find important applications in the fields of material growth, biosensors, and catalysis, as well as serving as building blocks for further fabrication.     

Comparing the structural stability of PbS nanocrystals assembled in fcc and bcc superlattice allotropes

We investigated the structural stability of colloidal PbS nanocrystals (NCs) self-assembled into superlattice (SL) allotropes of either face-centered cubic (fcc) or body-centered cubic (bcc) symmetry. Small-angle X-ray scattering analysis showed that the NC packing density is higher in the bcc than in the fcc SL; this is a manifestation of the cuboctahedral shape of the NC building block. Using the high-pressure rock-salt/orthorhombic phase transition as a stability indicator, we discovered that the transition pressure for NCs in a bcc SL occurs at 8.5 GPa, which is 1.5 GPa higher than the transition pressure (7.0 GPa) observed for a fcc SL. The higher structural stability in the bcc SL is attributed primarily to the effective absorption of loading force in specific SL symmetry and to a lesser extent to the surface energy of the NCs. The experimental results provide new insights into the fundamental relationship between the symmetry of the self-assembled SL and the structural stability of the constituent NCs.     

胶体刻蚀——纳米结构化表面的构筑与应用

综述了近年来胶体刻蚀领域的研究进展, 分别讨论了基于胶体微粒和胶体晶体为模板的可控沉积与可控刻蚀及在固体平面基质、曲面基质和气液界面等不同基质上构筑结构化表面的方法. 同时还探讨了利用胶体刻蚀方法形成的微纳结构在光、电、磁以及表面润湿和生物学等方面的应用.     

Shape memory hybrid based on polyvinyl alcohol and 0D silver nanoparticles

Shape memory hybrids (SMH) have drawn significant attention because they allow an easy alternative for the design of shape memory materials with tailored properties or features. In this work, a shape memory hybrid was made, based on polyvinyl alcohol (PVA) as the elastic domain and 0D silver nanoparticles (Agnps) as the transition domain, a dissolution method of mixing both components, and evaporation of water afterward allowed the formation of films of the hybrid material. Two different size distributions of silver nanoparticles were used (13.7 ± 2.6 and 67.9 ± 14.1 nm), in order to study the effect of the size on the shape memory effect (SME) of the final SMH, under temperature stimuli. The materials obtained were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy, infrared spectroscopy (IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The crystallinity of PVA was slightly altered with the addition of Agnps. Finally, the shape memory effect was tested on both hybrid materials, resulting in a better response to temperature for the SMH prepared with Agnps of 68 nm, also the shape recovery time can be tuned varying both the increase of temperature and the size distribution of Agnps used.     

Fabrication of Pascal‐triangle Lattice of Proteins by Inducing Ligand Strategy

A protein Pascal triangle has been constructed as new type of supramolecular architecture by using the inducing ligand strategy that we previously developed for protein assemblies. Although mathematical studies on this famous geometry have a long history, no work on such Pascal triangles fabricated from native proteins has been reported so far due to their structural complexity. In this work, by carefully tuning the specific interactions between the native protein building block WGA and the inducing ligand R‐SL , a 2D Pascal‐triangle lattice with three types of triangular voids has been assembled. Moreover, a 3D crystal structure was obtained based on the 2D Pascal triangles. The distinctive carbohydrate binding sites of WGA and the intralayer as well as interlayer dimerization of RhB was the key to facilitate nanofabrication in solution. This strategy may be applied to prepare and explore various sophisticated assemblies based on native proteins.     

Mapping noncovalent ligand binding to stemloop domains of the HIV-1 packaging signal by tandem mass spectrometry

The binding modes and structural determinants of the noncovalent complexes formed by aminoglycoside antibiotics with conserved domains of the HIV-1 packaging signal (Psi-RNA) were investigated using electrospray ionization (ESI) Fourier transform mass spectrometry (FTMS). The location of the aminoglycoside binding sites on the different stemloop structures was revealed by characteristic coverage gaps in the ion series obtained by sustained off-resonance irradiation collision induced dissociation (SORI-CID) of the antibiotic-RNA assemblies. The site positions were confirmed using mutants that eliminated salient structural features of the Psi-RNA domains. The effects of the mutations on the binding properties of the different substrates served to validate the position of the aminoglycoside site on the wild-type structures. Additional information was provided by docking experiments performed on the different aminoglycoside-stemloop complexes. The results have shown that, in the absence of features disrupting the regular A-helix of the double-stranded stem, aminoglycosides tend to bind in an area situated between the upper stem and the loop regions, as demonstrated for stemloop SL3. The presence of a tandem wobbles motif in SL4 modifies the regular geometry of the upper stem, which does not affect the general site location, but greatly increases its solution binding affinity compared with SL3. The platform motif in SL2 locates the binding site in the stem midsection and confers upon this stemloop an intermediate affinity toward aminoglycosides. In SL3 and SL4, the extensive overlap of the antibiotic site with the region used to bind the nucleocapsid (NC) protein provides the basis for a competition mechanism that could explain the aminoglycoside inhibition of the NC.SL3 and NC.SL4 assemblies. In contrast, the minimal overlap between the aminoglycoside and the NC sites in SL2 accounts for the absence of inhibition of the NC.SL2 complex.     

