Bioinspired Synthesis of Lepidocrocite‐Containing Material and Its Catalytic Behaviour in CO Oxidation

Leptothrix sp. was cultivated in Lieske 's medium in the presence of Al foil covered by anodic Alumina . Samples of biomass deposited on lamellae were studied by the methods of infrared, Mössbauer , and X‐ray photoelectron spectroscopy. Sole deposition of γ‐FeOOH on the lamellae was found to take place. This result is explained by the influence of γ‐AlOOH ingredient in the used support due to crystal structure similarity. Thus, iron oxyhydroxide crystallisation could be directed during bacteria cultivation. The catalytic activity of deposited γ‐FeOOH was examined in CO oxidation.     

Disposable Amperometric A-fetoprotein Immunosensor Based on the Biocompatible Silk Protein Membranes-Modified Indium Tin Oxide Electrodes

A simple and disposable electrochemical immunosensor for detection of 68 kDa alpha-fetoprotein (AFP) was fabricated based on films of silk fibroin protein membrane (SFPM)/Prussian blue (PB)/deposition of gold nanoparticles (DpAu). First, DpAu and PB were electrochemically deposited successively on the surface of indium tin oxide (ITO) electrode. Then, SFPM with excellent biocompatibility was modified on the surface of PB/DpAu/ITO. The SFPM could form a stable matrix on the electrode surface for the deposition of immunoactive agents. More importantly, the SFPM could prevent the possible leakage of electron mediator and enhance the stability of immunosensor. Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the assembly process of the modified electrode. The linear range of the proposed immunosensor extended from 1.0 to 200.0 ng/mL for detection of AFP with a detection limit of 0.6 ng/mL. Moreover, the CV test demonstrated the immunosensor exhibited acceptable reproducibility and stability. This composite membrane could be applied for the detection of different biomarkers, diagnosis, and monitoring of carcinoma.

[Supplementary materials are available for this article. Go to the publisher's online edition of Analytical Letters for the following free supplemental resources: additional figures.]     

Atomic Layer Deposition of Cobalt Phosphide for Efficient Water Splitting

Transition‐metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co‐P films were deposited by using PH₃ plasma as the phosphorus source and an extra H₂ plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self‐limited layer‐by‐layer growth, and the deposited Co‐P films were highly pure and smooth. The Co‐P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co‐P films prepared by the traditional post‐phosphorization method. Moreover, the deposition of ultrathin Co‐P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three‐dimensional (3D) architectures.     

Surfaces Coated with Polymer Brushes Work as Carriers for Histidine Ammonia Lyase

The immobilization of enzymes on solid supports is an important challenge in biotechnology and biomedicine. In contrast to other methods, enzyme deposition in polymer brushes offers the benefit of high protein loading that preserves enzymatic activity in part due to the hydrated 3D environment that is available within the brush structure. The authors equipped planar and colloidal silica surfaces with poly(2-(diethylamino)ethyl methacrylate)-based brushes to immobilize Thermoplasma acidophilum histidine ammonia lyase, and analyzed the amount and activity of the immobilized enzyme. The poly(2-(diethylamino)ethyl methacrylate) brushes are attached to the solid silica supports either via a “grafting-to” or a “grafting-from” method. It is found that the grafting-from method results in higher amounts of deposited polymer and, consequently, higher amounts of Thermoplasma acidophilum histidine ammonia lyase. All polymer brush-modified surfaces show preserved catalytic activity of the deposited Thermoplasma acidophilum histidine ammonia lyase. However, immobilizing the enzyme in polymer brushes using the grafting-from method resulted in twice the enzymatic activity from the grafting-to approach, illustrating a successful enzyme deposition on a solid support.     

Bioanalysis by Immobilization of Antibodies on Hafnium(IV) Oxide with 3-Aminopropyltriethoxysilane

Self-assembled monolayers of 3-aminopropyltriethoxysilane (APTES) are commonly used to promote adhesion between substrates and organic or metallic materials with applications ranging from advanced composites to biomolecular lab-on-a-chip devices. In this work, the silanization on hafnium oxide (HfO₂) films is reported. The layers of HfO₂ were deposited on Si (001) substrates by atomic layer deposition. The grown HfO₂ films were modified in accordance with three main steps: oxidation, silanization, and cross-linking of the APTES monolayer using glutaraldehyde as cross-linking agent. Microscopic features were characterized by atomic force microscopy. Further, both bovine serum albumin and antibovine serum albumin agents were deposited on the samples to test their potential use as the immunosensor.     

