Characterization of IgG Langmuir-Blodgett films immobilized on functionalized polymers

The bioactivity of anti-human IgG Langmuir-Blodgett (LB) films, the non-specific adsorption of protein and the topography of anti-IgG LB films have been studied for application in immunosensors. The antibody (AB) LB films were horizontally deposited on glass and functionalized polymers, such as carboxy-poly(vinyl chloride) (PVC-COOH), chloropropyl and aminopropyl sol-gel. The LB films were characterized by means of ellipsometry, atomic force microscopy (AFM) and bicinchoninic acid (BCA) protein test. The interpretation of ellipsometric data was performed using a one-layer model. Non-specifically adsorbed protein was desorbed by washing the IgG film in 0.5 M NaCl, 2 M NaCl and 1% N-cetyl-N,N,N-trimethylammoniumbromide detergent solution resulting in a 50% reduction of the film thickness. The mean thickness of an anti-IgG film on glass measured by ellipsometry, PVC-COOH and aminopropyl sol-gel was 9+/-2, 11+/-1 and 23+/-8 nm, respectively. According to the BCA test 6-8 mug antibody (AB) per slide was bound to the functionalized polymers, but only 3 mug AB per slide was adsorbed on glass. The average distance of anti-IgG granules as indicated by AFM measurements on PVC-COOH, chloropropyl and aminopropyl sol-gel was 42+/-20, 34+/-3 and 23+/-4 nm. The average distance of granular AB structures on glass, however, was 150+/-50 nm.     

Quantitative analysis of the photodegradation of emitting CdTe nanocrystals dispersed in glass films

CdTe nanocrystals (NCs, green- and red-emitting) prepared by an aqueous method were embedded into transparent glass films (15-20 microm thick) using a sol-gel method. Photodegradation of the NCs in the films due to UV irradiation (365 nm) was investigated quantitatively by measuring the PL efficiency as a function of the irradiation time for various irradiation intensities at several temperatures. Since CdTe NCs prepared by an aqueous method incorporate sulfur atoms from the surfactant (thioglycolic acid) during prolonged reflux in an alkaline region, the surface of red-emitting NCs (3.9 nm phi) is much more sulfur rich than that of green-emitting ones (2.6 nm phi), as previously reported. Due to this composition difference, the degradation behaviors of the two types of NCs differ significantly. The photodegradation of green-emitting glass films depended linearly on the irradiation intensity, whereas that of red-emitting ones showed a quadratic dependence. The activation energies of the photodegradation for both types of films were similar, 304 +/- 9 and 288 +/- 7 meV/particle, respectively. The NCs in the film were more than 2 orders of magnitude more robust than those in colloidal solutions. Comparison of the degradation of the glass films in air and in an Ar atmosphere revealed that the main mechanism of the photodegradation of the green-emitting NCs was oxidization from the first electronically excited state. The mechanism of the red-emitting NCs was not oxidization but a surface change probably related to a surfactant reaction.     

Photovoltaic effects of CdS and PbS quantum dots encapsulated in zeolite Y

Zeolite Y films (0.35-2.5 μm), into which CdS and PbS quantum dots (QDs) were loaded, were grown on ITO glass. The CdS QD-loaded zeolite Y films showed a photovoltaic effect in the electrolyte solution consisting of Na(2)S (1 M) and NaOH (0.1 M) with Pt-coated F-doped tin oxide glass as the counter electrode. In contrast, the PbS QD-loaded zeolite Y films exhibited a negligible PV effect. This contrasting behavior was proposed to arise from the large difference in driving force for the electron transfer from S(2-) in the solution to the hole in the valence band of QDs, with the former being much larger (~2 eV) than the latter (~1 eV). In the case of CdS QD-loaded zeolite Y with a loaded amount of CdS of 6.3 per unit cell, the short circuit current, open circuit voltage, fill factor, and efficiency were 0.3 mA cm(-2), 423 V, 28, and 0.1%, respectively, under the AM 1.5, 100 mW cm(-2) condition. This cell was stable for more than 18 days of continuous measurements. A large (3-fold) increase in overall efficiency was observed when PbS QD-loaded zeolite Y on ITO glass was used as the counter electrode. This phenomenon suggests that the uphill electron transfer from ITO glass to S in the solution is facilitated by the photoassisted pumping of the potential energy of the electron in ITO glass to the level that is higher than the reduction potential of S by PbS QDs. Under this condition, the incident-photon-to-current conversion efficiency (IPCE) value at 398 nm was 42% and the absorbed-photon-to-current conversion efficiency (APCE) value at 405 nm was 82%. The electrolyte-mediated interdot charge transport within zeolite films is concluded to be responsible for the overall current flow.     