Preparation of high-quality colloidal mask for nanosphere lithography by a combination of air/water interface self-assembly and solvent vapor annealing

Nanosphere lithography (NSL) has been regarded as an inexpensive, inherently parallel, high-throughput, materials-general approach to the fabrication of nanoparticle arrays. However, the order of the resulting nanoparticle array is essentially dependent on the quality of the colloidal monolayer mask. Furthermore, the lateral feature size of the nanoparticles created using NSL is coupled with the diameter of the colloidal spheres, which makes it inconvenient for studying the size-dependent properties of nanoparticles. In this work, we demonstrate a facile approach to the fabrication of a large-area, transferrable, high-quality latex colloidal mask for nanosphere lithography. The approach is based on a combination of the air/water interface self-assembly method and the solvent-vapor-annealing technique. It enables the fabrication of colloidal masks with a higher crystalline integrity compared to those produced by other strategies. By manipulating the diameter of the colloidal spheres and precisely tuning the solvent-vapor-annealing process, flexible control of the size, shape, and spacing of the interstice in a colloidal mask can be realized, which may facilitate the broad use of NSL in studying the size-, shape-, and period-dependent optical, magnetic, electronic, and catalytic properties of nanomaterials.     

多光子光刻用的杯[4]芳烃分子玻璃正性光刻胶

分子玻璃材料和多光子光刻技术分别是近年来光刻胶和光刻技术领域的研究热点.本文对分子玻璃正性光刻胶在多光子光刻中的应用进行了探索,设计合成了叔丁氧基羰基保护的杯[4]芳烃衍生物分子玻璃材料,将其作为主体材料与光生酸剂三氟甲磺酸三苯锍鎓盐进行复配,制备了分子玻璃正性光刻胶,探讨并优化了光刻胶的成分配比及其在紫外光曝光下的显影工艺.利用780nm波长飞秒激光对所制备的分子玻璃正性光刻胶进行了多光子光刻特性的评价,实验得到了最低线宽180nm的线条和复杂的二维微结构图形,结果表明杯[4]芳烃衍生物分子玻璃正性光刻胶有望应用于多光子光刻技术.     

Supramolecular assemblies of a naturally derived sophorolipid

Acidic sophorolipid (SL) molecules derived from yeasts represent a novel type of asymmetrical bolaamphiphiles due to their unique structural features that include an asymmetrical polar head size (disaccharide vs COOH), a kinked hydrophobic core (cis-9-octadecenoic chain), and a non-amide polar-nonpolar linkage. Light microscopy, small- and wide-angle X-ray scattering, FT-IR spectroscopy, and dynamic laser light scattering were used to investigate the supramolecular structures of the self-assembled aggregates of SL molecules at different pH values. In acidic conditions (pH < 5.5), giant twisted and helical ribbons of 5-11 microm width and several hundreds of micrometers length were observed for the first time. Increase in solution pH values slowed ribbon formation, decreased ribbon yield, and increased the helicity and entanglements of the giant ribbons. An interdigitated lamellar packing model of acidic SL-COOH molecules with a long period of 2.78 nm, stabilized by both the strong hydrophobic association between the cis-9-octadecenoic chains and strong disaccharide-disaccharide hydrogen bonding, is proposed. The neutralization of SL-COOH in water to SL-COONa produced clear solutions with the formation of short-range ordered aggregates. At concentrations below 1.0 mg/mL, the size of self-assembled aggregates increased as the concentration increased. At concentrations above 1.0 mg/mL, narrowly distributed micellar aggregates with a constant hydrodynamic radius (R(h)) of about 100 nm are formed. The large micelles show strong angular dependence with the fast mode appearing at scattering angle theta >/= 60 degrees.     

