Functional substrates for the gradual release of agents

This work describes the functionalization of a natural and a man-made textile substrate, namely cotton and polyamide 6.6, with inclusion agents, β-cyclodextrins (β-CDs) that are able to release gradually to the user active ingredients. In this study we used aescin (aesculus hippocastanum extract), which is a natural agent with benefits for the treatment of varicose veins.¹H NMR and UV–vis data supported the role of β-CDs as an aescin complexing agent, and the covalent nature of the linkage between β-cyclodextrins and the textile substrates, which showed a wash fastness to more than 45 washing cycles.     

Self-assembly of gold nanoparticles to silver microspheres as highly efficient 3D SERS substrates

Herein we report a simple, one-pot, surfactant-free synthesis of 3D Ag microspheres (AgMSs) in aqueous phase at room temperature. The 3D AgMSs act as supports to fix the gold nanoparticles (GNPs) in 3D space via the interaction between the carboxyl groups of GNPs and the Ag atoms of AgMSs. The ensemble of AgMSs@GNPs with high surface-enhanced Raman scattering (SERS) activity and sensitivity can be an ideal 3D substrate choice for practical SERS detection applications. The simple self-assembly strategy may be extended to other metallic materials with great potentials in SERS, catalysis, and photoelectronic devices.     

One-dimensional hybrid nanostructures: synthesis via layer-by-layer assembly and applications

Assembly techniques are being intensely sought for preparing nanocomposites with tunable compositions and structures. Compared to other assembly techniques, the layer-by-layer (LBL) technique, which is based on the electrostatic attraction between oppositely charged species, provides a simple, versatile and powerful method to synthesize various types of one-dimensional (1D) hybrid nanostructures. In this review, we begin with the developments in the LBL synthesis of nanocomposites, with a focus on our recent results for synthesizing 1D hybrid nanostructures via LBL assembly. Compared to previous LBL processes, we conducted the in situ reaction on the surface of 1D nanostructures via electrostatic attraction between oppositely charged 1D nanostructures and ions in the solution in an attempt to produce 1D hybrid nanostructures. Moreover, these core-shell nanostructures can be transformed into nanotubes by the removal of the templates. The as-synthesized 1D hybrid nanostructures and nanotubes with tunable composition exhibited enhanced performance for various applications such as gas sensors, lithium-ion batteries and cellular imaging.     

SERS基底Ag@Au的制备及其对氧氟沙星的检测

通过种子介导生长方法,合成了形貌、粒径均一,分散性良好的双金属Ag@Au纳米粒子,并将其作为表面增强拉曼散射（SERS）基底,对氧氟沙星（OFLX）进行检测。首先在最佳实验条件下对氧氟沙星主要拉曼峰进行归属,选取1 416 cm ^-1拉曼特征峰。其次,对其1 416 cm ^-1特征峰强度与氧氟沙星浓度作线性拟合,曲线方程为Y=291.48X+3 156.8,r=0.989,检测极限可达10 ^-10 mol/L。该方法操作简单,灵敏度高,重现性好,可为氧氟沙星类抗生素药物的SERS检测提供依据。     

Silver-coated magnetite-carbon core-shell microspheres as substrate-enhanced SERS probes for detection of trace persistent organic pollutants

Highly active surface-enhanced Raman scattering (SERS) substrates of Ag nanoparticle (Ag-NP) modified Fe(3)O(4)@carbon core-shell microspheres were synthesized and characterized. The carbon coated Fe(3)O(4) microspheres were prepared via a one-pot solvothermal method and were served as the magnetic supporting substrates. The Ag-NPs were deposited by in situ reduction of AgNO(3) with butylamine and the thickness of the Ag-NP layer was variable by controlling the AgNO(3) concentrations. The structure and integrity of the Fe(3)O(4)@C@Ag composite microspheres were confirmed by TEM, XRD, VSM and UV-visible spectroscopy. In particular, the Ag-NP coated Fe(3)O(4)@carbon core-shell microspheres were shown to be highly active for SERS detections of pentachlorophenol (PCP), diethylhexyl phthalate (DEHP) and trinitrotoluene (TNT). These analytes are representatives of environmentally persistent organic pollutants with typically low SERS activities. The results suggested that the interactions between the carbon on the microsphere substrates and the aromatic cores of the target molecules contributed to the facile pre-concentration of the analytes near the Ag-NP surfaces.     

Synthesis and characterization of nickel phosphonopropionate hybrid materials

Hydrothermal reaction of nickel acetate with 3-phosphonopropionic acid and 4,4′-bipyridine resulted in two novel phosphonate compounds Ni(HO₃PC₂H₄COO)(4,4′-bpy)(H₂O) · 0.5(4,4′-bpy) (bpy = bipyridine) (I) and Ni(O₃PC₂H₄COOH)(4,4′-bpy)(H₂O)₃ · H₂O (II). Single-crystal X-ray studies reveal that self-assemblies between the ligands and metal ion result in layer (I) and chain (II) structures. Magnetic measurement of I indicate there are ferromagnetic couplings between adjacent Ni²⁺ ions (C = 1.29 cm³ mol⁻¹ K and θ = 2.25 K).     