Arc plasma deposition of Pd seeding for Cu electroless deposition

Arc plasma deposition (APD) has been used for surface treatment of glass and polyimide (PI) substrates for Cu electroless deposition (ELD). The thickness of Cu ELD films increased linearly with time up to 2,000 nm on glass and 3,400 nm on PI substrates. Resistivity of Cu ELD films on glass (1.4–3.4 μΩ cm) and on PI (4.1–5.8 μΩ cm) was lower than that reported for conventional ELD processes (5–10 μΩ cm). The adhesion strength of Cu ELD films produced by our process was as good as, or better than, that for conventional Cu ELD films. APD is an effective, simple, and dry method for deposition of the seed layer for ELD on the surfaces of insulating materials.     

Robust, functionalizable, nanometer-thick poly(acrylic acid) films spontaneously assembled on oxidized aluminum substrates: structures and chemical properties

Immersion of oxidized aluminum substrates in ethanol solutions of poly(acrylic acid) (PAA), followed by extensive solvent immersion, results in tenaciously chemisorbed, nanometer scale, controllable thickness films for a wide range of solution concentrations and molecular weights. Atomic force microscope images reveal isolated polymer globules from adsorption in low-concentration solutions with crossover to conformal, highly uniform, nanometer-thickness films at higher concentrations, an indication that the chemisorbing chains start to overlap and trap underlying segments to form planar chemisorbed films only two or three chains in thickness. Quantitative IR reflection spectroscopy in combination with chemical derivitization on a standard set of 1.0(±0.2) nm thick films reveals a film structure with 5.5(±1) chemisorbed -CO(-)(2) groups/nm(2) and 6.3 unattached -CO(2)H groups/nm(2), with up to ～3.6/nm(2) available for chemical derivitization, a comparable number to typical self-assembled monolayer coverages of ～4-5 molecules/nm(2). Thermal treatment of the ～1 nm chemisorbed films, at even extreme temperatures of ～150 °C, results in almost no anhydride formation via adjacent -CO(2)H condensation, in strong contrast to bulk PAA, a clear indication that the films have a frozen glass structure with effectively no segment and side group mobility. Overall, these results demonstrate that these limiting thickness nanometer films provide a model surface for understanding the behavior of strongly bound polymer chains at substrates and show potential as a path to creating highly stable, chemically functionalized inorganic substrates with highly variable surface properties.     

Hydrothermal treatment of nanoparticle thin films for enhanced mechanical durability

The mechanical durability of nanoporous all-nanoparticle and polymer-nanoparticle layer-by-layer (LbL) films (80-150 nm thick) on both glass and polycarbonate substrates has been greatly enhanced by hydrothermal treatment (124-134 degrees C). Polymer-nanoparticle films were more durable than all-nanoparticle films after hydrothermal treatment. The optical properties of nanoporous antireflection (AR) films were exploited in an abrasion test (25-100 kPa normal stress) to quantify the extent of abrasive wear observed qualitatively by scanning electron microscopy (SEM). Marginal damage was observed under optimal reinforcement conditions. Untreated films not only delaminated from the surface completely but also damaged their underlying glass and polycarbonate substrates during testing. The nature of the substrate was found to play an important role in determining abrasion resistance, regardless of the level of particle fusion in the film. The low-temperature process enables in situ mechanical reinforcement of otherwise delicate nanoparticle assemblies on plastic substrates. Tribochemical wear was found to planarize the nanoscale surface texture of these films, similar to what is observed in chemo-mechanical polishing (CMP). This finding is useful for anyone trying to make robust superhydrophobic or superhydrophilic coatings. To our knowledge, this is the first report on hydrothermal reinforcement of LbL films.     

液相电化学沉积法制备高氮含量CNx薄膜及性能的研究

采用液相电化学沉积法,以二氰二胺的丙酮溶液为沉积液,以镀有ITO(铟锡氧化膜)的导电玻璃为衬底制备了CNx薄膜.初步探讨了沉积温度和沉积电压对薄膜中氮含量的影响.通过XPS、FTIR光谱、SEM和US-Vis光谱对得到的CNx薄膜的化学结合状态、结构形貌和光学性质进行了表征,并用高电阻仪对薄膜的绝缘性进行了分析.XPS结果表明,CNx薄膜中碳氮主要以单键连接,sp3杂化的C—N键占85%.在IR光谱中,仅出现了C—N键和CN双键的吸收峰.SEM图谱显示CNx薄膜呈颗粒状,粒径平均为80nm左右.在水浴加热条件下沉积的CNx薄膜在200～300nm近紫外区为非线性吸收.薄膜的电阻率随氮含量的增加而增大,测量值在1012～1016Ω·cm之间.     