Surface Characterization and Antimicrobial Activity of Chitosan-Deposited DBD Plasma-Modified Woven PET Surface

In this work, a woven PET with an antimicrobial activity was prepared by depositing chitosan on its surface. Firstly, the hydrophilic property of the PET surface was achieved by a plasma treatment using dielectric barrier discharge (DBD). The hydrophilic property of the PET surface was characterized by wickability and contact angle measurements. The XPS analysis revealed an increment of oxygen-containing polar groups, such as C–O and O–C=O, on the PET surface after the plasma treatment, resulting in an enhanced hydrophilic property. The plasma-treated PET specimen was further deposited with chitosan by immersing in a chitosan acetate aqueous solution. The effects of temperature, chitosan concentration, and number of rinses on the amount of deposited chitosan on the PET surface were investigated. The disappearance of the above-mentioned polar groups from the PET surface was clearly observed after the chitosan deposition, indicating the involvement of these functional groups in interacting with the chitosan. The chitosan-deposited plasma-treated woven PET possessed an exceptionally high antimicrobial activity against both E. coli (gram-negative bacteria) and S. aureus (gram-positive bacteria).     

Study of the first nucleation steps of thin films by XPS inelastic peak shape analysis

The initial steps in the formation of thin films have been investigated by analysis of the peak shape (both inelastic background and elastic contributions) of X‐ray photoelectron spectra. Surface coverage and averaged height of the deposited particles have been estimated for several overlayers (nanometre range) after successive deposition cycles. This study has permitted the assessment of the type of nucleation and growth mechanisms of the films. The experiments have been carried out in situ in the preparation chamber of an XPS spectrometer. To check the performance of the method, several materials (i.e. cerium oxide, vanadium oxide and cadmium sulfide) have been deposited on different substrates using a variety of preparation procedures (i.e. thermal evaporation, ion beam assisted deposition and plasma enhanced chemical vapour deposition). It is shown that the first deposited nuclei of the films are usually formed by three‐dimensional particles whose heights and degree of surface coverage depend on the chemical characteristics of the growing thin film and substrate materials, as well as the deposition procedure. It is concluded that XPS peak shape analysis can be satisfactorily used as a general method to characterize morphologically the first nanometric moieties that nucleate a thin film. Copyright © 2006 John Wiley & Sons, Ltd.     

Investigation of ruthenium deposition onto a platinized platinum electrode in sulfuric acid media

Ruthenium deposition onto platinized Pt electrode in 0.5 M H₂SO₄ solution is investigated. The I–V profiles of the Pt electrode covered with Ru depend on the potential of Ru deposition. This phenomenon is explained by the increasing degree of oxidation of the Ru layers deposited at higher potentials. Oxidation of Ru deposited at low potentials begins with comparatively slow processes. A mechanism for Ru deposition via ionization of hydrogen adsorbed on platinized Pt electrode is proposed.     

Enhanced Visible‐Light‐Induced Photoelectrocatalytic Degradation of Methyl Orange by CdS Sensitized TiO2 Nanotube Arrays Electrode

In this work, CdS sensitized TiO₂ nanotube arrays (CdS/TiO₂NTs) electrode was synthesized with the CdS deposition on the highly ordered titanium dioxide nanotube arrays (TiO₂NTs) by sequential chemical bath deposition method (S‐CBD). The as‐prepared CdS/TiO₂NTs was characterized by field‐emission scanning electron microscopy (FE‐SEM) and X‐ray diffraction (XRD). The results indicated that the CdS nanoparticles were effectively deposited on the surface of TiO₂NTs. The amperometric I‐t curve on the CdS/TiO₂NTs electrode was also presented. It was found that the photocurrent density was enhanced significantly from 0.5 to 1.85 mA/cm² upon illumination with applied potential of 0.5 V at the central wavelength of 253.7 nm. The photoelectrocatalytic (PEC) activity of the CdS/TiO₂NTs electrode was investigated by degradation of methyl orange (MO) in aqueous solution. Compared with TiO₂NTs electrode, the degradation efficiencies of CdS/TiO₂NTs electrode increased from 78% to 99.2% under UV light in 2 h, and from 14% to 99.2% under visible light in 3 h, which was caused by effective separation of the electrons and holes due to the effect of CdS, hence inhibiting the recombination of electron/hole pairs of TiO₂NTs.     