煤直接液化残渣制备水渣浆成浆性的研究

以煤直接液化残渣制备了水渣浆，考察了粒径分布、搅拌时间、分散剂的用量及种类对水渣浆性质的影响。根据实验确定了制备水渣浆的最佳工艺参数：Alfred粒径分布模型（d_280~154μm、d_154~74μm、d_<74μm 质量分数分别为14%、16%、70%），搅拌时间20 min，分散剂加入量为干渣基1.0%。实验结果表明，液化残渣制备水渣浆的定黏质量分数分别为73.5%（NSF）和71.0%（SL）。分散剂萘磺酸盐甲醛缩合物（NSF）的分散降黏效果优于改性碱木质素磺酸钠（SL），而水渣浆的流变性，分散剂SL要优于分散剂NSF。     

Nanoreactors for studying single nanoparticle coarsening

The ability to observe intermediate structures as part of coarsening processes that lead to the formation of single nanoparticles (NPs) is important in gaining fundamental insight pertaining to nanostructure growth. Here, we use scanning probe block copolymer lithography (SPBCL) to create "nanoreactors" having attoliter volumes, which confine Au NP nucleation and growth to features having diameters <150 nm on a substrate. With this technique, one can use in situ TEM to directly observe and study NP coarsening and differentiate Ostwald ripening from coalescence processes. Importantly, the number of metal atoms that can engage in coarsening can be controlled with this technique, and TEM "snapshots" of particle growth can be taken. The size of the resulting nanostructures can be controlled in the 2-10 nm regime.     

Shape-controllable Synthesis of Functional Nanomaterials on DNA Templates

DNA nanotechnology enables precise organization of nanoscale objects with extraordinarily structural programmability.Self-assembled DNA nanostructures possess a lot of interesting features,such as designable size and shape,and structural addressability at nanometer scale.Taking advantage of these properties,DNA nanostructures could work as templates or molds for the controllable synthesis of functional nanomaterials,such as organic macromolecules,metallic or inorganic nonmetallic nanomaterials.In this review,we summarize the recent progress in the shape-controllable synthesis of functional nanomaterials on DNA templates.The potential application fields of these nanomaterials are also discussed.     

3D Tungsten Trioxide Nanosheets as Optoelectronic Materials for On-chip Quantification of Global Antioxidant Capacity

The photoelectrochemical properties of semiconductors mainly depend on the size and shape of the corresponding nanoparticles. Herein, 3D WO₃ nanosheets were controllably synthesized with the aid of polyethyleneimine, which presents enhanced photocurrent responses. Based on this excellent photoelectrochemical property, a photoelectrochemical chip was prepared by lithography technology for the smart monitoring of the antioxidant capacity(AC) in red wine and exhibits a series of advantages inclu-ding rapid response time, high sensitivity, and long-lasting stability. The mechanism of the present photoelectrochemical sensing was explored and shows a single electron transfer reaction. Furthermore, only 200 μL of samples are required for one testing, which demonstrates that the present photoelectrochemical chip can be potentially integrated with a portable commercial device(such as a mobile phone) for further research and development of food and drug supervision.     

Structural Evolution Patterns of FCC-Type Gold Nanoclusters

Recent progress in the research of atomically-precise metal nanoclusters has identified a series of exceptionally stable nanoclusters with specific chemical compositions. Structural determination on such "magic size" nanoclusters revealed a variety of unique structures such as decahedron, icosahedron, as well as hexagonal close packing(hcp) and body-centered cubic(bcc) packing arrangements in gold nanoclusters, which are largely different from the face-centered cubic(fcc) structure in conventional gold nanoparticles. The characteristic geometrical structures enable the nanoclusters to exhibit interesting properties, and these properties are in close correlation with their atomic structures according to the recent studies. Experimental and theoretical analyses have been applied in the structural identification aiming to clarify the universal principle in the structural evolution of nanoclusters. In this mini-review, we summarize recent studies on periodic structural evolution of fcc-based gold nanoclusters protected by thiolates. A series of nanoclusters exhibit one-dimensional growth along the [001] direction in a layer-by-layer manner from Au_(23)(TBBT)_(20) to Au_(36)(TBBT)_(24),Au_(44)(TBBT)_(28), and to Au_(52)(TBBT)_(32)(TBBT: 4-tert-butylbenzenethiolate). The optical properties of these nanoclusters also evolve periodically based on steady-state and ultrafast spectroscopy. In addition, two-dimensional growth from Au_(44)(TBBT)_(28) toward both [100] and [010] directions leads to the Au_(92)(TBBT)_(44) nanocluster, and the recently reported Au_(52)(PET)_(32)(PET: 2-phenylethanethiol) also follows this growth pattern with partial removal of the layer. Theoretical predictions of relevant fcc nanoclusters include Au_(60)(SCH_3)_(36), Au_(68)(SCH_3)_(40), Au_(76)(SCH_3)_(44), etc, for the continuation of 1 D growth pattern, as well as Au_(68)(SR)_(38)mediating the 2 D growth pattern from Au_(44)(TBBT)_(28) to Au_(92)(TBBT)_(44). Overall, this mini-review provides guidelines on the rules of structural evolution of fcc gold nanoclusters based on 1 D, 2 D and 3 D growth patterns.     

