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Sample records for adsorbed protein films

  1. Influence of fluoride-detergent combinations on the visco-elasticity of adsorbed salivary protein films.

    PubMed

    Veeregowda, Deepak H; van der Mei, Henny C; Busscher, Henk J; Sharma, Prashant K

    2011-02-01

    The visco-elasticity of salivary-protein films is related to mouthfeel, lubrication, biofilm formation, and protection against erosion and is influenced by the adsorption of toothpaste components. The thickness and the visco-elasticity of hydrated films (determined using a quartz crystal microbalance) of 2-h-old in vitro-adsorbed salivary-protein films were 43.5 nm and 9.4 MHz, respectively, whereas the dehydrated thickness, measured using X-ray photoelectron spectroscopy, was 2.4 nm. Treatment with toothpaste slurries decreased the thickness of the film, depending on the fluoride-detergent combination involved. Secondary exposure to saliva resulted in a regained thickness of the film to a level similar to its original thickness; however, no association was found between the thickness of hydrated and dehydrated films, indicating differences in film structure. Treatment with stannous fluoride/sodium lauryl sulphate (SnF(2)/SLS)-containing toothpaste slurries yielded a strong, immediate two-fold increase in characteristic film frequency (f(c)) with respect to untreated films, indicating cross-linking in adsorbed salivary-protein films by Sn(2+) that was absent when SLS was replaced with sodium hexametaphosphate (NaHMP). Secondary exposure to saliva of films treated with SnF(2) caused a strong, six-fold increase in f(c) compared with primary salivary-protein films, regardless of whether SLS or NaHMP was the detergent. This suggests that ionized stannous is not directly available for cross-linking in combination with highly negatively charged NaHMP, but becomes slowly available after initial treatment to cause cross-linking during secondary exposure to saliva. PMID:21244507

  2. Conformational changes of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Allen, Scott

    2005-03-01

    The adsorption of bovine serum albumin (BSA) and pepsin to gold surfaces has been studied using surface plasmon resonance (SPR). Proteins are adsorbed from solution onto a gold surface and changes in the conformation of the adsorbed proteins are induced by changing the buffer solution. We selected pH and ionic strength values for the buffer solutions that are known from our circular dichroism measurements to cause conformational changes of the proteins in bulk solution. We find that for both BSA and pepsin the changes in conformation are impeded by the interaction of the protein with the gold surface.

  3. Computer simulations of adsorbed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  4. The density and refractive index of adsorbing protein layers.

    PubMed

    Vörös, Janos

    2004-07-01

    The structure of the adsorbing layers of native and denatured proteins (fibrinogen, gamma-immunoglobulin, albumin, and lysozyme) was studied on hydrophilic TiO(2) and hydrophobic Teflon-AF surfaces using the quartz crystal microbalance with dissipation and optical waveguide lightmode spectroscopy techniques. The density and the refractive index of the adsorbing protein layers could be determined from the complementary information provided by the two in situ instruments. The observed density and refractive index changes during the protein-adsorption process indicated the presence of conformational changes (e.g., partial unfolding) in general, especially upon contact with the hydrophobic surface. The structure of the formed layers was found to depend on the size of the proteins and on the experimental conditions. On the TiO(2) surface smaller proteins formed a denser layer than larger ones and the layer of unfolded proteins was less dense than that adsorbed from the native conformation. The hydrophobic surface induced denaturation and resulted in the formation of thin compact protein films of albumin and lysozyme. A linear correlation was found between the quartz crystal microbalance measured dissipation factor and the total water content of the layer, suggesting the existence of a dissipative process that is related to the solvent molecules present inside the adsorbed protein layer. Our measurements indicated that water and solvent molecules not only influence the 3D structure of proteins in solution but also play a crucial role in their adsorption onto surfaces. PMID:15240488

  5. Conformation Distributions in Adsorbed Proteins.

    NASA Astrophysics Data System (ADS)

    Meuse, Curtis W.; Hubbard, Joseph B.; Vrettos, John S.; Smith, Jackson R.; Cicerone, Marcus T.

    2007-03-01

    While the structural basis of protein function is well understood in the biopharmaceutical and biotechnology industries, few methods for the characterization and comparison of protein conformation distributions are available. New methods capable of measuring the stability of protein conformations and the integrity of protein-protein, protein-ligand and protein-surface interactions both in solution and on surfaces are needed to help the development of protein-based products. We are developing infrared spectroscopy methods for the characterization and comparison of molecular conformation distributions in monolayers and in solutions. We have extracted an order parameter describing the orientational and conformational variations of protein functional groups around the average molecular values from a single polarized spectrum. We will discuss the development of these methods and compare them to amide hydrogen/deuterium exchange methods for albumin in solution and on different polymer surfaces to show that our order parameter is related to protein stability.

  6. A Multi-technique Characterization of Adsorbed Protein Films: Orientation and Structure by ToF-SIMS, NEXAFS, SFG, and XPS

    NASA Astrophysics Data System (ADS)

    Baio, Joseph E.

    immobilization schemes. This protein contained both a hexahistidine tag and a cysteine residue, introduced at opposite ends of the HuLys Fv, for immobilization onto nitrilotriacetic acid (NTA) and maleimide oligo- (ethylene glycol) (MEG)-terminated substrates. The thiol group on the cysteine residue selectively binds to the MEG groups, while the his-tag selectively binds to the Ni-loaded NTA groups. XPS was used to monitor protein coverage on both surfaces by following the change in the nitrogen atomic %. The ToF-SIMS data provided a clear differentiation between the two samples due to the intensity differences of secondary ions originating from asymmetrically located amino acids in HuLys Fv. Indicating that the HuLys Fv fragment when adsorbed into the NTA and MEG substrates will be induced into two different orientations. On the NTA substrate the protein's binding site is accessible, while on the MEG substrate the binding site is oriented towards the surface. By taking advantage of the electron pathway through the heme group in cytochrome c (CytoC) electrochemists have built sensors based upon CytoC immobilized onto functionalized metal electrodes. When immobilized onto a charged surface, CytoC, with its distribution of lysine and glutamate residues around its surface, should orient and form a well-ordered protein film. Here a detailed examination of CytoC orientation when electrostatically immobilized onto both amine (NH 3+) and carboxyl (COO-) functionalized gold is presented. Again, protein coverage, on both surfaces, was monitored by the change in the atomic % N, as determined by XPS. ToF-SIMS data demonstrated a clear separation between the two samples based on the intensity differences of secondary ions stemming from amino acids located asymmetrically within CytoC, indicating opposite orientations of the protein on the two different surfaces. Spectral features within the in situ sum frequency generation vibrational spectra, acquired for the protein interacting with

  7. Structure and properties of water film adsorbed on mica surfaces

    NASA Astrophysics Data System (ADS)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  8. Hydraulic properties of adsorbed water films in unsaturated porous media

    SciTech Connect

    Tokunaga, Tetsu K.

    2009-03-01

    Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

  9. Volumetric Interpretation of Protein Adsorption: Capacity Scaling with Adsorbate Molecular Weight and Adsorbent Surface Energy

    PubMed Central

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A.

    2009-01-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near τo = 30 dyne/cm (θ~65o) for all protein/surface combinations studied (where τo≡γlvocosθ is the water adhesion tension, γlvo is the interfacial tension of pure-buffer solution, and θ is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining “layer” thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher

  10. Formation of High-Capacity Protein-Adsorbing Membranes Through Simple Adsorption of Poly(acrylic acid)-Containing Films at low pH

    PubMed Central

    Bhattacharjee, Somnath; Dong, Jinlan; Ma, Yiding; Hovde, Stacy; Geiger, James H; Baker, Gregory L.; Bruening, Merlin L.

    2012-01-01

    Layer-by-layer polyelectrolyte adsorption is a simple, convenient method for introducing ion-exchange sites in porous membranes. This study demonstrates that adsorption of poly(acrylic acid) (PAA)-containing films at pH 3 rather than pH 5 increases the protein-binding capacity of such polyelectrolyte-modified membranes 3- to 6-fold. The low adsorption pH generates a high density of –COOH groups that function as either ion-exchange sites or points for covalent immobilization of metal-ion complexes that selectively bind tagged proteins. When functionalized with nitrilotriacetate (NTA)-Ni2+ complexes, membranes containing PAA/polyethyleneimine (PEI)/PAA films bind 93 mg of histidine6-tagged (His-tagged) ubiquitin per cm3 of membrane. Additionally these membranes isolate His-tagged COP9 signalosome complex subunit 8 from cell extracts and show >90% recovery of His-tagged ubiquitin. Although modification with polyelectrolyte films occurs by simply passing polyelectrolyte solutions through the membrane for as little as 5 min, with low-pH deposition the protein binding capacities of such membranes are as high as for membranes modified with polymer brushes and 2–3 fold higher than for commercially available IMAC resins. Moreover, the buffer permeabilities of polyelectrolyte-modified membranes that bind His-tagged protein are ~30% of the corresponding permeabilities of unmodified membranes, so protein capture can occur rapidly with low pressure drops. Even at a solution linear velocity of 570 cm/h, membranes modified with PAA/PEI/PAA exhibit a lysozyme dynamic binding capacity (capacity at 10% breakthrough) of ~ 40 mg/cm3. Preliminary studies suggest that these membranes are stable under depyrogenation conditions (1 M NaOH). PMID:22468687

  11. Anomalous conformational transitions in cytochrome C adsorbing to Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, Kamatchi; Nair, B. U.; Dhathathreyan, A.

    2013-05-01

    Helix to beta conformational transitions in proteins has attracted much attention due to their relevance to fibril formation which is implicated in many neurological diseases. This study reports on unusual conformational transition of cytochrome C adsorbing to hydrophilic surface containing pure cationic lipid and mixed Langmuir-Blodgett films (LB films) of cationic and neutral lipids. Evidence for conformational changes of the protein from its native helical state to beta sheet comes from Circular dichroic spectroscopy (CD spectroscopy). Analysis of these samples using High resolution TEM (HRTEM) shows a typical fibrillar pattern with each strand spacing of about 0.41 nm across which can be attributed to the repeat distance of interdigitated neighboring hydrogen-bonded ribbons in a beta sheet. Changes in contact angles of protein adsorbing to the LB films together with the increased mass uptake of water using quartz crystal microbalance (QCM) confirm the role of positive charges in the conformational transition. Dehydration of the protein resulting from the excess water entrainment in the polar planes of the cationic lipid in hydrophilic surface seems to trigger the refolding of the protein to beta sheet while it retains its native conformation in hydrophobic films. The results suggest that drastic conformational changes in CytC adsorbing to cationic lipids may be of significance in its role as a peripheral membrane protein.

  12. Design and characterization of complex protein films

    NASA Astrophysics Data System (ADS)

    Bui, Holt P.

    Once a biomaterial is implanted into biological system, a layer of protein is immediately deposited on the surface of that material. The newly formed protein film will dictate how the implanted material will interact with the surrounding biological environment and lead to either the acceptance or rejection of the biomaterial. One method to enhance performance involves the activation the surface of the biomaterial with one or more proteins to direct specific interactions with the host environment. The focus of my dissertation was to develop and characterize model biomaterials surfaces that are activated with one or more proteins to help understand how the protein films may affect biological processes and a biomaterial's performance. One model system consisted of a patterned film of two proteins on a gold surface. Characterization of this protein pattern indicated that patterning protein films with a focused ion beam produced protein patterns with high biological contrast and high spatial control. The second model protein film involved the adsorption of fibronectin on surfaces with different surface energies. The characterization of the adsorbed fibronectin films suggest that fibronectin adsorbed on a hydrophilic surface is in an orientation that projects hydrophilic amino acid residues towards surface of the protein and dehydration causes reorientation to project hydrophobic amino acids towards the surface. In contrast, fibronectin is adsorbed onto a hydrophobic surface in a manner that resulted in dehydration and denaturation during the adsorption process. The last model protein film studied in this work consisted of fibronectin patterned in a manner so that the film consisted of spatially controlled domains of fibronectin adsorbed onto a hydrophilic surface as well as a hydrophobic surface. Lateral characterization of this pattern demonstrated a difference in secondary structure of fibronectin adsorbed on the two domains with varying surface energies.

  13. Anomalous thermal denaturing of proteins adsorbed to nanoparticles

    NASA Astrophysics Data System (ADS)

    Teichroeb, J. H.; Forrest, J. A.; Ngai, V.; Jones, L. W.

    2006-09-01

    We have used localized surface plasmon resonance (LSPR) to monitor the structural changes that accompany thermal denaturing of bovine serum albumin (BSA) adsorbed onto gold nanospheres of size 5nm-60nm. The effect of the protein on the LSPR was monitored by visible extinction spectroscopy. The position of the resonance is affected by the conformation of the adsorbed protein layer, and as such can be used as a very sensitive probe of thermal denaturing that is specific to the adsorbed protein. The results are compared to detailed calculations and show that full calculations can lead to significant increases in knowledge where gold nanospheres are used as biosensors. Thermal denaturing on spheres with diameter > 20 nm show strong similarity to bulk calorimetric studies of BSA in solution. BSA adsorbed on nanospheres with d ⩽ 15nm shows a qualitative difference in behavior, suggesting a sensitivity of denaturing characteristics on local surface curvature. This may have important implications for other protein-nanoparticle interactions.

  14. Optical anisotropy of flagellin layers: in situ and label-free measurement of adsorbed protein orientation using OWLS.

    PubMed

    Kovacs, Noemi; Patko, Daniel; Orgovan, Norbert; Kurunczi, Sandor; Ramsden, Jeremy J; Vonderviszt, Ferenc; Horvath, Robert

    2013-06-01

    The surface adsorption of the protein flagellin was followed in situ using optical waveguide lightmode spectroscopy (OWLS). Flagellin did not show significant adsorption on a hydrophilic waveguide, but very rapidly formed a dense monolayer on a hydrophobic (silanized) surface. The homogeneous and isotropic optical layer model, which has hitherto been generally applied in OWLS data interpretation for adsorbed protein films, failed to characterize the flagellin layer, but it could be successfully modeled as an uniaxial thin film. This anisotropic modeling revealed a significant positive birefringence in the layer, suggesting oriented protein adsorption. The adsorbed flagellin orientation was further evidenced by monitoring the surface adsorption of truncated flagellin variants, in which the terminal protein regions or the central (D3) domain were removed. Without the terminal regions the protein adsorption was much slower and the resulting films were significantly less birefringent, implying that intact flagellin adsorbs on the hydrophobic surface via its terminal regions. PMID:23631669

  15. Experimental characterization of adsorbed protein orientation, conformation, and bioactivity.

    PubMed

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-01-01

    Protein adsorption on material surfaces is a common phenomenon that is of critical importance in many biotechnological applications. The structure and function of adsorbed proteins are tightly interrelated and play a key role in the communication and interaction of the adsorbed proteins with the surrounding environment. Because the bioactive state of a protein on a surface is a function of the orientation, conformation, and accessibility of its bioactive site(s), the isolated determination of just one or two of these factors will typically not be sufficient to understand the structure-function relationships of the adsorbed layer. Rather a combination of methods is needed to address each of these factors in a synergistic manner to provide a complementary dataset to characterize and understand the bioactive state of adsorbed protein. Over the past several years, the authors have focused on the development of such a set of complementary methods to address this need. These methods include adsorbed-state circular dichroism spectropolarimetry to determine adsorption-induced changes in protein secondary structure, amino-acid labeling/mass spectrometry to assess adsorbed protein orientation and tertiary structure by monitoring adsorption-induced changes in residue solvent accessibility, and bioactivity assays to assess adsorption-induced changes in protein bioactivity. In this paper, the authors describe the methods that they have developed and/or adapted for each of these assays. The authors then provide an example of their application to characterize how adsorption-induced changes in protein structure influence the enzymatic activity of hen egg-white lysozyme on fused silica glass, high density polyethylene, and poly(methyl-methacrylate) as a set of model systems. PMID:25708632

  16. Experimental characterization of adsorbed protein orientation, conformation, and bioactivity

    PubMed Central

    Thyparambil, Aby A.; Wei, Yang; Latour, Robert A.

    2015-01-01

    Protein adsorption on material surfaces is a common phenomenon that is of critical importance in many biotechnological applications. The structure and function of adsorbed proteins are tightly interrelated and play a key role in the communication and interaction of the adsorbed proteins with the surrounding environment. Because the bioactive state of a protein on a surface is a function of the orientation, conformation, and accessibility of its bioactive site(s), the isolated determination of just one or two of these factors will typically not be sufficient to understand the structure–function relationships of the adsorbed layer. Rather a combination of methods is needed to address each of these factors in a synergistic manner to provide a complementary dataset to characterize and understand the bioactive state of adsorbed protein. Over the past several years, the authors have focused on the development of such a set of complementary methods to address this need. These methods include adsorbed-state circular dichroism spectropolarimetry to determine adsorption-induced changes in protein secondary structure, amino-acid labeling/mass spectrometry to assess adsorbed protein orientation and tertiary structure by monitoring adsorption-induced changes in residue solvent accessibility, and bioactivity assays to assess adsorption-induced changes in protein bioactivity. In this paper, the authors describe the methods that they have developed and/or adapted for each of these assays. The authors then provide an example of their application to characterize how adsorption-induced changes in protein structure influence the enzymatic activity of hen egg-white lysozyme on fused silica glass, high density polyethylene, and poly(methyl-methacrylate) as a set of model systems. PMID:25708632

  17. Adsorbed Methane Film Properties in Nanoporous Carbon Monoliths

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Chada, Nagaraju; Beckner, Matthew; Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter

    2013-03-01

    Carbon briquetting can increase methane storage capacity by reducing the useless void volume resulting in a better packing density. It is a robust and efficient space-filling form for an adsorbed natural gas vehicle storage tank. To optimize methane storage capacity, we studied three fabrication process parameters: carbon-to-binder ratio, compaction temperature, and pyrolysis temperature. We found that carbon-to-binder ratio and pyrolysis temperature both have large influences on monolith uptakes. We have been able to optimize these parameters for high methane storage. All monolith uptakes (up to 260 bar) were measured by a custom-built, volumetric, reservoir-type instrument. The saturated film density and the film thickness was determined using linear extrapolation on the high pressure excess adsorption isotherms. The saturated film density was also determined using the monolayer Ono-Kondo model. Film densities ranged from ca. 0.32 g/cm3 - 0.37 g/cm3.The Ono-Kondo model also determines the binding energy of methane. Binding energies were also determined from isosteric heats calculated from the Clausius-Clapeyron equation and compared with the Ono-Kondo model method. Binding energies from Ono-Kondo were ca. 7.8 kJ/mol - 10 kJ/mol. Work funded by California Energy Commission Contract #500-08-022.

  18. Pattern Recognition of Adsorbing HP Lattice Proteins

    NASA Astrophysics Data System (ADS)

    Wilson, Matthew S.; Shi, Guangjie; Wüst, Thomas; Landau, David P.; Schmid, Friederike

    2015-03-01

    Protein adsorption is relevant in fields ranging from medicine to industry, and the qualitative behavior exhibited by course-grained models could shed insight for further research in such fields. Our study on the selective adsorption of lattice proteins utilizes the Wang-Landau algorithm to simulate the Hydrophobic-Polar (H-P) model with an efficient set of Monte Carlo moves. Each substrate is modeled as a square pattern of 9 lattice sites which attract either H or P monomers, and are located on an otherwise neutral surface. The fully enumerated set of 102 unique surfaces is simulated with each protein sequence. A collection of 27-monomer sequences is used- each of which is non-degenerate and protein-like. Thermodynamic quantities such as the specific heat and free energy are calculated from the density of states, and are used to investigate the adsorption of lattice proteins on patterned substrates. Research supported by NSF.

  19. Adsorbed water and thin liquid films on Mars

    NASA Astrophysics Data System (ADS)

    Boxe, C. S.; Hand, K. P.; Nealson, K. H.; Yung, Y. L.; Yen, A. S.; Saiz-Lopez, A.

    2012-07-01

    At present, bulk liquid water on the surface and near-subsurface of Mars does not exist due to the scarcity of condensed- and gas-phase water, pressure and temperature constraints. Given that the nuclei of soil and ice, that is, the soil solid and ice lattice, respectively, are coated with adsorbed and/or thin liquid films of water well below 273 K and the availability of water limits biological activity, we quantify lower and upper limits for the thickness of such adsorbed/water films on the surface of the Martian regolith and for subsurface ice. These limits were calculated based on experimental and theoretical data for pure water ice and water ice containing impurities, where water ice containing impurities exhibit thin liquid film enhancements, ranging from 3 to 90. Close to the cold limit of water stability (i.e. 273 K), thin liquid film thicknesses at the surface of the Martian regolith is 0.06 nm (pure water ice) and ranges from 0.2 to 5 nm (water ice with impurities). An adsorbed water layer of 0.06 nm implies a dessicated surface as the thickness of one monolayer of water is 0.3 nm but represents 0.001-0.02% of the Martian atmospheric water vapour inventory. Taking into account the specific surface area (SSA) of surface-soil (i.e. top 1 mm of regolith and 0.06 nm adsorbed water layer), shows Martian surface-soil may contain interfacial water that represents 6-66% of the upper- and lower-limit atmospheric water vapour inventory and almost four times and 33%, the lower- and upper-limit Martian atmospheric water vapour inventory. Similarly, taking the SSA of Martian soil, the top 1 mm or regolith at 5 nm thin liquid water thickness, yields 1.10×1013 and 6.50×1013 litres of waters, respectively, 55-325 times larger than Mars' atmospheric water vapour inventory. Film thicknesses of 0.2 and 5 nm represent 2.3×104-1.5×106 litres of water, which is 6.0×10-7-4.0×10-4%, respectively, of a 10 pr μm water vapour column, and 3.0×10-6-4.0×10-4% and 6.0×10

  20. High capacity cryogel-type adsorbents for protein purification.

    PubMed

    Singh, Naveen Kumar; Dsouza, Roy N; Grasselli, Mariano; Fernández-Lahore, Marcelo

    2014-08-15

    Cryogel bodies were modified to obtain epoxy groups by graft-copolymerization using both chemical and gamma irradiation initiation techniques. The free epoxy adsorbents were reacted further to introduce diethylaminoethanol (DEAE) functionalities. The resulting weak anion-exchange cryogel adsorbents showed dynamic binding capacities of ca. 27±3mg/mL, which was significantly higher than previously reported for this type of adsorbent material. Gamma irradiated grafting initiation showed a 4-fold higher capacity for proteins than chemical grafting initiation procedures. The phosphate capacity for these DEAE cryogels was 119mmol/L and also showed similar column efficiency as compared to commercial adsorbents. The large pores in the cryogel structure ensure convective transport of the molecules to active binding sites located on the polymer-grafted surface of cryogels. However, as cryogels have relatively large pores (10-100μm), the BET area available for surface activation is low, and consequently, the capacity of the cryogels is relatively low for biomolecules, especially when compared to commercial beaded adsorbents. Nevertheless, we have shown that gamma ray mediated surface grafting of cryogel matrices greatly enhance their functional and adsorptive properties. PMID:24980092

  1. Candida albicans binds to saliva proteins selectively adsorbed to silicone.

    PubMed

    Holmes, Ann R; van der Wielen, Pauline; Cannon, Richard D; Ruske, Dean; Dawes, Patrick

    2006-10-01

    Explanted voice prostheses obtained from 5 patients at the time of prosthesis replacement were consistently colonized by yeast, in particular Candida albicans. A simple, reproducible, in vitro model of C. albicans adherence to saliva-coated voice prosthesis silicone was developed. Whole saliva promoted adherence of C. albicans to silicone in a dose-dependent manner. Saliva rinses from voice prosthesis patients also promoted binding of C. albicans to silicone in vitro (mean adherence 14.9% +/- 2.8% of input C. albicans cells). This was significantly higher than C. albicans adherence to silicone in the absence of saliva (P < .001) or adherence promoted by saliva rinses from healthy volunteers (P < .005). Polyacrylamide gel electrophoresis analysis and a blot overlay adherence assay revealed that certain salivary proteins were selectively adsorbed to silicone and that C. albicans yeast cells adhered specifically to the adsorbed salivary proteins. PMID:16997116

  2. Selective Gas Capture Ability of Gas-Adsorbent-Incorporated Cellulose Nanofiber Films.

    PubMed

    Shah, Kinjal J; Imae, Toyoko

    2016-05-01

    The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized cellulose nanofibers (TOCNF) were hybridized with cation and anion-exchange organoclays, where poly(amido amine) dendrimers were loaded to enhance the functionality of gas adsorption, since dendrimers have the high adsorbability and the enough selectivity on the gas adsorption. The thin films were prepared from the organoclay-TOCNF hybrids and supplied to the gas adsorption. The adsorption of CO2 and NH3 gases increased with an increasing amount of organoclays in TOCNF films, but the behavior of the increase depended on gases, clays, and dendrimers. The hydrotalcite organoclay-TOCNF films displayed the highest adsorption of both gases, but the desorption of CO2 gas from hydrotalcite organoclay-TOCNF films was drastically high in comparison with the other systems. While the CO2 gas is adsorbed and remained on cationic dendrimer sites in cation-exchange organoclay-TOCNF films, the CO2 gas is adsorbed on cationic clay sites in anion exchange organoclay-TOCNF films, and it is easily desorbed from the films. The NH3 adsorption is inversive to the CO2 adsorption. Then the CO2 molecules adsorbed on the cationic dendrimers and the NH3 molecules adsorbed on the anionic dendrimers are preferably captured in these adsorbents. The present research incorporated dendrimers will be contributing to the development of gas-specialized adsorbents, which are selectively storable only in particular gases. PMID:27035217

  3. Confocal Raman microscopy of protein adsorbed in chromatographic particles.

    PubMed

    Xiao, Yuewu; Stone, Thomas; Bell, David; Gillespie, Christopher; Portoles, Marta

    2012-09-01

    Confocal Raman microscopy is a nondestructive analytical technique that combines the chemical information from vibrational spectroscopy with the spatial resolution of confocal microscopy. It was applied, for the first time, to measure conformation and distribution of protein adsorbed in wetted chromatographic particles. Monoclonal antibody was loaded into the Fractogel EMD SO(3) (M) cation exchanger at 2 mS/cm or 10 mS/cm. Amide I and III frequencies in the Raman spectrum of the adsorbed protein suggest that there are no detectable changes of the original β-sheet conformation in the chromatographic particles. Protein depth profile measurements indicate that, when the conductivity is increased from 2 mS/cm to 10 mS/cm, there is a change in mass transport mechanism for protein adsorption, from the shrinking-core model to the homogeneous-diffusion model. In this study, the use of confocal Raman microscopy to measure protein distribution in chromatographic particles fundamentally agrees with previous confocal laser scanning microscopic investigations, but confocal Raman spectroscopy enjoys additional advantages: use of unlabeled protein to eliminate fluorescent labeling, ability for characterization of protein secondary structure, and ability for spectral normalization to provide a nondestructive experimental approach to correct light attenuation effects caused by refractive index (RI) mismatching in semiopaque chromatographic particles. PMID:22803776

  4. Ultra-Thin Optically Transparent Carbon Electrodes Produced from Layers of Adsorbed Proteins

    PubMed Central

    Alharthi, Sarah A.; Benavidez, Tomas E.; Garcia, Carlos D.

    2013-01-01

    This work describes a simple, versatile, and inexpensive procedure to prepare optically transparent carbon electrodes, using proteins as precursors. Upon adsorption, the protein-coated substrates were pyrolyzed under reductive conditions (5% H2) to form ultra-thin, conductive electrodes. Because proteins spontaneously adsorb to interfaces forming uniform layers, the proposed method does not require a precise control of the preparation conditions, specialized instrumentation, or expensive precursors. The resulting electrodes were characterized by a combination of electrochemical, optical, and spectroscopic means. As a proof-of-concept, the optically-transparent electrodes were also used as substrate for the development of an electrochemical glucose biosensor. The proposed films represent a convenient alternative to more sophisticated, and less available, carbon-based nanomaterials. Furthermore, these films could be formed on a variety of substrates, without classical limitations of size or shape. PMID:23421732

  5. Mobility of adsorbed proteins: a Brownian dynamics study.

    PubMed

    Ravichandran, S; Talbot, J

    2000-01-01

    We simulate the adsorption of lysozyme on a solid surface, using Brownian dynamics simulations. A protein molecule is represented as a uniformly charged sphere and interacts with other molecules through screened Coulombic and double-layer forces. The simulation starts from an empty surface and attempts are made to introduce additional proteins at a fixed time interval that is inversely proportional to the bulk protein concentration. We examine the effect of ionic strength and bulk protein concentration on the adsorption kinetics over a range of surface coverages. The structure of the adsorbed layer is examined through snapshots of the configurations and quantitatively with the radial distribution function. We extract the surface diffusion coefficient from the mean square displacement. At high ionic strengths the Coulombic interaction is effectively shielded, leading to increased surface coverage. This effect is quantified with an effective particle radius. Clustering of the adsorbed molecules is promoted by high ionic strength and low bulk concentrations. We find that lateral protein mobility decreases with increasing surface coverage. The observed trends are consistent with previous theoretical and experimental studies. PMID:10620278

  6. Effects of the Adsorbed Polymer Nanolayers on the Dewetting of Polystyrene Thin Films

    NASA Astrophysics Data System (ADS)

    Cheung, Justin; Wang, Jiaxun; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori

    2015-03-01

    It was previously reported that irreversibly adsorbed polymer nanolayers can be produced on solid substrates by thermal annealing. This study sought to determine the impact of the adsorbed nanolayers on film stability of ultrathin polystyrene (PS) films. A series of bilayers composed of the bottom PS adsorbed nanolayers and PS overlayers with different molecular weights were prepared as model systems. The surface structures of the bilayer films annealed above the bulk glass transition temperature were analyzed by using optical and atomic force microscopes. We will discuss the unique roles of the adsorbed polymer chains in the stability of the liquid thin films. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  7. Influence of ionic strength changes on the structure of pre-adsorbed salivary films. A response of a natural multi-component layer.

    PubMed

    Macakova, Lubica; Yakubov, Gleb E; Plunkett, Mark A; Stokes, Jason R

    2010-05-01

    Salivary films coating oral surfaces are critically important for oral health. This study focuses on determining the underlying nature of this adsorbed film and how it responds to departures from physiological conditions due to changes in ionic strength. Under physiological conditions, it is found that pre-adsorbed in vitro salivary film on hydrophobic surfaces is present as a highly hydrated viscoelastic layer. We follow the evolution of this film in terms of its effective thickness, hydration and viscoelastic properties, as well as adsorbed mass of proteins, using complementary surface characterisation methods: a Surface Plasmon Resonance (SPR) and a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Our results support a heterogeneous model for the structure of the salivary film with an inner dense anchoring layer and an outer highly extended hydrated layer. Further swelling of the film was observed upon decreasing the salt concentration down to 1mM NaCl. However, upon exposure to deionised water, a collapse of the film occurs that was associated with the loss of water contained within the adsorbed layer. We suggest that the collapse in deionised water is driven by an onset of electrostatic attraction between different parts of the multi-component salivary film. It is anticipated that such changes could also occur when the oral cavity is exposed to food, beverage, oral care and pharmaceutical formulations where drastic changes to the structural integrity of the film is likely to have implications on oral health, sensory perception and product performance. PMID:20133111

  8. Direct Measurement of the Adsorbed Film Volume for Estimating Heats of Adsorption

    NASA Astrophysics Data System (ADS)

    Gillespie, Andrew; Dohnke, Elmar; Rash, Tyler; Stalla, David; Knight, Ernest; Seydel, Florian; Sweany, Mark; Pfeifer, Peter

    Compressed hydrogen and methane require extremely high pressures or low temperatures in order to compete with the energy density of conventional fossil fuels. Adsorbent materials provide a means to increase the energy density of these gasses up to 6 times that of compressed gas at the same temperature and pressure. One major concern in engineering adsorbed gas systems is thermal management during charging and discharging. Adsorption is an exothermic process, releasing heat during charging and absorbing heat during discharging. To estimate the heat of adsorption, it is common to analyze excess adsorption isotherms by converting to absolute adsorption and employ the Clausius Clapeyron relation. However, this method requires an assumed volume of the adsorbed state. It is common for researchers to assume that the adsorbed film occupies the entire pore volume of the adsorbent material. However, the adsorbed film only occupies a fraction of the total pore volume. This yields heats of adsorption that are underestimated by as much as 10kJ/mol at high coverage. In this talk, we present a method to directly measure the adsorbed film volume as a function of temperature and present the resulting heats of adsorption for both methane and hydrogen.