介孔硅包金棒多聚体的制备及其对塑化剂的SERS检测

以种子生长法制备金纳米棒,用介孔硅包覆在金棒外,制备出高活性表面增强拉曼(SERS)基底。以乙醇和半胱氨酸诱导金纳米棒进行组装,再于金棒外包裹介孔硅壳层,制备出介孔硅包金棒多聚体SERS基底。以结晶紫(CV)为SERS探针,考察基底的灵敏性及重复性,并对邻苯二甲酸丁基苄酯(BBP)塑化剂进行SERS检测。结果表明,基底的灵敏性较高,重复性较好,对BBP塑化剂的检测限可达10^(-8) mol/L,且该基底在添加了中毒剂量(1.3 mg/kg)BBP的某在售白酒中可以检测出添加的塑化剂,因此该基底有望应用于实际食品检测中。     

Selective synthesis of diamond and CNT nanostructures directly on stainless steel substrates

Without surface pretreatment or applying additional interlayer, diamond films have been directly synthesized on an Fe-25Cr-5Al steel substrate by a hot filament chemical vapor deposition method from an H₂-1vol.% CH₄ gas mixture. Due to an effective removal of intermediate graphite phase from the diamond-steel interface, the coated diamond films were continuous and adherent well to the steel substrate. Aligned conical diamond structures were also achieved on this steel substrate by negatively biasing the substrate holder and inducing a glow discharge. The deposition behavior of carbon on Fe-Cr-Ni steel substrate was different. A graphite-rich carbon film incorporated with diamond particles grew in the absence of biasing, then aligned carbon nanotube bundles were formed in the presence of negative biasing and glow discharge. The different deposition behavior of carbon on the two kinds of steel substrates was addressed in terms of the effect of their chemical compositions.     

Spectrophotometric analysis of nickel colloid performances as catalysts for hydrogenation of nitro-phenol: Influence of the stabilizing agents

Nickel nanoparticles are prepared through thermolysis or polyol procedures and they are fully characterized through TEM and XRD. The catalytic efficiencies are tested toward the hydrogenation reaction of 4-nitrophenol, which was spectrophotometrically detected. A significant improvement of the reaction rate and turnover number (TON) and frequency (TOF) is observed using alkyl amine-stabilized nanoparticles, likely due to their reduced surface steric hindrance. However, the polymer stabilized-nanocatalysts show a better selectivity for product formation, since only hydrogenation products are observed, while azo-benzene derivatives are detected when alkyl amine-stabilized nanoparticles are used. The findings indicate an important impact of surface properties of colloids on the catalysed reaction.     

Measurement and assessment of substrates containing fluorescent whitening agents

White, as a color sensation, can be determined by colorimetric methods of measurement. With other than colorimetric methods, no satisfactory correlation between measured value and visual assessment can be expected. The contribution of hue, saturation and luminosity to the degree of whiteness as found by six formulas widely used in industry was analyzed and the results were plotted in the form of a graph. An easy-to-use nomogram for whiteness determination was developed, based on the CIE 1931 2°-color system. Another nomogram is presented which provides an easy means to determine the hue of a sample treated with fluorescent whiteining agents (FWAs). The new whiteness determination is based on the measurement of true tristimulus values for fluorescent samples using the new International Commission on Illumination standard illuminant D 65. The magnitude of the just perceptible difference in whiteness was determined in a panel test using 11 samples and 22 observers. The results were evaluated statistically. Pending standardization of an illuminant, not only for colorimetric measurements, but also for visual assessment of white samples containing FWAs, it would scarcely seem possible to arrive at a more accurate determination of degrees of whiteness. All visual rankings of fluorescent white substrates are widely scattered around a mean value for the different phases of natural daylight. The relative energy emitted by artificial daylight lamps in the near UV region is insufficient in many cases. Xenon lamps are quite satisfactory for instrumental evaluation. In an internationally approved system, with a known hue preference, it would be possible to compare an objective measured value with each subjective result obtained by visual evaluation.     

NiCo2O4 arrays nanostructures on nickel foam: Morphology control and application for pseudocapacitors

The design of electrode materials with desirable morphology is of great importance and challenge to fabricate high-performance supercapacitors. In this work, NiCo₂O₄ nanopetal, nanosheet, nanoneedle and nanorod arrays on nickel foam have been synthesized through a facile hydrothermal method. The morphologies of NiCo₂O₄ arrays can be easily controlled by adjusting the kinds of alkali source and the addition of NH₄F. The electrochemical results show that the NiCo₂O₄ nanoneedles electrode has the optimal electrochemical performance among four samples, demonstrating its promising application potential for high performance supercapacitors. This investigation about morphology control of NiCo₂O₄ electrode materials and the relationship between the morphologies and corresponding electrochemical performances provides strategies to enhance the performance of supercapacitor electrodes.     