Aerosol assisted chemical vapour deposition of tungsten oxide films from polyoxotungstate precursors: active photocatalysts

Aerosol assisted chemical vapour deposition of polyoxotungstate precursors [n-Bu4N]2[W6O19] and [n-Bu4N]4H3[PW11O39] produces films of WO(3 - x) and WO3 on glass substrates; the WO3 films show significant photocatalytic decomposition of a test organic pollutant--stearic acid--when irradiated with either 254 or 365 nm radiation.     

不同银膜粒径对单壁碳纳米管SERS谱的影响

利用化学沉积法和溶胶法制备了粒径在20～100nm范围内不同的表面增强纳米结构活性银膜,系统地研究了单壁碳纳米管（SWCNT）的表面增强拉曼光谱（SERS）的G—band和D—band、比较玻璃和石英两种不同基片上的结果发现,单壁碳管的SERS谱随银膜粒径的变化有相同的变化趋势,G-band峰移对20～100nm范围内活性银膜粒径的差异不敏感,表明该波段所对应的碳管六元环本征振动比较稳定,与界面的化学相互作用较弱．D—band的峰形随基片和活性银膜粒径不同均有改变,且随着粒径变小,高频振动贡献有增大的趋势,表明无序碳与活性银膜间存在很强的相互作用。     

4-(2-(4′-吡啶)乙炔)苯基重氮盐的光化学反应动力学及其自组装单分子膜的表征

以4-(2-(4′-吡啶)乙炔)苯基芳香重氮盐为研究对象,在紫外光(250W,245nm)照射下,利用紫外-可见吸收光谱对该芳香重氮盐的乙腈溶液以及自组装单分子膜室温光解反应动力学进行了研究,确定了两种状态下的光解过程都符合一级反应动力学规律,并且溶剂极性使该重氮盐更容易发生光解反应.通过X射线光电子能谱(XPS)和电化学表征证实了4-(2-(4′-吡啶)乙炔)苯基芳香重氮盐经光解反应实现对石英片和氧化铟锡导电玻璃(ITO)表面的组装修饰,得到了通过共价键与基底联结的4-(2-(4′-吡啶)乙炔)苯自组装单分子膜,从而为其后基于有机-金属层层自组装技术构筑新型功能超薄膜奠定了基础.     

不含亲水基团的偶氮苯衍生物L-B膜的制备和性质研究

本文合成了具有一定结构特点的偶氮苯的衍生物, 以元素分析和^1HNMR鉴定了B产物的组成和结构。采用L-B技术制备了其多层L-B膜, 以紫外可见光谱研究了膜中分子的聚集状态和膜的纵向均匀性; 以偏振紫外确定了膜中分子偶氮基的取向; L-B膜的小角度X射线衍射结果表明膜具有层状有序的周期性结构。     

Photocatalytic TiO2 Coatings: Effect of Substrate and Template

Summary. Transparent TiO₂ films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles, higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template (i.e. Pluronic F127) to the sol.     

Photocatalytic TiO2 Coatings: Effect of Substrate and Template

Transparent TiO₂ films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles, higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template (i.e. Pluronic F127) to the sol.     

Ga2O3 and GaN nanocrystalline film: reverse micelle assisted solvothermal synthesis and characterization

Gallium oxide (beta-Ga2O3) nanoparticles were successfully deposited on quartz glass substrates using sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-hexane/ethylene glycol monomethyl ether (EGME) reverse micelle-mediated solvothermal process with different omega values. The mean diameter of Ga2O3 particles was approximately 2-3 nm and found to be approximately independent of omega values of the reverse micelles. However, when the Ga2O3 nanocrystalline films were nitrided at 900 degrees C under flowing NH3 atmosphere for 1 h, the mean diameter of the resulted gallium nitride (wurtzite-GaN) nanoparticles varied from 3-9 nm. Both nanocrystalline films of Ga2O3 and GaN were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy and photoluminescence in order to study their chemical and physical properties explicitly.     

Anti-Reflective Coatings of Flowerlike Alumina on Various Glass Substrates by the Sol–Gel Process with the Hot Water Treatment

Anti-reflective (AR) properties of flowerlike alumina thin films with a small roughness of less than 100 nm have been studied on substrates such as soda-lime silica glass, non-alkali glass, and quartz glass. The highest AR effects were obtained on quartz glass substrate, which has the lowest refractive index of the three substrates. The reflectance of quartz glass substrates coated with flowerlike Al₂O₃ was less than 0.5% in the wavelength region from 300 to 720 nm.     