  9. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    SciTech Connect

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  10. Optical spectroscopy and scanning tunneling microscopy studies of molecular adsorbates and anisotropic ultrathin films. Final report

    SciTech Connect

    Hemminger, J.C.

    1998-09-01

    The bonding, chemistry and ordering of molecular adsorbates on well defined single crystal surfaces and in ultrathin films was to be studied in an effort to develop sufficient fundamental understanding to allow the controlled preparation of anisotropic ultrathin films of organic monolayers. In this research the authors combine the use of optical probes (Raman spectroscopy, laser induced thermal desorption with Fourier transform mass spectrometry detection) with scanning tunneling microscopy (STM) and conventional methods of UHV surface science (Auger electron spectroscopy, x-ray photoelectron spectroscopy, low energy electron diffraction, and thermal desorption spectroscopy). The conventional surface probes provide well tested methods for the preparation and characterization of single crystal substrates. The optical probes used in the experiments provide powerful methods for the molecular identification of adsorbates in monolayers and ultrathin films. Scanning tunneling microscopy provides one with the ability to determine the detailed molecular level ordering of the molecular adsorbates. The emphasis of this research is on more complex molecular absorbates some of which are monomer precursors to ultrathin polymer films. Enhanced methods of Raman spectroscopy have been developed for the study of monolayer adsorbates on surfaces in ultrahigh vacuum environments. This report gives an overview of recent research results, including the construction of UHV variable temperature STM, analysis of STM images, growth and chemistry of intermetallic single crystal ultrathin films, and electron beam induced chemistry of tetracyanoquinodimethane.

  11. Elastic mediated force between nanoparticles adsorbed on smectic films under an external field.

    PubMed

    Pereira, Maria S S; Lyra, Marcelo L; de Oliveira, Italo N

    2013-02-01

    Within the harmonic approximation, we analytically determine the elastic-mediated interaction between colloidal nanoparticles adsorbed on the surface of smectic films under the influence of an external field. Both cases of free-standing films and films deposited over a solid substrate are considered. We show that the asymptotic decay (1/R in free-standing and exponential in deposited films) is not altered by the external field. However, the external field plays distinct roles according to the film configuration, the interparticle distance, the film thickness, and the surface tension at the film-gas interface. We provide a detailed discussion under the light of the distinct mechanisms controlling the undulations of the surface layer. PMID:23496530

  12. Characterization of cross-linked cellulosic ion-exchange adsorbents: 2. Protein sorption and transport.

    PubMed

    Angelo, James M; Cvetkovic, Aleksandar; Gantier, Rene; Lenhoff, Abraham M

    2016-03-18

    Adsorption behavior in the HyperCel family of cellulosic ion-exchange materials (Pall Corporation) was characterized using methods to assess, quantitatively and qualitatively, the dynamics of protein uptake as well as static adsorption as a function of ionic strength and protein concentration using several model proteins. The three exchangers studied all presented relatively high adsorptive capacities under low ionic strength conditions, comparable to commercially available resins containing polymer functionalization aimed at increasing that particular characteristic. The strong cation- and anion-exchange moieties showed higher sensitivity to increasing salt concentrations, but protein affinity on the salt-tolerant STAR AX HyperCel exchanger remained strong at ionic strengths normally used in downstream processing to elute material fully during ion-exchange chromatography. Very high uptake rates were observed in both batch kinetics experiments and time-series confocal laser scanning microscopy, suggesting low intraparticle transport resistances relative to external film resistance, even at higher bulk protein concentrations where the opposite is typically observed. Electron microscopy imaging of protein adsorbed phases provided additional insight into particle structure that could not be resolved in previous work on the bare resins. PMID:26905881

  13. Quantitative surface studies of protein adsorption by infrared spectroscopy. II. Quantification of adsorbed and bulk proteins

    SciTech Connect

    Fink, D.J.; Hutson, T.B.; Chittur, K.K.; Gendreau, R.M.

    1987-08-15

    Attenuated total reflectance Fourier transform infrared spectra of surface-adsorbed proteins are correlated with concentration measurements determined by /sup 125/I-labeled proteins. This paper demonstrates that linear correlations between the intensity of the major bands of proteins and the quantity of proteins can be obtained for human albumin and immunoglobulin G up to surface concentrations of approximately 0.25 microgram/cm2. A poorer correlation was observed for human fibrinogen. A linear correlation was also observed between the concentration in the bulk solution and the major bands of albumin up to a concentration of 60 mg/ml.

  14. Adsorbate-induced demagnetization and restructuring of ultrathin magnetic films: CO chemisorbed on γ-Fe/Cu(100)

    NASA Astrophysics Data System (ADS)

    Spišák, D.; Hafner, J.

    2001-09-01

    First-principles local-spin-density (LSD) investigations of the structural, magnetic, and electronic properties of clean and CO-adsorbed ultrathin γ-iron films epitaxially grown on Cu(100) surfaces demonstrate that both the geometrical and the magnetic structures of the films are profoundly modified by the adsorption of CO. The enhanced magnetic moments of the top-layer atoms are strongly quenched by the presence of the adsorbate. Due to the pronounced magnetovolume effect, this leads also to a correlated change in the interlayer relaxations. Strikingly, the adsorbate-induced demagnetization is primarily limited to those surface atoms directly bonded to the adsorbate. This leads to the formation of an in-plane magnetic pattern in a partially adsorbate-covered film. The comparison of the calculated vibrational eigenfrequencies of the CO adsorbate with experiment confirms the picture based on the LSD calculations.

  15. Thermodynamic study of argon films adsorbed on boron nitride

    SciTech Connect

    Migone, A.D.; Alkhafaji, M.T. ); Vidali, G. ); Karimi, M. )

    1993-03-15

    We have performed a detailed adsorption isotherm study of Ar on BN for temperatures between 65 and 80 K. The isothermal compressibility of the films was obtained from adsorption data. At monolayer coverages, a small isotherm substep is present at melting. We found two isothermal compressibility peaks in the first layer: a sharp peak, corresponding to the melting substep, and a smaller, broader peak that occurs at lower pressures. At multilayer coverages we found reentrant layering occurring in the third and fourth layers of the film. We compare our layering results with predictions for the preroughening transition. We also found a series of small steps in the isotherms between the second and third layers and between the third and fourth layers of the film. These small steps are evidence of individual layer melting for the second and third layers. Our results at monolayer and at multilayer coverages are extensively compared to those found for Ar on graphite. We have also performed calculations of the rare-gas--BN interaction potentials. Our calculations indicate the substrate corrugation is smaller for the rare-gas--BN systems than it is for the same rare gases on graphite. The implications of this result for the possible existence of monolayer-commensurate solids on BN are discussed.

  16. Electron-Stimulated Oxidation of Thin Water Films Adsorbed on TiO2(110)

    SciTech Connect

    Lane, Christopher D.; Petrik, Nikolay G.; Orlando, Thomas M.; Kimmel, Greg A.

    2007-11-08

    Electron-stimulated reactions in thin (< 3 monolayer, ML) water films adsorbed on TiO2(110) are investigated. For electron fluences less than ~1×1016 e-/cm2, irradiation with 100 eV electrons results in electron-stimulated desorption (ESD) of atomic and molecular hydrogen, but no measurable O2. The ESD leaves adsorbed hydroxyls which oxidize the TiO2(110) surface and change the post-irradiation TPD spectra of the remaining water in characteristic ways. The species remaining on the TiO2(110) after irradiation of adsorbed water films are apparently similar to those produced without irradiation by co-dosing water and O2. Annealing above ~600 K reduces the oxidized surfaces, and water TPD spectra characteristic of ion sputtered and annealed TiO2(110) are recovered. The rate of electron-stimulated “oxidation” of the water films is proportional to the coverage of water in the first layer for coverages less than 1 ML. However, higher coverages suppress this reaction. When thin water films are irradiated, the rate of electron-stimulated oxidation is independent of the initial oxygen vacancy concentration, as is the final oxidized state achieved at high electron fluences. To explain the results, we propose that electron excitation of water molecules adsorbed on Ti4+ sites leads to desorption of hydrogen atoms and leaves an OH adsorbed at the site. If hydroxyls are present in the bridging oxygen rows, these react with the OH’s on the Ti4+ sites to reform water and heal the oxygen vacancy associated with the bridging OH. Once the bridge bonded hydroxyls have been eliminated, further irradiation increases the concentration of OH’s in the Ti4+ rows leading to the creation of species which block sites in the Ti4+ rows, perhaps H2O2 and/or HO2.

  17. Plasma protein adsorbed biomedical polymers: activation of human monocytes and induction of interleukin 1.

    PubMed

    Bonfield, T L; Colton, E; Anderson, J M

    1989-06-01

    These studies involved the evaluation of human monocyte/macrophage activation by biomedical polymers coated with human blood proteins. The biomedical polymers were polyethylene, polydimethylsiloxane, woven Dacron fabric, expanded polytetrafluoroethylene, Biomer, and tissue culture treated polystyrene as the control. They were adsorbed with human blood proteins: albumin, fibrinogen, fibronectin, hemoglobin, and gamma globulin. The protein adsorbed polymers were evaluated for their potential to activate the monocyte/macrophage cellular population in vitro as assessed by the induction of the monocyte/macrophage inflammatory mediator, Interleukin 1 (IL1). Suppression of IL1 was observed when protein adsorbed polymers were compared to the appropriate protein adsorbed control. Protein adsorbed polymers, when compared to polymers without protein adsorption, stimulated IL1 production. The data presented in this manuscript show the level of induction and secretion of IL1 was dependent on the biomedical polymer and the protein adsorbed, as well as the requirement of lipopolysaccharide. These results show differential interactions occur between the proteins, monocytes/macrophages, and biomedical polymers which alter activation and induction of IL1. PMID:2786877

  18. Unusual Morphologies of Poly(vinyl alcohol) Thin Films Adsorbed on Poly(dimethylsiloxane) Substrates.

    PubMed

    Karki, Akchheta; Nguyen, Lien; Sharma, Bhanushee; Yan, Yan; Chen, Wei

    2016-04-01

    Adsorption of poly(vinyl alcohol) (PVOH), 99% and 88% hydrolyzed poly(vinyl acetate), to poly(dimethylsiloxane) (PDMS) substrates was studied. The substrates were prepared by covalently attaching linear PDMS polymers of 2, 9, 17, 49, and 116 kDa onto silicon wafers. As the PDMS molecular weight/thickness increases, the adsorbed PVOH thin films progressively transition from continuous to discontinuous morphologies, including honeycomb and fractal/droplet. The structures are the result of thin film dewetting that occurs upon exposure to air. The PVOH film thickness does not vary significantly on these PDMS substrates, implicating the PDMS thickness as the cause for the morphology differences. The adsorbed PVOH thin films are less stable and have a stronger tendency to dewet on thicker, more liquid-like PDMS layers. When PVOH(99%) and PVOH(88%) thin films are compared, fractal and droplet morphologies are observed on high molecular weight PDMS substrates, respectively. The formation of the unique fractal features in the PVOH(99%) thin films as well as other crystalline and semicrystalline thin films is most likely driven by crystallization during the dehydration process in a diffusion-limited aggregation fashion. The only significant enhancement in hydrophilicity via PVOH adsorption was obtained on PDMS(2k), which is completely covered with a PVOH thin film. To mimic the lower receding contact angle and less liquid-like character of the PDMS(2k) substrate, light plasma treatment of the higher molecular weight PDMS substrates was carried out. On the treated PDMS substrates, the adsorbed PVOH thin films are in the more continuous honeycomb morphology, giving rise to significantly enhanced wettability. Furthermore, hydrophobic recovery of the hydrophilized PDMS substrates was not observed during a 1 week period. Thus, light plasma oxidation and subsequent PVOH adsorption can be utilized as a means to effectively hydrophilize conventional PDMS substrates. This study

  19. Multi-technique Characterization of Adsorbed Peptide and Protein Orientation: LK310 and Protein G B1

    SciTech Connect

    Baio, J.; Weidner, T; Samuel, N; McCrea, K; Baugh, L; Stayton, P; Castner, D

    2010-01-01

    The ability to orient biologically active proteins on surfaces is a major challenge in the design, construction, and successful deployment of many medical technologies. As methods to orient biomolecules are developed, it is also essential to develop techniques that can accurately determine the orientation and structure of these materials. In this study, two model protein and peptide systems are presented to highlight the strengths of three surface analysis techniques for characterizing protein films: time-of-flight secondary-ion mass spectrometry (ToF-SIMS), sum-frequency generation (SFG) vibrational spectroscopy, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. First, the orientation of Protein G B1, a rigid 6 kDa domain covalently attached to a maleimide-functionalized self-assembled monolayer, was examined using ToF-SIMS. Although the thickness of the Protein G layer was similar to the ToF-SIMS sampling depth, orientation of Protein G was successfully determined by analyzing the C{sub 2}H{sub 5}S{sup +} intensity, a secondary-ion derived from a methionine residue located at one end of the protein. Next, the secondary structure of a 13-mer leucine-lysine peptide (LK{sub 310}) adsorbed onto hydrophilic quartz and hydrophobic fluorocarbon surfaces was examined. SFG spectra indicated that the peptide's lysine side chains were ordered on the quartz surface, while the peptide's leucine side chains were ordered on the fluorocarbon surface. NEXAFS results provided complementary information about the structure of the LK{sub 310} film and the orientations of amide bonds within the LK{sub 310} peptide.

  20. Copper iodide staining and determination of proteins adsorbed to microtiter plates.

    PubMed

    Root, D D; Reisler, E

    1990-04-01

    Copper iodide staining and determination of proteins adsorbed to polystyrene microtiter plates are described. The minimum amount of copper iodide-stained protein detected in densitometric measurements is approximately 20 pg/mm2. Enzyme immunoassay readers may also be used for the determination of copper iodide-stained proteins, but are less sensitive than densitometers. The densitometric readings of copper iodide-stained proteins vary linearly with the amount of protein present as verified by enzymatic and radioactive probes. Staining is complete in 2-3 min and may be removed by a 30-min treatment with EDTA without loss of adsorbed protein or immunoreactivity. The exact amount of protein adsorbed to microtiter plate wells can be measured by using protein bound and stained on nitrocellulose as a calibration curve. Copper iodide staining is a rapid, convenient, and inexpensive alternative to radioactive measurements of similar parameters. PMID:1694063

  1. Structural investigations of adsorbed films of Methyl Halides on Boron Nitride

    NASA Astrophysics Data System (ADS)

    Sprung, Michael; Freitag, Andrea; Hanson, Jonathan; Larese, John

    2000-03-01

    The Methyl Halides are a group of molecules whose properties of thin adsorbed films on Graphite have been well characterized. Boron Nitride forms a hexagonal structure with a slightly larger (about 2% ) unit cell than Graphite. The study of thin films of Methyl Halides (CH_3R, R=Cl, Br and I) on Boron Nitride is motivated by the hope to gain a better understanding of adsorbate-substrate interaction. High resolution adsorption isotherms and x-ray powder diffraction have been used to investigate the monolayer structures of CH_3R adsorbed on Boron Nitride. The experiments were carried out at the Beamline X7B of the NSLS. The gases were dosed onto the sample with an automated gas handling system, and a Mar345 image plate detector was used to collect the data. The measurements were performed in a temperature range between 50 and 175 K. All three adsorbates form a solid monolayer structure on Boron Nitride at low temperature. The structure of Methyl Chloride and Methyl Bromide is very similar to the high-density structure of CH_3Cl on Graphite. This is surprising for CH_3Br because it forms a different structure on Graphite. Methyl Iodide forms similar structures on both substrates.

  2. Aggregate formation of eosin-Y adsorbed on nanocrystalline TiO2 films

    NASA Astrophysics Data System (ADS)

    Yaguchi, Kaori; Furube, Akihiro; Katoh, Ryuzi

    2012-11-01

    We have studied the adsorption of eosin-Y on nanocrystalline TiO2 films with two different solvents namely acetonitrile (ACN) and ethanol (EtOH). A Langmuir-type adsorption isotherm was observed with ACN. In contrast, a Freundlich-type adsorption isotherm was observed with EtOH, suggesting that EtOH molecules co-adsorbed on TiO2 surface. Absorption spectra of the dye adsorbed films clearly show aggregate formation at high concentrations of dye in the solutions. From the analysis of the spectra, we conclude that head-to-tail type aggregates are observed with ACN, whereas various types of aggregates, including H-type and head-to-tail type aggregates, are observed with EtOH.

  3. Identification of vitronectin as a major plasma protein adsorbed on polymer surfaces of different copolymer composition.

    PubMed

    Bale, M D; Wohlfahrt, L A; Mosher, D F; Tomasini, B; Sutton, R C

    1989-12-01

    The arrays of proteins adsorbed from plasma onto a series of polystyrene copolymeric latexes were analyzed by enzyme-linked immunosorbent assay (ELISA) of washed beads and immunoblotting of proteins desorbed from the beads and separated by polyacrylamide gel electrophoresis (PAGE). Beads were prepared by continuous emulsion polymerization in the absence of surfactant. Coomassie brilliant blue staining of gel electropherograms of desorbed proteins indicated that the presence of small amounts of comonomers (1 to 10 mole %) significantly influenced the composition of the adsorbed protein layer. Immunoblotting revealed that fibrinogen, fibronectin, and vitronectin were adsorbed by all surfaces investigated. C3 and Clq adsorption varied significantly with copolymer composition. The ELISAs revealed that although the concentrations of vitronectin and fibronectin in plasma are similar, the extent of vitronectin adsorption from 70% to 85% plasma was greater by two orders of magnitude than fibronectin adsorption. Vitronectin adsorbed on carboxylic acid-containing copolymers reacted more strongly with a conformationally sensitive antivitronectin monoclonal antibody (MoAb) than vitronectin adsorbed to polystyrene and was more susceptible to cleavage by plasma proteases(s). The results show that vitronectin is a major protein adsorbed from concentrated plasma and that small changes in the chemical composition of a copolymer profoundly affects the extent and nature of protein adsorption from complex mixtures such as plasma. PMID:2479428

  4. Protein immobilization in hollow nanostructures and investigation of the adsorbed protein behavior.

    PubMed

    Qian, Xi; Levenstein, Alex; Gagner, Jennifer E; Dordick, Jonathan S; Siegel, Richard W

    2014-02-11

    Understanding nanomaterial-biomolecule interactions is critical to develop broad applications in sensors, devices, and therapeutics. During the past decade, in-depth studies have been performed on the effect of nanoscale surface topography on adsorbed protein structure and function. However, a fundamental understanding of nanobio interactions at concave surfaces is limited; the greatest challenge is to create a nanostructure that allows such interactions to occur and to be characterized. We have synthesized hollow nanocages (AuNG) through careful control of morphology and surface chemistry. Lysozyme was used as a model to probe interactions between a protein and these nanostructures. Solid Au nanoparticles with a similar morphology and surface chemistry were also used as a reference. Through a series of quantitative analyses of protein adsorption profiles and enzymatic activity assays of both nanobioconjugates, we discovered that a significant amount of protein could be delivered into the core of AuNG, while maintaining a substantial fraction of native activity. PMID:24450578

  5. Heat capacity of quantum adsorbates: Hydrogen and helium on evaporated gold films

    SciTech Connect

    Birmingham, J.T. |

    1996-06-01

    The author has constructed an apparatus to make specific heat measurements of quantum gases adsorbed on metallic films at temperatures between 0.3 and 4 K. He has used this apparatus to study quench-condensed hydrogen films between 4 and 923 layers thick with J = 1 concentrations between 0.28 and 0.75 deposited on an evaporated gold surface. He has observed that the orientational ordering of the J = 1 molecules depends on the substrate temperature during deposition of the hydrogen film. He has inferred that the density of the films condensed at the lowest temperatures is 25% higher than in bulk H{sub 2} crystals and have observed that the structure of those films is affected by annealing at 3.4 K. The author has measured the J = 1 to J = 0 conversion rate to be comparable to that of the bulk for thick films; however, he found evidence that the gold surface catalyzes conversion in the first two to four layers. He has also used this apparatus to study films of {sup 4}He less than one layer thick adsorbed on an evaporated gold surface. He shows that the phase diagram of the system is similar to that for {sup 4}He/graphite although not as rich in structure, and the phase boundaries occur at different coverages and temperatures. At coverages below about half a layer and at sufficiently high temperatures, the {sup 4}He behaves like a two-dimensional noninteracting Bose gas. At lower temperatures and higher coverages, liquidlike and solidlike behavior is observed. The Appendix shows measurements of the far-infrared absorptivity of the high-{Tc} superconductor La{sub 1.87}Sr{sub 0.13}CuO{sub 4}.

  6. Excitation energy migration in yellow fluorescent protein (citrine) layers adsorbed on modified gold surfaces

    NASA Astrophysics Data System (ADS)

    Yusoff, Hanis Mohd; Rzeźnicka, Izabela I.; Hoshi, Hirotaka; Kajimoto, Shinji; Horimoto, Noriko Nishizawa; Sogawa, Kazuhiro; Fukumura, Hiroshi

    2013-09-01

    The nature of functional proteins adsorbed on solid surfaces is interesting from the perspective of developing of bioelectronics and biomaterials. Here we present evidence that citrine (one of yellow fluorescent protein variants) adsorbed on modified gold surfaces would not undergo denaturation and energy transfer among the adsorbed citrine molecules would occur. Gold substrates were chemically modified with 3-mercaptopropionic acid and tert-butyl mercaptan for the preparation of hydrophilic and hydrophobic surfaces, respectively. A pure solution of citrine was dropped and dried on the modified gold substrates and their surface morphology was studied with scanning tunnelling microscopy (STM). The obtained STM images showed multilayers of citrine adsorbed on the modified surfaces. On hydrophobic surfaces, citrine was adsorbed more randomly, formed various non-uniform aggregates, while on hydrophilic surfaces, citrine appeared more aligned and isolated uniform protein clusters were observed. Fluorescence lifetime and anisotropy decay of these dried citrine layers were also measured using the time correlated single photon counting method. Fluorescence anisotropy of citrine on the hydrophobic surface decayed faster than citrine on the hydrophilic surface. From these results we concluded that fluorescence energy migration occurred faster among citrine molecules which were randomly adsorbed on the hydrophobic surface to compare with the hydrophilic surface.

  7. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H{sub 2} multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx_lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx_lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  8. AC microcalorimetry of adsorbates on evaporated metal films: Orientational ordering of H sub 2 multilayers

    SciTech Connect

    Phelps, R.B.

    1991-11-01

    We have improved and extended a novel ac calorimetric technique for measuring the heat capacity of adsorbates on evaporated metal films. Metallic substrates are of particular interest in current studies of the thermodynamics of adsorbed molecules. The method described in the present work is only calorimetric technique which allows measurements of molecules on simple metallic surfaces. Among other improvements, we have achieved significant progress in the preparation and characterization of the evaporated metal film. We have applied this novel technique to a study of hydrogen multilayers on gold and sapphire substrates. We have shown that samples of normal-hydrogen with a nominal coverage n of approximately 25 monolayers (ML) undergo a bulk-like orientational ordering transition. The transition is suppressed as the coverage is decreased, and no sign of the transition remains above 1.6 K for n {approx} 1 ML. For n {approx lt} 8 ML, the peak in the heat capacity exhibits signs of finite-size effects. At higher coverages, finite-size effects are not observed, and the shape of the peak depends strongly on the substrate. We conclude that the peak is inhomogeneously broadened for n {approx lt} 8 ML. This work represents the first measurements of the heat capacity due to orientational ordering in adsorbed hydrogen. The results of an earlier experiment involving vibrational spectroscopy of adsorbed molecules are included in the Appendix. In this work, we have used infrared emission spectroscopy to study the spectral region in the vicinity of the C=O stretch vibration of bridge-bonded CO on Pt(111).

  9. Effect of the interplay between protein and surface on the properties of adsorbed protein layers.

    PubMed

    Ouberai, Myriam M; Xu, Kairuo; Welland, Mark E

    2014-08-01

    Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials. PMID:24780165

  10. Fibronectin Terminated Multilayer Films: Protein Adsorption and Cell Attachment Studies

    PubMed Central

    Wittmer, Corinne R.; Phelps, Jennifer A.; Saltzman, W. Mark; Van Tassel, Paul R.

    2006-01-01

    Electrostatically driven layer-by-layer (LbL) assembly is a simple and robust method for producing structurally tailored thin film biomaterials, of thickness ca. 10 nanometers, containing biofunctional ligands. We investigate the LbL formation of multilayer films composed of polymers of biological origin (poly(L-lysine) (PLL) and dextran sulfate (DS)), the adsorption of fibronectin (Fn) - a matrix protein known to promote cell adhesion - onto these films, and the subsequent spreading behavior of human umbilical vein endothelial cells (HUVEC). We employ optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microgravimetry with dissipation (QCMD) to characterize multilayer assembly in situ, and find adsorbed Fn mass on PLL terminated films to exceed that on DS terminated films by 40%, correlating with the positive charge and lower degree of hydration of PLL terminated films. The extent and initial rate of Fn adsorption to both PLL and DS terminated films exceed those onto the bare substrate, indicating the important role of electrostatic complexation between negatively charged protein and positively charged PLL at or near the film surface. We use phase contrast optical microscopy to investigate the time dependent morphological changes of HUVEC as a function of layer number, charge of terminal layer, and the presence of Fn. We observe HUVEC to attach, spread, and lose circularity on all surfaces. (Positively charged) PLL terminated films exhibit a greater extent of cell spreading than do (negatively charged) DS terminated films, and spreading is enhanced while circularity loss is suppressed by the presence of adsorbed Fn. The number of layers plays a significant role only for DS terminated films with Fn, where spreading on a bilayer greatly exceeds that on a multilayer, and PLL terminated films without Fn, where initial spreading is significantly higher on a monolayer. We observe initial cell spreading to be followed by retraction (i.e. decreased cell

  11. Atomic force microscopy of AgBr crystals and adsorbed gelatin films

    SciTech Connect

    Haugstad, G.; Gladfelter, W.L.; Keyes, M.P.; Weberg, E.B.

    1993-06-01

    Atomic force microscopy of the (111) surface of macroscopic AgBr crystals revealed steps ranging in height from two atomic layers up to 10 nm, lying predominantly along the (110) and (112) families of crystal directions. Rods of elemental Ag, formed via photoreduction, were observed along the (110) family of directions. Images of adsorbed gelatin films revealed circular pores with diameters of order 10-100 nm, extending to the AgBr surface. The length of deposition time, the pH and concentration of the gelatin solution, and the presence of steps on the AgBr surface were observed to affect the size, number, and location of pores in the gelatin films. 12 refs., 7 figs.

  12. Nanotribological properties of water films adsorbing atop, and absorbing below, graphene layers supported by metal substrates

    NASA Astrophysics Data System (ADS)

    Liu, Zijian; Curtis, C. K.; Stine, R.; Sheehan, P.; Krim, J.

    The tribological properties of graphite, a common lubricant with known sensitivity to the presence of water, have been studied extensively at the macroscopic and microscopic scales. Although far less attention has been devoted to the tribological properties of graphene, it has been established that the tribological response to the presence of water is dissimilar from that of graphite. We report here a quartz crystal microbalance study of the nanotribological properties of water films adsorbed/absorbed on graphene layers prepared by either chemical decomposition on nickel(111) substrates or transfer of freestanding graphene layers to aluminum substrates. Sliding friction levels of the water films were also measured for metal surfaces in the absence of a graphene layer. We observe very high friction levels for water adsorbed atop graphene on Ni(111) and very low levels for water on aluminum. For the case of graphene/aluminum, the data indicate that the water is absorbing between the graphene layer and the aluminum. Dissipation levels moreover indicate the presence of an interstitial water increases sliding friction between the graphene and the aluminum substrate Work supported by NSF and NRL.

  13. Atomic Motion in Low-Coverage Helium Films Adsorbed in FSM Nanochannels

    NASA Astrophysics Data System (ADS)

    Matsushita, Taku; Kuze, Atsushi; Kawai, Ryosuke; Hieda, Mitsunori; Wada, Nobuo

    2013-06-01

    4He and 3He films adsorbed in nanoporous silicates have shown similar heat capacities until the quantum-fluid layer appears at coverages over the first-layer completion n 1. To obtain information on dynamics of adatoms at low coverages below the quantum fluid region, we have done pulsed-NMR experiment at 3.3 MHz for 3He films adsorbed in straight 2.4 nm nanochannels of FSM silicates. The spin-lattice and spin-spin relaxation times T 1 and T 2 observed at 0.54-7 K were well described by the two-dimensional version of the Bloembergen-Purcell-Pound model. At coverages 0.4-1.7 n 1, minima of T 1, indicating the spin correlation time τ c of 4.8×10-8 sec, were observed at temperatures between 6 and 3 K. With decreasing temperature, changes in T 1 and T 2 become small below about 1.5 K, suggesting crossover from thermally-activated motion to quantum tunneling. In contrast to large variations below n 1, both relaxation times above n 1 are almost independent of coverage, which is likely to indicate that τ c is determined by interlayer exchange of adatoms. Below n 1, onsets for localization of adatoms were suggested by a decrease in T 2.

  14. Kinetic silver staining and quantification of proteins adsorbed to microtiter plates.

    PubMed

    Root, D D; Wang, K

    1993-03-01

    A silver stain was used to detect and quantitate proteins adsorbed to microtiter plate wells. The kinetics of the development of the silver stain were analyzed with an automated microtiter plate reader. The lag time for stain development was found to be a consistent indicator of the amount of protein adsorbed to a microtiter plate well. Protein which was not preadsorbed to the microtiter plate was not effectively stained by silver. Complete adsorption of protein applied to the microtiter plate was possible by drying small amounts of protein in very dilute buffers. Variations in sensitivity for different proteins were less than 30% for the panel of proteins examined. Determinations from kinetic silver staining agreed with those from copper staining for bovine albumin adsorbed to microtiter plates. The precision of kinetic silver staining assay was optimal in the range of 40 to 200 ng per microtiter plate well. In this range, the standard deviations averaged less than 5%. Even smaller amounts of protein can be detected and interpolated down to approximately 10 ng per well. The kinetic silver staining method can be used on standard microtiter plate readers without special filters and is readily adaptable to automated systems. PMID:8470810

  15. Adsorbed Proteins Influence the Biological Activity and Molecular Targeting of Nanomaterials

    SciTech Connect

    Dutta, Debamitra; Sundaram, S. K.; Teeguarden, Justin G.; Riley, Brian J.; Fifield, Leonard S.; Jacobs, Jon M.; Addleman, Raymond S.; Kaysen, George A.; Moudgil, Brij M.; Weber, Thomas J.

    2007-11-01

    The possible combination of unique physicochemical properties operating at unique sites of action within cells and tissues has led to considerable uncertainty surrounding nanomaterial toxic potential. Here we have investigated the relative importance of proteins adsorbed onto nanomaterial surfaces in guiding uptake and toxicity to determine whether a priori identification of adsorbed proteins will contribute to nanomaterial toxicity assessment. Albumin was identified as the major protein adsorbed onto single walled carbon nanotubes (SWCNTs) following incubation with fetal bovine or human serum/plasma, but not when plasma from the Nagase Analbuminemic Rat (NAR) was used, and precoating SWCNTs with a non-ionic surfactant (Pluronic F127) inhibited albumin adsorption. Damaged or structurally altered albumin is rapidly cleared by scavenger receptors. In the RAW 264.7 macrophage-like model, we observed that SWCNTs inhibited the induction of cyclooxygenase-2 (Cox-2) by lipopolysaccharide (LPS; 1 ng/ml, 6 hr) and this anti-inflammatory response was inhibited by fucoidan (scavenger receptor antagonist) and by precoating SWCNTs with Pluronic F127. Fucoidan also reduced the uptake of fluorescent SWCNTs (Alexa647) in RAW 264.7 cells. Albumin-coated SWCNTs reduced LPS-mediated Cox-2 induction. SWCNTs did not appear to reduce binding of a fluorescent LPS (Alexa488) to RAW 264.7 cells. The profile of proteins adsorbed onto amorphous silica (50 – 1000 nm) was qualitatively different, relative to SWCNTs, and coating amorphous silica with Pluronic F127 dramatically reduced protein binding and toxicity. Collectively, these observations are consistent with an important role for adsorbed proteins in guiding nanomaterial disposition and toxicity.

