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The results of a study of the thermal expansion of thin silver films obtained by thermal vacuum evaporation are presented. It is shown that, after single heating, the films consist of two types of crystallites. The nanosized fraction, for which the main area of the film is accounted, is represented by crystallites with a size of 50–60 nm. In addition to them, separate grains of hundreds of nanometers in size are observed in the samples, many of which are formed during the condensation process. The coefficient of linear thermal expansion of nanocrystalline films which is only 7 × 10−6 K−1 is determined by electron diffraction using the method of measurement standard. This is significantly lower than the value which is typical for bulk samples. The decrease in the coefficient of thermal expansion is explained by the nanocrystalline nature of the films. The closeness of the obtained value to the coefficient of thermal expansion of silicon and germanium allows us to consider the use of nanocrystalline silver films as an effective way to improve the reliability and efficiency of modern and prospective microelectronics. [ABSTRACT FROM AUTHOR]

The impact of real sintering structures on the macroscopic stress state and yield locus of sintered silver was investigated and a novel continuum modelling approach that predicts the macroscopic properties in an accurate, simple and efficient way was derived. Focused-Ion-Beam (FIB) tomography was utilized to study silver films, which were sintered under a wide range of processing conditions. With reconstructed three-dimensional representative volume elements (RVE), linear elastic and linear elastic–perfect plastic Finite-Element-Analyses were performed for a variety of loading states. The stress state ratios and the plastic yielding were investigated with respect to the mesostructural quantities obtained from the FIB tomography. The specific pore surface area and the fractional density were found to represent characteristic scalar measures for the sintering structure, which were further used to formulate a thermodynamic consistent continuum model for the macroscopic stress state and yield locus. An assessment of the modelling approach showed good coincidence of the macroscopic stress state with experiments and simulations from literature and a 43 % better prediction accuracy for the yield locus compared to established modelling approaches. The transferability of the model parameters to different silver sintering raw materials was partially proved by literature results and promises reduced parameterization effort.

The ‘quantum engineering’ of creation of the new forms of matter grown on the surface of semiconductor crystals is reviewed. The growth mechanisms for metal films on the semiconductor substrates are analyzed. The effects of a semiconductor substrate of III–V group on the morphology of the silver-films’ growth are considered. An influence of temperature on the morphology of films is described. The stability conditions for a low-temperature growth of Ag films on the Si(001)2×1 and Si(111)7×7 surfaces are revealed. As concluded, the quantum effects play a crucial role in the design of atomically flat metallic silver layers on the series of single crystal planes.

In this study, indium-zinc oxide (IZO)/silver (Ag)/IZO (ZAZ) flexible transparent electrodes were prepared on polyethylene terephthalate substrate using radio frequency sputtering technique. Experimental results showed that when the Ag film transited from semi-continuous state to continuous state, the ZAZ electrode exhibited high optoelectronic performance. The best ZAZ sample had a quite wide range of high transmittance and an average transmittance of 78.9% in visible light region, and sheet resistance of 6. 5 4 Ω /sq and a Haacke Index of Φ vis = 1 4. 4 1 × 1 0 − 3 Ω − 1 . The bending test revealed that the R c (change in sheet resistance) of ZAZ electrodes after 1000 bends was still less than 25% while the electrical properties of IZO films deteriorated after only 100 bending tests. [ABSTRACT FROM AUTHOR]

Atomic diffusion bonding (ADB) of wafers at room temperature in air was studied using Ag films. Using an ultra-high vacuum magnetron sputtering system, Ag (20 nm) films with Ti (5 nm) underlayers were deposited. The propagation speed of crystal lattice rearrangement in the bonding process decreased with an increased exposure time of film surfaces to air (t exp). Propagation did not occur at t exp of 500 s. The cohesion of Ag film surfaces by film surface exposure to air and reduction of the Ag film surface energy by Ag oxide or sulfide formation probably cause ADB performance degradation. [ABSTRACT FROM AUTHOR]