Synthesis and properties of highly stable nickel/carbon core/shell nanostructures

A simple and cost effective technique for obtaining highly stable carbon coated nickel nanostructures at relatively low reaction temperatures is reported. Thermogravimetric analysis was carried out to optimize the annealing temperatures. The powder X-ray diffraction pattern reveals peaks corresponding to face centered cubic nickel. High resolution transmission electron micrograph shows the formation of nickel nanostructures with ∼5 nm thick carbon coating. This is confirmed by Raman spectroscopy. The nickel/carbon core/shell nanostructures exhibited a shelf life of more than a year, with high thermal stability and excellent magnetic properties. This synthesis route provides scope for large scale production of nickel/carbon nanostructures.     

Self-assembly of metal-cholesterol oxidase hybrid nanostructures and application in bioconversion of steroids derivatives

A cholesterol oxidase (COD) was hybridized with Ca²⁺, Zn²⁺, Al³⁺, Fe²⁺ and Mn²⁺. After precipitation with PO₄^3– at 4 °C for 72 h, the resulting pellets were freeze-dried. In scanning electron microscopy assays, the metal-COD complexes revealed flower-like or granular structures after hybridization. Fourier transform infrared spectroscopy assay revealed the characteristic peaks of both the enzyme and metal materials. X-ray diffraction analysis indicated that COD was encapsulated in CaHPO₄·2H₂O-, Zn₃(PO₄)₂·4H₂O-, AlPO₄-, FeP₄- and Mn₃(PO₄)₂·3H₂O-based nanostructures, respectively. Differential scanning calorimetry assay indicated significant increases in thermo-denaturation temperatures from 60.5 °C to 167.02 °C, 167.02 °C, 137.70 °C, 172.85 °C and 160.99 °C, respectively. Using steroid derivatives as substrates, this enzyme could convert cholesterol, pregnenolone, dehydroepiandrosterone, ergosterol, b-sitosterol and stigmasterol to related single products. Hybridization in metal-based nanostructures could significantly enhance the initial conversion ratio and reaction stability of the enzyme. In addition, substrate selectivity could be affected by various metal materials. Briefly, using Ca²⁺, Zn²⁺, Al³⁺, Fe²⁺ and Mn²⁺ as hybrid raw materials could help to encapsulate COD in related metal-enzyme nanostructures, and could help to promote the stability and tolerant properties of the enzyme, while also enhancing its catalytic characteristics.     

Fabrication of 2D titanium carbide MXene/Au nanorods as a nanosensor platform for sensitive SERS detection

As an emerging label-free detection technology, surface-enhanced Raman scattering (SERS) has been used for biological detection, food safety, and environmental pollution owing to its high sensitivity, specificity and rapid response. However, traditional SERS substrates are unstable, prone to agglomeration, and demonstrate low productivity and high production cost. In this work, hybrids of a two-dimensional electron gas (2DEG) Ti₃C₂T_x monolayer and Au nanorods (AuNRs) were fabricated via self-assembly. Ti₃C₂T_x:AuNRs ratios were prepared, and each hybrid's SERS activity was evaluated through 4-aminothiophenol (pATP) detection. The Ti₃C₂T_x/AuNRs-1 substrate exhibited the weakest SERS performance, whereas the Ti₃C₂T_x/AuNRs-3 substrate had the best SERS activity enhancement, with a pATP limit of detection (LOD) of 10⁻⁹ M. When 30 sites on substrates were selected for SERS detection, the relative standard deviation (RSD) was found to be only 7.18 %, revealing the good performance sensitivity and high reproducibility of the Raman signal. The sensitivity of Ti₃C₂T_x/AuNRs-3 was also assessed with respect to a hazardous chemical, 1,2-bis (4-pyridyl) ethylene (BPE), revealing an LOD of 10⁻¹² M. For thiram, the LOD of Ti₃C₂T_x/AuNRs-3 was 10⁻⁸ M, which is considerably lower than the 1 ppm industry safety standard. A relative standard deviation RSD of 7.94 % indicates the high reproducibility and uniformity of the Raman signal of thiram for Ti₃C₂T_x/AuNRs-3. Compared with the LODs of 10⁻⁵ M and 10⁻⁶ M for commercial substrates T-SERS and Au nanorod arrays (AuNRAs), respectively, the 10⁻⁸ M LOD of our synthesized Ti₃C₂T_x/AuNRs indicates good sensitivity. Three kinds of pesticides were detected by Ti₃C₂T_x/AuNRs, and only Raman signal of thiram can be found, revealing the good selectivity for thiram. These results for Ti₃C₂T_x/AuNRs suggest its potential to serve as a novel SERS platform.     