  16. Dissociative electron attachment and charging of SF6 adsorbed on rare-gas films

    NASA Astrophysics Data System (ADS)

    Weik, Fritz; Illenberger, Eugen

    1998-10-01

    Electron stimulated desorption (ESD) of fragment ions in the energy range between 0 and 18 eV from SF6 adsorbed on rare-gas films (Kr, Xe) is reported. The ESD results are compared with previous experiments on dissociative electron attachment (DA) to gas-phase SF6. At energies characteristic for the respective rare-gas substrate strong resonant enhancements in the ESD yield of F- are observed. This enhancement is explained by the appearance of an "electron-exciton complex" in the rare-gas film (the analogue to the anionic Feshbach resonances in single atoms) which couples to the first dipole allowed excitation of the SF6 molecule. After electron and energy transfer, the highly excited SF6*- ion dissociates at the surface resulting in the desorption of F- fragments. At low electron energies (in the range from 0 to 0.6 eV) charging of the rare-gas film covered with SF6 is observed. From these experiments a charging cross section of 2.1(±1.8)×10-15 cm2 is derived.

  17. Thermodynamic and dynamic characteristics of hydroxypropylmethylcellulose adsorbed films at the air-water interface.

    PubMed

    Pérez, Oscar E; Sánchez, Cecilio Carrera; Rodríguez Patino, Juan M; Pilosof, Ana M R

    2006-01-01

    Surface pressure isotherms and structural and surface dilatational properties of three hydroxypropylmethycelluloses (HPMCs, called E4M, E50LV, and F4M) adsorbed films at the air-water interface were determined. In this work we present evidence that HPMC molecules are able to diffuse and saturate the air-water interface at very low concentrations in the bulk phase. As bulk concentration increased, structural changes at a molecular level occurred at the interface. These changes corresponded to transition from an expanded structure (structure I) to a condensed one (structure II). When the surface concentration of HPMC was high enough, the collapse of the monolayer was observed. The three HPMCs formed very elastic films at the air-water interface, even at low surface pressures. E4M showed features that make it unique. For instance it showed the highest surface activity, mainly at low bulk concentrations (<10(-4) wt %). The differences observed in surface activity may be attributed to differences in the hydroxypropyl molar substitution and molecular weight of HPMC. All three HPMCs formed films of similar viscoelasticity and elastic dilatational modulus, which can be accounted for by their similar degree of methyl substitution. PMID:16398540

  18. Identification of polymer surface adsorbed proteins implicated in pluripotent human embryonic stem cell expansion.

    PubMed

    Hammad, Moamen; Rao, Wei; Smith, James G W; Anderson, Daniel G; Langer, Robert; Young, Lorraine E; Barrett, David A; Davies, Martyn C; Denning, Chris; Alexander, Morgan R

    2016-08-16

    Improved biomaterials are required for application in regenerative medicine, biosensing, and as medical devices. The response of cells to the chemistry of polymers cultured in media is generally regarded as being dominated by proteins adsorbed to the surface. Here we use mass spectrometry to identify proteins adsorbed from a complex mouse embryonic fibroblast (MEF) conditioned medium found to support pluripotent human embryonic stem cell (hESC) expansion on a plasma etched tissue culture polystyrene surface. A total of 71 proteins were identified, of which 14 uniquely correlated with the surface on which pluripotent stem cell expansion was achieved. We have developed a microarray combinatorial protein spotting approach to test the potential of these 14 proteins to support expansion of a hESC cell line (HUES-7) and a human induced pluripotent stem cell line (ReBl-PAT) on a novel polymer (N-(4-Hydroxyphenyl) methacrylamide). These proteins were spotted to form a primary array yielding several protein mixture 'hits' that enhanced cell attachment to the polymer. A second array was generated to test the function of a refined set of protein mixtures. We found that a combination of heat shock protein 90 and heat shock protein-1 encourage elevated adherence of pluripotent stem cells at a level comparable to fibronectin pre-treatment. PMID:27466628

  19. Sputtering and secondary ion emission properties of alkali metal films and adsorbed monolayers

    SciTech Connect

    Krauss, A R; Gruen, D M

    1980-01-01

    The secondary ion emission of alkali metal adsorbed monlayer and multilayer films has been studied. Profiling with sub-monolayer resolution has been performed by Auger, x-ray photoemission and secondary ion mass spectroscopy. Characteristic differences in the sputtering yields, and ion fraction have been observed which are associated with both the surface bonding properties and the mechanism leading to the formation of secondary ions. By sputtering with a negative bias applied to the sample, positive secondary ions are returned to the surface, resulting in a reduced sputter-induced erosion rate. Comparison with the results obtained with K and Li overlayers sputtered without sample bias provides an experimental value of both the total and secondary ion sputtering yields. The first and second monolayers can be readily identified and the first monolayer exhibits a lower sputtering yield and higher secondary ion fraction. This result is related to adsorption theory and measured values are compared with those obtained by thermal desorption measurements.

  20. Mesoscopic Hamiltonian for the fluctuations of adsorbed Lennard-Jones liquid films.

    PubMed

    Fernández, Eva M; Chacón, Enrique; MacDowell, Luis G; Tarazona, Pedro

    2015-06-01

    We use Monte Carlo simulations of a Lennard-Jones fluid adsorbed on a short-range planar wall substrate to study the fluctuations in the thickness of the wetting layer, and we get a quantitative and consistent characterization of their mesoscopic Hamiltonian, H[ξ]. We have observed important finite-size effects, which were hampering the analysis of previous results obtained with smaller systems. The results presented here support an appealing simple functional form for H[ξ], close but not exactly equal to the theoretical nonlocal proposal made on the basis a generic density-functional analysis by Parry and coworkers. We have analyzed systems under different wetting conditions, as a proof of principle for a method that provides a quantitative bridge between the molecular interactions and the phenomenology of wetting films at mesoscopic scales. PMID:26172722

  1. Friction and transfer of copper, silver, and gold to iron in the presence of various adsorbed surface films

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with the noble metals copper, silver, and gold and two binary alloys of these metals contacting iron in the presence of various adsorbates including, oxygen, methyl mercaptan, and methyl chloride. A pin on disk specimen configuration was used with a load of 100 grams, sliding velocity of 60 mm/min; at 25 C with the surfaces saturated with the adsorbates. Auger emission spectroscopy was used to monitor surface films. Results of the experiments indicate that friction and transfer characteristics are highly specific with respect to both the noble metal and surface film present. With all three metals and films transfer of the noble metal to iron occurred very rapidly. With all metals and films transfer of the noble metal to iron continuously increased with repeated passes except for silver and copper sliding on iron sulfide.

  2. Effect of acidification and heating on the rheological properties of oil-water interfaces with adsorbed milk proteins.

    PubMed

    Mellema, M; Isenbart, J G

    2004-09-01

    The behavior of casein and whey proteins at the oil-water interface was studied using a dynamic drop tensiometer (DDT). The dilational modulus of the interface was measured for aqueous solutions of skim milk powder (SMP) and whey protein concentrate (WPC) with various additions (salt, calcium, lactose) and (order of) various processing steps. Acidification or heating was performed before or after creation of the interface. The elastic properties of oil-water interfaces with adsorbed milk proteins could partly determine the rate of partial coalescence and resulting product instability. For WPC, preacidification slows down the adsorption, but the modulus is not affected. This is probably because, although the whey proteins change conformation more slowly at the interface, still a homogeneous film is formed. If postacidification is applied, coarsening of the protein film leads to loss of interfacial rigidity. Preheating of the aqueous phase with WPC leads to denaturation and aggregation, but the aggregates formed are still surface active and give high moduli. If preheating of a WPC solution is followed by postacidification, the resulting modulus is high (approximately 60 mN/m). The oil-water interfacial properties of SMP are only minimally affected by preheating or by choice of powder (low, medium, or high heat). At low pH, however, aggregates are formed that are less surface active, and interfacial moduli are lower. If measurements are performed at high temperature (i.e., if postheating is applied), for both SMP and WPC systems, moduli became much lower (approximately 10 mN/m). This is probably because of accelerated rearrangements, leading to the formation of inhomogeneous film structures. PMID:15375034

  3. Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films

    SciTech Connect

    Savara, Aditya

    2014-03-15

    Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ∼15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10{sup −7} millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.

  4. 4-Mercaptopyridine adsorbed on pure palladium island films: A combined SERS and DFT investigation

    NASA Astrophysics Data System (ADS)

    Guo, Hao; Ding, Li; Zhang, Tianjie; Mo, Yujun

    2013-03-01

    Surface-enhanced Raman scattering (SERS) can provide vibrational information with molecular specificity and potential single-molecule sensitivity. SERS studies on pure transition metals, however, remain challenging due to the weak SERS activity of transition metals compared to coinage metals. Here we fabricated alumina-supported Pd island films by depositing laser-ablated Pd colloids onto an Al substrate. Robust SERS signal employing 4-mercaptopyridine (4-Mpy) as a probe was registered from the as-prepared films. The adsorption information of 4-Mpy molecules such as orientation and coordinating site was discussed in detail based on SERS data. It was inferred that 4-Mpy adsorbs via its sulfur atom to Pd surface with a tilted binding configuration. The Raman wavenumber and intensity of an adsorption model including one 4-Mpy and Pd atom were computed using density functional theory (DFT) at the Beck's three-parameter Lee-Yang-Parr (B3LYP) level with the LANL2DZ basis set. The simulated Raman spectrum was in good agreement with the experimental one except for the relative intensity. The current investigation could be helpful to gain a comprehensive understanding of SERS.

  5. O the Transition from - to Three-Dimensional Behavior in Adsorbed Films

    NASA Astrophysics Data System (ADS)

    Day, Peter Kenneth

    1993-01-01

    Argon and krypton films adsorbed on graphite foam have been studied in detail using vapor pressure and high resolution, heat capacity measurements. Heat capacity features near the bulk triple point temperature, previously associated with the surface melting of the uniform film, are shown to be due to the melting of bulk material condensed in pores in the substrate. The melting curve of the capillary condensate agrees with the prediction of a modified Clausius -Claperon equation. The second and third layers in argon and the second layer in krypton have a triple point at which two-dimensional solid, liquid, and gas phases coexist atop a solid lower layer. Commensurate-incommensurate transitions are found in the first two layers of argon and in the second layer of krypton, so that monolayer argon melts from a registered phase, but the second layers of both systems melt from incommensurate bilayer phases. The melting of the second and third layers in both systems are likely to be first order, but the data are not conclusive. At coverages starting with 3{1over 2} layers, heat capacity features that are due to reentrant layering-transitions are seen in both systems, confirming the result of recent ellipsometry studies. Further heat capacity peaks suggest phase transitions that join the newly observed reentrant layering-transitions with the well studied layering-transitions at low temperature. These heat capacity peaks may be related to the recently proposed preroughening transition. A mean field theory is developed that reproduced the reentrant layering behavior for ratios of nearest and next nearest neighbor interaction energies greater than a critical value. The mean field theory gives an explanation for the appearance of reentrant layering -transitions at different film thicknesses depending on the substrate-adsorbate interaction parameter. Multilayer phase diagrams are drawn from the data that suggest a crossover from two-dimensional behavior in the second layer to

  6. Study on Wear Reduction Mechanisms of Artificial Cartilage by Synergistic Protein Boundary Film Formation

    NASA Astrophysics Data System (ADS)

    Nakashima, Kazuhiro; Sawae, Yoshinori; Murakami, Teruo

    Poly(vinyl alcohol) (PVA) hydrogel is one of the anticipated materials for artificial cartilage. PVA hydrogel has high water content and a low elastic modulus similar to natural cartilage, but its major disadvantage is its lower strength. PVA hydrogel experienced rapid wear under severe conditions such as mixed or boundary lubrication. Therefore, the existence of a protective surface film with low friction becomes important to prevent surface failure. In this study, the reciprocating frictional tests for a sliding pair of PVA hydrogel and glass plate were carried out, and fluorescent observations were performed to identify the roles of adsorbed protein film. Albumin and γ-globulin, which are contained in natural synovial fluid, were used by mixing into the lubricant. It appears that groups of albumin molecules adsorb on the smooth γ-globulin adsorbed layer at content of 2.1wt% of proteins with an appropriate ratio. But in the case of a lubricant which has excessive protein at 2.8wt%, albumin and γ-globulin adsorbed separately. Considering the wear reduction at 2.1wt% content of protein, albumin and γ-globulin constituted synergistic adsorbed film for wear reduction. It is indicated that albumin constructs a low shear layer and γ-globulin forms a layer protecting PVA hydrogel from wear. It is considered that wear and friction of PVA hydrogel were reduced due to slip of the boundary of adsorbed albumin and γ-globulin layer. Content of protein and ratio of albumin to γ-globulin (AG ratio) are important to constitute the appropriate protein film.

  7. Controllable Nonspecific Protein Adsorption by Charged Hyperbranched Polyglycerol Thin Films.

    PubMed

    Yu, Yaming; Frey, Holger

    2015-12-01

    Antifouling thin films derived from charged hyperbranched polyglycerol (hbPG) layers were fabricated and evaluated. The anionic hbPG (a-hbPG) monolayers and cationic hbPG/anionic hbPG (c/a-hbPG) bilayers were adsorbed on the underlying self-assembled monolayers (SAMs) of cysteamine and 3-mercaptopropionic acid (3-MPA) by electrostatic interaction, respectively, and their procession was monitored by surface plasmon resonance spectroscopy (SPR). The adsorption of bovine serum albumin (BSA) and fibrinogen on the premade a-hbPG and c/a-hbPG thin films was measured and the capability of these thin films to resist nonspecific protein adsorption was evaluated by SPR as well. It is observed that the c/a-hbPG bilayer films possessed good antifouling properties. With c/a-hbPG bilayers consisting of higher molecular weight a-hbPG, the adsorption of BSA and fibrinogen were as low as 0.015 ng/mm(-2) and 0.0076 ng/mm(-2), respectively, comparable to the traditionally ultralow antifouling surfaces (<0.05 ng/mm(-2) of nonspecific protein adsorption). This work proved that the charged hbPG thin films can strongly reduce the nonspecific protein adsorption and have the promise for the antifouling coatings with improved performance. PMID:26562213

  8. Preparation of dye-adsorbing ZnO thin films by electroless deposition and their photoelectrochemical properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa

    2013-09-25

    Dye-adsorbing ZnO thin films were prepared on ITO films by electroless deposition. The films were formed in an aqueous solution containing zinc nitrate, dimethylamine-borane, and eosin Y at 328 K. The film thickness was 1.2-2.0 μm. Thinner and larger-plane hexagonal columns were produced from the solution containing a higher concentration of eosin Y. A photocurrent was observed in the electrodes containing such ZnO films during light irradiation. The photoelectrochemical performance of the film was improved by increasing the concentration of eosin Y because of increases in the amount of absorbed photons and the electronic conductivity of ZnO. PMID:24020721

  9. Adsorbed plasma proteins modulate the effects of single-walled carbon nanotubes on neutrophils in blood.

    PubMed

    Vlasova, Irina I; Mikhalchik, Elena V; Barinov, Nikolay A; Kostevich, Valeria A; Smolina, Natalia V; Klinov, Dmitry V; Sokolov, Alexey V

    2016-08-01

    Proteins adsorbed on a surface may affect the interaction of this surface with cells. Here, we studied the binding of human serum albumin (HSA), fibrinogen (FBG) and immunoglobulin G (IgG) to PEGylated single-walled carbon nanotubes (PEG-SWCNTs) and evaluated the impact of PEG-SWCNT treated by these proteins on neutrophils in whole blood samples. Measurements of adsorption parameters revealed tight binding of proteins to PEG-SWCNTs. AFM was employed to directly observe protein binding to sidewalls of PEG-SWCNTs. Fluorescein-labeled IgG was used to ascertain the stability of PEG-SWCNT-IgG complexes in plasma. In blood samples, all plasma proteins mitigated damage of neutrophils observed just after blood exposure to PEG-SWCNTs, while only treatment of PEG-SWCNTs with IgG resulted in dose- and time-dependent enhancement of CNT-induced neutrophil activation and in potentiation of oxidative stress. Our study demonstrates the ability of adsorbed plasma proteins to influence neutrophil response caused by PEG-SWCNTs in whole blood. PMID:27015767

  10. Prediction of the orientations of adsorbed protein using an empirical energy function with implicit solvation.

    PubMed

    Sun, Yu; Welsh, William J; Latour, Robert A

    2005-06-01

    When simulating protein adsorption behavior, decisions must first be made regarding how the protein should be oriented on the surface. To address this problem, we have developed a molecular simulation program that combines an empirical adsorption free energy function with an efficient configurational search method to calculate orientation-dependent adsorption free energies between proteins and functionalized surfaces. The configuration space is searched systematically using a quaternion rotation technique, and the adsorption free energy is evaluated using an empirical energy function with an efficient grid-based calculational method. In this paper, the developed method is applied to analyze the preferred orientations of a model protein, lysozyme, on various functionalized alkanethiol self-assembled monolayer (SAM) surfaces by the generation of contour graphs that relate adsorption free energy to adsorbed orientation, and the results are compared with experimental observations. As anticipated, the adsorbed orientation of lysozyme is predicted to be dependent on the discrete organization of the functional groups presented by the surface. Lysozyme, which is a positively charged protein, is predicted to adsorb on its 'side' on both hydrophobic and negatively charged surfaces. On surfaces with discrete positively charged sites, attractive interaction energies can also be obtained due to the presence of discrete local negative charges present on the lysozyme surface. In this case, 'end-on' orientations are preferred. Additionally, SAM surface models with mixed functionality suggest that the interactions between lysozyme and surfaces could be greatly enhanced if individual surface functional groups are able to access the catalytic cleft region of lysozyme, similar to ligand-receptor interactions. The contour graphs generated by this method can be used to identify low-energy orientations that can then be used as starting points for further simulations to investigate

  11. Modeling colloid deposition on a protein layer adsorbed to iron-oxide-coated sand

    NASA Astrophysics Data System (ADS)

    Yang, X.; Flynn, R.; von der Kammer, F.; Hofmann, T.

    2012-11-01

    Our recent study reported that conformation change of granule-associated Bovine Serum Albumin (BSA) may influence the role of the protein controlling colloid deposition in porous media (Flynn et al., 2012). The present study conceptualized the observed phenomena with an ellipsoid morphology model, describing BSA as an ellipsoid taking a side-on or end-on conformation on granular surface, and identified the following processes: (1) at low adsorbed concentrations, BSA exhibited a side-on conformation blocking colloid deposition; (2) at high adsorbed concentrations, BSA adapted to an end-on conformation promoted colloid deposition; and (3) colloid deposition on the BSA layer may progressively generate end-on molecules (sites) by conformation change of side-on BSA, resulting in sustained increasing deposition rates. Generally, the protein layer lowered colloid attenuation by the porous medium, suggesting the overall effect of BSA was inhibitory at the experimental time scale. A mathematical model was developed to interpret the ripening curves. Modeling analysis identified the site generation efficiency of colloid as a control on the ripening rate (declining rate in colloid concentrations), and this efficiency was higher for BSA adsorbed from a more dilute BSA solution.

  12. Adsorbed films of three-patch colloids: continuous and discontinuous transitions between thick and thin films.

    PubMed

    Dias, C S; Araújo, N A M; Telo da Gama, M M

    2014-09-01

    We investigate numerically the role of spatial arrangement of the patches on the irreversible adsorption of patchy colloids on a substrate. We consider spherical three-patch colloids and study the dependence of the kinetics on the opening angle between patches. We show that growth is suppressed below and above minimum and maximum opening angles, revealing two absorbing phase transitions between thick and thin film regimes. While the transition at the minimum angle is continuous, in the directed percolation class, that at the maximum angle is clearly discontinuous. For intermediate values of the opening angle, a rough colloidal network in the Kardar-Parisi-Zhang universality class grows indefinitely. The nature of the transitions was analyzed in detail by considering bond flexibility, defined as the dispersion of the angle between the bond and the center of the patch. For the range of flexibilities considered we always observe two phase transitions. However, the range of opening angles where growth is sustained increases with flexibility. At a tricritical flexibility, the discontinuous transition becomes continuous. The practical implications of our findings and the relation to other nonequilibrium transitions are discussed. PMID:25314441

  13. Third Sound in Superfluid 4He Films Adsorbed on Packed Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Menachekanian, Emin

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT , and then a recovery back to linear variation with fill, although the slope is considerably smaller than the KT prediction. These effects might be related to changes in the gas-liquid coexistence regions.

  14. Isolation of calcium-binding proteins on selective adsorbents. Application to purification of bovine calmodulin.

    PubMed

    Chaga, G S; Ersson, B; Porath, J O

    1996-05-01

    We report the fractionation of calcium-binding proteins using immobilized metal ion affinity chromatography (IMAC) with hard metal ions. Various hard metal ions (Mn2+, La3+, Nd3+, Eu(3 were immobilized on cross-linked agarose substituted with Tris(carboxymethyl)ethylenediamine (TED) and used as an adsorbent. After systematic studies, europium was selected for further work on the fractionation of calcium-binding proteins. It was found that the presence of Ca2+ in the sample and the solvent strongly promoted the adsorption and selectivity. Selective elution was accomplished in stepwise mode by the addition of calcium chelators such as malonate, citrate and phosphate. Calmodulin of high purity was isolated from a crude extract. Similar behavior of other calcium-binding proteins indicates that the reported chromatographic procedure can be generally applied to such proteins. PMID:8653201

  15. Determinants of protein elution rates from preparative ion-exchange adsorbents.

    PubMed

    Angelo, James M; Lenhoff, Abraham M

    2016-04-01

    The rate processes involved in elution in preparative chromatography can affect both peak resolution and hence selectivity as well as practical factors such as facility fit. These processes depend on the physical structure of the adsorbent particles, the amount of bound solute, the solution conditions for operation or some combination of these factors. Ion-exchange adsorbents modified with covalently attached or grafted polymer layers have become widely used in preparative chromatography. Their often easily accessible microstructures offer substantial binding capacities for biomolecules, but elution has sometimes been observed to be undesirably slow. In order to determine which physicochemical phenomena control elution behavior, commercially available cellulosic, dextran-grafted and unmodified agarose materials were characterized here by their elution profiles at various conditions, including different degrees of loading. Elution data were analyzed under the assumption of purely diffusion-limited control, including the role of pore structure properties such as porosity and tortuosity. In general, effective elution rates decreased with the reduction of accessible pore volume, but differences among different proteins indicated the roles of additional factors. Additional measurements and analysis, including the use of confocal laser scanning microscopy to observe elution within single chromatographic particles, indicated the importance of protein association within the particle during elution. The use of protein stabilizing agents was explored in systems presenting atypical elution behavior, and l-arginine and disaccharide excipients were shown to alleviate the effects for one protein, lysozyme, in the presence of sodium chloride. Incorporation of these excipients into eluent buffer gave rise to faster elution and significantly lower pool volumes in elution from polymer-modified adsorbents. PMID:26948763

  16. The leucine rich amelogenin protein (LRAP) adsorbs as monomers or dimers onto surfaces

    SciTech Connect

    Tarasevich, Barbara J.; Lea, Alan S.; Shaw, Wendy J.

    2010-03-15

    Amelogenin and amelogenin splice variants are believed to be involved in controlling the formation of the highly anisotropic and ordered hydroxyapatite crystallites that form enamel. The adsorption behavior of amelogenin proteins onto substrates is very important because protein-surface interactions are critical to it’s function. We have studied the adsorption of LRAP, a splice variant of amelogenin which may also contribute to enamel function, onto model self-assembled monolayers on gold containing of COOH, CH3, and NH2 end groups. Dynamic light scattering (DLS) experiments indicated that LRAP in phosphate buffered saline (PBS) and solutions at saturation with calcium phosphate contained aggregates of nanospheres. Null ellipsometry and atomic force microscopy (AFM) were used to study protein adsorption amounts and structures. Relatively high amounts of adsorption occurred onto the CH3 and NH2 surfaces from both calcium phosphate and PBS solutions. Adsorption was also promoted onto COOH surfaces when calcium was present in the solutions suggesting an interaction that involves calcium bridging with the negatively charged C-terminus. The ellipsometry and AFM studies suggested that the protein adsorbed onto all surfaces as LRAP monomers. We propose that the monomers adsorb onto the surfaces by disassembling or “shedding” from the nanospheres that are present in solution. This work reveals the importance of small subnanosphere-sized structures of LRAP at interfaces, structures that may be important in the biomineralization of tooth enamel.

  17. Aging of the nanosized photochromic WO3 films and the role of adsorbed water in the photochromism

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, A. I.

    2016-02-01

    Here it has been reported on aging of the nanosized WO3 film, which is revealed is continuous reduction of the photochromic sensitivity over time. Water molecules physically adsorbed on the film surface from ambient air form donor-acceptor and hydrogen bonds, changing gradually the adsorption state to chemisorption which prevents an access of organic molecules that serve as hydrogen donors by the photochromism. The mechanism of the process has been investigated and discussed. The role of water in the photochromism has been highlighted. The difference in the efficiency for being of a hydrogen donor in the photochromic process between water and organic molecules is discussed.

  18. Shotgun proteomic analytical approach for studying proteins adsorbed onto liposome surface.

    PubMed

    Capriotti, Anna Laura; Caracciolo, Giulio; Cavaliere, Chiara; Crescenzi, Carlo; Pozzi, Daniela; Laganà, Aldo

    2011-09-01

    The knowledge about the interaction between plasma proteins and nanocarriers employed for in vivo delivery is fundamental to understand their biodistribution. Protein adsorption onto nanoparticle surface (protein corona) is strongly affected by vector surface characteristics. In general, the primary interaction is thought to be electrostatic, thus surface charge of carrier is supposed to play a central role in protein adsorption. Because protein corona composition can be critical in modifying the interactive surface that is recognized by cells, characterizing its formation onto lipid particles may serve as a fundamental predictive model for the in vivo efficiency of a lipidic vector. In the present work, protein coronas adsorbed onto three differently charged cationic liposome formulations were compared by a shotgun proteomic approach based on nano-liquid chromatography-high-resolution mass spectrometry. About 130 proteins were identified in each corona, with only small differences between the different cationic liposome formulations. However, this study could be useful for the future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins into body fluids. PMID:21725631

  19. Influence of Chemical Composition on the Reaction Products Observed During Electron Stimulated Decomposition of Organohalides Adsorbed in Water (Ice) Films

    NASA Astrophysics Data System (ADS)

    Fairbrother, Howard; Perry, Christopher; Faradzhev, Nadir; Madey, Theodore

    2004-03-01

    We report on the reactions of CF_2Cl2 and other organohalides codeposited_ in water (ice) films (≈100 nm thick on Au) at ˜ 100K during X-ray or electron beam irradiation. X-ray irradiation produces a distribution of low energy secondary electrons that in CF_2Cl_2/H_2O(ice) films produce H_3O^+, CO2 and COF2 (carbonyl fluoride). Chloride and fluoride anions are also produced and solvated (trapped) within the ice film during X-ray or electron irradiation. Product partitioning is dependent on the film's chemical composition; in water rich films, CO2 and COF2 production is favored, while a thermally stable partially halogenated CF_xCly film is detected in CF_2Cl2 rich films. During the early stages of irradiation, the dominance of Cl^- anions indicates that DEA of CF_2Cl2 via C-Cl cleavage (CF_2Cl2 + e^- → ot CF_2Cl + Cl^-) is the primary initial process. These results obtained for CF_2Cl2 are compared with electron stimulated reactions of other organohalides (CCl_4, CDCl_3, CD_2Cl2 and CH_3I) adsorbed in water(ice)films.

  20. Nanoporous Gyroid-Structured Epoxy from Block Copolymer Templates for High Protein Adsorbability.

    PubMed

    Wang, Xin-Bo; Lin, Tze-Chung; Hsueh, Han-Yu; Lin, Shih-Chieh; He, Xiao-Dong; Ho, Rong-Ming

    2016-06-28

    Nanoporous epoxy with gyroid texture is fabricated by using a nanoporous polymer with gyroid-forming nanochannels as a template for polymerization of epoxy. The nanoporous polymer template is obtained from the self-assembly of degradable block copolymer, polystyrene-b-poly(l-lactide) (PS-PLLA), followed by hydrolysis of PLLA blocks. Templated polymerization can be conducted under ambient conditions to create well-defined, bicontinuous epoxy networks in a PS matrix. By taking advantage of multistep curing of epoxy, well-ordered robust nanoporous epoxy can be obtained after removal of PS template, giving robust porous materials. The through-hole nanoporous epoxy in the film state can be used as a coated layer to enhance the adsorbability for both lysozyme and bovine serum albumin. PMID:27245380

  1. Study of the conformational change of adsorbed proteins on biomaterial surfaces using hydrogen-deuterium exchange with mass spectroscopy.

    PubMed

    Kim, Jinku

    2016-05-01

    There is no doubt that protein adsorption plays a crucial role in determining biocompatibility of biomaterials. Despite the information of the identity and composition of blood plasma/serum proteins adsorbed on surfaces of biomaterials to understand which proteins are involved in blood/biomaterial interactions, it still does not provide information about the conformations and orientations of adsorbed protein, which are very important in determining biological responses to biomaterials. Therefore, our laboratory has developed an experimental technology to probe protein conformations on materials that is applicable to mixtures of proteins. Herein, the new application of hydrogen/deuterium (H/D) exchange combined with mass spectrometry was applied to determine conformational changes of adsorbed proteins at biomaterial surfaces. The results suggest that there may be a significant conformational change in adsorbed proteins at 'low' bulk concentrations that leads to a large change in the kinetics of H/D exchange as compared to 'high' bulk concentrations. This technique may eventually be useful for the study of the kinetics of protein conformational changes. PMID:26896658

  2. Protein-triggered instant disassembly of biomimetic Layer-by-Layer films.

    PubMed

    Abdelkebir, Khalil; Gaudière, Fabien; Morin-Grognet, Sandrine; Coquerel, Gérard; Atmani, Hassan; Labat, Béatrice; Ladam, Guy

    2011-12-01

    Layer-by-Layer (LbL) coatings are promising tools for the biofunctionalization of biomaterials, as they allow stress-free immobilization of proteins. Here, we explore the possibility to immobilize phosvitin, a highly phosphorylated protein viewed as a model of bone phosphoproteins and, as such, a potential promotive agent of surface-directed biomineralization, into biomimetic LbL architectures. Two immobilization protocols are attempted, first, using phosvitin as the polyanionic component of phosvitin/poly-(L-lysine) films and, second, adsorbing it onto preformed chondroitin sulfate/poly-(L-lysine) films. Surprisingly, it is neither possible to embed phosvitin as the constitutive polyanion of the LbL architectures nor to adsorb it atop preformed films. Instead, phosvitin triggers instant massive film disassembly. This unexpected, incidentally detected behavior constitutes the first example of destructive interactions between LbL films and a third polyelectrolyte, a fortiori a protein, which might open a route toward new stimuli-responsive films for biosensing or drug delivery applications. Interestingly, additional preliminary results still indicate a promotive effect of phosvitin-containing remnant films on calcium phosphate deposition. PMID:22007998

  3. Dry powder pulmonary delivery of cationic PGA-co-PDL nanoparticles with surface adsorbed model protein.

    PubMed

    Kunda, Nitesh K; Alfagih, Iman M; Dennison, Sarah R; Somavarapu, Satyanarayana; Merchant, Zahra; Hutcheon, Gillian A; Saleem, Imran Y

    2015-08-15

    Pulmonary delivery of macromolecules has been the focus of attention as an alternate route of delivery with benefits such as; large surface area, thin alveolar epithelium, rapid absorption and extensive vasculature. In this study, a model protein, bovine serum albumin (BSA) was adsorbed onto cationic PGA-co-PDL polymeric nanoparticles (NPs) prepared by a single emulsion solvent evaporation method using a cationic surfactant didodecyldimethylammonium bromide (DMAB) at 2% w/w (particle size: 128.64±06.01 nm and zeta-potential: +42.32±02.70 mV). The optimum cationic NPs were then surface adsorbed with BSA, NP:BSA (100:4) ratio yielded 10.01±1.19 μg of BSA per mg of NPs. The BSA adsorbed NPs (5 mg/ml) were then spray-dried in an aqueous suspension of L-leucine (7.5 mg/ml, corresponding to a ratio of 1:1.5/NP:L-leu) using a Büchi-290 mini-spray dryer to produce nanocomposite microparticles (NCMPs) containing cationic NPs. The aerosol properties showed a fine particle fraction (FPF, dae<4.46 μm) of 70.67±4.07% and mass median aerodynamic diameter (MMAD) of 2.80±0.21 μm suggesting a deposition in the respiratory bronchiolar region of the lungs.The cell viability was 75.76±03.55% (A549 cell line) at 156.25 μg/ml concentration after 24 h exposure. SDS-PAGE and circular dichroism (CD) confirmed that the primary and secondary structure of the released BSA was maintained. Moreover, the released BSA showed 78.76±1.54% relative esterolytic activity compared to standard BSA. PMID:26169146

  4. Targeted Mutagenesis and Combinatorial Library Screening Enables Control of Protein Orientation on Surfaces and Increased Activity of Adsorbed Proteins.