Preparation of Ba(Ti,Sn)O<Subscript>3</Subscript> thin films by PVP-assisted sol–gel method and their dielectric properties

Ba(Ti_1−x Sn _x )O₃ (x = 0.10 or 0.15) thin films were deposited on Si(100) and Pt(111)/TiO _x /SiO₂/Si(100) substrates via sol–gel spin-coating. Crack-free thin films could be obtained by single-step deposition, where the thickness was about 0.46 and 0.29 μm at 1000 and 2000 rpm, respectively. Circular delaminated parts 100 μm in diameter, however, tended to appear in thicker films deposited at 1000 rpm. On both kinds of substrates, the films were crystallized between 500 and 600 °C, where the perovskite phase emerged as the primary phase, and the formation of single-phase perovskite was basically achieved between 700–800 °C. The films deposited on Pt(111)/TiO _x /SiO₂/Si(100) substrates, however, tended to have small SnO₂ and BaCO₃ diffraction peaks, which decreased with increasing spinning rate. The dielectric properties were evaluated on the films deposited on Pt(111)/TiO _x /SiO₂/Si(100) substrates at 2000 rpm. The films prepared by single-step depositions had dielectric constants of 350 and 230, and dielectric loss of 0.30 and 0.10 at x = 0.1 and 0.15, respectively. The films prepared by two time deposition had dielectric constants of 450 and 250, and dielectric loss of 0.21 and 0.19 at x = 0.10 and 0.15, respectively.     

In situ ATR-FTIR and SFM Studies on the Influence of Adsorption time on Deposition and Nanostructure of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers

Summary: The deposition and the nanostructure of polyelectrolyte multilayers (PEM) of branched poly(ethyleneimine)/poly(acrylic acid) (PEI/PAC) was studied in dependence of the adsorption time (t_ADS) of the individual steps. PEM were reproducibly deposited applying up to z = 20 adsorption steps at the fixed pH combination of 10/4 and polyelectrolyte concentration c_PEL = 0.005 M in a flow cell using an automated valve system. in situ ATR-FTIR spectroscopy and SFM were used for quantitative determination of deposited amount and thickness, respectively. A linear relation between PEL band integrals and thickness of thin PEM films was found. Varying t_ADS from 0.5 to 5 min in each of the adsorption steps resulted in a steep rise of the deposited PEM amount. For t_ADS > 5 min the deposition did only marginally increase. Evidence for the release of outermost located PEI upon PAC immersion (even step) and of outermost PAC upon PEI immersion (odd step) was obtained. SFM images on consecutively deposited PEM-6 showed a slight increase in structure size and roughness for increasing t_ADS. These studies help to prepare polyelectrolyte based films with controlled thickness for the interaction with biofluids in the biomedical and food field.     

Surface characterization of the SiOx films prepared by a remote atmospheric pressure plasma jet

The deposition rate and surface properties of SiO_x films were prepared and investigated using remote atmospheric pressure plasma (APP) jet. The APP, generated with low frequency power at 16 kHz, was fed with tetraethoxysilane (TEOS)/air gas mixture. After deposition, the SiO_x films were analyzed for chemical characteristics, elemental composition, surface morphology, and hardness. It was found that the deposition substrate temperature is the key factor to affect the deposition rate of remote APP chemical vapor deposition process. Fourier transform infrared (FTIR) spectra indicated that APP deposited SiO_x films are an inorganic feature. XPS examination revealed that the SiO_x films contained approximately 30% silicon, 58% oxygen and 12% carbon. Atomic forced microscopy (AFM) analysis results indicated a smooth surface of SiO_x films in deposition under higher substrate temperature. Also, pencil hardness tests indicated that the hardness of APP deposited SiO_x films was greatly improved with increasing substrate temperatures. Copyright © 2008 John Wiley & Sons, Ltd.     