Flexible and wearable strain sensors for human-computer interaction, health monitoring, and soft robotics have drawn widespread attention to promising applications in the next generation of artificial intelligence devices. However, conventional semiconductor sensors are difficult to meet the requirements of flexibility and stretchability. Here, we reported a kind of novel and simple sensor based on layer-by-layer (LBL) method. Carbon nanotubes (CNTs) layer provides high ductility and stability in the process of tension sensing, while silver layer provides low initial resistance and fast reflecting in the process of tension sensing. LBL method ensures the uniformity of the conductive layer. The sensor has superior sheet resistance of 9.44 Ω/sq., high elongation at break of 104%. For sensing capability, the sensor has wide reflecting range of 60%, high gauge factor (GF) of 1000 up to 60% strain, fast reflecting time of 165 ms. Excellent reliability and stability have also been verified. It is also worth mentioning that the entire process does not require any expensive equipments, complicated processes or harsh experimental conditions. The above features provide an idea for large-scale application of flexible stretchable sensors. [ABSTRACT FROM AUTHOR]

Different redispersate solutions of a silver–sorbitan monooleate nanocomposite in n-heptane with silver concentration of 8 × 10−5–1 × 10−3 M are used to obtain thin double-sided silver films on glass and quartz substrates. Photon correlation spectroscopy is used to show that the size of particles in solutions varies in the range of 9–90 nm. The films are characterized via atomic absorption, spectrophotometry, measuring angles of wetting, and scanning electron microscopy. The plasmon absorption of silver (λ = 402–440 nm) is confirmed for films obtained in (0.8–2) × 10−4 M solutions, and after subjecting all films to heat treatment at 200°C. [ABSTRACT FROM AUTHOR]

Uniform near-spherical nanoscale silver films (NSFs) as a very sensitive and stable SERS-active substrate were synthesized by a facile and efficient in situ liquid–solid–solid (LSS) reaction method without expensive equipment and harmful reagent assistance. In this method, the in situ formation and thermal decomposition reactions of the Ag–melamine coordination polymer (AgM CP) nanowires was utilized to control the morphology and microstructure of the NSFs. The sensing performances of the synthetic NSFs as SERS substrates were investigated by using R6G as a probe molecule. The research results showed that the prepared NSFs possessed a very low detection limit down to 10–13 M, a high analytical enhancement factor, and stable detection capabilities for the R6G molecule, which made them promising as cost-effective and high-performance SERS sensing platforms for trace molecular species detection. [ABSTRACT FROM AUTHOR]

Tethered bilayer lipid membranes (tBLMs) have been known as stable and versatile experimental platforms for protein–membrane interaction studies. In this work, the assembly of functional tBLMs on silver substrates and the effect of the molecular chain-length of backfiller molecules on their properties were investigated. The following backfillers 3-mercapto-1-propanol (3M1P), 4-mercapto-1-butanol (4M1B), 6-mercapto-1-hexanol (6M1H), and 9-mercapto-1-nonanol (9M1N) mixed with the molecular anchor WC14 (20-tetradecyloxy-3,6,9,12,15,18,22 heptaoxahexatricontane-1-thiol) were used to form self-assembled monolayers (SAMs) on silver, which influenced a fusion of multilamellar vesicles and the formation of tBLMs. Spectroscopic analysis by SERS and RAIRS has shown that by using different-length backfiller molecules, it is possible to control WC14 anchor molecules orientation on the surface. An introduction of increasingly longer surface backfillers in the mixed SAM may be related to the increasing SAMs molecular order and more vertical orientation of WC14 at both the hydrophilic ethylenoxide segment and the hydrophobic lipid bilayer anchoring alkane chains. Since no clustering of WC14 alkane chains, which is deleterious for tBLM integrity, was observed on dry samples, the suitability of mixed-component SAMs for subsequent tBLM formation was further interrogated by electrochemical impedance spectroscopy (EIS). EIS showed the arrangement of well-insulating tBLMs if 3M1P was used as a backfiller. An increase in the length of the backfiller led to increased defectiveness of tBLMs. Despite variable defectiveness, all tBLMs responded to the pore-forming cholesterol-dependent cytolysin, vaginolysin in a manner consistent with the functional reconstitution of the toxin into phospholipid bilayer. This experiment demonstrates the biological relevance of tBLMs assembled on silver surfaces and indicates their utility as biosensing elements for the detection of pore-forming toxins in liquid samples.