    PubMed

    Cruz-Teran, Carlos A; Carlin, Kevin B; Efimenko, Kirill; Genzer, Jan; Rao, Balaji M

    2016-08-30

    While nonspecific adsorption is widely used for immobilizing proteins on solid surfaces, the random nature of protein adsorption may reduce the activity of immobilized proteins due to occlusion of the active site. We hypothesized that the orientation a protein assumes on a given surface can be controlled by systematically introducing mutations into a region distant from its active site, thereby retaining activity of the immobilized protein. To test this hypothesis, we generated a combinatorial protein library by randomizing six targeted residues in a binding protein derived from highly stable, nonimmunoglobulin Sso7d scaffold; mutations were targeted in a region that is distant from the binding site. This library was screened to isolate binders that retain binding to its cognate target (chicken immunoglobulin Y, cIgY) as well as exhibit adsorption on unmodified silica at pH 7.4 and high ionic strength conditions. A single mutant, Sso7d-2B5, was selected for further characterization. Sso7d-2B5 retained binding to cIgY with an apparent dissociation constant similar to that of the parent protein; both mutant and parent proteins saturated the surface of silica with similar densities. Strikingly, however, silica beads coated with Sso7d-2B5 could achieve up to 7-fold higher capture of cIgY than beads coated with the parent protein. These results strongly suggest that mutations introduced in Sso7d-2B5 alter its orientation relative to the parent protein, when adsorbed on silica surfaces. Our approach also provides a generalizable strategy for introducing mutations in proteins so as to improve their activity upon immobilization, and has direct relevance to development of protein-based biosensors and biocatalysts. PMID:27490089

  5. Inhibition of Lipid Oxidation in Oil-in-Water Emulsions by Interface-Adsorbed Myofibrillar Protein.

    PubMed

    Yang, Jiayi; Xiong, Youling L

    2015-10-14

    This study investigated the role of interfacial myofibrillar protein (MFP) in the oxidative stabilization of meat emulsions. Emulsions with 10% oil were prepared using either 2% (w/v) Tween 20 or 0.25, 0.5, and 1% (w/v) MFP and then subjected to hydroxyl radical oxidation at 4 °C for 0, 2, and 24 h. MFP was more readily oxidized (intrinsic fluorescence quenching, sulfur losses, and carbonyl formation) than oil [conjugated dienes and 2-thiobarbituric acid-reactive substances (TBARS)]. However, oxidized MFP in the continuous phase stimulated lipid oxidation after 24 h, sharply contrasting with interface-adsorbed MFP that inhibited TBARS formation nearly 90% (p < 0.05). Interfacial MFP from 2 h oxidized samples exhibited greater losses of fluorescence and more extensive polymerization of myosin (detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) than MFP present in the continuous phase. Results indicated that, due to the physical localization, interface-adsorbed MFP in general and myosin in particular provided accentuated protection of emulsions against oxidation. PMID:26414649

  6. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane.

    PubMed

    Doig, Michael; Warrens, Chris P; Camp, Philip J

    2014-01-14

    The structure and friction of fatty acid surfactant films adsorbed on iron oxide surfaces lubricated by squalane are examined using large-scale molecular dynamics simulations. The structures of stearic acid and oleic acid films under static and shear conditions, and at various surface coverages, are described in detail, and the effects of unsaturation in the tail group are highlighted. At high surface coverage, the measured properties of stearic acid and oleic acid films are seen to be very similar. At low and intermediate surface coverages, the presence of a double bond, as in oleic acid, is seen to give rise to less penetration of lubricant in to the surfactant film and less layering of the lubricant near to the film. The kinetic friction coefficient is measured as a function of shear rate within the hydrodynamic (high shear rate) lubrication regime. Lubricant penetration and layering are observed to be correlated with friction coefficient. The friction coefficient with oleic acid depends only weakly on surface coverage, while stearic acid admits more lubricant penetration, and its friction coefficient increases significantly with decreasing surface coverage. Connections between film structure and friction are discussed. PMID:24364665

  7. Protein adsorption on polyanion/polycation layer-by-layer assembled polyelectrolyte films.

    PubMed

    Yang, Jen Ming; Tsai, Rong-Ze; Hsu, Chih-Chin

    2016-06-01

    As layer-by-layer self-assembly deposition (LbL) is a versatile technique for surface modification, protein adsorption on the LbL modified glass is evaluated in this study. At the beginning, glass slides was silanized by 3-aminopropyltriethoxysilane (APTES). Sodium alginate (Alg), poly(γ-glutamic acid) (PGA) and poly(aspartic acid) (PAsp) were selected as polyanion electrolytes and chitosan (CS) was used as the polycation electrolyte. Both polyanion and polycation electrolytes alternately deposited on the silanized glass slide surface by the LbL technique to get three different polyanion/chitosan series of LbL films ([Alg/CS], [PGA/CS], and [PAsp/CS]). Three kinds of kinetic model including pseudo-first-order, second-order kinetic and intraparticle diffusion model were used to evaluate the adsorption of albumin on the three different polyanion/chitosan series of LbL films. It is found that the adsorption of albumin on the polyanion/chitosan series of LbL films can be described well with the pseudo-second-order kinetic mechanism. To make sure if the pseudo-second-order kinetic mechanism of protein adsorbed on the other polyanion/polycation LbL films is also suitable, poly(allylamine hydrochloride) (PAH) and poly(L-lysine) (PLL) are used as two other polycations. The [polyanion/PAH] and [polyanion/PLL] series of LbL films were prepared with the same LbL technique for albumin, fibrinogen, and fibronectin adsorption. From the results, it is found that albumin, fibrinogen, and fibronectin adsorption on the various polyanion/polycation LbL films can be described well with the pseudo-second-order kinetic mechanism. The protein adsorbed at equilibrium and rate constant of protein adsorbed on the various LbL films can be determined. PMID:26938325

  8. Exploring the interfacial structure of protein adsorbates and the kinetics of protein adsorption: an in situ high-energy X-ray reflectivity study.

    PubMed

    Evers, Florian; Shokuie, Kaveh; Paulus, Michael; Sternemann, Christian; Czeslik, Claus; Tolan, Metin

    2008-09-16

    The high energy X-ray reflectivity technique has been applied to study the interfacial structure of protein adsorbates and protein adsorption kinetics in situ. For this purpose, the adsorption of lysozyme at the hydrophilic silica-water interface has been chosen as a model system. The structure of adsorbed lysozyme layers was probed for various aqueous solution conditions. The effect of solution pH and lysozyme concentration on the interfacial structure was measured. Monolayer formation was observed for all cases except for the highest concentration. The adsorbed protein layers consist of adsorbed lysozyme molecules with side-on or end-on orientation. By means of time-dependent X-ray reflectivity scans, the time-evolution of adsorbed proteins was monitored as well. The results of this study demonstrate the capabilities of in situ X-ray reflectivity experiments on protein adsorbates. The great advantages of this method are the broad wave vector range available and the high time resolution. PMID:18715021

  9. Solubility, tensile, and color properties of modified soy protein isolate films.

    PubMed

    Rhim, J W; Gennadios, A; Handa, A; Weller, C L; Hanna, M A

    2000-10-01

    Protein solubility (PS) values of different soy protein isolate (SPI) films were determined in water, 0.01 N HCl, 0.01 N NaOH, 4 M urea, and 0.2 M 2-mercaptoethanol. Tensile and color (L, a, and b values) properties of films also were determined. Control films were cast from heated (70 degrees C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 mL of water) and glycerin (50% w/w of SPI). Additional films were cast after incorporation of dialdehyde starch (DAS) at 10% w/w of SPI or small amounts of formaldehyde in the film-forming solutions. Also, control film samples were subjected to heat curing (90 degrees C for 24 h), UV radiation (51.8 J/m(2)), or adsorption of formaldehyde vapors. PS of control films was highest (P < 0.05) in 2-mercaptoethanol, confirming the importance of disulfide bonds in SPI film formation. All treatments were effective in reducing (P < 0.05) film PS in all solvents. Both DAS and adsorbed formaldehyde rendered the protein in films practically insoluble in all solvents. Adsorption of formaldehyde vapors and heat curing also substantially increased (P < 0.05) film tensile strength from 8.2 to 15.8 or 14.7 MPa, respectively. However, heat curing decreased (P < 0.05) film elongation at break from 30 to 6%. Most treatments had small but significant (P < 0.05) effects on b color values, with DAS-containing films having the greatest (P < 0. 05) mean b value (most yellowish). Also, DAS-containing, heat-cured, and UV-irradiated films were darker, as evidenced by their lower (P < 0.05) L values, than control films. It was demonstrated that PS of SPI films can be notably modified through chemical or physical treatments prior to or after casting. PMID:11052759

  10. Evaluation of the Effectiveness of Surfactants and Denaturants to Elute and Denature Adsorbed Protein on Different Surface Chemistries.

    PubMed

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-11-01

    The elution and/or denaturation of proteins from material surfaces by chemical excipients such as surfactants and denaturants is important for numerous applications including medical implant reprocessing, bioanalyses, and biodefense. The objective of this study was to develop and apply methods to quantitatively assess how surface chemistry and adsorption conditions influence the effectiveness of three commonly used surfactants (sodium dodecyl sulfate, n-octyl-β-d-glucoside, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and two denaturants (guanidium hydrochloride and urea) to elute protein (hen egg white lysozyme and bovine pancreatic ribonuclease A) from three different surface chemistries (silica glass, poly(methyl methacrylate), and high-density polyethylene). The structure and bioactivity of residual protein on the surface following elution were characterized using circular dichroism spectropolarimetry and enzyme assays to assess the extent of protein denaturation. Our results indicate that the denaturants were generally more effective than the surfactants in removing the adsorbed proteins from each type of surface. Also, the denaturing capacity of these excipients on the residual proteins on the surfaces was distinctly different from their influence on the proteins in solution and was unique for each of the adsorption conditions. Taken altogether, these results reveal that the effectiveness of surfactants and denaturants to elute and denature adsorbed protein is significantly influenced by surface chemistry and the conditions from which the protein was adsorbed. These results provide a basis for the selection, design, and further development of chemical agents for protein elution and surface decontamination. PMID:26449787

  11. Nanostructured functional films from engineered repeat proteins

    PubMed Central

    Grove, Tijana Z.; Regan, Lynne; Cortajarena, Aitziber L.

    2013-01-01

    Fundamental advances in biotechnology, medicine, environment, electronics and energy require methods for precise control of spatial organization at the nanoscale. Assemblies that rely on highly specific biomolecular interactions are an attractive approach to form materials that display novel and useful properties. Here, we report on assembly of films from the designed, rod-shaped, superhelical, consensus tetratricopeptide repeat protein (CTPR). We have designed three peptide-binding sites into the 18 repeat CTPR to allow for further specific and non-covalent functionalization of films through binding of fluorescein labelled peptides. The fluorescence signal from the peptide ligand bound to the protein in the solid film is anisotropic, demonstrating that CTPR films can impose order on otherwise isotropic moieties. Circular dichroism measurements show that the individual protein molecules retain their secondary structure in the film, and X-ray scattering, birefringence and atomic force microscopy experiments confirm macroscopic alignment of CTPR molecules within the film. This work opens the door to the generation of innovative biomaterials with tailored structure and function. PMID:23594813

  12. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  13. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Feng, Yiyu; Wu, Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-07-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO2-s-MWNTs) was prepared from a suspension of TiO2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO2-s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO2 into consideration.

  14. NMR Study of Phase Transitions in Pure Water and Binary H(2)O/HNO(3) Films Adsorbed on Surface of Pyrogenic Silica.

    PubMed

    Bogdan; Kulmala; Gorbunov; Kruppa

    1996-01-15

    Pyrogenic silica (aerosil) was employed as host within which the phase transitions in the adsorbed pure water and binary H(2)O/HNO(3) films have been studied with NMR spectroscopy. The median freezing temperature and freezing temperature region were shown to be highly sensitive both to the average thickness of the adsorbed films and to the amount of adsorbed nitric acid. The molar concentration of nitric acid in the adsorbed films was found to be very small, on the order of 10(-3)-10(-2) (M/liter). The concentration was found to be greater in the layers adjacent to the surface of silica and sharply decreases with distance from the surface. The difference between the median freezing temperatures for adsorbed pure water and for the binary system was found to be about 9 K for films of equal thickness. This is about 150 times greater than the difference between the freezing temperatures of bulk pure water and a solution with the same concentration of nitric acid. PMID:10479419

  15. Isolation and Characterization Of Chimeric Human Fc-expressing Proteins Using Protein A Membrane Adsorbers And A Streamlined Workflow

    PubMed Central

    Burdick, Monica M.; Reynolds, Nathan M.; Martin, Eric W.; Hawes, Jacquelyn V.; Carlson, Grady E.; Cuckler, Chaz M.; Bates, Michael C.; Barthel, Steven R.; Dimitroff, Charles J.

    2014-01-01

    Laboratory scale to industrial scale purification of biomolecules from cell culture supernatants and lysed cell solutions can be accomplished using affinity chromatography. While affinity chromatography using porous protein A agarose beads packed in columns is arguably the most common method of laboratory scale isolation of antibodies and recombinant proteins expressing Fc fragments of IgG, it can be a time consuming and expensive process. Time and financial constraints are especially daunting in small basic science labs that must recover hundreds of micrograms to milligram quantities of protein from dilute solutions, yet lack access to high pressure liquid delivery systems and/or personnel with expertise in bioseparations. Moreover, product quantification and characterization may also excessively lengthen processing time over several workdays and inflate expenses (consumables, wages, etc.). Therefore, a fast, inexpensive, yet effective protocol is needed for laboratory scale isolation and characterization of antibodies and other proteins possessing an Fc fragment. To this end, we have devised a protocol that can be completed by limited-experience technical staff in less than 9 hr (roughly one workday) and as quickly as 4 hr, as opposed to traditional methods that demand 20+ work hours. Most required equipment is readily available in standard biomedical science, biochemistry, and (bio)chemical engineering labs, and all reagents are commercially available. To demonstrate this protocol, representative results are presented in which chimeric murine galectin-1 fused to human Fc (Gal-1hFc) from cell culture supernatant was isolated using a protein A membrane adsorber. Purified Gal-1hFc was quantified using an expedited Western blotting analysis procedure and characterized using flow cytometry. The streamlined workflow can be modified for other Fc-expressing proteins, such as antibodies, and/or altered to incorporate alternative quantification and characterization

  16. Characterization of crosslinked artificial protein films

    NASA Astrophysics Data System (ADS)

    Nowatzki, Paul

    Genetically engineered artificial proteins are promising candidates for new biomaterials because their amino acid sequences can be precisely controlled. This work describes the characterization of crosslinked films of biomimetic artificial extracellular matrix (aECM) proteins with hybrid functions designed to meet materials needs in applications such as small diameter vascular grafts and corneal tissue implants. Elastin-derived polypeptides give the proteins flexibility, while RGD and CS5 peptide domains from fibronectin serve to adhere cells. Techniques were sought to crosslink aECM proteins in ways that resulted in tunable mechanical properties. Hexamethylene diisocyanate was used to crosslink aECM proteins into uniform, transparent, highly-extensible hydrogel films with low water contents characteristic of native elastin. Their elastic moduli, 0.1--1.1 MPa, depended on crosslinker concentration and aECM protein length, and spanned the observed range of elastin fibers. The suitability of biomaterials implants depends strongly on their susceptibility to proteolytic degradation in vivo. It was shown that small sequence changes in the elastin-like portion of aECM proteins were sufficient to decrease their rate of degradation by elastase sevenfold, illustrating a simple method to tune the protease sensitivity of designed proteins. The effects were seen in both soluble proteins and crosslinked films analyzed by measuring their decrease in elastic modulus during degradation. An aECM protein was examined for its effectiveness as a corneal onlay, i.e., a permanent contact lens. The protein was crosslinked into transparent, elastic, water-rich lenses and was implanted into rabbit corneas. The onlays were stable and well-tolerated, and full re-epithelialization occurred within 4-7 days. Histological examination revealed normal regenerating epithelial cell morphology on the anterior surface, good interfaces between the onlay and surrounding tissue, and only minimal

  17. A novel adsorbent for protein chromatography: supermacroporous monolithic cryogel embedded with Cu2+-attached sporopollenin particles.

    PubMed

    Erzengin, Mahmut; Ünlü, Nuri; Odabaşı, Mehmet

    2011-01-21

    The aim of this study is to prepare supermacroporous cryogels embedded with Cu(2+)-attached sporopollenin particles (Cu(2+)-ASP) having large surface area for high protein adsorption capacity. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic cryogel column embedded with Cu(2+)-ASP was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA). Firstly, Cu(2+) ions were attached to sporopollenin particles (SP), then the supermacroporous PHEMA cryogel with embedded Cu(2+)-ASP was produced by free radical polymerization using N,N,N',N'-tetramethylene diamine (TEMED) and ammonium persulfate (APS) as initiator/activator pair in an ice bath. Embedded particles (10 mg) in PHEMA-based cryogel column were used in the adsorption/desorption of HSA from aqueous solutions. Optimum conditions of adsorption experiments were performed at pH 8.0 phosphate buffer, with flow rate of 0.5 mL/min, and at 5°C. The maximum amount of HSA adsorption from aqueous solution was very high (677.4 mg/g SP) with initial concentration 6 mg/mL. It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Cu(2+)-ASP in PHEMA cryogel without significant loss of adsorption capacity. PMID:21176840

  18. Analysis of Chemical Reactions between Radical Growth Precursors Adsorbed on Plasma-Deposited Silicon Thin-Film Surfaces

    NASA Astrophysics Data System (ADS)

    Bakos, Tamas; Valipa, Mayur; Maroudas, Dimitrios

    2006-03-01

    The dominant precursor in the plasma deposition of hydrogenated amorphous silicon (a-Si:H) thin films is the SiH3 radical. In this presentation, we report results of first-principles density functional theory calculations on the crystalline Si(001)-(2x1):H surface and molecular-dynamics simulations on a-Si:H surfaces for the interactions between SiH3 radicals adsorbed on Si thin-film surfaces. The analysis reveals that two SiH3 radicals may either form disilane (Si2H6) that desorbs from the surface or undergo a disproportionation reaction producing an SiH2 radical that is incorporated in the film and a silane molecule that is released in the gas phase. The corresponding activation barriers depend on the local atomic coordination of the surface Si atoms; Si2H6 formation is barrierless if both radicals are bonded to overcoordinated surface Si atoms and exhibits barriers in excess of 1 eV for two chemisorbed SiH3 radicals.

  19. Fluorescence and photoelectrochemical behavior of chlorophyll {ital a} adsorbed on a nanocrystalline SnO{sub 2} film

    SciTech Connect

    Bedja, I.; Kamat, P.V.; Hotchandani, S.

    1996-10-01

    Fluorescence and photoelectrochemical studies of chlorophyll {ital a} (Chl {ital a}) adsorbed on nanocrystalline SnO{sub 2} film were carried out. The results of fluorescence and incident photon to current conversion efficiency (IPCE) as a function of applied bias suggest that the fluorescence quenching and the photocarrier generation are interrelated. Fluorescence quenching has thus been utilized to determine the photogeneration efficiency, {eta}({ital e}), of charges in a SnO{sub 2}/Chl {ital a} based photoelectrochemical cell. A value of 0.75 was obtained for {eta}({ital e}) for unbiased cells. With an IPCE of 13{percent}, {eta}({ital e}) of 75{percent}, and a light harvesting efficiency of 70{percent}, the charge collection efficiency of {approximately}23{percent} was evaluated. These results suggest that the losses due to the charge recombination are a major factor that limit the efficiency of the cells. {copyright} {ital 1996 American Institute of Physics.}

  20. Relationship between surface viscosity and surface composition of adsorbed surfactant films

    SciTech Connect

    Djabbarah, N.F.; Wasan, D.T.

    1982-02-01

    The single-bubble foaming technique was used to determine the surface excess concentrations of aqueous solutions of sodium lauryl sulfate (SLS) and lauryl alcohol (LOH). The excess concentrations of sodium lauryl sulfate-lauryl alcohol showed that lauryl alcohol is preferentially adsorbed at the surface, but only partially displaces sodium lauryl sulfate. This causes a higher total surface concentration and, consequently, a closer packing of surfactant molecules. The total surface excess concentration increases with an increase in the bulk concentration of the 2 surfactants until the critical micelle concentration (CMC) is reached. At concentrations exceeding the CMC, the surface excess concentration of LOH remains virtually constant, while that of SLS declines. This is due to the formation of SLS micelles. The surface excess concentration data have been used to estimate the extent of molecular packing at the gas/liquid interface and to assess interactions among surfactant molecules in order to explain trends in surface viscosity of a mixed surfactant system adsorbed from an aqueous solution. 30 references.

  1. Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

    NASA Astrophysics Data System (ADS)

    Yuan, Huihui; Qian, Bin; Zhang, Wei; Lan, Minbo

    2016-02-01

    An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU-PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU-PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU-PVP (6.0 h) film reduced greatly to 0.08 μg/cm2, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

  2. Entropy-Driven Conformational Control of α,ω-Difunctional Bidentate-Dithiol Azo-Based Adsorbates Enables the Fabrication of Thermally Stable Surface-Grafted Polymer Films.

    PubMed

    Lee, Han Ju; Jamison, Andrew C; Lee, T Randall

    2016-06-22

    Thermally stable radical initiator monolayers were prepared from uniquely designed α,ω-difunctional adsorbates with bidentate headgroups for the growth of nanoscale polymer films on metal surfaces. The length of the spacer separating the bidentate headgroups was varied to afford 4,4'-(diazene-1,2-diyl)bis(N-(16-(3,5-bis(mercaptomethyl)phenoxy)hexadecyl)-4-cyanopentanamide) (B16), 4,4'-(diazene-1,2-diyl)bis(N-(16-(3,5-bis(mercapto-methyl)phenoxy)decyl)-4-cyanopentanamide) (B10), and 4,4'-(diazene-1,2-diyl)bis(N-(4-(3,5-bis(mercaptomethyl)phenoxy)butyl)-4-cyanopentanamide) (B4). The structural features of the self-assembled monolayers (SAMs) derived from B16, B10, and B4 were characterized by X-ray photoelectron spectroscopy (XPS), ellipsometry, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and compared to those derived from an analogous α,ω-difunctional adsorbate with monodentate headgroups, 4,4'-(diazene-1,2-diyl)bis(4-cyano-N-(16-mercaptohexadecyl)pentanamide (M). These studies demonstrate that the conformation (i.e., hairpin vs standing up) of the bidentate initiator adsorbates on gold surfaces was easily controlled by adjusting the concentration of the adsorbates in solution. The results of solution-phase thermal desorption tests revealed that the radical initiator monolayers generated from B16, B10, and B4 exhibit an enhanced thermal stability when compared to those generated from M. Furthermore, a study of the growth of polymer films was performed to evaluate the utility of these new bidentate adsorbate SAMs as film-development platforms for new functional materials and devices. Specifically, surface-grafted polystyrene films were successfully generated from SAMs derived from B16. In contrast, attempts to grow polystyrene films from SAMs derived from M under a variety of analogous conditions were unsuccessful. PMID:27219525

  3. Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

    PubMed Central

    Behm, R Jürgen

    2014-01-01

    Summary As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm−1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed. PMID:24991512

  4. Effect of adsorbed films on friction of Al2O3-metal systems

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1976-01-01

    The kinetic friction of polycrystalline Al2O3 sliding on Cu, Ni, and Fe in ultrahigh vacuum was studied as a function of the surface chemistry of the metal. Clean metal surfaces were exposed to O2, Cl2, C2H4, and C2H3Cl, and the change in friction due to the adsorbed species was observed. Auger electron spectroscopy assessed the elemental composition of the metal surface. It was found that the systems exposed to Cl2 exhibited low friction, interpreted as the van der Waals force between the Al2O3 and metal chloride. The generation of metal oxide by oxygen exposures resulted in an increase in friction, interpreted as due to strong interfacial bonds established by reaction of metal oxide with Al2O3 to form the complex oxide (spinel). The only effect of C2H4 was to increase the friction of the Fe system, but C2H3Cl exposures decreases friction in both Ni and Fe systems, indicating the dominance of the chlorine over the ethylene complex on the surface

  5. Modulation of protein behavior through light responses of TiO2 nanodots films

    NASA Astrophysics Data System (ADS)

    Cheng, Kui; Hong, Yi; Yu, Mengfei; Lin, Jun; Weng, Wenjian; Wang, Huiming

    2015-08-01

    In this work, the behavior of protein molecules adsorbed on TiO2 nanodots films are modulated through the light responses of the nanodots. TiO2 nanodots films are first prepared through phase separation induced self assembly. Then, bovine serum albumin (BSA) is adsorbed on TiO2 nanodots films and exposed to ultraviolet (365 nm) illumination. It is found the conformation of surface-bound BSA molecules changes with ultraviolet illumination. Moreover, the BSA molecules conjugate to the surface-bound molecules, which are in the overlayer, are released. The reason is ascribed to that TiO2 nanodots absorb ultraviolet and result in the increase of surface hydroxyl groups on nanodots. Such increase further leads to intensified attraction of -NH3 groups in the surface-bound BSA molecules. That not only changes the conformation of the surface-bound BSA molecules, but also weaken the conjugation between surface-bound molecules and other BSA molecules in the overlayer. Eventually, the overlayer of BSA molecules is released. It is believed that such protein conformation variation and release behavior induced through light responses of TiO2 nanodots are crucial in understanding the biomedical performance of TiO2 nanostructures. Also, it could be widely utilized in tailoring of the materials-protein interactions.

  6. Thick-Film Carbon Dioxide Sensor via Anodic Adsorbate Stripping Technique and Its Structural Dependence

    PubMed Central

    Photinon, Kanokorn; Wang, Shih-Han; Liu, Chung-Chiun

    2009-01-01

    A three-electrode based CO2 sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum nanoparticles. The sensing output was linearly related to the CO2 presented. Stability measurements demonstrated that the decline of the active surface area and the sensitivity of the sensor were 8% and 13%, respectively, over a two week period of time. The sensor response appeared to be a structural dependence of the crystallographic orientation of platinum electrode. PMID:22399993

  7. Kosterlitz-Thouless Transition in 4He Films Adsorbed to Rough Calcium Fluoride

    SciTech Connect

    Luhman, D. R.; Hallock, R. B.

    2006-09-07

    Previous measurements in our lab have shown that the onset of superfluidity at the KT transition, typically seen as a sharp change in the frequency of a smooth-surface quartz crystal microbalance, becomes less identifiable in the presence of increasing surface roughness or disorder, while the peak in the dissipation is unchanged. Using a series of microbalances coated with increasingly rough CaF2, we have extended our measurements to lower 4He film coverages and thus lower temperatures. We find at lower 4He coverages that the presence of disorder on the substrate has a diminished effect on the frequency shift.

  8. Third Sound Generation in Superfluid 4He Films Adsorbed on Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Iaia, Vito; Menachekanian, Emin; Williams, Gary

    2014-03-01

    A technique is developed for generating third sound in superfluid 4He films coating the surface of multiwall carbon nanotubes. Third sound is a thickness and temperature wave of the helium film, and in our case we detect the temperature oscillations with a carbon resistance bolometer. The nanotubes are packed in an annular resonator that is vibrated with a mechanical shaker assembly consisting of a permanent magnet mounted on springs, and surrounded by a superconducting coil. The coil is driven with an oscillating current, vibrating the cell at that frequency. Sweeping the drive frequency over the range 100-200 Hz excites the resonant third sound mode of the cell, seen as a high-Q signal in the FFT analysis of the bolometer signal. A problem with our original cell was that the mechanical drive would also shake the dilution refrigerator cooling the cell to low temperatures, and increasing the drive would start to heat up the refrigerator and the cell, which were rigidly coupled together. A new configuration now suspends the cell as a pendulum on a string, with thermal contact made by copper wires. Piezo sensor measurements show this reduces the vibration reaching the refrigerator by two orders of magnitude, which should allow measurements at lower temperatures.

  9. Filming protein fibrillogenesis in real time

    NASA Astrophysics Data System (ADS)

    Bella, Angelo; Shaw, Michael; Ray, Santanu; Ryadnov, Maxim G.

    2014-12-01

    Protein fibrillogenesis is a universal tool of nano-to-micro scale construction supporting different forms of biological function. Its exploitable potential in nanoscience and technology is substantial, but the direct observation of homogeneous fibre growth able to underpin a kinetic-based rationale for building customized nanostructures in situ is lacking. Here we introduce a kinetic model of de novo protein fibrillogenesis which we imaged at the nanoscale and in real time, filmed. The model helped to reveal that, in contrast to heterogeneous amyloid assemblies, homogeneous protein recruitment is principally characterized by uniform rates of cooperative growth at both ends of growing fibers, bi-directional growth, with lateral growth arrested at a post-seeding stage. The model provides a foundation for in situ engineering of sequence-prescribed fibrous architectures.

  10. Filming protein fibrillogenesis in real time

    PubMed Central

    Bella, Angelo; Shaw, Michael; Ray, Santanu; Ryadnov, Maxim G.

    2014-01-01

    Protein fibrillogenesis is a universal tool of nano-to-micro scale construction supporting different forms of biological function. Its exploitable potential in nanoscience and technology is substantial, but the direct observation of homogeneous fibre growth able to underpin a kinetic-based rationale for building customized nanostructures in situ is lacking. Here we introduce a kinetic model of de novo protein fibrillogenesis which we imaged at the nanoscale and in real time, filmed. The model helped to reveal that, in contrast to heterogeneous amyloid assemblies, homogeneous protein recruitment is principally characterized by uniform rates of cooperative growth at both ends of growing fibers, bi-directional growth, with lateral growth arrested at a post-seeding stage. The model provides a foundation for in situ engineering of sequence-prescribed fibrous architectures. PMID:25519825

  11. Effect of divalent ions on the optical emission behavior of protein thin films

    NASA Astrophysics Data System (ADS)

    Bhowal, Ashim Chandra; Kundu, Sarathi

    2016-05-01

    Photoluminescence behaviors of proteinthin film, bovine serum albumin (BSA) have been studied in the presence of three divalent ions (Mg2+, Ca2+ and Ba2+) at different temperatures using fluorescence spectroscopy. Film thickness and morphology have been studied using atomic force microscopy. Variation of different physicochemical parameters like temperature, solvent polarity, pH, ionic strength, substrate binding etc. can make conformational changes in the protein structure and hence influences the emission behavior.In thin film conformation of BSA, dynamic quenching behavior has beenidentified in the presence of all the three divalent ions at pH≈ 5.5. Depending upon the charge density of the divalent ions interaction with protein molecules modifies and as a result quenching efficiency varies. Also after heat treatment, conformation of the protein molecules changes and as a result the quenching efficiency enhances than that of the unheated films. Studies on such protein-ion interactions and conformational variation may explore various functions of protein when it will adsorb on soft surfaces like membranes, vesicles, etc.

  12. Infrared spectroscopy of water clusters co-adsorbed with hydrogen molecules on a sodium chloride film

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koichiro; Fukutani, Katsuyuki

    2016-06-01

    Hydrogen gas containing a trace of water vapor was dosed on a vacuum-evaporated sodium chloride film at 13 K, and water clusters formed on the substrate were investigated by infrared absorption spectroscopy. Absorption bands due to (H2O)n clusters with n = 3-6 and an induced absorption band due to hydrogen were clearly observed. With increasing gas dosage, the intensities of the cluster bands increased linearly while the intensity of the hydrogen band was constant. This suggests that the water clusters were formed in two-dimensional matrices of hydrogen. We found that the water clusters did exist on the surface upon heating even after the hydrogen molecules had desorbed. A further rise of the substrate temperature up to 27 K yielded the formation of larger clusters, (H2O)n with n > 6 . We also discuss the origins of the two bands of the trimer in terms of pseudorotation and a metastable isomer.