Patterned growth of vertically aligned ZnO nanowire arrays on inorganic substrates at low temperature without catalyst

We report an approach for growing aligned ZnO nanowire arrays with a high degree control over size, orientation, dimensionality, uniformity, and possibly shape. Our method combines e-beam lithography and a low temperature hydrothermal method to achieve patterned and aligned growth of ZnO NWs at <100degreesC on general inorganic substrates, such as Si and GaN, without using catalyst. This approach opens up the possibility of applying ZnO nanowires as sensor arrays, piezoelectric antenna arrays, two-dimensional photonic crystals, IC interconnects, and nanogenerators.     

Graphene quantum dots from chemistry to applications

Graphene quantum dots (GQDs) have been widely studied in recent years due to its unique structure-related properties, such as optical, electrical and optoelectrical properties. GQDs are considered new kind of quantum dots (QDs), as they are chemically and physically stable because of its intrinsic inert carbon property. Furthermore, GQDs are environmentally friendly due to its non-toxic and biologically inert properties, which have attracted worldwide interests from academic and industry. In this review, a number of GQDs preparation methods, such as hydrothermal method, microwave-assisted hydrothermal method, soft-template method, liquid exfoliation method, metal-catalyzed method and electron beam lithography method etc., are summarized. Their structural, morphological, chemical composition, optical, electrical and optoelectrical properties have been characterized and studied. A variety of elemental dopant, such as nitrogen, sulphur, chlorine, fluorine and potassium etc., have been doped into GQDs to diversify the functions of the material. The control of its size and shape has been realized by means of preparation parameters, such as synthesis temperature, growth time, source concentration and catalyst etc. As far as energy level engineering is concerned, the elemental doping has shown an introduction of energy level in GQDs which may tune the optical, electrical and optoelectrical properties of the GQDs. The applications of GQDs in biological imaging, optoelectrical detectors, solar cells, light emitting diodes, fluorescent agent, photocatalysis, and lithium ion battery are described. GQD composites, having optimized contents and properties, are also discussed to extend the applications of GQDs. Basic physical and chemical parameters of GQDs are summarized by tables in this review, which will provide readers useful information.     

Chemically Organizable Nanosized Materials Preparation and Applications

We are interested in fabricating well-organized assemblies of nanosized materials with wet chemical approaches for the purpose of investigating various interfacial and mesoscopic phenomena. The paper describes how to use self-assembling techniques to prepare assemblies of colloidal nanoparticles and single walled carbon nanotubes on solid surfaces. Gold nanocolloids are taken as the model system, including preparation of functionalized nanoparticles, assembling on tailored substrates, surface reorganization, and 1D, 0D controlled assembling with the aid of scanning probe lithography. The typical work we have been doing using these elaborated nanoparticle assemblies includes, the quantitative investigations of die electromagnetic coupling of particle-particle and particle-substrate in surface enhanced Raman scattering (SERS), the single electron tunneling in nanoparticle assemblies measured with scanning probe microscopy (SPM) technique, the atomic force microscopy (AFM) lithography using the surface-confined gold nanoparticles as mask.     

Conformation of microcontact-printed proteins by atomic force microscopy molecular sizing

We investigated the structural changes occurring in proteins patterned via microcontact printing. This was done by molecular sizing using atomic force microscopy to observe the structure of printed individual metalloprotein molecules in the unlabeled and untreated states. We observed that the size of the printed proteins were more than 2-fold smaller than the native shape, which indicates that some deformations take place upon the contact-assisted adsorption on silanized silicon dioxide. This can be attributed to simultaneously occurring effects, and particularly to the sandwiching between surfaces of very different hydrophilic/hydrophobic properties during contact lithography.     

Coexistence and growth of micellar species in a sugar-based surfactant/phenol mixture studied by analytical ultracentrifugation

Knowledge of the shape and size of surfactant micelles in the presence of small organic molecules is important for understanding the solubilization properties of micellar phases. In this work, structural information on micelles of mixed n-dodecyl-beta-d-maltoside (DM) and phenol, including the aggregation number, diffusion coefficient, and effective radius, was obtained using an analytical ultracentrifugation technique. The micelles were found to increase in size and undergo shape transition from quasispherical to cylindrical with an increase in the surfactant and phenol concentrations in the micellar phase. Importantly, the coexistence of different micellar species was observed in certain cases with the larger species double the size of the smaller one. Based on the results obtained, a two-step micellar growth model is proposed to describe the micelles shape transition in the system. In the first step, the micelles expand continuously, whereas in the second step, it undergoes a sudden shift from the existing micellar species to a larger species causing the coexistence of two micellar species. This micellar growth is attributed to molecular packing and intermicellar interaction energy parameters. The mechanism proposed can be applied to other mixed systems and utilized for devising chemicals for the efficient removal of pollutants.