A facile and low-cost two components spray deposition technique has been developed to fabricate highly conductive silver films on carbon fiber fabrics (CFFs) surface for electromagnetic interference (EMI) shielding applications. Microstructures and components of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS), respectively. As measured by four-point probe instrument, silver maintains its unique conductivity as a film on CFFs surface. Additionally, the vector network analyzer (VNA) data illustrated that the incident electromagnetic waves were efficiently attenuated by the reflection on the surface of the network structure and then absorbed in the composites, which primarily integrates the high conductivity of silver film. Compared with the pristine CFFs, the EMI shielding effectiveness (SE) of Ag-coated CFFs with 100 spraying passes could reach to 80.82 dB. Therefore, it is expected that this work will open up a convenient and compatible strategy to exploiting fabrics materials with high-performance EMI shielding. Unlabelled Image • A simple and controllable two components spray deposition method was firstly used to synthesize silver films on CFFs. • The EMI shielding efficiency of CFFs with 100 spraying passes could reach to 99.999996% via spray deposition method. • The main EMI shielding mechanisms of Ag@CFFs materials have been studied in detail. • ased on metallized CFFs, the technique might be applied to fabricating Ag films on other fabrics surface for EMI shielding. [ABSTRACT FROM AUTHOR]

In this work, we characterize the oxidation and degradation of protected silver thin films through the Kirkendall effect. We then present a solution to reduce the degradation of silver films exposed to a reactive oxidizing environment. In particular, we study the growth of silver deposited by magnetron sputtering on glass substrates pre-coated with three different underlayers: SiO 2 , ZnO and a self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (MPTMS). The films are then covered with a 2-nm barrier titanium film and exposed to reactive oxygen plasma. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy reveal that the degradation process begins with the migration of silver through the top titanium barrier. We quantify the degradation by comparing the atomic content of silver present at the top of the degraded samples. We find that in the case of the ZnO and SiO 2 , a significantly higher amount of silver migrates through the top barrier and onto the surface, as compared to the MPTMS-treated surface. We attribute this difference to the chemisorption of silver atoms to the MPTMS layer. Unlabelled Image • Very thin Ti barriers protect Ag films in a reactive plasma environment. • Ag atoms migrate through the Ti barrier during prolonged O 2 plasma exposure. • Ag migration causes severe degradation of the film optoelectronic properties. • An MPTMS surface treatment prevents Ag migration through chemisorption. [ABSTRACT FROM AUTHOR]

Copyright of Progress in Physics of Metals / Uspehi Fiziki Metallov is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Irradiation induced creep (IIC) rates are measured in compression on Ag nanopillar (square) beams in the sink-limited regime. The IIC rate increases linearly with stress at lower stresses, i.e. below ≈2/3 the high temperature yield stress and parabolically with pillar width, L, for L less than ≈300 nm. The data are obtained by combining in situ transmission electron imaging with simultaneous ion irradiation, laser heating, and nanopillar compression. Results in the larger width regime are consistent with prior literature. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Through the years, nanosphere lithography (NSL) has attracted a growing interest because of its potential to manufacture a wide variety of homogeneous arrays of nanostructures. In this work, NSL was used for the fabrication of Surface-Enhanced Raman Spectroscopy (SERS) substrates. The proposed Raman-SERS substrates consist of 50 nm or 120 nm thick silver thin films evaporated over a monolayer of silica microspheres (AgFOSM) onto silicon or quartz substrates. The samples were tested as SERS substrates using Rhodamine 6G as analyte. As a comparison and to determine the Raman enhancement factor, not only the AgFOSM samples were measured, but also we studied similar samples obtained when the Ag film is directly deposited onto the silicon or quartz substrate. Our results show that the R6G Raman signal is always more intense by two or three orders of magnitude for the AgFOSM samples than for the Ag maskless ones. In the case of the 120 nm thick Ag films, the calculated enhancement factors for the AgFOSM samples are of the order of 10 4 for both silicon and quartz substrates. [ABSTRACT FROM AUTHOR]