  13. Fabrication of Robust Protein Films Using Nanoimprint Lithography.

    PubMed

    Jeoung, Eunhee; Duncan, Bradley; Wang, Li-Sheng; Saha, Krishnendu; Subramani, Chandramouleeswaran; Wang, Peijian; Yeh, Yi-Cheun; Kushida, Takashi; Engel, Yoni; Barnes, Michael D; Rotello, Vincent M

    2015-10-28

    A nanoimprint-lithography-based fabrication method to generate stable protein films is described. The process is environmentally friendly and generalizable with respect to the protein building blocks. These non-fouling surfaces are readily patternable, incorporate intrinsic protein charge into the film, and able to control cellular adhesion. PMID:26390179

  14. David Adler Lectureship Award Talk: Friction and energy dissipation mechanisms in adsorbed molecules and molecularly thin films

    NASA Astrophysics Data System (ADS)

    Krim, Jacqueline

    2015-03-01

    Studies of the fundamental origins of friction have undergone rapid progress in recent years, with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales. The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat. Measurements of the sliding friction of physisorbed monolayers and bilayers can provide information on the relative contributions of these various dissipative mechanisms. Adsorbed films, whether intentionally applied or present as trace levels of physisorbed contaminants, moreover are ubiquitous at virtually all surfaces. As such, they impact a wide range of applications whose progress depends on precise control and/or knowledge of surface diffusion processes. Examples include nanoscale assembly, directed transport of Brownian particles, material flow through restricted geometries such as graphene membranes and molecular sieves, passivation and edge effects in carbon-based lubricants, and the stability of granular materials associated with frictional and frictionless contacts. Work supported by NSFDMR1310456.

  15. Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

    NASA Astrophysics Data System (ADS)

    He, Xin; Barthel, Anthony J.; Kim, Seong H.

    2016-06-01

    The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

  16. Inhibition of wave-driven two-dimensional turbulence by viscoelastic films of proteins

    NASA Astrophysics Data System (ADS)

    Francois, N.; Xia, H.; Punzmann, H.; Combriat, T.; Shats, M.

    2015-08-01

    To model waves, surface flows, and particle dispersion at the air-water interface one needs to know the essential mechanisms affecting the fluid motion at the surface. We show that a thin film (less than 10-nm thick) of adsorbed protein dramatically affects two-dimensional turbulence generated by Faraday waves at the fluid surface. Extremely low concentrations (≈1 ppm) of soluble proteins form a strong viscoelastic layer which suppresses turbulent diffusion at the surface, changes wave patterns, and shows strong resilience to the wave-induced droplet generation. Surface shear properties of the film play a key role in this phenomenon by inhibiting the creation of vorticity at the surface. The addition of surfactants, on the other hand, destroys the nanolayer and restores the fluid mobility.

  17. Synthesis of adsorbents with dendronic structures for protein hydrophobic interaction chromatography.

    PubMed

    Mata-Gómez, Marco A; Yaman, Sena; Valencia-Gallegos, Jesus A; Tari, Canan; Rito-Palomares, Marco; González-Valdez, José

    2016-04-22

    Here, we introduced a new technology based on the incorporation of dendrons-branched chemical structures-onto supports for synthesis of HIC adsorbents. In doing so we studied the synthesis and performance of these novel HIC dendron-based adsorbents. The adsorbents were synthesized in a facile two-step reaction. First, Sepharose 4FF (R) was chemically modified with polyester dendrons of different branching degrees i.e. third (G3) or fifth (G5) generations. Then, butyl-end valeric acid ligands were coupled to dendrons via ester bond formation. UV-vis spectrophotometry and FTIR analyses of the modified resins confirmed the presence of the dendrons and their ligands on them. Inclusion of dendrons allowed the increment of ligand density, 82.5 ± 11 and 175.6 ± 5.7 μmol ligand/mL resin for RG3 and RG5, respectively. Static adsorption capacity of modified resins was found to be ∼ 60 mg BSA/mL resin. Interestingly, dynamic binding capacity was higher at high flow rates, 62.5 ± 0.8 and 58.0 ± 0.5mg/mL for RG3 and RG5, respectively. RG3 was able to separate lipase, β-lactoglobulin and α-chymotrypsin selectively as well as fractionating of a whole proteome from yeast. This innovative technology will improve the existing HIC resin synthesis methods. It will also allow the reduction of the amount of adsorbent used in a chromatographic procedure and thus permit the use of smaller columns resulting in faster processes. Furthermore, this method could potentially be considered as a green technology since both, dendrons and ligands, are formed by ester bonds that are more biodegradable allowing the disposal of used resin waste in a more ecofriendly manner when compared to other exiting resins. PMID:27018188

  18. Preparation and characterization of films from pea protein.

    PubMed

    Viroben, G; Barbot, J; Mouloungui, Z; Guéguen, J

    2000-04-01

    The conditions for protein film preparation from an alkaline dispersion of a pea protein isolate were investigated in the presence of polyols as plasticizers. Mechanical and barrier properties of resulting films were studied as a function of protein dispersion conditions, protein and plasticizer concentrations and ratios, chain length of the plasticizer, and pH and composition of the alkaline medium. Neither the mode of protein hydration nor the pea isolate origin had a significant effect on the mechanical properties of pea protein films. However, increasing the plasticizer chain length induced slightly higher surface hydrophobicity but poor mechanical properties. Addition of monoglycerides to film-forming solution allowed a significant improvement of the films during aging. Both tensile strength and surface hydrophobicity increased when ammonium hydroxide was used as protein dispersing agent instead of sodium hydroxide. PMID:10775350

  19. Effects of molecule-insulator interaction on geometric property of a single phthalocyanine molecule adsorbed on an ultrathin NaCl film

    NASA Astrophysics Data System (ADS)

    Miwa, Kuniyuki; Imada, Hiroshi; Kawahara, Shota; Kim, Yousoo

    2016-04-01

    The adsorption structure and orientation of a metal-free phthalocyanine (H2Pc ) and a magnesium phthalocyanine (MgPc) on a bilayer of NaCl films were investigated both theoretically and experimentally by means of first-principles calculations based on density functional theory and by scanning tunneling microscopy. H2Pc is adsorbed with its center over the sodium cation, and H-N bonds in the molecule are aligned with the [100] or [010] surface direction of a bilayer (001)-terminated NaCl film. The most stable structures of MgPc on the NaCl film show two kinds of orientations corresponding to the molecule rotated by ±7∘ relative to the [110] surface direction, with the Mg cation positioned over the chlorine anion in both cases. The energetic barrier for switching between these orientations is as low as 9.0 meV, and during an STM measurement, an orientational change of MgPc can be observed. The interaction between the adsorbed molecule and the NaCl film were analyzed in terms of dispersion interaction, Mg-Cl chemical bonding, and electrostatic interaction. It is found that the small electrostatic interaction between the molecule and the film gives a dominant contribution to determining the molecular orientation. Our detailed and comprehensive studies of the molecule-insulator interaction will provide knowledge to understand and control the properties of molecules on an insulating material.

  20. Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry

    PubMed Central

    Doan, Tran T.; Freeman, Michael H.; Schmidt, Adrienne R.; Nguyen, Natalie D. T.; Leopold, Michael C.

    2011-01-01

    Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified with alkanethiol self-assembled monolayers (SAM).1-3 In this paper, MPCs functionalized with hexanethiolate ligands are synthesized using a modified Brust reaction4 and characterized with ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and proton (1H) nuclear magnetic resonance (NMR). MPC films are assembled on SAM modified gold electrode interfaces by using a "dip cycle" method of alternating MPC layers and dithiol linking molecules. Film growth at gold electrode is tracked electrochemically by measuring changes to the double layer charging current of the system. Analogous films assembled on silane modified glass slides allow for optical monitoring of film growth and cross-sectional TEM analysis provides an estimated film thickness. During film assembly, manipulation of the MPC ligand protection as well as the interparticle linkage mechanism allow for networked films, that are readily adaptable, to interface with redox protein having different adsorption mechanism. For example, Pseudomonas aeruginosa azurin (AZ) can be adsorbed hydrophobically to dithiol-linked films of hexanethiolate MPCs and cytochrome c (cyt c) can be immobilized electrostatically at a carboxylic acid modified MPC interfacial layer. In this

  1. Affinity binding of antibodies to supermacroporous cryogel adsorbents with immobilized protein A for removal of anthrax toxin protective antigen.

    PubMed

    Ingavle, Ganesh C; Baillie, Les W J; Zheng, Yishan; Lis, Elzbieta K; Savina, Irina N; Howell, Carol A; Mikhalovsky, Sergey V; Sandeman, Susan R

    2015-05-01

    Polymeric cryogels are efficient carriers for the immobilization of biomolecules because of their unique macroporous structure, permeability, mechanical stability and different surface chemical functionalities. The aim of the study was to demonstrate the potential use of macroporous monolithic cryogels for biotoxin removal using anthrax toxin protective antigen (PA), the central cell-binding component of the anthrax exotoxins, and covalent immobilization of monoclonal antibodies. The affinity ligand (protein A) was chemically coupled to the reactive hydroxyl and epoxy-derivatized monolithic cryogels and the binding efficiencies of protein A, monoclonal antibodies to the cryogel column were determined. Our results show differences in the binding capacity of protein A as well as monoclonal antibodies to the cryogel adsorbents caused by ligand concentrations, physical properties and morphology of surface matrices. The cytotoxicity potential of the cryogels was determined by an in vitro viability assay using V79 lung fibroblast as a model cell and the results reveal that the cryogels are non-cytotoxic. Finally, the adsorptive capacities of PA from phosphate buffered saline (PBS) were evaluated towards a non-glycosylated, plant-derived human monoclonal antibody (PANG) and a glycosylated human monoclonal antibody (Valortim(®)), both of which were covalently attached via protein A immobilization. Optimal binding capacities of 108 and 117 mg/g of antibody to the adsorbent were observed for PANG attached poly(acrylamide-allyl glycidyl ether) [poly(AAm-AGE)] and Valortim(®) attached poly(AAm-AGE) cryogels, respectively, This indicated that glycosylation status of Valortim(®) antibody could significantly increase (8%) its binding capacity relative to the PANG antibody on poly(AAm-AGE)-protien-A column (p < 0.05). The amounts of PA which remained in the solution after passing PA spiked PBS through PANG or Valortim bound poly(AAm-AGE) cryogel were significantly (p < 0

  2. Difference in Surface Properties between Insoluble Monolayer and Adsorbed Film from Kinetics of Water Evaporation and BAM Image.

    PubMed

    Moroi, Yoshikiyo; Rusdi, Muhammad; Kubo, Izumi

    2004-05-20

    The evaporation rate of water molecules across three kinds of interfaces (air/water interface (1), air/surfactant solution interface (2), and air/water interface covered by insoluble monolayer (3)) was examined using a remodeled thermogravimetric balance. There was no difference in both the evaporation rate and the activation energy for the first two interfaces for three types of surfactant solutions below and above the critical micelle concentration (cmc). This means that the molecular surface area from the Gibbs surface excess has nothing to do with the evaporation rate. In the third case, the insoluble monolayer of 1-heptadecanol decreased the evaporation rate and increased the activation energy, indicating a clear difference between an insoluble monolayer and an adsorbed film of soluble surfactant. This difference was substantiated by BAM images, too. The images of three surfactant solution interfaces were similar to that of just the water surface, while distinct structures of molecular assemblies were observed for the insoluble monolayer. The concentration profile of water molecules in an air/liquid interfacial region was derived by Fix's second law. The profile indicates that a definite layer just beneath the air/liquid interface of the surfactant solution is made mostly of water molecules and that the layer thickness is a few times the root-mean-square displacement %@mt;sys@%%@rl;;@%2%@ital@%Dt%@rsf@%%@rlx@%%@mx@% of the water molecules. The thickness was found to be more than a few nanometers, as estimated from several relaxation times derived from the other kinetics than evaporation of amphiphilic molecules in aqueous systems and a maximum evaporation rate of purified water. PMID:18950121

  3. Pluripotency transcription factor Sox2 is strongly adsorbed by heparin but requires a protein transduction domain for cell internalization

    SciTech Connect

    Albayrak, Cem; Yang, William C.; Swartz, James R.

    2013-02-15

    Highlights: ► Both R9Sox2 and Sox2 bind heparin with comparable affinity. ► Both R9Sox2 and Sox2 bind to fibroblasts, but only R9Sox2 is internalized. ► Internalization efficiency of R9Sox2 is 0.3% of the administered protein. ► Heparan sulfate adsorption may be part of a mechanism for managing cell death. -- Abstract: The binding of protein transduction domain (PTD)-conjugated proteins to heparan sulfate is an important step in cellular internalization of macromolecules. Here, we studied the pluripotency transcription factor Sox2, with or without the nonaarginine (R9) PTD. Unexpectedly, we observed that Sox2 is strongly adsorbed by heparin and by the fibroblasts without the R9 PTD. However, only the R9Sox2 fusion protein is internalized by the cells. These results collectively show that binding to heparan sulfate is not sufficient for cellular uptake, thereby supporting a recent hypothesis that other proteins play a role in cell internalization of PTD-conjugated proteins.

  4. Protein-protein nanoimprinting of silk fibroin films

    PubMed Central

    Brenckle, Mark A; Tao, Hu; Kim, Sunghwan; Paquette, Mark; Kaplan, David L; Omenetto, Fiorenzo G

    2013-01-01

    Control of the interface between biological tissue and high technology materials is paramount for the development of future applications in biomedicine, especially in the case of implantable integrated devices for signal transduction.[1]-[3] Such work requires careful materials design to develop devices that can efficiently perform technological functions while retaining biocompatibility and biological integration. Silk fibroin protein from the Bombyx mori silkworm has come of considerable interest in this context, owing to its attractive mechanical,[4]-[7] biological, [8][9] and optical properties.[10][11] Recent work has shown adaptation of common micro- and nano-fabrication tools to silk films,[12]-[18] as well as silk protein secondary structure patterning techniques,[19] leading to biocompatible and degradable electronic and photonic devices which can simultaneously act as a carrier and stabilizer for protein pharmaceuticals and other bioactive reagents.[20]-[23] In particular, silk based nanoscale photonic devices face the challenge of sub-wavelength resolution fabrication on a soft polymeric substrate.[15][24] Previous work introduced the possibility of direct, rapid nanoimprinting in silk for the fabrication of photonic structures by leveraging the material properties of this protein.[25] PMID:23483712

  5. In-plane conductance of thin films as a probe of surface chemical environment: Adsorbate effects on film electronic properties of indium tin oxide and gold

    NASA Astrophysics Data System (ADS)

    Swint, Amy Lynn

    Changes in the in-plane conductance of conductive thin films are observed as a result of chemical adsorption at the surface. Reaction of the indium tin oxide (ITO) surface with Bronsted acids (bases) leads to increases (decreases) in its in-plane conductance as measured by a four-point probe configuration. The conductance varies monotonically with pH suggesting that the degree of surface protonation or hydroxylation controls the surface charge density, which in turn affects the width of the n-type depletion layer, and ultimately the in-plane conductance. Measurements at constant pH with a series of tetraalkylammonium hydroxide species of varying cation size indicate that surface dipoles also affect ITO conductance by modulating the magnitude of the surface polarization. Modulating the double layer with varying aqueous salt solutions also affects ITO conductance, though not to the same degree as strong Bronsted acids and bases. Solvents of varying dielectric constant and proton donating ability (ethanol, dimethylformamide) decrease ITO conductance relative to H2O. In addition, changing solvent gives rise to thermally-derived conductance transients, which result from exothermic solvent mixing. The self-assembly of alkanethiols at the surface increases the conductance of ITO films, most likely through carrier population effects. In all cases examined the combined effects of surface charge, adsorbed dipole layer magnitude and carrier injection are responsible for altering the ITO conductance. Besides being directly applicable to the control of electronic properties, these results also point to the use of four-point probe resistance measurements in condensed phase sensing applications. Ultrasensitive conductance-based gas phase sensing of organothiol adsorption to gold nanowires is accomplished with a limit of detection in the 105 molecule range. Further refinement of the inherently low noise resistance measurement may lead to observation of single adsorption events at

  6. Theory and applications of refractive index-based optical microscopy to measure protein mass transfer in spherical adsorbent particles.

    PubMed

    Bankston, Theresa E; Stone, Melani C; Carta, Giorgio

    2008-04-25

    This work provides the theoretical foundation and a range of practical application examples of a recently developed method to measure protein mass transfer in adsorbent particles using refractive index-based optical microscopy. A ray-theoretic approach is first used to predict the behavior of light traveling through a particle during transient protein adsorption. When the protein concentration gradient in the particle is sharp, resulting in a steep refractive index gradient, the rays bend and intersect, thereby concentrating light in a sharp ring that marks the position of the adsorption front. This behavior is observed when mass transfer is dominated by pore diffusion and the adsorption isotherm is highly favorable. Applications to protein cation-exchange, hydrophobic interaction, and affinity adsorption are then considered using, as examples, the three commercial, agarose-based stationary phases SP-Sepharose-FF, Butyl Sepharose 4FF, and MabSelect. In all three cases, the method provides results that are consistent with measurements based on batch adsorption and previously published data confirming its utility for the determination of protein mass transfer kinetics under a broad range of practically relevant conditions. PMID:18353343

  7. Sum Frequency Generation Vibrational Spectroscopy of Adsorbed Amino Acids, Peptides and Proteins of Hydrophilic and Hydrophobic Solid-Water Interfaces

    SciTech Connect

    Holinga IV, George Joseph

    2010-09-01

    Sum frequency generation (SFG) vibrational spectroscopy was used to investigate the interfacial properties of several amino acids, peptides, and proteins adsorbed at the hydrophilic polystyrene solid-liquid and the hydrophobic silica solid-liquid interfaces. The influence of experimental geometry on the sensitivity and resolution of the SFG vibrational spectroscopy technique was investigated both theoretically and experimentally. SFG was implemented to investigate the adsorption and organization of eight individual amino acids at model hydrophilic and hydrophobic surfaces under physiological conditions. Biointerface studies were conducted using a combination of SFG and quartz crystal microbalance (QCM) comparing the interfacial structure and concentration of two amino acids and their corresponding homopeptides at two model liquid-solid interfaces as a function of their concentration in aqueous solutions. The influence of temperature, concentration, equilibration time, and electrical bias on the extent of adsorption and interfacial structure of biomolecules were explored at the liquid-solid interface via QCM and SFG. QCM was utilized to quantify the biological activity of heparin functionalized surfaces. A novel optical parametric amplifier was developed and utilized in SFG experiments to investigate the secondary structure of an adsorbed model peptide at the solid-liquid interface.

  8. [Melting in adsorbed films

    SciTech Connect

    Simon, M.I.

    1992-01-01

    Over the past several years we have been developing a new approach to cloning large fragments of mammalian DNA in E. coli. which will permit detailed analysis of complex genomes. In January 1992 we began construction of an arrayed total human genomic library prepared in our BAC vector. Our goal is to create a 4-5X library which will be accessible for screening both by colony hybridization and by PCR. Our efforts in 1992 have been focused on expanding this library, characterizing specific clones isolated from the library, and demonstrating the use of BACs and Fosmids in creating physical maps. As a Model for the use of BACs in physical mapping, we have begun mapping human chromosome 22. In addition to their stability and ease of handling, BACs and Fosniids offer the advantage of permitting isolation of relatively large amounts of pure DNA which should greatly facilitate contig construction. We have created a 7X chromosome 22-specific Fosmid library consisting of clones obtained from DNA from a hybrid cell line.

  9. Preparation of Modified Films with Protein from Grouper Fish.

    PubMed

    Valdivia-López, M A; Tecante, A; Granados-Navarrete, S; Martínez-García, C

    2016-01-01

    A protein concentrate (PC) was obtained from Grouper fish skin and it was used to prepare films with different amounts of sorbitol and glycerol as plasticizers. The best performing films regarding resistance were then modified with various concentrations of CaCl2, CaSO4 (calcium salts), and glucono-δ-lactone (GDL) with the purpose of improving their mechanical and barrier properties. These films were characterized by determining their mechanical properties and permeability to water vapor and oxygen. Formulations with 5% (w/v) protein and 75% sorbitol and 4% (w/v) protein with a mixture of 15% glycerol and 15% sorbitol produced adequate films. Calcium salts and GDL increased the tensile fracture stress but reduced the fracture strain and decreased water vapor permeability compared with control films. The films prepared represent an attractive alternative for being used as food packaging materials. PMID:27597950

  10. Preparation of Modified Films with Protein from Grouper Fish

    PubMed Central

    Tecante, A.; Granados-Navarrete, S.; Martínez-García, C.

    2016-01-01

    A protein concentrate (PC) was obtained from Grouper fish skin and it was used to prepare films with different amounts of sorbitol and glycerol as plasticizers. The best performing films regarding resistance were then modified with various concentrations of CaCl2, CaSO4 (calcium salts), and glucono-δ-lactone (GDL) with the purpose of improving their mechanical and barrier properties. These films were characterized by determining their mechanical properties and permeability to water vapor and oxygen. Formulations with 5% (w/v) protein and 75% sorbitol and 4% (w/v) protein with a mixture of 15% glycerol and 15% sorbitol produced adequate films. Calcium salts and GDL increased the tensile fracture stress but reduced the fracture strain and decreased water vapor permeability compared with control films. The films prepared represent an attractive alternative for being used as food packaging materials. PMID:27597950

  11. Protein immobilization and fluorescence quenching on polydopamine thin films.

    PubMed

    Chen, Daqun; Zhao, Lei; Hu, Weihua

    2016-09-01

    Mussel inspired polydopamine (PDA) film has attracted great interest as a versatile functional coating for biomolecule immobilization in various bio-related devices. However, the details regarding the interaction between a protein and PDA film remain unclear. Particularly, there is very limited knowledge regarding the protein immobilization on PDA film, even though it is of essential importance in various fields. The situation is even more complicated if considering the fact that quite a number of approaches (e.g., different oxidizing reagent, buffer pH, grown time, grown media, etc.) have been developed to grow PDA films. In this work, protein attachment on PDA film was systematically investigated by using the real-time and label-free surface plasmon resonance (SPR) technique. The kinetics of protein-PDA interaction was explored and the influence of buffer pH and deposition media on the protein attachment was studied. Fluorescent protein microarray was further printed on PDA-coated glass slides for quantitative investigations and together with SPR data, the interesting fluorescence quenching phenomenon of PDA film was revealed. This work may deepen our understanding on the PDA-protein interaction and offer a valuable guide for efficient protein attachment on PDA film in various bio-related applications. PMID:27254254

  12. Elastic response of a protein monolayer adsorbed at decorated water surface

    NASA Astrophysics Data System (ADS)

    Singh, Amarjeet; Konovalov, Oleg

    2015-05-01

    Under the in-plane isothermal compression the self-assembled protein monolayer expand in the direction perpendicular to the applied force as a function of applied compression. The structure finally buckle beyond a critical compression, which finally returns to the initial structure when the compression force was removed, behaving like an elastic body. We modelled the layer as homogeneous elastic medium and calculated elastic constants. Young's modulus of the protein layer is 2 orders of magnitude smaller than the bulk lysozyme crystals. It is of fundamental significance to be able to predict the elastic properties of the proteins at air-water interface since protein remains in their natural environment unlike protein crystals.

  13. Porous ceramic/agarose composite adsorbents for fast protein liquid chromatography.

    PubMed

    Xia, Haifeng; Jin, Xionghua; Wu, Puqiang; Zheng, Zhiyong

    2012-02-01

    Porous ceramic/agarose composite adsorbents were designed and prepared with silica ceramic beads and 4% agarose gel, and then functionalized with a special ligand carboxymethyl. A novel method was introduced to fabricating of the porous silica ceramic beads. The morphology of SEM shows a spherical shape and a porous structure of the ceramic beads. Nitrogen adsorption-desorption analysis gives an average pore size of 287.5 Å, a BET surface area of 29.33 m²/g and a porosity of 41.8%, respectively. Additionally, X-ray diffraction pattern indicates that the amorphous silica has been transformed into two crystal phases of quartz and cristobalite, leading to a porous and rigid skeleton and ensuring the application of the composite beads at high flow velocities. Lysozyme of hen egg-white with the activity of 12,700 U/mg was purified by the composite ion-exchanger in one step and the recovery and purification factor reaches 95.2% and 7.9, respectively. PMID:22226554

  14. Rapid protein immobilization for thin film continuous flow biocatalysis.

    PubMed

    Britton, Joshua; Raston, Colin L; Weiss, Gregory A

    2016-08-01

    A versatile enzyme immobilization strategy for thin film continuous flow processing is reported. Here, non-covalent and glutaraldehyde bioconjugation are used to immobilize enzymes on the surfaces of borosilicate reactors. This approach requires only ng of protein per reactor tube, with the stock protein solution readily recycled to sequentially coat >10 reactors. Confining reagents to thin films during immobilization reduced the amount of protein, piranha-cleaning solution, and other reagents by ∼96%. Through this technique, there was no loss of catalytic activity over 10 h processing. The results reported here combines the benefits of thin film flow processing with the mild conditions of biocatalysis. PMID:27461146

  15. Quantitative proteomics analysis of adsorbed plasma proteins classifies nanoparticles with different surface properties and size

    SciTech Connect

    Zhang, Haizhen; Burnum, Kristin E.; Luna, Maria L.; Petritis, Brianne O.; Kim, Jong Seo; Qian, Weijun; Moore, Ronald J.; Heredia-Langner, Alejandro; Webb-Robertson, Bobbie-Jo M.; Thrall, Brian D.; Camp, David G.; Smith, Richard D.; Pounds, Joel G.; Liu, Tao

    2011-12-01

    In biofluids (e.g., blood plasma) nanoparticles are readily embedded in layers of proteins that can affect their biological activity and biocompatibility. Herein, we report a study on the interactions between human plasma proteins and nanoparticles with a controlled systematic variation of properties using stable isotope labeling and liquid chromatography-mass spectrometry (LC-MS) based quantitative proteomics. Novel protocol has been developed to simplify the isolation of nanoparticle bound proteins and improve the reproducibility. Plasma proteins associated with polystyrene nanoparticles with three different surface chemistries and two sizes as well as for four different exposure times (for a total of 24 different samples) were identified and quantified by LC-MS analysis. Quantitative comparison of relative protein abundances were achieved by spiking an 18 O-labeled 'universal reference' into each individually processed unlabeled sample as an internal standard, enabling simultaneous application of both label-free and isotopic labeling quantitation across the sample set. Clustering analysis of the quantitative proteomics data resulted in distinctive pattern that classifies the nanoparticles based on their surface properties and size. In addition, data on the temporal study indicated that the stable protein 'corona' that was isolated for the quantitative analysis appeared to be formed in less than 5 minutes. The comprehensive results obtained herein using quantitative proteomics have potential implications towards predicting nanoparticle biocompatibility.

  16. Capillary electrophoresis-mass spectrometry of basic proteins using a new physically adsorbed polymer coating. Some applications in food analysis.

    PubMed

    Simó, Carolina; Elvira, Carlos; González, Nieves; San Román, J; Barbas, Coral; Cifuentes, Alejandro

    2004-07-01

    A new physically adsorbed capillary coating for capillary electrophoresis-mass spectrometry (CE-MS) of basic proteins is presented, which is easily obtained by flushing the capillary with a polymer aqueous solution for two min. This coating significantly reduces the electrostatic adsorption of a group of basic proteins (i.e., cytochrome c, lysozyme, and ribonuclease A) onto the capillary wall allowing their analysis by CE-MS. The coating protocol is compatible with electrospray inonization (ESI)-MS via the reproducible separation of the standard basic proteins (%RSD values (n = 5) < 1% for analysis time reproducibility and < 5% for peak heights, measured from the total ion electropherograms (TIEs) within the same day). The LODs determined using cytochrome c with total ion current and extracted ion current defection were 24.5 and 2.9 fmol, respectively. Using this new coating lysozymes from chicken and turkey egg white could be easily distinguished by CE-MS, demonstrating the usefulness of this method to differentiate animal species. Even after sterilization at 120 degrees C for 30 min, lysozyme could be detected, as well as in wines at concentrations much lower than the limit marked by the EC Commission Regulation. Adulteration of minced meat with 5% of egg-white could also be analysed by our CE-MS protocol. PMID:15237406

  17. Localized entrapment of green fluorescent protein within nanostructured polymer films

    NASA Astrophysics Data System (ADS)

    Ankner, John; Kozlovskaya, Veronika; O'Neill, Hugh; Zhang, Qiu; Kharlampieva, Eugenia

    2012-02-01

    Protein entrapment within ultrathin polymer films is of interest for applications in biosensing, drug delivery, and bioconversion, but controlling protein distribution within the films is difficult. We report on nanostructured protein/polyelectrolyte (PE) materials obtained through incorporation of green fluorescent protein (GFP) within poly(styrene sulfonate)/poly(allylamine hydrochloride) multilayer films assembled via the spin-assisted layer-by-layer method. By using deuterated GFP as a marker for neutron scattering contrast we have inferred the architecture of the films in both normal and lateral directions. We find that films assembled with a single GFP layer exhibit a strong localization of the GFP without intermixing into the PE matrix. The GFP volume fraction approaches the monolayer density of close-packed randomly oriented GFP molecules. However, intermixing of the GFP with the PE matrix occurs in multiple-GFP layer films. Our results yield new insight into the organization of immobilized proteins within polyelectrolyte matrices and open opportunities for fabrication of protein-containing films with well-organized structure and controllable function, a crucial requirement for advanced sensing applications.

  18. Paramagnetic Nanoparticles Leave Their Mark on Nuclear Spins of Transiently Adsorbed Proteins.

    PubMed

    Zanzoni, Serena; Pedroni, Marco; D'Onofrio, Mariapina; Speghini, Adolfo; Assfalg, Michael

    2016-01-13

    The successful application of nanomaterials in biosciences necessitates an in-depth understanding of how they interface with biomolecules. Transient associations of proteins with nanoparticles (NPs) are accessible by solution NMR spectroscopy, albeit with some limitations. The incorporation of paramagnetic centers into NPs offers new opportunities to explore bio-nano interfaces. We propose NMR paramagnetic relaxation enhancement as a new tool to detect NP-binding surfaces on proteins with increased sensitivity, also extending the applicability of NMR investigations to heterogeneous biomolecular mixtures. The adsorption of ubiquitin on gadolinium-doped fluoride-based NPs produced residue-specific NMR line-broadening effects mapping to a contiguous area on the surface of the protein. Importantly, an identical paramagnetic fingerprint was observed in the presence of a competing protein-protein association equilibrium, exemplifying possible interactions taking place in crowded biological media. The interaction was further characterized using isothermal titration calorimetry and upconversion emission measurements. The data indicate that the used fluoride-based NPs are not biologically inert but rather are capable of biomolecular recognition. PMID:26683352

  19. The Development of an Edible Peanut Protein Film

    NASA Technical Reports Server (NTRS)

    Patrick, N.; Jones, G.; Aglan, H.; Lu, J.