Synthesis of hybrid materials in polyelectrolyte matrixes: Control over sizes and spatial organization of metallic nanostructures

This review is concerned with the synthesis of hybrid materials in solutions, suspensions, and gels of polyelectrolytes with emphasis being placed on the role of interaction between functional groups of macromolecules and ions/surfaces of metals in the control over the processes of nucleation and growth of nanoparticles. The use of several macromolecules carrying nonionogenic groups for the effective control over the sizes and shapes of nanoparticles is exemplified. As the main method for the synthesis of metal nanostructures in colloidal systems, a method based on the reduction of metal ions is discussed. Mechanisms and conditions determining the assembly of metal–polymer nanocomposites of various architectures in polyelectrolyte matrixes and organized polymer systems are considered.     

Electrospinning and hydrothermal synthesis of recyclable MoS2/CNFs hybrid with enhanced visible-light photocatalytic performance

In this work, a two-step synthesis route combining an electrospinning method and a hydrothermal process was used to prepare MoS₂/CNFs hybrid. CNFs was applied as the matrix for the nucleation and growth of MoS₂ nanosheets. In this hybrid, the crisscrossed MoS₂ nanosheets were randomly aligned and densely packed over the surface of CNFs. We probed the photocatalytic activity of MoS₂/CNFs hybrid to degrade rhodamine B (Rh B) in an aqueous solution under visible light irradiation. The hybrid displayed higher photodegradation performance relative to MoS₂ and mechanical mixture of MoS₂ with CNFs, with 67% Rh B completely degraded over 5 h-period. We attributed such enhancement in photocatalytic activity to the enhanced absorption property and electrical conductivity due to the synergy between MoS₂ and CNFs. The hybrid can furthermore be easily separated from the solution and reused for the subsequent photodegradation cycles. We verified the negligible loss in the photodegradation activity of MoS₂/CNFs hybrid towards Rh B during the three subsequent cycles. The high photocatalytic activity and recyclability of the hybrid render its practical application to degrade organic pollutants (i.e., dye compounds) in industrial wastewater.     

种子介导法制备SERS基底Ag@Au及对阿莫西林的痕量检测

通过种子介导的生长过程,合成了形貌、粒径均一、分散性好的双金属Ag@Au纳米粒子。Ag@Au纳米粒子的表面增强拉曼散射(SERS)性能有了很大的提高,增强因子高达3.9×10⁵,具有较高的灵敏度,可检测浓度为105,具有较高的灵敏度,可检测浓度为10^(-11) mol/L的阿莫西林,具有较好的光谱重现性以及较强的SERS强度。对阿莫西林(AMC)的浓度和1 139 cm(-11) mol/L的阿莫西林,具有较好的光谱重现性以及较强的SERS强度。对阿莫西林(AMC)的浓度和1 139 cm^(-1)特征峰强度线性关系良好,r为0.996。可用于对食品、药品的快速检测。     

Synthesis and characterization of graphene–nickel oxide nanostructures for fast charge–discharge application

Graphene–metal oxide composites as anode materials for Li-ion batteries have been investigated extensively, but these attempts are mostly limited to moderate rate charge–discharge applications. Here, graphene–nickel oxide nanostructures have been synthesised using a controlled hydrothermal method, which enabled in situ formation of NiO with a coralloid nanostructure on graphene. Graphene/NiO (20%), graphene/NiO (50%) and pure NiO show stable discharge capacities of 185 mAh/g at 20 C (1 C = 300 mA/g), 450 mAh/g at 1 C, and 400 mAh/g at 1 C, respectively. High rate capability and good stability in prolonged charge–discharge cycling permit the application of the material in fast charging batteries for upcoming electric vehicles. To the best of our knowledge such fast rate performance of graphene/metal oxide composite as anode and such stability for pure NiO as anode have not been reported previously.     

Polyimide-Siloxane hybrid materials: Influence of coupling agents addition on microstructure and properties

Polyimide-silica hybrid materials were prepared by polycondensation, polyimidization, and sol-gel coreactions. Several aminoalkoxysilane precursors providing a chemical bonding between the inorganic and the organic phase were used. During the synthesis, the molecular structure of the materials prepared with these precursors were followed at various steps by ²⁹Si-NMR (nuclear magnetic resonance). The final materials were characterized at the macroscopic level by thermogravimetric analysis and scanning electron microscopy and at the molecular level by infrared spectrometry and ²⁹Si-MAS-NMR spectroscopy. It has been demonstrated that the properties of the organic sidegroups of the bonding agent are determinent on the properties of the final material. © 1996 John Wiley & Sons, Inc.