Using ellipsometry, the film structure is characterized by optical indices n, k (visible region, 450 nm <  < 580 nm) and the thickness (15 < d < 35 nm). The optical indices change with the quantity of silver deposited, obtaining effective indices of 1.0 < n < 1.8 and 1.6 < k < 2.6 to the smaller deposits that belong to a volumetric fraction between 0.35 and 0.5 of silver in the air. An effective optical thickness film decrease is observed when the silver volumetric fraction increases, and a thickness increase with close indices to solid silver when the deposited silver increases. Optical and effective medium theory indices are compared.

Ultra-thin silver films were deposited by thermal evaporation, and the dielectric functions of samples were simulated using Drude-Lorentz oscillators. When s-polarized incident light from the BK7 glass into thin silver film at 45° angle using attenuated total reflection (ATR) mode, we experimental observed that the reflection reach a minimum of 1.87% at 520 nm for thickness of d~6.3 nm silver film, and it reach a minimum of 10.1% at 500 nm for thickness of d~4.1 nm. Moreover, we simulated the absorption changes with incident angles at 520 nm for both p-polarized (TM wave) and s-polarized (TE wave) light using transfer matrix theory, and calculated the electric field distributions. The absorption as a function of incident angles of TM wave and TE wave showed different characteristics under ATR mode, TE wave reached the maximum absorption around the critical angle θ ~41.1°, while TM wave reached the minimum absorption. [ABSTRACT FROM AUTHOR]

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avances en Ciencias e Ingeniería is the property of Avances en Ciencias e Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A simple approach for synthesis of palladium and silver nanostructures with readily adjustable morphologies was developed using galvanic electrochemical deposition, for application to surface-assisted laser desorption/ionization (SALDI) of small biological molecules. A range of fatty acids, triglycerides, carbohydrates, and antibiotics were investigated to assess the performance of the new materials. Intense analyte cations were generated from the galvanic surfaces upon UV laser irradiation such as potassium adducts for a film thickness <100 nm (originating from impurities of the electrolyte solution) and Pd and Ag cluster ions for films with a thickness >120 nm. Possible laser desorption/ionization mechanisms of these galvanic structures are discussed. The films exhibited self-organizing abilities and adjustable morphologies by changing electrochemical parameters. They did not require any stabilizing agents and were inexpensive and very easy to produce. SALDI analysis showed that the materials were stable under ambient conditions and analytical results with excellent measurement reproducibility and detection sensitivity similar to MALDI were obtained. Finally, we applied the galvanic surfaces to fast screening of natural oils with minimum sample preparation. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A mono-6-thio-β-cyclodextrin-modified silver film was synthesized via galvanic displacement on copper foil. The prepared silver films could enrich non-polar polychlorinated biphenyls (PCBs) molecules from hydrophilic phase using thiolate β-cyclodextrins (SH-β-CDs) as receptors. The components of as-prepared Ag-coated-Cu (Ag–Cu) film were confirmed by powder X-ray diffraction (XRD). Both surface-enhanced Raman spectroscopy (SERS) and energy dispersive X-ray spectroscopy (EDS) measurements gave strong evidences that the thiolated β-cyclodextrins (SH-β-CDs) had been immobilized on the surface of silver film. Compared to the substrates prepared in the absence of SH-β-CD, the surface morphology of the CD-modified Ag films was obviously changed. The interfacial enrichment and the capability of substrates to form inclusion complexes with PCBs molecules were tested by using PCB-15 (4,4′-dichlorobiphenyl) as the probe molecules via SERS technique. The measured SERS spectra could distinguish the PCB-15 molecules at micro-molar level according to the most intense CCC bending in-plane mode of PCBs. The enhancement factor (EF) of the SERS substrates for PCB-15 was 1.2×105, which was comparable with a number of previous reports. [Copyright &y& Elsevier]