    1998-01-01

    The peanut is one of the crops chosen for use in NASA's Advanced Life Support Program (ALS). The peanut is a source of both oil and protein. After oil is extracted from the peanut, a protein rich flour remains. An edible peanut protein film is one use for this flour. Two types of film are developed for this study, one set of film contains 10% fat while the other set contains no fat. For film without fat the defatting of the peanut by the Soxhlet method is the first step in the manufacturing process of the film. Secondly, the protein is precipitated at its isoelectric point (pH 4.5) and centrifuged to separate the protein from the non-protein. After freeze-drying the protein it is milled in a ceramic ball mill to decrease particle size and sifted through a series of sieves to determine particle size distribution. Those particles retained on the 100 mesh sieves are utilized for film formation. Larger particles are re-ground and sifted. Five grams of protein is mixed with 50 mL of distilled water, 70 mL of 80% ethanol, 15 mL of 6N ammonium hydroxide and a plasticizer. This mixture is heated for 30 minutes until the temperature reaches 70 C. The mixture is then poured onto a level Teflon coated glass surface. After allowing the film to form overnight under a ventilation hood, it is manually removed from the plate. The processes and methods adopted have created flexible films of uniform thickness that are free of air bubbles. Thickness of films made from defatted peanut protein and partially defatted peanut protein were 0.10 Lm and 0.13 Lm respectively. Films with natural peanut fat are approximately three times as flexible and almost four times as strong as the films made without fat. Further research will be performed to evaluate its mechanical properties. This paper will greatly contribute to food preservation and waste management. Potential applications of this film are edible/biodegradable containers, wrapping for food preservation (against water, oxygen and oil

  20. Thermoplastic processing of proteins for film formation--a review.

    PubMed

    Hernandez-Izquierdo, V M; Krochta, J M

    2008-03-01

    Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability. PMID:18298745

  1. In situ x-ray photoelectron spectroscopic and density-functional studies of Si atoms adsorbed on a C60 film.

    PubMed

    Onoe, Jun; Nakao, Aiko; Hara, Toshiki

    2004-12-01

    The interaction between C(60) and Si atoms has been investigated for Si atoms adsorbed on a C(60) film using in situ x-ray photoelectron spectroscopy (XPS) and density-functional (DFT) calculations. Analysis of the Si 2p core peak identified three kinds of Si atoms adsorbed on the film: silicon suboxides (SiO(x)), bulk Si crystal, and silicon atoms bound to C(60). Based on the atomic percent ratio of silicon to carbon, we estimated that there was approximately one Si atom bound to each C(60) molecule. The Si 2p peak due to the Si-C(60) interaction demonstrated that a charge transfer from the Si atom to the C(60) molecule takes place at room temperature, which is much lower than the temperature of 670 K at which the charge transfer was observed for C(60) adsorbed on Si(001) and (111) clean surfaces [Sakamoto et al., Phys. Rev. B 60, 2579 (1999)]. The number of electrons transferred between the C(60) molecule and Si atom was estimated to be 0.59 based on XPS results, which is in good agreement with the DFT result of 0.63 for a C(60)Si with C(2v) symmetry used as a model cluster. Furthermore, the shift in binding energy of both the Si 2p and C 1s core peaks before and after Si-atom deposition was experimentally obtained to be +2.0 and -0.4 eV, respectively. The C(60)Si model cluster provides the shift of +2.13 eV for the Si 2p core peak and of -0.28 eV for the C 1s core peak, which are well corresponding to those experimental results. The covalency of the Si-C(60) interaction was also discussed in terms of Mulliken overlap population between them. PMID:15634092

  2. Heterogeneous patterns on block copolymer thin film via solvent annealing: Effect on protein adsorption

    NASA Astrophysics Data System (ADS)

    Shen, Lei; Zhu, Jintao; Liang, Haojun

    2015-03-01

    Heterogeneous patterns consisting of nanometer-scaled hydrophobic/hydrophilic domains were generated by self-assembly of poly(styrene)-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) block copolymer thin film. The effect of the heterogeneity of the polymer film surface on the nonspecific adsorption of the protein human plasma fibrinogen (FBN, 5.0 × 5.0 × 47.5 nm3) was investigated. The kinetics of the FBN adsorption varies from a single-component Langmuir model on homogeneous hydrophilic PHEMA to a two-stage spreading relaxation model on homogeneous hydrophobic PS surface. On a heterogeneous PS-b-PHEMA surface with majority PS part, the initial FBN adsorption rate remains the same as that on the homogeneous PS surface. However, hydrophilic PHEMA microdomains on the heterogeneous surface slow down the second spreading stage of the FBN adsorption process, leading to a surface excess of adsorbed FBN molecules less than the presumed one simply calculated as adsorption onto multiple domains. Importantly, when the PS-b-PHEMA surface is annealed to form minority domelike PS domains (diameter: ˜50-100 nm) surrounded by a majority PHEMA matrix, such surface morphology proves to be strongly protein-repulsive. These interesting findings can be attributed to the enhancement of the spread FBN molecule in a mobile state by the heterogeneity of polymer film surface before irreversible adsorption occurs.

  3. Application of an Antimicrobial Protein Film in Beef Patties Packaging.

    PubMed

    Lee, Ji-Hyun; Song, Kyung Bin

    2015-01-01

    This study was performed to apply a protein film containing a natural antimicrobial compound to meat packaging and determine quality change of meat during storage. Proteins obtained from the by-products of food processing have been utilized as biodegradable film sources. Porcine meat and bone meal (MBM) is obtained during meat processing, and proteins from the MBM can be extracted and used as a film base material. Previously, an antimicrobial MBM film containing coriander oil (CO) was prepared and its physical properties and antimicrobial activity were characterized. In this study, the antimicrobial MBM-CO film was applied to beef patties packaging, and the microbial population and the degree of lipid oxidation were determined during storage at 4℃ for 15 d. The population of inoculated E. coli O157:H7 in the samples wrapped with the MBM-CO film was 6.78 log colony forming unit (CFU)/g after 15 d of storage, whereas the control had 8.05 Log CFU/g, thus reducing the microbial population by 1.29 Log CFU/g. In addition, retardation of lipid oxidation in the patties was observed during storage for the samples packaged by the MBM-CO film, compared with the control samples. These results suggest that the MBM-CO film can be useful for enhancing the quality of beef patties during storage. PMID:26761888

  4. Application of an Antimicrobial Protein Film in Beef Patties Packaging

    PubMed Central

    2015-01-01

    This study was performed to apply a protein film containing a natural antimicrobial compound to meat packaging and determine quality change of meat during storage. Proteins obtained from the by-products of food processing have been utilized as biodegradable film sources. Porcine meat and bone meal (MBM) is obtained during meat processing, and proteins from the MBM can be extracted and used as a film base material. Previously, an antimicrobial MBM film containing coriander oil (CO) was prepared and its physical properties and antimicrobial activity were characterized. In this study, the antimicrobial MBM-CO film was applied to beef patties packaging, and the microbial population and the degree of lipid oxidation were determined during storage at 4℃ for 15 d. The population of inoculated E. coli O157:H7 in the samples wrapped with the MBM-CO film was 6.78 log colony forming unit (CFU)/g after 15 d of storage, whereas the control had 8.05 Log CFU/g, thus reducing the microbial population by 1.29 Log CFU/g. In addition, retardation of lipid oxidation in the patties was observed during storage for the samples packaged by the MBM-CO film, compared with the control samples. These results suggest that the MBM-CO film can be useful for enhancing the quality of beef patties during storage. PMID:26761888

  5. Selective Ni-P electroless plating on photopatterned cationic adsorption films influenced by alkyl chain lengths of polyelectrolyte adsorbates and additive surfactants.

    PubMed

    Nakagawa, Masaru; Nawa, Nozomi; Iyoda, Tomokazu

    2004-10-26

    We demonstrated that the photopatterned single-layer adsorption film of poly(1-dodecyl-4-pyridinium bromide) on a silica surface was available for a template of nickel-phosphorus (Ni-P) electroless plating through sensitization with a SnCl(2) aqueous solution and activation with a PdCl(2) aqueous solution. Four kinds of poly(1-alkyl-4-vinylpyridinium halide)s bearing methyl, propyl, hexyl, and dodecyl groups were prepared. The cationic polymers were adsorbed by a negatively charged silica surface from their solutions, to form single-layer adsorption films exhibiting desorption-resistance toward deionized water and ethanol. The organic adsorption films could be decomposed completely by exposure to 172 nm deep-UV light. The formation and decomposition of the single-layer films were confirmed by deep-UV absorption spectral measurement and zeta-potential measurement. Ni-P electroless plating was carried out on the photopatterned adsorption films, using three types of SnO(x) colloidal materials without and with cationic or anionic surfactant as catalyst precursors in the sensitization step. In the case of the negatively charged SnO(x) colloids surrounded by anionic surfactant, Ni-deposition took place preferentially on the cationic adsorption films remaining in unexposed regions. The Ni-deposition was accelerated significantly on the cationic adsorption film bearing dodecyl groups. It was obvious by ICP-AES analyses that the hydrophobic long-chain dodecyl groups in the adsorption film could promote the adsorption of the negative SnO(x) colloids on the film surface, followed by much nucleus formation of zerovalent Pd catalysts useful for the electroless plating. The result of our experiment clearly showed that, in addition to electrostatic interaction, van der Waals interaction generating between the hydrophobic long-chain hydrocarbons of the adsorption film and the surfactant improved significantly the adsorption stability of the SnO(x) colloids, resulting in highly

  6. Elastic Properties of Protein Functionalized Nanoporous Polymer Films.

    PubMed

    Wang, Haoyu; Black, Charles T; Akcora, Pinar

    2016-01-12

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Our results show that protein functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces. PMID:26672623

  7. Elastic properties of protein functionalized nanoporous polymer films

    SciTech Connect

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that protein functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.

  8. Adsorbent phosphates

    NASA Technical Reports Server (NTRS)

    Watanabe, S.

    1983-01-01

    An adsorbent which uses as its primary ingredient phosphoric acid salts of zirconium or titanium is presented. Production methods are discussed and several examples are detailed. Measurements of separating characteristics of some gases using the salts are given.

  9. Elastic properties of protein functionalized nanoporous polymer films

    DOE PAGESBeta

    Charles T. Black; Wang, Haoyu; Akcora, Pinar

    2015-12-16

    Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that proteinmore » functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.« less

  10. Conformational changes of α-lactalbumin adsorbed at oil-water interfaces: interplay between protein structure and emulsion stability.

    PubMed

    Zhai, Jiali; Hoffmann, Søren V; Day, Li; Lee, Tzong-Hsien; Augustin, Mary Ann; Aguilar, Marie-Isabel; Wooster, Tim J

    2012-02-01

    The conformation and structural dimensions of α-lactalbumin (α-La) both in solution and adsorbed at oil-water interfaces of emulsions were investigated using synchrotron radiation circular dichroism (SRCD) spectroscopy, front-face tryptophan fluorescence (FFTF) spectroscopy, and dual polarization interferometry (DPI). The near-UV SRCD and the FFTF results demonstrated that the hydrophobic environment of the aromatic residues located in the hydrophobic core of native α-La was significantly altered upon adsorption, indicating the unfolding of the hydrophobic core of α-La upon adsorption. The far-UV SRCD results showed that adsorption of α-La at oil-water interfaces created a new non-native secondary structure that was more stable to thermally induced conformational changes. Specifically, the α-helical conformation increased from 29.9% in solution to 45.8% at the tricaprylin-water interface and to 58.5% at the hexadecane-water interface. However, the β-sheet structure decreased from 18.0% in solution to less than 10% at both oil-water interfaces. The DPI study showed that adsorption of α-La to a hydrophobic C18-water surface caused a change in the dimensions of α-La from the native globule-like shape (2.5-3.7 nm) to a compact/dense layer approximately 1.1 nm thick. Analysis of the colloidal stability of α-La stabilized emulsions showed that these emulsions were physically stable against droplet flocculation at elevated temperatures both in the absence and in the presence of 120 mM NaCl. In the absence of salt, the thermal stability of emulsions was due to the strong electrostatic repulsion provided by the adsorbed α-La layer, which was formed after the adsorption and structural rearrangement. In the presence of salt, although the electrostatic repulsion was reduced via electrostatic screening, heating did not induce strong and permanent droplet flocculation. The thermal stability of α-La stabilized emulsions in the presence of salt is a combined effect of

  11. The relationship between redox enzyme activity and electrochemical potential-cellular and mechanistic implications from protein film electrochemistry.

    PubMed

    Gates, Andrew J; Kemp, Gemma L; To, Chun Yip; Mann, James; Marritt, Sophie J; Mayes, Andrew G; Richardson, David J; Butt, Julea N

    2011-05-01

    In protein film electrochemistry a redox protein of interest is studied as an electroactive film adsorbed on an electrode surface. For redox enzymes this configuration allows quantification of the relationship between catalytic activity and electrochemical potential. Considered as a function of enzyme environment, i.e., pH, substrate concentration etc., the activity-potential relationship provides a fingerprint of activity unique to a given enzyme. Here we consider the nature of the activity-potential relationship in terms of both its cellular impact and its origin in the structure and catalytic mechanism of the enzyme. We propose that the activity-potential relationship of a redox enzyme is tuned to facilitate cellular function and highlight opportunities to test this hypothesis through computational, structural, biochemical and cellular studies. PMID:21423952

  12. New diffusive gradients in a thin film technique for measuring inorganic arsenic and selenium(IV) using a titanium dioxide based adsorbent.

    PubMed

    Bennett, William W; Teasdale, Peter R; Panther, Jared G; Welsh, David T; Jolley, Dianne F

    2010-09-01

    A new diffusive gradients in a thin film (DGT) technique, using a titanium dioxide based adsorbent (Metsorb), has been developed and evaluated for the determination of dissolved inorganic arsenic and selenium. As(III), As(V), and Se(IV) were found to be quantitatively accumulated by the adsorbent (uptake efficiencies of 96.5-100%) and eluted in 1 M NaOH (elution efficiencies of 81.2%, 75.2%, and 88.7%). Se(VI) was not quantitatively accumulated by the adsorbent (<20%). Laboratory DGT validation experiments gave linear mass uptake over time (R(2) >or= 0.998) for As(III), As(V), and Se(IV). Consistent uptake occurred over pH (3.5-8.5) and ionic strength (0.0001-0.75 mol L(-1) NaNO(3)) ranges typical of natural waters, including seawater. Field deployments of DGT probes with various diffusive layer thicknesses confirmed the use of the technique in situ, allowing calculation of the diffusive boundary layers and an accurate measurement of inorganic arsenic. Reproducibility of the technique in field deployments was good (relative standard deviation <8%). Limits of detection (4 day deployments) were 0.01 microg L(-1) for inorganic arsenic and 0.05 microg L(-1) for Se(IV). The results of this study confirmed that DGT with Metsorb was a reliable and robust method for the measurement of inorganic arsenic and the selective measurement of Se(IV) within useful limits of accuracy. PMID:20695441

  13. Immunological Identification of Fibrinogen in Dual-Component Protein Films by AFM Imaging

    PubMed Central

    Soman, Pranav; Rice, Zachary; Siedlecki, Christopher A.

    2009-01-01

    The success of long-term blood-contacting implanted devices is largely dependent upon the interaction of the blood components with the device biomaterial surface. The ability to study these interactions has been hindered by a lack of methods to measure single-molecule interactions in complex multi-protein environments similar to the environment found in-vivo. In this paper, we demonstrate the use of atomic force microscopy (AFM) in conjunction with gold nanolabels to detect the protein fibrinogen under aqueous conditions without the topographical clues usually necessary for high resolution visualization. BSA was patterned onto both muscovite mica and plasma-treated polydimethylsiloxane (PDMS) substrates and these test substrates were subsequently backfilled with fibrinogen to yield a featureless protein layer. The fibrinogen in this dual protein layer was detected using high resolution AFM imaging following infusion of anti-fibrinogen conjugated with nanogold particles. This AFM immuno-detection technique will potentially be applicable to complex multi-component protein films adsorbed on clinically-relevant polymers used in medical devices. PMID:18294855

  14. 3He Bilayer Film Adsorbed on Graphite Plated with a Bilayer of 4He: a New Frustrated 2D Magnetic System

    NASA Astrophysics Data System (ADS)

    Neumann, Michael; Nyéki, Ján; Cowan, Brian; Saunders, John

    2006-09-01

    The heat capacity and NMR response of a 3He bilayer adsorbed on graphite plated with a bilayer of 4He have been measured over the temperature range 1-80 mK. We find that the first 3He layer requires the presence of a 3He fluid overlayer before it solidifies. Solidification is completed at a total coverage close to 9.85 nm-2, On further increasing the coverage the heat capacity maximum grows from `antiferromagnetic-like' (AFM-like) to `ferromagnetic-like' (FM-like). On the other hand, when the 3He layer first solidifies, it has a low temperature saturation magnetisation corresponding to a significant fraction of full polarisation, and this increases with increasing coverage. Furthermore the effective exchange constant inferred from the high temperature magnetisation data is always ferromagnetic. The effective exchange constants inferred from the heat capacity and magnetisation are significantly larger than those observed in the second layer of pure 3He films adsorbed on bare graphite. Otherwise there are strong similarities in the coverage dependence of the heat capacity and magnetisation, providing fresh insights into how the magnetic ground state of such 2D magnets evolves as the frustration is tuned with increasing coverage.

  15. Interaction of Human Plasma Proteins with Thin Gelatin-Based Hydrogel Films: A QCM-D and ToF-SIMS Study

    PubMed Central

    2015-01-01

    In the fields of surgery and regenerative medicine, it is crucial to understand the interactions of proteins with the biomaterials used as implants. Protein adsorption directly influences cell-material interactions in vivo and, as a result, regulates, for example, cell adhesion on the surface of the implant. Therefore, the development of suitable analytical techniques together with well-defined model systems allowing for the detection, characterization, and quantification of protein adsorbates is essential. In this study, a protocol for the deposition of highly stable, thin gelatin-based films on various substrates has been developed. The hydrogel films were characterized morphologically and chemically. Due to the obtained low thickness of the hydrogel layer, this setup allowed for a quantitative study on the interaction of human proteins (albumin and fibrinogen) with the hydrogel by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). This technique enables the determination of adsorbant mass and changes in the shear modulus of the hydrogel layer upon adsorption of human proteins. Furthermore, Secondary Ion Mass Spectrometry and principal component analysis was applied to monitor the changed composition of the topmost adsorbate layer. This approach opens interesting perspectives for a sensitive screening of viscoelastic biomaterials that could be used for regenerative medicine. PMID:24956040

  16. Nanoscale confinement and interfacial effects on the dynamics and glass transition/crystallinity of thin adsorbed films on silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Madathingal, Rajesh Raman

    The research investigated in this dissertation has focused on understanding the structure-property-function relationships of polymer nanocomposites. The properties of composite systems are dictated by the properties of their components, typically fillers in a polymer matrix. In nanocomposites, the polymer near an interface has significantly different properties compared with the bulk polymer, and the contribution of the adsorbed polymer to composite properties becomes increasingly important as the filler size decreases. Despite many reports of highly favorable properties, the behavior of polymer nanocomposites is not generally predictable, and thus requires a better understanding of the interfacial region. The ability to tailor the filler/matrix interaction and an understanding of the impact of the interface on macroscopic properties are keys in the design of nanocomposite properties. In this original work the surface of silica nanoparticles was tailored by: (a) Changing the number of sites for polymer attachment by varying the surface silanols and, (b) By varying the size/curvature of nanoparticles. The effect of surface tailoring on the dynamic properties after the adsorption of two model polymers, amorphous polymethyl methacrylate (PMMA) and semicrystalline polyethylene oxide (PEO) was observed. The interphase layer of polymers adsorbed to silica surfaces is affected by the surface silanol density as well as the relative size of the polymer compared with the size of the adsorbing substrate. The non-equilibrium adsorption of PMMA onto individual colloidal Stober silica (SiO2) particles, where Rparticle (100nm) > RPMMA (˜6.5nm) was compared with the adsorption onto fumed silica, where Rparticle (7nm) ˜ RPMMA (6.5nm) < Raggregate (˜1000nm), both as a function of silanol density [SiOH] and hydrophobility. In the former case, TEM images showed that the PMMA adsorbed onto individual nanoparticles, so that the number of PMMA chains/bead could be calculated, whereas

  17. In situ ATR-IR spectroscopy study of adsorbed protein: Visible light denaturation of bovine serum albumin on TiO2

    NASA Astrophysics Data System (ADS)

    Bouhekka, A.; Bürgi, T.

    2012-11-01

    In this work in situ Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy in a flow-through cell was used to study the effect of visible light irradiation on bovine serum albumin (BSA) adsorbed on porous TiO2 films. The experiments were performed in water at concentrations of 10-6 mol/l at room temperature. The curve fitting method of the second derivative spectra allowed us to explore details of the secondary structure of pure BSA in water and conformation changes upon adsorption as well as during and after illumination by visible light. The results clearly show that visible light influences the conformation of adsorbed BSA. The appearance of a shift of the amide I band, in the original spectra, from 1653 cm-1 to 1648 cm-1, is interpreted by the creation of random coil in the secondary structure of adsorbed BSA. The second derivative analysis of infrared spectra permits direct quantitative analysis of the secondary structural components of BSA, which show that the percentage of α-helix decreases during visible light illumination whereas the percentage of random coil increases.

  18. Preparation of Polypyrrole-Protein Composite Films and the Electrochemically Controlled Release of Proteins.

    PubMed

    Jin, Juan; Huang, Zhongbing; Yin, Guangfu; Lin, Jiangli; Li, Qiuping; Han, Donghui

    2016-03-01

    It is fabricated that an electrically controlled release system based on the (poly-L-lactic acid)-mixed polypyrrole (PLLA-PPy) films through casting film of PPy and PLLA mixed solution on the glass plate, in which polyglutamic acid (PGlu)-doped PPy nanoparticles (NPs) with -50 nm diameter are synthesized via chemical oxidation. Surface conductivity of the composite film is (3.33 ± 2.01) x 10(-3) S/cm. Bovine serum albumin (BSA), as a model protein drug, is chemically linked onto the composite film via carbodiimide chemistry due to the good surface nano-structure of PLLA-PPy film. The releases of BSA from PLLA-PPy film under constant current and constant voltage can be achieved using the two-electrode electrochemical system. 6 h accumulative releases of BSA are 276 μg/cm2 and 176 μg/cm2 under 3 mA and 1 V electrical stimulation, respectively, accompanied with de-doping of PGlu and separation of a part of PPy NPs from the composite film. The results of cell experiment indicate that PGlu-doped PPy NPs in the prepared composite film have good cyto-compatibility. These results suggest that PPy-PLLA composite film would be able to be applied in the construction of degradable protein-drug-loaded scaffold for nerve tissue repair. PMID:27455630

  19. Molecular orientation distributions in protein films: III. Yeast cytochrome c immobilized on pyridyl disulfide-capped phospholipid bilayers.

    PubMed Central

    Edmiston, P L; Saavedra, S S

    1998-01-01

    Molecular orientation in a hydrated monolayer film of yeast cytochrome c, immobilized via disulfide bonding between Cys-102 and a pyridyl disulfide-capped phospholipid bilayer deposited from an air-water interface onto glass substrates, was investigated. The orientation distribution of the heme groups in the protein film was determined using a combination of absorption linear dichroism, measured in a planarintegrated optical waveguide-attenuated total reflection geometry- and fluorescence anisotropy, measured in a total internal reflection geometry. A gaussian model for the orientation distribution was used to recover the mean heme tilt angle and angular distribution about the mean, which were 40 and 11 degrees, respectively. Additional experiments showed that a large fraction of the cytochrome c was disulfide bonded to the bilayer, which correlates with the high degree of macroscopic order in the protein film. However, a subpopulation of yeast cytochrome c molecules in the film (approximately 30% of the total) appeared to be nonspecifically adsorbed. The orientation distribution of this subpopulation was found to be much broader than the specifically bound fraction. PMID:9533712

  20. Integrated system for temperature-controlled fast protein liquid chromatography comprising improved copolymer modified beaded agarose adsorbents and a travelling cooling zone reactor arrangement.

    PubMed

    Müller, Tobias K H; Cao, Ping; Ewert, Stephanie; Wohlgemuth, Jonas; Liu, Haiyang; Willett, Thomas C; Theodosiou, Eirini; Thomas, Owen R T; Franzreb, Matthias

    2013-04-12

    An integrated approach to temperature-controlled chromatography, involving copolymer modified agarose adsorbents and a novel travelling cooling zone reactor (TCZR) arrangement, is described. Sepharose CL6B was transformed into a thermoresponsive cation exchange adsorbent (thermoCEX) in four synthetic steps: (i) epichlorohydrin activation; (ii) amine capping; (iii) 4,4'-azobis(4-cyanovaleric acid) immobilization; and 'graft from' polymerization of poly(N-isopropylacrylamide-co-N-tert-butylacrylamide-co-acrylic acid-co-N,N'-methylenebisacrylamide). FT-IR, (1)H NMR, gravimetry and chemical assays allowed precise determination of the adsorbent's copolymer composition and loading, and identified the initial epoxy activation step as a critical determinant of 'on-support' copolymer loading, and in turn, protein binding performance. In batch binding studies with lactoferrin, thermoCEX's binding affinity and maximum adsorption capacity rose smoothly with temperature increase from 20 to 50 °C. In temperature shifting chromatography experiments employing thermoCEX in thermally jacketed columns, 44-51% of the lactoferrin adsorbed at 42 °C could be desorbed under binding conditions by cooling the column to 22 °C, but the elution peaks exhibited strong tailing. To more fully exploit the potential of thermoresponsive chromatography adsorbents, a new column arrangement, the TCZR, was developed. In TCZR chromatography, a narrow discrete cooling zone (special assembly of copper blocks and Peltier elements) is moved along a bespoke fixed-bed separation columnfilled with stationary phase. In tests with thermoCEX, it was possible to recover 65% of the lactoferrin bound at 35 °C using 8 successive movements of the cooling zone at a velocity of 0.1mm/s; over half of the recovered protein was eluted in the first peak in more concentrated form than in the feed. Intra-particle diffusion of desorbed protein out of the support pores, and the ratio between the velocities of the cooling

  1. Development of high-productivity, strong cation-exchange adsorbers for protein capture by graft polymerization from membranes with different pore sizes

    PubMed Central

    Chenette, Heather C.S.; Robinson, Julie R.; Hobley, Eboni; Husson, Scott M.

    2012-01-01

    This paper describes the surface modification of macroporous membranes using ATRP (atom transfer radical polymerization) to create cation-exchange adsorbers with high protein binding capacity at high product throughput. The work is motivated by the need for a more economical and rapid capture step in downstream processing of protein therapeutics. Membranes with three reported nominal pore sizes (0.2, 0.45, 1.0 μm) were modified with poly(3-sulfopropyl methacrylate, potassium salt) tentacles, to create a high density of protein binding sites. A special formulation was used in which the monomer was protected by a crown ether to enable surface-initiated ATRP of this cationic polyelectrolyte. Success with modification was supported by chemical analysis using Fourier-transform infrared spectroscopy and indirectly by measurement of pure water flux as a function of polymerization time. Uniformity of modification within the membranes was visualized with confocal laser scanning microscopy. Static and dynamic binding capacities were measured using lysozyme protein to allow comparisons with reported performance data for commercial cation-exchange materials. Dynamic binding capacities were measured for flow rates ranging from 13 to 109 column volumes (CV)/min. Results show that this unique ATRP formulation can be used to fabricate cation-exchange membrane adsorbers with dynamic binding capacities as high as 70 mg/mL at a throughput of 100 CV/min and unprecedented productivity of 300 mg/mL/min. PMID:23175597

  2. Making novel bio-interfaces through bacterial protein recrystallization on biocompatible polylactide derivative films

    NASA Astrophysics Data System (ADS)

    Lejardi, Ainhoa; López, Aitziber Eleta; Sarasua, José R.; Sleytr, U. B.; Toca-Herrera, José L.

    2013-09-01

    Fabrication of novel bio-supramolecular structures was achieved by recrystallizing the bacterial surface protein SbpA on amorphous and semicrystalline polylactide derivatives. Differential scanning calorimetry showed that the glass transition temperature (Tg) for (poly-L-lactide)-PLLA, poly(L,D-lactide)-PDLLA, poly(lactide-co-glycolide)-PLGA and poly(lactide-co-caprolactone)-PLCL was 63 °C, 53 °C, 49 °C and 15 °C, respectively. Tensile stress-strain tests indicated that PLLA, PLGA, and PDLLA had a glassy behaviour when tested below Tg. The obtained Young modulus were 1477 MPa, 1330 MPa, 1306 MPa, and 9.55 MPa for PLLA, PLGA, PDLLA, and PLCL, respectively. Atomic force microscopy results confirmed that SbpA recrystallized on every polymer substrate exhibiting the native S-layer P4 lattice (a = b = 13 nm, γ = 90°). However, the polymer substrate influenced the domain size of the S-protein crystal, with the smallest size for PLLA (0.011 μm2), followed by PDLLA (0.034 μm2), and PLGA (0.039 μm2), and the largest size for PLCL (0.09 μm2). quartz crystal microbalance with dissipation monitoring (QCM-D) measurements indicated that the adsorbed protein mass per unit area (˜1800 ng cm-2) was independent of the mechanical, thermal, and crystalline properties of the polymer support. The slowest protein adsorption rate was observed for amorphous PLCL (the polymer with the weakest mechanical properties and lowest Tg). QCM-D also monitored protein self-assembly in solution and confirmed that S-layer formation takes place in three main steps: adsorption, self-assembly, and crystal reorganization. Finally, this work shows that biodegradable polylactide derivatives films are a suitable support to form robust biomimetic S-protein layers.

  3. Graft copolymer composed of cationic backbone and bottle brush-like side chains as a physically adsorbed coating for protein separation by capillary electrophoresis.

    PubMed

    Zhou, Dan; Xiang, Lina; Zeng, Rongju; Cao, Fuhu; Zhu, Xiaoxi; Wang, Yanmei

    2011-12-01

    To stabilize electroosmotic flow (EOF) and suppress protein adsorption onto the silica capillary inner wall, a cationic hydroxyethylcellulose-graft-poly (poly(ethylene glycol) methyl ether methacrylate) (cat-HEC-g-PPEGMA) graft copolymer composed of cationic backbone and bottle brush-like side chains was synthesized for the first time and used as a novel physically adsorbed coating for protein separation by capillary electrophoresis. Reversed (anodal) and very stable EOF was obtained in cat-HEC-g-PPEGMA-coated capillary at pH 2.2-7.8. The effects of degree of cationization, PEGMA grafting ratio, PEGMA molecular mass, and buffer pH on the separation of basic proteins were investigated. A systematic comparative study of protein separation in bare and HEC-coated capillaries and in cat-HEC-g-PPEGMA-coated capillary was also performed. The basic proteins can be well separated in cat-HEC-g-PPEGMA-coated capillary over the pH range of 2.8-6.8 with good repeatability and high separation efficiency, because the coating combines good protein-resistant property of bottle brush-like PPEGMA side chains with excellent coating ability of cat-HEC backbone. Besides its success in separation of basic proteins, the cat-HEC-g-PPEGMA coating was also superior in the fast separation of other protein samples, such as protein mixture, egg white, and saliva, which indicates that it is a promising coating for further proteomics analysis. PMID:22038787

  4. Characterisation of protein adsorption on different liquid crystal phthalocyaninethin films.

    PubMed

    Paul, S; Paul, D; Basova, T; Ray, A K

    2010-03-01

    Bovine serum albumin (BSA) protein adsorption on thin spun films of different metal octakishexylthiophthalocyanine [(C(6)S)(8)PcM, M=Cu, Ni] derivatives is investigated by using three independent spectroscopic measurements namely Raman spectroscopy, ellipsometry and surface plasmon resonance imaging. Thermally induced molecular self-reorganisations in the phthalocyanine films are found to have produced the changes in the surface energy which, in turn, control protein adsorption. The amount of BSA adsorption on [(C(6)S)(8)PcNi] is more limited than that on [(C(6)S)(8)PcCu] and this observation is consistent with the results on the surface wettability obtained from the contact angle measurements. The shift from the plasmonic resonance wavelength because of the BSA adsorption was significantly larger for the heat-treated [(C(6)S)(8)PcCu] than as-deposited film. Similar measurements on the [(C(6)S)(8)PcNi] films showed a limited BSA adsorption. The results of surface plasmon resonance experiments are consistent with those obtained from Raman spectroscopic and ellipsometric techniques. PMID:20170253

  5. Performance of PF BL-13A, a vacuum ultraviolet and soft X-ray undulator beamline for studying organic thin films adsorbed on surfaces

    NASA Astrophysics Data System (ADS)

    Toyoshima, Akio; Kikuchi, Takashi; Tanaka, Hirokazu; Mase, Kazuhiko; Amemiya, Kenta; Ozawa, Kenichi

    2013-03-01

    We report on the present status of a vacuum ultraviolet and soft X-ray undulator beamline, BL-13A, located at the Photon Factory. BL-13A is mainly dedicated to the study of organic thin films adsorbed on well-defined surfaces, using angle-resolved photoelectron spectroscopy (ARPES), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). The photon-energy resolution (E/ΔE) is estimated to be about 10000 at a photon energy of 64 eV with an exit-slit width of 30 μm. The photon intensity is estimated to be 2.9 × 1012 to 5.6 × 108 photons/s for photon energies of 30-1600 eV with an exit-slit width of 100 μm at the ring current of 450 mA. An ultrahigh vacuum (UHV) chamber equipped with an electron-energy analyzer (Gamma Data/Scienta, SES 200) is used as the main end station for ARPES, XPS, and XAS measurements. A sample can be transferred from a UHV chamber for sample preparation or from a UHV chamber for the evaporation of organic materials. The sample-holder acceptors are equipped with a heating and cooling system. The overall electron-energy resolution is estimated to be about 12 meV at a photon energy of 30 eV.

  6. Ion-imprinted silica adsorbent modified diffusive gradients in thin films technique: Tool for speciation analysis of free lead species.