Study on the behavior of129I in the terrestrial environment

Transfer parameters for dose assessment such as deposition velocity (V _g), fraction of directly deposited on plants to the edible parts (r) and transfer factors (B _iv) have been evaluated. Deposition velocity under drying and wet conditions was evaluated about 0.8 cm/s. Fraction of directly deposited on plants and transfer factors in plants showed a lognormal distribution. Geometric means of fraction of deposited in rice, leafy vegetable and grass were <9·10^–3, 0.2 and about 9·10^–2, respectively. Geometric mean of the transfer factor in leafy vegetable was about 3·10^–2. These results were compared with the parameters given in the US NRC Regulatory Guide and previous literature values. The results showed that the fraction of directly deposited on plants were smaller than the recommended value in the NRC Regulatory Guide. They also showed that the deposition velocity and transfer factors were almost similar to the results reported in the literature.     

Antibacterial properties of polyaniline-silver films

In situ polymerised thin polyaniline (PANI) films produced on polystyrene dishes were tested for their antibacterial activity with respect to Escherichia coli and Staphylococcus aureus, representing both gram-positive and gram-negative bacteria. PANI films were subsequently used for the reduction of silver ions to metallic Ag. PANI salt and base in original forms and after the deposition of Ag were studied. PANI salt showed a significant antibacterial effect against both bacteria strains while the efficacy of neat PANI base was only marginal. After the Ag deposition, the PANI base exhibited different levels of antibacterial effect depending on the type of the bacterial strain; the growth of gram-positive Staphylococcus aureus was inhibited depending on the Ag concentration on the film, while Escherichia coli remained uninfluenced. Efficacy of the PANI salt with deposited Ag against both bacteria strains was comparable with that of PANI alone and was not affected by the Ag concentration. The results show that Ag deposition can be a suitable method for the preparation of PANI base films with improved antibacterial properties.     

Characterization of the interfacial structure and perpendicular magnetic anisotropy in CoFeB‐MgO structures with different buffer layers

In this study, we describe the deposition of Hf and Mo metal layers individually on Ta to compose new buffer layers, ie, Ta/Hf and Ta/Mo, where CoFeB/MgO stacks are deposited using magnetron sputtering. The synthesised Ta/Hf buffer has higher surface roughness, while the Ta/Mo buffer has lower surface roughness as compared with the Ta buffer. The surface roughness of the buffer appears to influence the interface of the subsequently deposited layers, resulting in rougher or smoother CoFeB/MgO interfaces. Additionally, we present a report on the magnetic properties of Ta, Ta/Hf, and Ta/Mo buffer samples. As the annealing temperature is below 200 °C, the saturation magnetisation (Ms) values for all buffer layers increase at similar rates, whereas the effective magnetic anisotropy energy (K_eff) values increase at varying rates. After annealing at 350 °C, K_eff reaches its maximum value for Ta/Hf and Ta/Mo buffer layers, whereas the CoFeB/MgO interface width decreases to a minimum value. The width increases as the annealing temperature is increased over 350 °C, and K_eff gradually decreases with increase in the annealing temperature. The CoFeB/MgO interface width is primarily dependent on the buffer/CoFeB interface width, which is a critical parameter to obtain high perpendicular magnetic anisotropy (PMA) and high‐quality films. This work provides perspectives for understanding and controlling PMA from the viewpoint of interfacial structure.     