We report the use of surface plasmon-coupled emission (SPCE) as an analytical tool to study the photophysics of surface-adsorbed fluorescently labeled proteins. The study uses plasma etching of PMMA surface followed by deposition of poly(diallyldimethylammonium chloride) (PDDA) for surface protein detection. PDDA increases the overall amount of the captured protein and also promotes dye aggregation. The photon-sorting properties of the SPCE process allows for wavelength separation of the individual components from the protein-dye aggregates. This has been exploited to study the fluorescence emissions from casein labeled with fluorescein isothiocyanate and concanavalin A labeled with tetramethylrhodamine. Based on the current findings, the proteins can be used to measure background fluorescence or to monitor the microenvironments in fluoroimmunoassays on SPCE substrates. [ABSTRACT FROM AUTHOR]

Metal-enhanced fluorescence (MEF) from lanthanide chelates in close proximity to silver films was studied. Different thicknesses of silver films (20 and 50 nm) were deposited onto quartz substrates using magnetron sputtering, while silver island films were prepared using a previously published procedure. Obviously enhanced emissions from the lanthanide chelates were observed on the silver films. The effect of using different concentrations of aqueous solutions polyvinyl alcohol (PVA) on MEF was also investigated. Fluorescence close to a 20-nm-thick silver film showed that the enhancement of emission is a function of the thickness of the PVA film, reaching a maximum (~2.5-fold increase in intensity) at 83 nm. In conclusion, the MEF induced by the silver films is caused by an electric field effect arising from surface plasmon resonance. [ABSTRACT FROM AUTHOR]

We report the deposition of highly uniform thin silver films on plastic materials using a wet-chemistry method, suitable for surface plasmon-coupled emission (SPCE). This approach is reproducible for diverse low-cost applications and versatile to generate silver surfaces on various plastics substrates. An oxygen plasma pretreatment of the plastic provides for rapid silvering, leading to a 47-nm-thick continuous film for SPCE applications. The surface smoothness and thickness of the films have been estimated using atomic force microscope. The higher refractive index of polycarbonate, resulted in an SPCE angle of θ F = 470 for Rhodamine B, compared to glass ( θ F = 500). The current study presents details on film deposition conditions, appropriate choice of index matching fluids, substrates, and light sources that play a vital role to augment SPCE emission intensity. [ABSTRACT FROM AUTHOR]

Abstract: Growth of silver films was studied by supercritical fluid deposition (SCFD) using H2 and acetone as reducing agents for (1,5-cyclooctadiene)(hexafluoroacetylacetonato)silver(I) in supercritical CO2 (scCO2). H2 reduction did not yield continuous Ag films, whereas continuous films were deposited on Ru substrates by acetone-assisted reduction of 0.006–0.03mol% precursor in the temperature range of 150–250°C. Surface qualities of the Ag films were effectively improved by decreasing water content in acetone reagent, as well as reducing acetone and precursor concentrations in scCO2. Ultimately, a 50nm-thick film with shiny surface was obtained in optimized conditions. A possible mechanism for acetone reduction of Ag precursor on Ru surface was also proposed. [Copyright &y& Elsevier]