    PubMed

    Sui, Dian-Peng; Chen, Hua-Xia; Liu, Lin; Liu, Ming-Xuan; Huang, Cong-Cong; Fan, Hong-Tao

    2016-02-01

    A new diffusive gradients in thin films (DGT) device, using Pb(II) ion-imprinted silica (IIS) as the binding agents and commercial cellulose acetate dialysis (CAD) membrane as the diffusion layer (CAD/IIS-DGT), has been developed and evaluated for sampling and measurement of free Pb(II) species. The CAD/IIS-DGT devices were successfully applied to the measurement of free Pb(II) species in synthetic solutions, in natural freshwaters and in industrial wastewaters. The CAD/IIS-DGT provides reliable results over pH range of 4.5-6.5 and a wide range of ionic strength from 1.0×10(-3) to 0.7 mol L(-1). The concentrations of the free Pb(II) species in synthetic solution containing different concentrations of ligands measured by CAD/IIS-DGT showed a good agreement with the value measured by Pb-ion selective electrode. Field deployments of the CAD/IIS-DGT devices allowed accurate measurements of the concentrations of free Pb(II) species. PMID:26653451

  7. Impact of temperature and electrical potentials on the stability and structure of collagen adsorbed on the gold electrode

    NASA Astrophysics Data System (ADS)

    Meiners, Frank; Ahlers, Michael; Brand, Izabella; Wittstock, Gunther

    2015-01-01

    The morphology and structure of collagen type I adsorbed on gold electrodes were studied as a function of electrode potential and temperature by means of capacitance measurements, polarization modulation infrared reflection-absorption spectroscopy and scanning force microscopy at temperatures of 37 °C, 43 °C and 50 °C. The selected temperatures corresponded to the normal body temperature, temperature of denaturation of collagen molecules and denaturation of collagen fibrils, respectively. Independently of the solution temperature, collagen was adsorbed on gold electrodes in the potential range - 0.7 V < E < 0.4 V vs. Ag/AgCl, where the protein film was very stable. Fragments of collagen molecules made a direct contact to the gold surface and water was present in the film. Protein molecules were oriented preferentially with their long axis towards the gold surface. Collagen molecules in the adsorbed state preserved their native triple helical structure even at temperatures corresponding to collagen denaturation in aqueous solutions. Application of E < - 0.75 V vs. Ag/AgCl leads to the swelling of the protein film by water and desorption from the electrode surface. IR spectra provided no evidence of the thermal denaturation of adsorbed collagen molecules. A temperature increase to 50 °C leads to a distortion of the collagen film. The processes of aggregation and fibrilization were preferred over thermal denaturation for collagen adsorbed on the electrode surface and exposed to changing potentials.

  8. Effects of adsorbed proteins, an antifouling agent and long-duration DC voltage pulses on the impedance of silicon-based neural microelectrodes.

    PubMed

    Sommakia, Salah; Rickus, Jenna L; Otto, Kevin J

    2009-01-01

    The successful use of implantable neural microelectrodes as neuroprosthetic devices depends on the mitigation of the reactive tissue response of the brain. One of the factors affecting the ultimate severity of the reactive tissue response and the in vivo electrical properties of the microelectrodes is the initial adsorption of proteins onto the surface of the implanted microelectrodes. In this study we quantify the increase in microelectrode impedance magnitude at physiological frequencies following electrode immersion in a 10% bovine serum albumin (BSA) solution. We also demonstrate the efficacy of a common antifouling molecule, poly(ethylene glycol) (PEG), in preventing a significant increase in microelectrode impedance. In addition, we show the feasibility of using long-duration DC voltage pulses to remove adsorbed proteins from the microelectrode surface. PMID:19963693

  9. Nanostructured films from hierarchical self-assembly of amyloidogenic proteins

    PubMed Central

    Knowles, Tuomas P. J.; Oppenheim, Tomas W.; Buell, Alexander K.; Chirgadze, Dimitri Y.; Welland, Mark E.

    2015-01-01

    In nature, sophisticated functional materials are created through hierarchical self-assembly of simple nanoscale motifs1–4. In the laboratory, much progress has been made in the controlled assembly of molecules into one-5–7, two-6,8,9 and three-dimensional10 artificial nanostructures, but bridging from the nanoscale to the macroscale to create useful macroscopic materials remains a challenge. Here we show a scalable self-assembly approach to making free-standing films from amyloid protein fibrils. The films were well ordered and highly rigid, with a Young’s modulus of up to 5–7 GPa, which is comparable to the highest values for proteinaceous materials found in nature. We show that the self-organizing protein scaffolds can align otherwise unstructured components (such as fluorophores) within the macroscopic films. Multiscale self-assembly that relies on highly specific biomolecular interactions is an attractive path for realizing new multifunctional materials built from the bottom up. PMID:20190750

  10. Surface characteristics and protein adsorption on combinatorial binary Ti-M (Cr, Al, Ni) and Al-M (Ta, Zr) library films.

    PubMed

    Bai, Zhijun; Filiaggi, M J; Sanderson, R J; Lohstreter, L B; McArthur, M A; Dahn, J R

    2010-02-01

    Systematic studies of protein adsorption onto metallic biomaterial surfaces are generally lacking. Here, combinatorial binary library films with compositional gradients of Ti(1-x)Cr(x), Ti(1-x)Al(x), Ti(1-x)Ni(x) and Al(1-x)Ta(x), (0 films were sputtered onto clean Si surfaces. Bulk and surface chemistry, film microstructure, and surface roughness were subsequently correlated to fibrinogen or albumin adsorption measured using a high throughput wavelength dispersive spectroscopy technique. X-ray diffraction revealed these binary films to have crystalline phases present primarily at either extreme of the compositional library and an amorphous zone dominating along the gradient. These mirror-like films were generally found by atomic force microscopy to have a roughness of less than 8 nm, with any relative increases in roughness consistent with the development of crystalline phases. Surface chemistry by quantitative high-resolution X-ray photoelectron spectroscopy differed significantly from bulk film composition as measured by electron microprobe, with TiO(2) and Al(2)O(3) preferentially forming on the binary film surfaces. Correspondingly, protein adsorption onto these films closely correlated with their surface oxide fractions. Aluminum deposited as either a constant-composition film or as part of a binary library consistently adsorbed the least amount of albumin and fibrinogen, with alumina-enrichment of the surface oxide correlating with this adsorption. Overall, this combinatorial materials approach coupled with high-throughput surface analytical methods provides an efficient method of screening potential metallic biomaterials that may enable as well systematic studies of surface properties driving protein adsorption on these metal / metal oxide systems. PMID:19235218

  11. Functional properties and applications of edible films made of milk proteins.

    PubMed

    Chen, H

    1995-11-01

    Edible films and coatings based on milk proteins have been developed to be used as a protective layer on foods or between food components. The most important functionalities of an edible film or coating include control of mass transfers, mechanical protection, and sensory appeal. Control of mass transfers involves preventing foods from desiccation, regulating microenvironments of gases around foods, and controlling migration of ingredients and additives in the food systems. Adequate mechanical strength of an edible film is necessary to protect the integrity of packaging throughout distribution. The sensory properties of an edible coating or film are a key factor for acceptance of final products. Simple milk protein films are good barriers to gas transfers because of their complex intermolecular bindings. Lipid is frequently incorporated into protein films to improve their properties as barriers to moisture vapor. Protein films are distinctly different in mechanical profiles from those films made of other materials. Approaches traditionally used in material sciences have been adapted and modified for studying the functionality of edible films. Potential uses of innovative processing technologies in film making to alter the film functionality are briefly discussed. A survey of potential applications of edible film based on milk protein is presented. PMID:8747343

  12. Adsorbed Water Illustration

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Thermal and Electrical Conductivity Probe on NASA's Phoenix Mars Lander detected small and variable amounts of water in the Martian soil.

    In this schematic illustration, water molecules are represented in red and white; soil minerals are represented in green and blue. The water, neither liquid, vapor, nor solid, adheres in very thin films of molecules to the surfaces of soil minerals. The left half illustrates an interpretation of less water being adsorbed onto the soil-particle surface during a period when the tilt, or obliquity, of Mars' rotation axis is small, as it is in the present. The right half illustrates a thicker film of water during a time when the obliquity is greater, as it is during cycles on time scales of hundreds of thousands of years. As the humidity of the atmosphere increases, more water accumulates on mineral surfaces. Thicker films behave increasingly like liquid water.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  13. Preparation and characterization of milk protein films and their application for packaging of Cheddar cheese.

    PubMed

    Wagh, Y R; Pushpadass, Heartwin A; Emerald, F Magdaline Eljeeva; Nath, B Surendra

    2014-12-01

    Casein and whey protein concentrate (WPC) films, plasticized with glycerol and sorbitol independently, were prepared by casting. The film thickness, water vapour and oxygen permeation and tensile and moisture sorption properties of the films were determined. The tensile strength (TS), tensile strain (TE) and elastic modulus (EM) of the films ranged from 0.71 to 4.58 MPa, 19.22 to 66.63 % and 2.05 to 6.93 MPa, respectively. The film properties were influenced by the type of biopolymer (casein and whey protein concentrate), plasticizer and its concentration. Increasing the plasticizer concentration, increased the film thickness, TE and water vapour permeability (WVP), but decreased the TS and EM. As the concentration of plasticizer increased to the highest level, the film thickness increased from 0.168 to 0.305 mm for glycerol-plasticized films and from 0.251 to 0.326 mm for sorbitol-plasticized films. The film thickness increased because the amount of plasticizer in the film network increased and the amount of biopolymer remained same. Casein films showed superior tensile properties as compared to WPC films. The WVP of both casein and WPC films lied between 3.87 and 13.97 g.mm./(m(2).h.kPa). The moisture sorption isotherms of both films were typical of high-protein material, and were adequately described by the GAB model. The oxygen permeability of casein films was relatively lower than that of WPC films, regardless of the plasticizer used. The sensory data revealed that the organoleptic quality of Cheddar cheese was unaffected by milk-protein film packaging. PMID:25477643

  14. Effect of the incorporation of antimicrobial/antioxidant proteins on the properties of potato starch films.

    PubMed

    Moreno, Olga; Atarés, Lorena; Chiralt, Amparo

    2015-11-20

    Glycerol plasticized potato starch films containing bioactive proteins (lactoferrin (LF) and/or lysozyme (LZ), at 0.1 and 0.2 ratio with respect to starch) were obtained by casting method and characterized as to their microstructural, thermal and physical (water content, mechanical, water and oxygen barrier, optical) properties. The bioactive properties, named antioxidant and antimicrobial, of the proteins and the films were also characterized. The incorporation of proteins affected the structural and physical properties of potato starch films, while modifying their thermal behavior and increasing the glass transition temperature. Both proteins showed a certain degree of compatibility with starch chains through the bond formations (increase in Tg), while a part is separated and migrates to the film surface. Their incorporation, especially that of lactoferrin, greatly increased the film's brittleness, regardless of the films water content, although they enhance the water vapor and oxygen barrier properties, whatever the age of the film. Protein also reduced the film's transparency and gloss, while lactoferrin induced color changes. The thermal degradation of blend films and isolated proteins occurred at temperatures of over 250°C, which means that blend starch films can be thermoprocessed, according to their thermoplastic properties and following the usual practices of the plastics industries. A synergistic antimicrobial action against Escherichia coli and coliforms was observed when both LZ and LF were simultaneously applied. Both of these exhibited antioxidant capacity. PMID:26344291

  15. Fabrication Of Nano-Silver Thin Films Using Self Assembly And Its Interaction With Proteins

    SciTech Connect

    Verma, Gunjan; Choudhury, Sipra; Hassan, P. A.

    2010-12-01

    The silver nanoparticle thin films were prepared with an aim to use them for sensing of biomolecules. The monolayers of arachidic acid were deposited on glass plates by Langmuir Blodgett (LB) technique and silver nanoparticles thin films were deposited within the arachidic acid films. Small angle XRD studies confirm the formation of ordered array of nanoparticles. These thin films were treated with a model protein, bovine serum albumin (BSA a natural protein). From the optical absorption spectra a shift in the intensity as well as lambda max ({lambda}max) could be observed when silver thin films were treated with BSA.

  16. Properties of cast films from hemp (Cannabis sativa L.) and soy protein isolates. A comparative study.

    PubMed

    Yin, Shou-Wei; Tang, Chuan-He; Wen, Qi-Biao; Yang, Xiao-Quan

    2007-09-01

    The properties of cast films from hemp protein isolate (HPI) including moisture content (MC) and total soluble mass (TSM), tensile strength (TS) and elongation at the break (EAB), and surface hydrophobicity were investigated and compared to those from soy protein isolate (SPI). The plasticizer (glycerol) level effect on these properties and the interactive force pattern for the film network formation were also evaluated. At some specific glycerol levels, HPI films had similar MC, much less TSM and EAB, and higher TS and surface hydrophobicity (support matrix side), as compared to SPI films. The TS of HPI and SPI films as a function of plasticizer level (in the range of 0.3-0.6 g/g of protein) were well fitted with the exponential equation with coefficient factors of 0.991 and 0.969, respectively. Unexpectedly, the surface hydrophobicity of HPI films (including air and support matrix sides) increased with increasing the glycerol level (from 0.3 to 0.6 g/g of protein). The analyses of protein solubility of film in various solvents and free sulfydryl group content showed that the disulfide bonds are the prominent interactive force in the HPI film network formation, while in the SPI case, besides the disulfide bonds, hydrogen bonds and hydrophobic interactions are also to a similar extent involved. The results suggest that hemp protein isolates have good potential to be applied to prepare protein film with some superior characteristics, e.g., low solubility and high surface hydrophobicity. PMID:17696443

  17. Influence of surface chemistry on the structural organization of monomolecular protein layers adsorbed to functionalized aqueous interfaces.

    PubMed Central

    Lösche, M; Piepenstock, M; Diederich, A; Grünewald, T; Kjaer, K; Vaknin, D

    1993-01-01

    The molecular organization of streptavidin (SA) bound to aqueous surface monolayers of biotin-functionalized lipids and binary lipid mixtures has been investigated with neutron reflectivity and electron and fluorescence microscopy. The substitution of deuterons (2H) for protons (1H), both in subphase water molecules and in the alkyl chains of the lipid surface monolayer, was utilized to determine the interface structure on the molecular length scale. In all cases studied, the protein forms monomolecular layers underneath the interface with thickness values of approximately 40 A. A systematic dependence of the structural properties of such self-assembled SA monolayers on the surface chemistry was observed: the lateral protein density depends on the length of the spacer connecting the biotin moiety and its hydrophobic anchor. The hydration of the lipid head groups in the protein-bound state depends on the dipole moment density at the interface. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 5 FIGURE 11 FIGURE 12 FIGURE A1 PMID:8298041

  18. Characterization of agar/soy protein biocomposite films: Effect of agar on the extruded pellets and compression moulded films.

    PubMed

    Garrido, T; Etxabide, A; Guerrero, P; de la Caba, K

    2016-10-20

    Agar/soy protein biocomposite films were successfully processed by extrusion and compression moulding, obtaining transparent and homogeneous films. The conformational changes occurred during the extrusion process and the effect of agar on the final properties were analyzed. As shown by differential scanning calorimetry (DSC) and specific mechanical energy (SME) values, during the extrusion process protein denatured and unfolded protein chains could interact with agar. These interactions were analyzed by Fourier transform infrared spectroscopy (FTIR) and the secondary structure was determined from the amide I band. Those interactions were supported by the decrease of film solubility. Furthermore, the good compatibility between agar and soy protein was confirmed by the images from scanning electron microscopy (SEM). PMID:27474583

  19. Analyte induced water adsorbability in gas phase biosensors: the influence of ethinylestradiol on the water binding protein capacity.

    PubMed

    Snopok, Borys; Kruglenko, Ivanna

    2015-05-01

    An ultra-sensitive gas phase biosensor/tracer/bio-sniffer is an emerging technology platform designed to provide real-time information on air-borne analytes, or those in liquids, through classical headspace analysis. The desired bio-sniffer measures gaseous 17α- ethinylestradiol (ETED) as frequency changes on a quartz crystal microbalance (QCM), which is a result of the interactions of liquid sample components in the headspace (ETED and water) with a biorecognition layer. The latter was constructed by immobilization of polyclonal antiserum against a phenolic A-ring of estrogenic receptors through protein A. The QCM response exhibited stretched exponential kinetics of negative frequency shifts with reversible and "irreversible" components of mass uptake onto the sensor surface in static headspace conditions when exposed to water solutions of ETED over the sensor working range, from 10(-10) to 10(-17) g L(-1). It was shown that the variations in the QCM response characteristics are due to the change of the water-binding capacity of the sensing layer induced by protein transformations initiated by the binding of ETED molecules. This result is well correlated with the natural physiological function of estrogens in controlling the homeostasis of body fluids in living beings. PMID:25763411

  20. Mechanical and thermal properties of irradiated films based on Tilapia ( Oreochromis niloticus) proteins

    NASA Astrophysics Data System (ADS)

    Sabato, S. F.; Nakamurakare, N.; Sobral, P. J. A.

    2007-11-01

    Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia ( Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.

  1. Catalytic Protein Film Electrochemistry Provides a Direct Measure of the Tetrathionate/Thiosulfate Reduction Potential.

    PubMed

    Kurth, Julia M; Dahl, Christiane; Butt, Julea N

    2015-10-21

    The tetrathionate/thiosulfate interconversion is a two-electron process: S4O6(2-) + 2 e(-) ↔ 2 S2O3(2-). Both transformations can support bacterial growth since S2O3(2-) provides an energy source, while S4O6(2-) serves as respiratory electron acceptor. Interest in the corresponding S2O3(2-) oxidation also arises from its widespread use in volumetric analysis of oxidizing agents and bleach neutralization during water treatment. Here we report protein film electrochemistry that defines the reduction potential of the S4O6(2-)/S2O3(2-) couple. The relevant interconversion is not reversible at inert electrodes. However, facile reduction of S4O6(2-) to S2O3(2-) and the reverse reaction are catalyzed by enzymes of the thiosulfate dehydrogenase, TsdA, family adsorbed on graphite electrodes. Zero-current potentials measured with different enzymes, at three pH values, and multiple S4O6(2-) and S2O3(2-) concentrations together with the relevant Nernst equation resolved the tetrathionate/thiosulfate reduction potential as +198 ± 4 mV versus SHE. This potential lies in the ∼250 mV window encompassing previously reported values calculated from parameters including the free energy of formation. However, the value is considerably more positive than widely used in discussions of bacterial bioenergetics. As a consequence anaerobic respiration by tetrathionate reduction is likely to be more prevalent than presently thought in tetrathionate-containing environments such as marine sediments and the human gut. PMID:26437022

  2. Design of molecularly imprinted conducting polymer protein-sensing films via substrate-dopant binding.

    PubMed

    Komarova, Elena; Aldissi, Matt; Bogomolova, Anastasia

    2015-02-21

    Addressing the challenge of protein biosensing using molecularly imprinted polymers (MIP), we have developed and tested a novel approach to creating sensing conducive polymer films imprinted with a protein substrate, ricin toxin chain A (RTA). Our approach for creating MIP protein sensing films is based on a concept of substrate-guided dopant immobilization with subsequent conducting polymer film formation. In this proof-of-concept work we have tested three macromolecular dopants with strong protein affinity, Ponceau S, Coomassie BB R250 and ι-Carrageenan. The films were formed using sequential interactions of the substrate, dopant and pyrrole, followed by electrochemical polymerization. The films were formed on gold array electrodes allowing for extensive data acquisition. The thickness of the films was optimized to allow for efficient substrate extraction, which was removed by a combination of protease and detergent treatment. The MIP films were tested for substrate rebinding using electrochemical impedance spectroscopy (EIS). The presence of macromolecular dopants was essential for MIP film specificity. Out of three dopants tested, RTA-imprinted polypyrrole films doped with Coomassie BB performed with highest specificity towards detection of RTA with a level of detection (LOD) of 0.1 ng ml(-1). PMID:25574520

  3. Physical, Chemical and Biochemical Modifications of Protein-Based Films and Coatings: An Extensive Review.

    PubMed

    Zink, Joël; Wyrobnik, Tom; Prinz, Tobias; Schmid, Markus

    2016-01-01

    Protein-based films and coatings are an interesting alternative to traditional petroleum-based materials. However, their mechanical and barrier properties need to be enhanced in order to match those of the latter. Physical, chemical, and biochemical methods can be used for this purpose. The aim of this article is to provide an overview of the effects of various treatments on whey, soy, and wheat gluten protein-based films and coatings. These three protein sources have been chosen since they are among the most abundantly used and are well described in the literature. Similar behavior might be expected for other protein sources. Most of the modifications are still not fully understood at a fundamental level, but all the methods discussed change the properties of the proteins and resulting products. Mastering these modifications is an important step towards the industrial implementation of protein-based films. PMID:27563881

  4. Mechanical, barrier and morphological properties of pea starch and peanut protein isolate blend films.

    PubMed

    Sun, Qingjie; Sun, Cuixia; Xiong, Liu

    2013-10-15

    Mechanical, barrier and morphological properties of edible films based on blends of Pea starch (PS) and Peanut protein isolate (PPI) plasticized with glycerol (30%, w/w) were investigated. As PPI ratio in PS/PPI blends increased, the thickness of films decreased, the opacity slightly elevated and color intensified. The addition of PPI to the PS film significantly reduced tensile strength from 5.44 MPa to 3.06 MPa, but increased elongation from 28.56% to 98.12% with the incorporation of PPI into PS at 50% level. Film solubility value fell from 22.31% to 9.78% upon the incorporation of PPI ranged from 0 to 50% level. When PPI was added into PS film at 40% level, the WVP and WVTR of the films markedly dropped from 11.18% to 4.19% and 6.16 to 1.95%, respectively. Scanning electron microscopy (SEM) of the surface of films showed that many swollen starch granules were presented in the 100% PS film, while 100% PPI film was observed to have rougher surfaces with presence of pores or cavities. The PS/PPI blend films upon the incorporation of PPI at 20% and 50% level were not homogeneous. However, the smoother film surface was observed in PS/PPI blend films with the addition of PPI at 40% level. SEM image of the cross-sections of the films revealed that the 100% PS film showed a uniform and compact matrix without disruption, and pore formation and 100% PPI film displayed a smooth structure. Rougher and flexible network was shown in blend film with the addition of PPI reaching 40% level. PMID:23987392

  5. Recombinant production and film properties of full-length hornet silk proteins.

    PubMed

    Kambe, Yusuke; Sutherland, Tara D; Kameda, Tsunenori

    2014-08-01

    Full-length versions of the four main components of silk cocoons of Vespa simillima hornets, Vssilk1-4, were produced as recombinant proteins in Escherichia coli. In shake flasks, the recombinant Vssilk proteins yielded 160-330mg recombinant proteinl(-1). Films generated from solutions of single Vssilk proteins had a secondary structure similar to that of films generated from native hornet silk. The films made from individual recombinant hornet silk proteins had similar or enhanced mechanical performance compared with films generated from native hornet silk, possibly reflecting the homogeneity of the recombinant proteins. The pH-dependent changes in zeta (ζ) potential of each Vssilk film were measured, and isoelectric points (pI) of Vssilk1-4 were determined as 8.9, 9.1, 5.0 and 4.2, respectively. The pI of native hornet silk, a combination of the four Vssilk proteins, was 4.7, a value similar to that of Bombyx mori silkworm silk. Films generated from Vssilk1 and 2 had net positive charge under physiological conditions and showed significantly higher cell adhesion activity. It is proposed that recombinant hornet silk is a valuable new material with potential for cell culture applications. PMID:24862540

  6. Cytocompatible and water-stable camelina protein films for tissue engineering.

    PubMed

    Zhao, Yi; Jiang, Qiuran; Xu, Helan; Reddy, Narendra; Xu, Lan; Yang, Yiqi

    2014-05-01

    In this research, films with compressive strength and aqueous stability were developed from camelina protein (CP) for tissue engineering. Protein based scaffolds have poor mechanical properties and aqueous stability and generally require chemical or physical modifications to make them applicable for medical applications. However, these modifications such as crosslinking could reduce biocompatibility and/or degradability of the scaffolds. Using proteins that are inherently water-stable could avoid modifications and provide scaffolds with the desired properties. CP with a high degree of disulfide cross-linkage has the potential to provide water-stable biomaterials, but it is difficult to dissolve CP and develop scaffolds. In this study, a new method of dissolving highly cross-linked proteins that results in limited hydrolysis and preserves the protein backbone was developed to produce water-stable films from CP without any modification. Only 12 % weight loss of camelina films was observed after 7 days in phosphate buffer saline (PBS) at 37°C. NIH 3T3 fibroblasts could attach and proliferate better on camelina films than on citric acid cross-linked collagen films. Therefore, CP films have the potential to be used for tissue engineering, and this extraction-dissolution method can be used for developing biomedical materials from various water-stable plant proteins. PMID:24142899

  7. Continuous Reduction of Protein-Bound Uraemic Toxins with Improved Oxidative Stress by Using the Oral Charcoal Adsorbent AST-120 in Haemodialysis Patients

    PubMed Central

    Yamamoto, Suguru; Kazama, Junichiro J.; Omori, Kentaro; Matsuo, Koji; Takahashi, Yoshimitsu; Kawamura, Kazuko; Matsuto, Takayuki; Watanabe, Hiroshi; Maruyama, Toru; Narita, Ichiei

    2015-01-01

    Accumulation of protein-bound uraemic toxins (PBUTs) is one of the reasons for the development of uraemia-related complications including cardiovascular disease; however, conventional haemodialysis is limited in its ability to remove PBUTs. We aimed to examine whether the oral charcoal adsorbent AST-120 has an additive effect on PBUT removal in haemodialysis patients. During the 4-week study, anuric patients undergoing haemodialysis received AST-120 (6 g/day) in the last 2 weeks (n = 10) or the first 2 weeks (n = 10). Serum levels of total and free PBUTs such as indoxyl sulfate, p-cresyl sulfate, and phenyl sulfate at the pre- and postdialysis sessions were measured before and after AST-120 use and after discontinuation. Levels of the oxidative stress markers oxidized albumin and 8-isoprostane were also measured. AST-120 use induced dramatic reduction of indoxyl sulfate (total, 45.7% [33.2–50.5%]; free, 70.4% [44.8–79.8%]), p-cresyl sulfate (total, 31.1% [25.0–48.0%]; free, 63.5% [49.3–70.9%]), and phenyl sulfate (free, 50.6% [32.3–71.2%]) levels; however, this effect disappeared after the discontinuation of AST-120. AST-120 use also induced substantial reduction of the oxidized albumin and 8-isoprostane levels. In conclusion, oral administration of AST-120 had additive effects on the continuous reduction of some PBUTs in anuric patients undergoing haemodialysis. PMID:26395517

  8. The origin of inverse absorption bands observed in the far-infrared RAIRS spectra of SnCl 4 and SnBr 4 adsorbed on thin-film SnO 2 surfaces

    NASA Astrophysics Data System (ADS)

    Awaluddin, A.; Pilling, M. J.; Wincott, P. L.; LeVent, S.; Surman, M.; Pemble, M. E.; Gardner, P.

    2002-04-01

    The adsorption of SnCl 4 and SnBr 4 on polycrystalline SnO 2 has been studied using synchrotron radiation based far-infrared reflection absorption infrared spectroscopy FIR-RAIRS. In order to exploit the sensitivity advantages of the buried metal layer method, the SnO 2 is in the form of a thin film deposited on a tungsten foil substrate. Adsorption of SnCl 4 and SnBr 4 on an oxygen sputtered surface at 120 K results in spectra characteristic of condensed multilayers. In addition, both spectra exhibit an inverse absorption band centred at 355 cm -1. Modified 4-layer, wavelength-dependent, Greenler calculations show that this inverse absorption band is induced by the presence of the adsorbate but is characteristic of the SnO 2 layer. The lack of any frequency shift upon changing the adsorbate from SnCl 4 to SnBr 4 rules out the possibility that the inverse absorption band is due to a dipole-forbidden parallel mode of the molecule excited via the interaction with free electron oscillations in the metal, resulting from the radiation induced oscillating electric field just below the surface.

  9. Dynamic contact angle analysis of protein adsorption on polysaccharide multilayer's films for biomaterial reendothelialization.

    PubMed

    Benni, Safiya; Avramoglou, Thierry; Hlawaty, Hanna; Mora, Laurence

    2014-01-01

    Atherosclerosis is a major cardiovascular disease. One of the side effects is restenosis. The aim of this work was to study the coating of stents by dextran derivates based polyelectrolyte's multilayer (PEM) films in order to increase endothelialization of injured arterial wall after stent implantation. Films were composed with diethylaminoethyl dextran (DEAE) as polycation and dextran sulphate (DS) as polyanion. One film was composed with 4 bilayers of (DEAE-DS)4 and was labeled D-. The other film was the same as D- but with an added terminal layer of DEAE polycation: (DEAE-DS)4-DEAE (labeled D+). The dynamic adsorption/desorption of proteins on the films were characterized by dynamic contact angle (DCA) and atomic force microscopy (AFM). Human endothelial cell (HUVEC) adhesion and proliferation were quantified and correlated to protein adsorption analyzed by DCA for fibronectin, vitronectin, and bovine serum albumin (BSA). Our results showed that the endothelial cell response was optimal for films composed of DS as external layer. Fibronectin was found to be the only protein to exhibit a reversible change in conformation after desorption test. This behavior was only observed for (DEAE-DS)4 films. (DEAE-DS)4 films could enhance HUVEC proliferation in agreement with fibronectin ability to easily change from conformation. PMID:25276808

  10. O K-edge x-ray magnetic circular dichroism of atomic O adsorbed on an ultrathin Co/Cu(100) film: Comparison with molecular CO on Co/Cu(100)

    NASA Astrophysics Data System (ADS)

    Amemiya, Kenta; Yokoyama, Toshihiko; Yonamoto, Yoshiki; Matsumura, Daiju; Ohta, Toshiaki

    2001-10-01

    We observed O K-edge x-ray magnetic circular dichroism (XMCD) of atomic O adsorbed on a fcc Co thin film grown epitaxially on Cu(100). The XMCD of c(2×2)O showed a negative sign at the O1s-->2p transition. The negative sign indicates parallel alignment of the O orbital moment with the substrate magnetization. This finding is in contrast to the CO/Co/Cu(100) case where a positive XMCD was observed at the O1s-->CO2π* transition. A possible explanation for this discrepancy is proposed referring to recent theoretical prediction [Pick et al., Phys. Rev. B 59, 4195 (1999)].

  11. Infrared Reflection-Absorption Spectroscopy: Principles and Applications to Lipid-Protein Interaction in Langmuir Films

    PubMed Central

    Mendelsohn, Richard; Mao, Guangru; Flach, Carol R.

    2010-01-01

    Infrared reflection-absorption spectroscopy (IRRAS) of lipid/protein monolayer films in situ at the air/water interface provides unique molecular structure and orientation information from the film constituents. The technique is thus well suited for studies of lipid/protein interaction in a physiologically relevant environment. Initially, the nature of the IRRAS experiment is described and the molecular structure information that may be obtained is recapitulated. Subsequently, several types of applications, including the determination of lipid chain conformation and tilt as well as elucidation of protein secondary structure are reviewed. The current article attempts to provide the reader with an understanding of the current capabilities of IRRAS instrumentation and the type of results that have been achieved to date from IRRAS studies of lipids, proteins and lipid/protein films of progressively increasing complexity. Finally, possible extensions of the technology are briefly considered. PMID:20004639

  12. Infrared reflection-absorption spectroscopy: principles and applications to lipid-protein interaction in Langmuir films.

    PubMed

    Mendelsohn, Richard; Mao, Guangru; Flach, Carol R

    2010-04-01

    Infrared reflection-absorption spectroscopy (IRRAS) of lipid/protein monolayer films in situ at the air/water interface provides unique molecular structure and orientation information from the film constituents. The technique is thus well suited for studies of lipid/protein interaction in a physiologically relevant environment. Initially, the nature of the IRRAS experiment is described and the molecular structure information that may be obtained is recapitulated. Subsequently, several types of applications, including the determination of lipid chain conformation and tilt as well as elucidation of protein secondary structure are reviewed. The current article attempts to provide the reader with an understanding of the current capabilities of IRRAS instrumentation and the type of results that have been achieved to date from IRRAS studies of lipids, proteins, and lipid/protein films of progressively increasing complexity. Finally, possible extensions of the technology are briefly considered. PMID:20004639

  13. Characterization of whey protein-carboxymethylated chitosan composite films with and without transglutaminase treatment.