Microstructure and performance of AZO thin films prepared by sol–gel processing

Al-doped zinc oxide (AZO) films were prepared by a wet-chemical coating technique, their microstructure and crystal growth were characterized as a function of the single layer thickness. When similar final thicknesses are attained by more multiple subsequent coating-firing cycles, film porosity is reduced from over 14 to 2 %. Simultaneously the AZO crystallite size is increased from approximately 23 to 60 nm, a preferential c-axis oriented growth is observed. Different substrates (soda-lime glass, soda-lime glass with a SiO₂ barrier coating, borosilicate glass and alkali-free display glass) were used and the resulting AZO films were compared. It is found that the substrate composition primarily affects grain growth and subsequently the electrical performance of the AZO films.     

长链香豆素LB膜对n-Si/Ni液结上的光致电荷转移的影响

本文研究了由硬脂酸香豆素制得的LB膜对n-Si/Ni电极性能的修饰作用.该LB膜沉积方式是Z型的,成膜之后吸收蓝移(由343nm移至325nm).在60mW·cm^-2溴钨灯光照下,n-Si/Ni/3LB/Fe(CN) /Pt电池的光电转换效率增大了一倍,稳定性亦有明显改善.交流阻抗测量表明,光照使n-Si/Ni/3LB电极的电解电阻大大减小,实验结果表明,硬脂酸香豆素LB膜对n-Si/Ni电极上的光致电荷传递过程的修饰作用是良好的.     

Bulk and interfacial glass transitions of water

Fast scanning calorimetry (FSC) was employed to investigate glass softening dynamics in bulk-like and ultrathin glassy water films. Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor-deposition approach was also used to grow multiple nanoscale (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 K below the onset of crystallization. However, no such transition was observed in bulk-like samples prior to their crystallization. These results indicate that thin-film water demonstrates glass softening dynamics that are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition, which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these findings for past studies of glass softening dynamics in various glassy water samples are discussed.     

Synchrotron light scattering on nanostructured V/Ce oxide films intercalated with Li+ ions

Vanadium oxide and new V/Ce oxide films on a glass substrate were obtained by the sol-gel process. The morphology of these nanostructured and porous films was studied by grazing-incidence small-angle X-ray scattering (GISAXS) at the ELETTRA synchrotron (Italy, Trieste). The aim of performing GISAXS was to study changes, which might occur in the grain sizes and the porosity of vanadium oxide and V/Ce oxide at 38 and 55 atom % of V, upon the intercalation of Li+ ions. The average grain radius obtained by GISAXS varied with the layer thickness and upon the intercalation of Li+ ions. The layer structure in V/Ce oxides was revealed by the grazing-incidence X-ray reflectivity (GIXR) method. The average grain radius , obtained by GISAXS, was correlated with the intercalation of Li+ ions. The specific surface area of these films was also determined and generally varied from 0.5 nm(-1) to 0.03 nm(-1).     

Columnar self-assembly and alignment of planar carbenium ions in Langmuir-Blodgett films

Structural and optical properties of multilayer Langmuir-Blodgett (LB) films of two amphiphilic carbenium salts 2-didecylamino-6,10-bis(dimethylamino)-4,8,12-trioxatriangulenium hexafluorophosphate (ATOTA-1) and 2,6-bis(decylmethylamino)-10-dimethylamino-4,8,12-trioxatriangulenium hexafluorophosphate (ATOTA-2) are described. The LB films were prepared on lipophilic glass by standard vertical dipping. Grazing incidence X-ray diffraction (GIXD) measurements show that the planar organic cores, in spite of their positive charge, form closely packed columns with a repeating distance of ～3.45 ?. Specular X-ray reflectivity (SXR) reveals the LB multilayers to consist of Y-type bilayers with thickness 31 ? for ATOTA-1 and 41 ? for ATOTA-2. This significant difference is ascribed to the different packing motifs of the alkyl chains in the two LB films. GIXD and polarized UV-vis absorption and emission spectroscopy show that the columnar aggregates in the LB films are oriented along the dipping direction. This alignment is attributed to shear effects during LB transfer. The main absorption band of the LB films is blue-shifted compared to that in solution, while the fluorescence is red-shifted by more than 100 nm. These findings suggest the presence of H-aggregates in agreement with the cofacial packing derived from the X-ray measurements. Polarized absorption spectroscopy with variable angle of incidence was used to resolve two perpendicular optical transitions in the visible range, one at 460 nm polarized perpendicular to the columnar direction, in the plane of the film, and one at 420 nm polarized along the film normal.