Abstract: In this work thin silver (Ag) films are grown employing high power pulsed magnetron sputtering (HPPMS) for various pulse on/off time configurations, as well as by dc magnetron sputtering (dcMS), for reference. It is shown that the increase of the pulse off-time from 450 μs to 3450 μs, while the pulse on-time is kept constant at 50 μs, results in an increase of the peak target current (I Tp) from 3 A to 22 A. The increase of I Tp is accompanied by an increase of the ion flux towards the growing film. This is particularly pronounced for I Tp >11 A. The microstructure, the surface topography and the electrical properties of Ag films grown at I Tp =11 A, I Tp =22 A and by dcMS are investigated, as a function of the film thickness d. It is shown that for d >20 nm the electrical resistivity of films sputtered at I Tp =22 A is similar to that of films grown by dcMS. Slightly higher values are measured for films grown at I Tp =11 A. It is found that in this thickness range the film conductivity is strongly affected by the vertical grain size and the scattering of the charged carriers at the film interfaces. For d <15 nm the resistivity of films deposited at I Tp =22 A is substantially lower as compared to that of films grown by dcMS. Films deposited at I Tp =11 A exhibit also in this case a higher conductivity. In this thickness regime the electronic transport and, thus the conductivity are profoundly determined by the surface topography and the film density. [Copyright &y& Elsevier]

Silver fluorocarboxylate tertiary phosphine complexes [Ag(O2CR)(PR'3)] (where R = CF3, C2F5, Me3SiCH2; R' = Me, Et) have been used as precursors in the hot-wall Chemical Vapour Deposition (CVD) of silver films. The pyrolysis of Ag(I) compounds and the thermal stability of metallic species transported in the gas phase were characterized by temperature variable IR (VT-IR) and MS (MS-EI) methods. Metallic films were produced between 403 and 423 K under the deposition pressure of 0.8-2.0 mbar, under an Ar atmosphere and on Si(111) substrates. They were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) integrated with EDX equipment. [ABSTRACT FROM AUTHOR]

Using giant Raman scattering spectroscopy methods, we have studied the structure and also the thermo and phototransformations of dimethylphthalanspirobenzopyran (PhSBP) adsorbed on the surface of silver films. It is shown that on adsorption of PhSBP from ethanol solutions, on the surface of the silver films there are predominantly open forms of molecules which do not exhibit photochromic properties. It is established that cooling of the specimen to 77 K initiates thermoreversible reconstruction of the adsorption layer with formation of the aggregates of the PhSBP molecules. These reversible structural changes in frozen specimens are enhanced on exposure to the light of a visible range. [ABSTRACT FROM AUTHOR]

Silver thin films (1–10 nm thick) were deposited on titanium by magnetron sputtering. We study the effect of the current (20–65 mA) and the argon pressure (5–20 mtorr) on the films morphology. Their structure is characterized by electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). The ESCA data are analysed by means of the quases™ code. The data are fitted by means of a model in which the surface is assumed to be composed of two kinds of features: islands and a thin layer. It is shown that the islands coverage coefficient may attain 95%. The films are also characterized by AFM. It appears that the surface roughness is important, due to the roughness of the initial Ti film. A comparison of the AFM and quases™ results shows that the structure is such that clusters of Ti are covered by a thin layer of Ag. The space between Ti clusters is filled with clusters of Ag. The coverage and the thickness of the films depend on the deposition rate and the total argon pressure. [Copyright &y& Elsevier]