Photo-Induced Hydrophilicity of TiO<Subscript>2</Subscript> Films Deposited on Stainless Steel via Sol-Gel Technique

The photo-induced hydrophilicity of TiO₂ films deposited on stainless steel substrates and silicon wafers using two different sol-gel routes has been investigated. The results indicate that crystalline titanium oxide films with excellent hydrophilic properties can be obtained on silicon wafer with both routes. XPS and XRD data reveal that films deposited on stainless steel exhibit crystallization features similar to those of films deposited on silicon wafers, and only differ by their oxidation degree owing to a TiO₂ reduction process associated to a diffusion of iron ions during deposition of the acidic sol and/or high temperature post-treatment. Consequently, hydrophilic properties of films deposited on stainless steel are inhibited. The deposition of a SiO_x barrier layer at the film/substrate interface allows preventing such a detrimental substrate influence. A low temperature deposition route of the TiO₂ film associated to the presence of a barrier layer yields best results in preventing iron contamination of the films.     

Direct biosensor coating with a photopolymerised microlayer through a controllable step-procedure

Biosensors are based on the intimate association of a transducer and of a sensing layer. The latter can be a preformed membrane further connected to the transducer, or a thin film directly deposited on its surface. As the stability is a key parameter to be considered, a polymer with high potentialities for this purpose was chosen to form a direct surface coating: a poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ). Choline oxidase was entrapped in this photo-cross-linkable gel for making an enzyme electrode through controllable steps. The influence of the ratio PVA-SbQ/enzyme was studied and the stability of the resulting modified electrodes was determined. After deposition of minute volumes (10–45 l) including no more than one unit of choline oxidase and 0.3 mg of polymer, an efficient choline sensor was obtained. It exhibited a fast response time lower than 30 s, a low detection limit of 2.5 nM choline, a wide linear range extending up toca. 10^–4 M and good stability, both operational and on storage. This method appears promising for making miniaturized biosensors.     

Deposition of SiO2-Like Films by HMDSN/O2 Plasmas at Low Pressure in a MMP-DECR Reactor

The effects of process parameters such as O₂/HMDSN (hexamethyldisilazane) ratio, microwave discharge power and deposition pressure on the growth rate, chemical bonding nature, and refractive index of thin films deposited by microwave plasma from HMDSN with oxygen, have been investigated. The plasma was created in a Microwave Multipolar reactor excited by Distributed Electron Cyclotron Resonance. The films were deposited at room temperature and characterized by Fourier Transform Infrared spectroscopy and ellipsometry. Growth rate increased with the discharge power P or the deposition pressure but decreased significantly with increasing O₂/HMDSN ratio. A large change in the film composition was observed when the O₂/HMDSN ratio was varied: films deposited with only HMDSN precursor are polymer-like but as the O₂/HMDSN ratio increased, organic groups decreased. For relative pressure values over 70%, deposited films are SiO₂-like with refractive index values close to those found for thermal silicon dioxide.     

Fabrication of convex-shaped polybenzylsilsesquioxane micropatterns by the electrophoretic sol–gel deposition process using indium tin oxide substrates with a hydrophobic-hydrophilic-patterned surface

Polybenzylsilsesquioxane (BnSiO_3/2) particles become a supercooled liquid through a heat treatment above the glass transition temperature (T _g) of the particles. Micropatterns of BnSiO_3/2 thick films with high transparency were obtained by the electrophoretic deposition of the BnSiO_3/2 particles on indium tin oxide (ITO)-coated substrates with a hydrophobic-hydrophilic-patterned surface and subsequent heating above T _g of the particles. It was found that the control of electrophoretic deposition conditions, in which the amounts of the particles deposited on the substrates were changed, led to two types of micropatterning processes of the BnSiO_3/2 thick films. In the first process, the particles were selectively deposited on the hydrophilic areas after the electrophoretic deposition. In the second process, the particles were deposited on the whole area of the ITO-coated substrate with hydrophobic-hydrophilic patterns after the electrophoretic deposition. Due to the difference in wettability of BnSiO_3/2 molten liquids between hydrophobic and hydrophilic surfaces, the molten liquids on the hydrophobic areas, which were obtained by heating above T _g of the particles, migrated toward the hydrophilic areas. In both the processes, convex-shaped BnSiO_3/2 micropatterns with high transparency were fabricated only on the hydrophilic areas after a heat treatment above T _g of the particles.     

Ag活化的p型硅(111)表面化学镀Ag膜表面形貌研究

A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3＋NH3＋acetic acid＋NH2NH2 （pH 10.2）. The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film.