Tethered bilayer lipid membranes (tBLMs) have been known as stable and versatile experimental platforms for protein–membrane interaction studies. In this work, the assembly of functional tBLMs on silver substrates and the effect of the molecular chain-length of backfiller molecules on their properties were investigated. The following backfillers 3-mercapto-1-propanol (3M1P), 4-mercapto-1-butanol (4M1B), 6-mercapto-1-hexanol (6M1H), and 9-mercapto-1-nonanol (9M1N) mixed with the molecular anchor WC14 (20-tetradecyloxy-3,6,9,12,15,18,22 heptaoxahexatricontane-1-thiol) were used to form self-assembled monolayers (SAMs) on silver, which influenced a fusion of multilamellar vesicles and the formation of tBLMs. Spectroscopic analysis by SERS and RAIRS has shown that by using different-length backfiller molecules, it is possible to control WC14 anchor molecules orientation on the surface. An introduction of increasingly longer surface backfillers in the mixed SAM may be related to the increasing SAMs molecular order and more vertical orientation of WC14 at both the hydrophilic ethylenoxide segment and the hydrophobic lipid bilayer anchoring alkane chains. Since no clustering of WC14 alkane chains, which is deleterious for tBLM integrity, was observed on dry samples, the suitability of mixed-component SAMs for subsequent tBLM formation was further interrogated by electrochemical impedance spectroscopy (EIS). EIS showed the arrangement of well-insulating tBLMs if 3M1P was used as a backfiller. An increase in the length of the backfiller led to increased defectiveness of tBLMs. Despite variable defectiveness, all tBLMs responded to the pore-forming cholesterol-dependent cytolysin, vaginolysin in a manner consistent with the functional reconstitution of the toxin into phospholipid bilayer. This experiment demonstrates the biological relevance of tBLMs assembled on silver surfaces and indicates their utility as biosensing elements for the detection of pore-forming toxins in liquid samples. [ABSTRACT FROM AUTHOR]

In this work, the assembly of functional tethered bilayer membranes (tBLMs) on silver surface was demonstrated for the first time. To avoid degradation of thin silver films the non-corrosive mixture of thiols composed of WC14 molecular anchor and 3-mercapto-1-propanol (3M1P) serving as a backfiller was used to self-assemble monolayers which allowed fusion of multilamellar vesicles and tBLM formation. tBLMs on silver films exhibited high stability and low residual defect densities as measured by the electrochemical impedance spectroscopy (EIS). Silver supported tBLMs demonstrated all features typical for interactions of pore-forming proteins and bilayer membranes. Specifically, the EIS spectral response was typical for the formation of water filled defects when tBLMs were exposed to the solution of vaginolysin (VLY), the cholesterol dependent cytolysin. Increase of defect density was observed only in case tBLMs contained significant amount, e.g., 50 %, of cholesterol, thus confirming functional reconstitution of vaginolysin into tBLMs. This observation is consistent with the biological nature of interaction between the bilayer and the cholesterol dependent cytolysins. The reconstitution of VLY was confirmed by the direct imaging of the protein entities in tBLMs by the atomic force microscopy (AFM). Notably, the quantitative estimate of the functional protein-pores in tBLMs measured by EIS, was found to be close to the number of VLY entities in tBLMs measured by the AFM. Our work demonstrates that silver can serve as less expensive alternative to gold in designing tBLM based devices, for example phospholipid biosensors, as well as the experimental platform for studying membrane protein interactions by electrochemical, and microscopy techniques. [ABSTRACT FROM AUTHOR]

Increased microorganisms resistance to drugs is currently a challenging problem as more powerful drugs are necessary for successful treatments. Current research is investigating for the first time reinforced bactericidal effects in wastewater resulted by simultaneous use of metallic thin films deposited on water filter papers combined with electrical power directly applied to the coated structures. Silver and copper were deposited at room temperature onto water filter papers by using high vacuum magnetron sputtering system. The metallic coated structures efficiently eliminated common types of wastewater bacteria (e.g. Escherichia coli and other coliforms). The antibacterial effects were reinforced by using electrical power applied to the structures. Increasing the electricity levels resulted in stronger bactericidal effects and subsequently shorter exposure times were required to reduce bacteria from contaminated water. Thin films adherence to filter fibers and the morphology of the coated structures were examined using digital optical microscopy and Scanning Electron Microscopy (SEM). The method used for assessing antibacterial performance was the standardized membrane filtering technique for wastewater examination. Water was collected from local basins and the bacterial content was monitored before and after exposure to uncoated, silver and copper coated filter fibers, and electrically activated metallic coated filter fibers. The metallic thin films were retained on the fibers surface after water treatment consequently reducing the nanoparticles release to the surroundings. [ABSTRACT FROM AUTHOR]