    PubMed

    Jiang, Shu-Juan; Zhang, Xuan; Ma, Ying; Tuo, Yanfeng; Qian, Fang; Fu, Wenjia; Mu, Guangqing

    2016-11-20

    Edible composite packaging has the advantage of complementary functional properties over its each bio-components. However, reports on whey protein concentrates (WPC)-carboxymethylated chitosan (CMC) composite films have not yet been released. To investigate the preparation of WPC-CMC composite films and its functional properties, four types of WPC-CMC composite films were prepared with and without Transglutaminase (TGase) treatment by mixing WPC aqueous solutions (10%, w/v) with CMC aqueous solutions (3%, w/v) at WPC to CMC volume ratios of (100:0), (75:25), (50:50), and (25:75). SDS-PAGE confirmed that TGase catalyzed crosslinking of whey protein. Results revealed that CMC incorporation conferred a smooth and even surface microstructure on the films and markedly improved the transparency, water barrier properties, mechanical properties and solubility of the composite film. Furthermore, TGase resulted in an improvement in the water vapor barrier properties and mechanical properties of WPC-CMC (75:25 and 50:50, v/v) composite films, and there was no impairment of thermal stability of composite films. Therefore, TGase successfully facilitated the formation of WPC-CMC composite films with some improved functional properties. This offers potential applications as an alternative approach to the preparation of edible packaging films. PMID:27561482

  14. The structure of deuterated benzene films adsorbed on the graphite (0001) basal plane: what happens below and above the monolayer coverage?

    PubMed

    Bahn, Emanuel; Hedgeland, Holly; Jardine, Andrew P; Henry, Paul F; Hansen, Thomas C; Fouquet, Peter

    2014-10-28

    An exact description of the interactions in aromatic carbon systems is a key condition for the design of carbon based nanomaterials. In this paper we investigate the binding and adsorbate structure of the simplest prototype system in this class - the single aromatic ring molecule benzene on graphite. We have collected neutron diffraction data of the ordered phase of deuterated benzene, C6D6, adsorbed on the graphite (0001) basal plane surface. We examined relative coverages from 0.15 up to 1.3 monolayers (ML) in a temperature range of 80 to 250 K. The results confirm the flat lying commensurate (√7 × √7)R19.1° monolayer with lattice constants a = b = 6.5 Å at coverages of less than 1 ML. For this structure we observe a progressive melting well below the desorption temperature. At higher coverages we do neither observe an ordered second layer nor a densification of the structure by upright tilting of first layer molecules, as generally assumed up to now. Instead, we see the formation of clusters with a bulk crystalline structure for coverages only weakly exceeding 1 ML. PMID:25209023

  15. Effect of protein and glycerol concentration on the mechanical, optical, and water vapor barrier properties of canola protein isolate-based edible films.

    PubMed

    Chang, Chang; Nickerson, Michael T

    2015-01-01

    Biodegradable edible films prepared using proteins are both economically and environmentally important to the food packaging industry relative to traditional petroleum-derived synthetic materials. In the present study, the mechanical and water vapor barrier properties of casted canola protein isolate edible films were investigated as a function of protein (5.0% and 7.5%) and glycerol (30%, 35%, 40%, 45%, and 50%) content. Specifically, tensile strength and elongation, elastic modulus, puncture strength and deformation, opacity, and water vapor permeability were measured. Results indicated that tensile strength, puncture strength, and elastic modulus decreased, while tensile elongation and puncture deformation values increased as glycerol concentration increased for both 5.0% and 7.5% canola protein isolate films. Furthermore, tensile strength, puncture strength, and elastic modulus values were found to increase at higher protein concentrations within the canola protein isolate films, whereas puncture deformation values decreased. Tensile elongation was found to be similar for both canola protein isolate protein levels. Canola protein isolate films became more transparent with increasing of glycerol concentration and decreasing of canola protein isolate concentration. Water vapor permeability value was also found to increase with increasing glycerol and protein contents. Overall, results indicated that canola protein isolate films were less brittle, more malleable and transparent, and had greater water vapor permeability at higher glycerol levels. However, as protein level increased, canola protein isolate films were more brittle, less malleable and more opaque, and also had increased water vapor permeability. PMID:24072788

  16. Protein immobilization on epoxy-activated thin polymer films: effect of surface wettability and enzyme loading.

    PubMed

    Chen, Bo; Pernodet, Nadine; Rafailovich, Miriam H; Bakhtina, Asya; Gross, Richard A

    2008-12-01

    A series of epoxy-activated polymer films composed of poly(glycidyl methacrylate/butyl methacrylate/hydroxyethyl methacrylate) were prepared. Variation in comonomer composition allowed exploration of relationships between surface wettability and Candida antartica lipase B (CALB) binding to surfaces. By changing solvents and polymer concentrations, suitable conditions were developed for preparation by spin-coating of uniform thin films. Film roughness determined by AFM after incubation in PBS buffer for 2 days was less than 1 nm. The occurrence of single CALB molecules and CALB aggregates at surfaces was determined by AFM imaging and measurements of volume. Absolute numbers of protein monomers and multimers at surfaces were used to determine values of CALB specific activity. Increased film wettability, as the water contact angle of films increased from 420 to 550, resulted in a decreased total number of immobilized CALB molecules. With further increases in the water contact angle of films from 55 degrees to 63 degrees, there was an increased tendency of CALB molecules to form aggregates on surfaces. On all flat surfaces, two height populations, differing by more than 30%, were observed from height distribution curves. They are attributed to changes in protein conformation and/or orientation caused by protein-surface and protein-protein interactions. The fraction of molecules in these populations changed as a function of film water contact angle. The enzyme activity of immobilized films was determined by measuring CALB-catalyzed hydrolysis of p-nitrophenyl butyrate. Total enzyme specific activity decreased by decreasing film hydrophobicity. PMID:18991420

  17. Composite films from pectin and fish skin gelatin or soybean flour protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composite films were prepared from pectin and fish skin gelatin (FSG) or pectin and soybean flour protein (SFP). The inclusion of protein promoted molecular interactions, resulting in a well-organized homogeneous structure, as revealed by scanning electron microscopy and fracture-acoustic emission ...

  18. Making Ordered DNA and Protein Structures from Computer-Printed Transparency Film Cut-Outs

    ERIC Educational Resources Information Center

    Jittivadhna, Karnyupha; Ruenwongsa, Pintip; Panijpan, Bhinyo

    2009-01-01

    Instructions are given for building physical scale models of ordered structures of B-form DNA, protein [alpha]-helix, and parallel and antiparallel protein [beta]-pleated sheets made from colored computer printouts designed for transparency film sheets. Cut-outs from these sheets are easily assembled. Conventional color coding for atoms are used…

  19. Molecular description of the formation and structure of plasticized globular protein films.

    PubMed

    Lefèvre, Thierry; Subirade, Muriel; Pézolet, Michel

    2005-01-01

    To optimize the properties of plasticized globular proteins films, a clear comprehension of the structure and molecular events occurring during film formation is required. In this work, the structural organization of beta-lactoglobulin (beta-lg) films plasticized with diethyelene glycol are investigated for the first time during the entire film formation process by attenuated total reflectance and transmission infrared spectroscopy. The films are made by a common two-step procedure consisting of a first heat treatment (80 degrees C/30 min) followed by the casting of the film-forming solution for dehydration. Heating at 80 degrees C leads to the self-aggregation of the proteins with a conversion of regular secondary structures into antiparallel beta-sheets. The kinetics of the conformational conversion shows that approximately 10% of the amino acids are involved in beta-sheets after the first step. Dehydration induces a further aggregation, with approximately 46% of the amino acids involved in beta-sheets in the final film. Water evaporation results in the association of the aggregates formed during the heating step. The presence of the plasticizer during water removal is essential as it allows specific conformational rearrangements into extended beta-sheets and ordering of the polypeptide chains. This work underlines that the assembly of building blocks is common in beta-lg networks and it emphasizes the widespread occurrence of beta-structures in synthetic and natural protein networks. PMID:16283748

  20. Effect of transglutaminase on properties of tilapia scale gelatin films incorporated with soy protein isolate.

    PubMed

    Weng, Wuyin; Zheng, Huibin

    2015-02-15

    The effect of transglutaminase (TGase) on the properties of tilapia scale gelatin films in the presence of soy protein isolate (SPI) was investigated. When 3% TGase was added into gelatin films, the total soluble matter and protein solubility of films were decreased from 89.36% and 92.78% to 35.83% and 40.05%, respectively, and the decline was promoted by adding 5% SPI. The strength of the films was increased by adding 1% TGase irrespective of SPI addition, but decreased when the TGase concentration was further raised. No obvious colour change was observed in the films with or without TGase and SPI. Based on the results of SDS-PAGE, DSC and SEM, it was revealed that the movement of low molecular weight hydrophilic protein was depressed by the cross-linking network structure induced by TGase and SPI during film drying, indicating that adding SPI is essential to improve the thermal stability and water resistance properties of TGase-induced gelatin films. PMID:25236224

  1. Pulsed laser deposited metal oxide thin films mediated controlled adsorption of proteins

    NASA Astrophysics Data System (ADS)

    Kim, Se Jin

    Several metal oxide thin films were grown on Si substrate by pulsed laser deposition for controlling adsorption of proteins. No intentional heating of substrate and introduction of oxygen gas during growth were employed. Additionally, fibrinogen, bovine serum albumin (BSA), and lysozyme were used as model protein in this study. The film properties such as cyratllinity, surface roughness, surface electrical charge and chemistry were investigated by many techniques in order to obtain the relationship with protein adsorption. Firstly, as grown Ta2O5 and ZnO thin film were used to study the effects of surface charge on the behaviors of BSA and lysozyme adsorption. The protein thickness results by ellipsometry showed that negatively charged Ta2O5 had a stronger affinity to positively charged lysozyme, while positively charged ZnO had a stronger affinity to negatively charged BSA. The results confirmed electrostatic interaction due to surface charge is one of main factors for determining adsorption of proteins. Furthermore, annealing studies were performed by heat treatment of as grown Ta2O5 and ZnO at 800°C in air ambience. Annealed Ta2O5 thin film had almost wetting property (from 10.02° to less than 1˜2°) and the change of cystallinity (from amorphous to cyrsalline) while annealed ZnO thin film had a reduced contact angle (from 75.65° to 39.41°) and remained to crystalline structure. The fibrinogen thickness on annealed Ta2O5 film was increased compared with as grown sample, while heat treated ZnO film showed much reduction of fibrinogen adsorption. Binary Ta-Zn oxide thin films (TZ) were grown by preparing PLD target composed of 50 wt% Ta2O5 and 50 wt% ZnO. This binary film had IEP pH 7.1 indicating nearly neutral charge in pH 7.4 PBS solution, and hydrophilic property. Ellipsometrical results showed that TZ film had the lowest fibrinogen, BSA and lysozyme thickness after 120 min adsorption compared with Ta2O5 and ZnO. Other samples, bilayer oxide films in

  2. Gelation Mechanisms and Characterization of Electrochemically Generated Protein Films at Metal Interfaces

    NASA Astrophysics Data System (ADS)

    Martin, Elizabeth J.

    Although the electrochemical behavior of metals used in orthopedic implants has been studied extensively, the material interactions with proteins during corrosion processes remains poorly understood. Some studies suggest that metal-protein interactions accelerate corrosion, while others suggest that proteins protect the material from degradation. Corrosion of implant materials is a major concern due to the metal ion release that can sometimes cause adverse local tissue reactions and ultimately, failure of the implant. The initial purpose of this research was therefore to study the corrosion behavior of CoCrMo, an alloy commonly used in hip replacements, with a quartz crystal microbalance (QCM) in physiologically relevant media. The QCM enables in situ characterization of surface changes accompanying corrosion and is sensitive to viscoelastic effects at its surface. Results of QCM studies in proteinaceous media showed film deposition on the alloy surface under electrochemical conditions that otherwise produced mass loss if proteins were not present in the electrolyte. Additional studies on pure Co, Cr, and Mo demonstrated that the protein films also form on Mo surfaces after a release of molybdate ions, suggesting that these ions are essential for film formation. The electrochemically generated protein films are reminiscent of carbonaceous films that form on implant surfaces in vivo, therefore a second goal of the research was to delineate mechanisms that cause the films to form. In the second stage of this research, electrochemical QCM tests were conducted on models of the CoCrMo system consisting of Cr electrodes in proteinaceous or polymeric media containing dissolved molybdate ions. Studies indicated that films can be generated through electrochemical processes so long as both amine functional groups and molybdate ions are present in the electrolyte solution. These results suggest that the films form due to an ionic cross-linking reaction between the positively

  3. Preparation of core-shell structure Fe3 O4 @SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His-tag protein purification.

    PubMed

    Ni, Qian; Chen, Bing; Dong, Shaohua; Tian, Lei; Bai, Quan

    2016-04-01

    The core-shell structure Fe3 O4 /SiO2 magnetic microspheres were prepared by a sol-gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu(2+) , Ni(2+) and Zn(2+) , were chelated on the Fe3 O4 @SiO2 -IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni(2+) -chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe3 O4 @SiO2 -IDA-Ni(2+) magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His-tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26268650

  4. Advances in food packaging films from milk proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most commercial petroleum-based food packaging films are poor oxygen barriers, do not biodegrade, and some are suspected to even leach compounds into the food product. For instance, three-perfluorinated coatings were banned from convenience food packaging earlier this year. These shortcomings are a ...

  5. Nonfouling tunable βCD dextran polymer films for protein applications.

    PubMed

    Städe, Lars W; Nielsen, Thorbjørn T; Duroux, Laurent; Hinge, Mogens; Shimizu, Kyoko; Gurevich, Leonid; Kristensen, Peter K; Wingren, Christer; Larsen, Kim L

    2015-02-25

    Polymeric β-cyclodextrin (βCD) films tunable with respect to thickness and βCD content were prepared in order to develop a suitable platform, allowing for inclusion of nonpolar guest molecules in the βCD cavity, while suppressing nonspecific protein adsorption. The βCD films were synthesized from linear βCD dextran polymers, and grafted onto silicon oxide surfaces by "click" chemistry. Topographic and morphological characteristics are controllable by reaction conditions and polymer type, with average film heights from 2.5 to 12.5 nm. Reversible introduction of electrostatic charges in the βCD dextran by complex formation with 1-adamantanecarboxylic acid prior to surface grafting resulted in a thinner and denser film, presumably by decompaction of the polymers. Total internal reflection fluorescence spectroscopy (TIRF) was employed to evaluate the accessibility of βCD cavities to the fluorescent probe 2-anilinonaphthalene-6-sulfonic acid. Only a minor fraction of the βCD cavities was accessible in the thicker and less dense films; however, accessibility was largely improved with increased ionic strength using NaCl up to 1 M. Antifouling properties of the βCD dextran polymer films were assessed by TIRF real-time monitoring, using bovine serum albumin as a model protein, and showed a 5- to 10-fold reduction in nonspecific adsorption as compared to a bare quartz surface with the degree of reduction reflecting film thickness and interfacial polymer density. PMID:25639169

  6. Growth of gold nanoclusters and nanocrystals induced by lysozyme protein in thin film conformation

    NASA Astrophysics Data System (ADS)

    Bhowal, Ashim Chandra; Kundu, Sarathi

    2016-08-01

    Structures and growth behavior of gold nanoclusters and nanocrystals have been explored on thin films of globular protein lysozyme by using UV-vis and photoluminescence spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). A simple and one-step environment friendly method has been used to grow nanocrystals on protein surface from HAuCl4 solution. It has been found that if different interaction times are provided between lysozyme films and HAuCl4 solution, then initially formed tiny gold nanoclusters on protein surface transform into nanocrystals with the passage of time. XRD analysis shows the formation of faced-centered cubic lattice along (1 1 1) crystalline direction and AFM images confirm the presence of circular, rod-like, triangular and hexagonal crystal structures. Langmuir-like growth behavior has been identified for both the gold nanoclusters and nanocrystals formation induced by the lysozyme films, however, nanocrystal growth is relatively slower than nanocluster.

  7. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  8. Development of ecofriendly bionanocomposite: Whey protein isolate/pullulan films with nano-SiO2.

    PubMed

    Hassannia-Kolaee, Mahbobeh; Khodaiyan, Faramarz; Pourahmad, Rezvan; Shahabi-Ghahfarrokhi, Iman

    2016-05-01

    During the past decade, the limitation of petroleum based polymers, the high price of oil, and the environmental concern were attracted the attention of researchers to develop biobased polymers. The composition of different biopolymers and the reinforcement with nano filler are common methods to improve the drawbacks of biopolymers. In this study whey protein isolate/pullulan (WPI/PUL) films contain 1%, 3%, and 5% (w/w) nano-SiO2 (NS) were prepared by a casting method. Tensile strength of nanocomposite films increased after increasing NS content, but elongation at break decreased, simultaneously. Water absorption, moisture content, solubility in water improved in the wake of increasing NS content because NS increase the cohesiveness of the polymer matrix and improved the barrier and water resistance properties of the films. water vapor permeability of film specimens decreased by increasing NS content. Uniform distribution of NS into polymer matrix was confirmed by scanning electron microscopy (SEM). XRD pattern and thermal analysis revealed increasing crystallinity and increasing Tg of film specimens with increasing NS content, respectively. According to our result WPI/PUL/NS films possess potential to be used as environment friendly packaging films to improve shelf life of food and can be used as promising alternative to petroleum based packaging films. PMID:26774376

  9. Multilayer Films Assembled from Naturally-Derived Materials for Controlled Protein Release

    PubMed Central

    Hsu, Bryan B.; Hagerman, Samantha R; Jamieson, Kelsey; Veselinovic, Jovana; O’Neill, Nicholas; Holler, Eggehard; Ljubimova, Julia Y.; Hammond, Paula T.

    2014-01-01

    Herein we designed and characterized films composed of naturally derived materials for controlled release of proteins. Traditional drug delivery strategies rely on synthetic or semi-synthetic materials, or utilize potentially denaturing assembly conditions that are not optimal for sensitive biologics. Layer-by-Layer (LbL) assembly of films uses benign conditions and can generate films with various release mechanisms including hydrolysis-facilitated degradation. These use components such as synthetic polycations that degrade into non-natural products. Herein we report the use of a naturally-derived, biocompatible and degradable polyanion, poly(β-l-malic acid), alone and in combination with chitosan in an LbL film, whose degradation products of malic acid and chitosan are both generally recognized as safe (GRAS) by the FDA. We have found that films based on this polyanion have shown sustained release of a model protein, lysozyme that can be timed from tens of minutes to multiple days through different film architectures. We also report the incorporation and release of a clinically used biologic, basic fibroblast growth factor (bFGF), which demonstrates the use of this strategy as a platform for controlled release of various biologics. PMID:24825478

  10. Soy protein films for wound-healing applications: antibiotic release, bacterial inhibition and cellular response.

    PubMed

    Peles, Zachi; Binderman, Itzhak; Berdicevsky, Israela; Zilberman, Meital

    2013-05-01

    Use of naturally derived materials is becoming widespread in the biomedical field. Soy protein has advantages over the various types of natural proteins employed for biomedical applications, due to its low price, non-animal origin and relatively long storage time and stability. In the current study, soy protein isolate (SPI) was investigated as a matrix for wound-dressing applications. The antibiotic drug gentamicin was incorporated into the matrix for local controlled release and thus continuous bactericidal effect. Homogeneous high-quality films were cast from aqueous solutions and tested for the effects of gentamicin release on bacterial inhibition. The cytotoxicity and in vitro biocompatibility of these films were also examined. The gentamicin release profiles exhibited a moderate burst effect followed by a decreasing release rate, which was maintained for at least 4 weeks, thus enabling a suitable bacterial inhibition effect. The materials released from the films during an indirect cytotoxicity test were found to be safe, except for a slight inhibitory effect in the presence of high concentrations of glycerol. The biocompatibility test showed confluent cell cultures in close proximity to the SPI films. It is clear that these new antibiotic-eluting SPI films exhibit a high potential for use as wound dressings. PMID:22411912

  11. Nanopatterned Protein Films Directed by Ionic Complexation with Water-Soluble Diblock Copolymers

    PubMed Central

    Kim, Bokyung; Lam, Christopher N.; Olsen, Bradley D.

    2014-01-01

    The use of ionic interactions to direct both protein templating and block copolymer self-assembly into nanopatterned films with only aqueous processing conditions is demonstrated using block copolymers containing both thermally responsive and pH responsive blocks. Controlled reversible addition-fragmentation chain-transfer (RAFT) polymerization is employed to synthesize poly(N-isopropylacrylamide-b-2-(dimethylamino)ethyl acrylate) (PNIPAM-b-PDMAEA) diblock copolymers. The pH-dependent ionic complexation between the fluorescent protein, mCherry, and the ionic PDMAEA block is established using dynamic light scattering (DLS) and UV-Vis spectroscopy. DLS shows that the size of the resulting coacervate micelles depends strongly on pH, while UV-Vis spectroscopy shows a correlation between the protein’s absorption maximum and the ionic microenvironment. Zeta potential measurements clearly indicate the ionic nature of the complex-forming interactions. Spin casting was used to prepare nanostructured films from the protein-block copolymer coacervates. After film formation, the lower critical solution temperature (LCST) of the PNIPAM blocks allows the nanomaterial to be effectively immobilized in aqueous environments at physiological temperatures, enabling potential use as a controlled protein release material or polymer matrix for protein immobilization. At pH 9.2 and 7.8, the release rates are at least 10 times faster than that at pH 6.4 due to weaker interaction between protein and PNIPAM-b-PDMAEA (PND) diblock copolymer. Due to the ionic environment in which protein is confined, the majority of the protein (80%) remains active, independent of pH, even after having been dehydrated in vacuum and confined in the films. PMID:24904186

  12. Thiophilic adsorbents for RIA and ELISA procedures.

    PubMed

    Oscarsson, S; Chaga, G; Porath, J

    1991-10-25

    Three types of agarose derivatives have been prepared and investigated as adsorbents for radioimmunoassay and ELISA analysis. The analytical systems were evaluated using beta 2 microglobulin as a model. After a competitive reaction between the immunocomponents in solution, the formed immune complexes were adsorbed onto the adsorbent in the presence of 0.5 M potassium sulfate in 0.1 M Tris, pH 7.5. The binding constant between the interaction site on human IgG and the adsorbent 3-(2-pyridylthio)-2-hydroxypropylagarose (Py-S-gel) was determined to be 1.5 x 10(7) M-1 and the binding capacity was 20 mg/ml gel. The immune complex was desorbed by deleting potassium sulfate from the buffer, and only 0.5% of the total applied protein remained after washing the adsorbent with 0.5 M NaOH. The same adsorbent can be used repetitively with different systems. PMID:1940385

  13. STRUCTURE AND FUNCTION OF PROTEIN-BASED EDIBLE FILMS AND COATINGS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research and development on films and coatings made from various agricultural proteins has been conducted over the past 20 years but recently has been of heightened interest because of the demand for environmentally friendly, renewable replacements for petroleum-based polymeric materials and plastic...

  14. Use of /γ-irradiation to produce films from whey, casein and soya proteins: structure and functionals characteristics

    NASA Astrophysics Data System (ADS)

    Lacroix, M.; Le, T. C.; Ouattara, B.; Yu, H.; Letendre, M.; Sabato, S. F.; Mateescu, M. A.; Patterson, G.

    2002-03-01

    γ-irradiation and thermal treatments have been used to produce sterilized cross-linked films. Formulations containing variable concentrations of calcium caseinate and whey proteins (whey protein isolate (WPI) and commercial whey protein concentrate) or mixture of soya protein isolate (SPI) with WPI was investigated on the physico-chemical properties of these films. Results showed that the mechanical properties of cross-linked films improved significantly the puncture strength for all types of films. Size-exclusion chromatography showed for no cross-linked proteins, a molecular mass of around 40 kDa. The soluble fractions of the cross-linked proteins molecular distributions were between 600 and 3800 kDa. γ-irradiation seems to modify to a certain extent the conformation of proteins which will adopt structures more ordered and more stable, as suggested by X-ray diffraction analysis. Microstructure observations showed that the mechanical characteristics of these films are closely related to their microscopic structure. Water vapor permeability of films based on SPI was also significantly decreased when irradiated. Microbial resistance was also evaluated for cross-linked films. Results showed that the level of biodegradation of cross-linked films was 36% after 60 d of fermentation in the presence of Pseudomonas aeruginosa.

  15. Understanding surface core-level shifts using the Auger parameter: A study of Pd atoms adsorbed on ultrathin SiO2 films

    NASA Astrophysics Data System (ADS)

    Kaden, William E.; Büchner, Christin; Lichtenstein, Leonid; Stuckenholz, Stefanie; Ringleb, Franziska; Heyde, Markus; Sterrer, Martin; Freund, Hans-Joachim; Giordano, Livia; Pacchioni, Gianfranco; Nelin, Connie J.; Bagus, Paul S.

    2014-03-01

    Auger parameter (Δα) measurements have been employed to determine the extent to which initial- and final-state effects govern surface core-level shifts in x-ray photoelectron spectroscopy (XPS) measurements of Pd atoms confined between a bilayer SiO2 film and its Ru(0001) support. For atoms bound in this manner, we note negative binding energy shifts (ΔBEs) of ˜0.3 eV, relative to the Pd 3d peak position in the bulk, and attribute these shifts to large variations in the initial-state orbital energies of the supported atoms (˜1.1 eV towards EF), coupled with decreased final-state relaxation contributions (˜0.8 eV). Theoretical calculations reveal that, despite small partial positive charges and decreased final-state screening, the decreased 4d-5sp hybridization of the undercoordinated Pd atoms results in large enough upward 3d orbital-energy shifts to yield the net-negative ΔBE noted by XPS.

  16. Regenerative adsorbent heat pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  17. The influence of protein aggregation on adsorption kinetics

    NASA Astrophysics Data System (ADS)

    Rovner, Joel; Roberts, Christopher; Furst, Eric; Hudson, Steven

    2015-03-01

    When proteins adsorb to an air-water interface they lower the surface tension and may form an age-dependent viscoelastic film. Protein adsorption to surfaces is relevant to both commercial uses and biological function. The rate at which the surface tension decreases depends strongly on temperature, solution pH, and protein structure. These kinetics also depend on the degree to which the protein is aggregated in solution. Here we explore these differences using Chymotrypsinogen as a model protein whose degree of aggregation is adjusted through controlled heat treatment and measured by chromatography. To study these effects we have used a micropipette tensiometer to produce a spherical-cap bubble whose interfacial pressure was controlled - either steady or oscillating. Short heat treatment produced small soluble aggregates, and these adsorbed faster than the original protein monomer. Longer heat treatment produced somewhat larger soluble aggregates which adsorbed more slowly. These results point to complex interactions during protein adsorption.

  18. In situ spectroelectrochemical and theoretical study on the oxidation of a 4H-imidazole-ruthenium dye adsorbed on nanocrystalline TiO2 thin film electrodes.

    PubMed

    Zhang, Ying; Kupfer, Stephan; Zedler, Linda; Schindler, Julian; Bocklitz, Thomas; Guthmuller, Julien; Rau, Sven; Dietzek, Benjamin

    2015-11-28

    Terpyridine 4H-imidazole-ruthenium(II) complexes are considered promising candidates for use as sensitizers in dye sensitized solar cells (DSSCs) by displaying broad absorption in the visible range, where the dominant absorption features are due to metal-to-ligand charge transfer (MLCT) transitions. The ruthenium(III) intermediates resulting from photoinduced MLCT transitions are essential intermediates in the photoredox-cycle of the DSSC. However, their photophysics is much less studied compared to the ruthenium(II) parent systems. To this end, the structural alterations accompanying one-electron oxidation of the RuIm dye series (including a non-carboxylic RuIm precursor, and, carboxylic RuImCOO in solution and anchored to a nanocrystalline TiO2 film) are investigated via in situ experimental and theoretical UV-Vis absorption and resonance Raman (RR) spectroelectrochemistry. The excellent agreement between the experimental and the TDDFT spectra derived in this work allows for an in-depth assignment of UV-Vis and RR spectral features of the dyes. A concordant pronounced wavelength dependence with respect to the charge transfer character has been observed for the model system RuIm, and both RuImCOO in solution and attached on the TiO2 surface. Excitation at long wavelengths leads to the population of ligand-to-metal charge transfer states, i.e. photoreduction of the central ruthenium(III) ion, while high-energy excitation features an intra-ligand charge transfer state localized on the 4H-imidazole moiety. Therefore, these 4H-imidazole ruthenium complexes investigated here are potential multi-photoelectron donors. One electron is donated from MLCT states, and additionally, the 4H-imidazole ligand reveals electron-donating character with a significant contribution to the excited states of the ruthenium(III) complexes upon blue-light irradiation. PMID:26478575

  19. Carbon nanodots-chitosan composite film: a platform for protein immobilization, direct electrochemistry and bioelectrocatalysis.

    PubMed

    Sheng, Meili; Gao, Yue; Sun, Junyong; Gao, Feng

    2014-08-15

    A novel composite film based on carbon nanodots (CNDs) and chitosan was readily prepared and used as immobilization matrix to entrap a heme protein, hemoglobin (Hb) for direct electrochemistry and bioelectrocatalysis. A modified electrode was obtained by casting Hb-CNDs-chitosan composites on the glassy carbon (GC) electrode surface. Spectroscopic and electrochemical studies showed that Hb entrapped in the composite film remained in its native structures, and CNDs in the film can greatly facilitate DET between the protein and the GC electrode. The electron-transfer kinetics of Hb in composite film was qualitatively evaluated by using the Marcus theory, and the apparent heterogeneous electron-transfer rate constant (ks) was estimated to be 2.39(±0.03)s(-1) with Laviron equations. The modified electrode showed excellent electrocatalytic behavior to the substrate, hydrogen peroxide (H2O2). The linear current response for H2O2 was from 1×10(-6) to 1.18×10(-4)M with a detection limit of 0.27(±0.02)μM at the signal-to-noise ratio of 3, and the apparent Michaelis-Menten constant was 0.067(±0.02)mM. These important features of CNDs-chitosan film have implied to be a promising platform for elaborating bioelectrochemical devices such as biosensors and biofuel cells. PMID:24681154

  20. Contribution of the starch, protein, and lipid fractions to the physical, thermal, and structural properties of amaranth (Amaranthus caudatus) flour films.

    PubMed

    Tapia-Blácido, D; Mauri, A N; Menegalli, F C; Sobral, P J A; Añón, M C

    2007-06-01

    Amaranth protein-lipid (PL) and protein (P) films were elaborated and compared with amaranth flour films in order to determine the contribution of the interactions between the biopolymer (starch and protein) and the lipids to the film properties. The films were made by the casting method, using the same glycerol concentration (0.9 g glycerol/100 g solution). A separation of the lipid fraction in the PL films and a polymorphic transformation of the corresponding fatty acids were observed by differential scanning calorimetry (DSC) and verified by an analysis of the microstructure by scanning electron microscopy (SEM). The flour films showed no separation of the lipid fraction, evidence that the lipids were strongly associated with the proteins and homogenously distributed throughout the starch network, contributing to the good mechanical properties when compared to the PL films and to the excellent barrier properties when compared to both the PL and P films. The protein-protein interactions also contributed to the mechanical properties of the flour films. The presence of proteins and lipids in the flour films had an important effect on film solubility, and also on the color and opacity of the films. This study showed that the flour film properties depended on the interactions formed by their polymers (starches and proteins) and by the lipid, on the distribution of these interactions within the film matrix and on the concentrations of each component in the film. PMID:17995729

  1. Blend-modification of soy protein/lauric acid edible films using polysaccharides.

    PubMed

    Pan, Hongyang; Jiang, Bo; Chen, Jie; Jin, Zhengyu

    2014-05-15

    Different types of polysaccharides (propyleneglycol alginate (PGA), pectin, carrageenan and aloe polysaccharide) were incorporated into soy protein isolate (SPI)/lauric acid (La) films using a co-drying process or by direct addition to form biodegradable composite films with modified water vapour permeability (WVP) and mechanical properties. The WVP of SPI/La/polysaccharide films decreased when polysaccharides were added using the co-drying process, regardless of the type of polysaccharide. The tensile strength of SPI/La film was increased by the addition of polysaccharides, and the percentage elongation at break was increased by incorporating PGA using the co-drying process. Regarding oxygen-barrier performance, no notable differences were observed between the SPI/La and SPI/La/polysaccharide films. The most significant improvement was observed by blending PGA, with the co-dried preparation exhibiting better properties than the direct-addition preparation. Scanning electron microscopy (SEM) revealed that the microstructures of the films are the basis for the differences in the barrier and mechanical properties of the modified blends of SPI, polysaccharides and La. PMID:24423494

  2. Effect of glycosylation with xylose on the mechanical properties and water solubility of peanut protein films.

    PubMed

    Lin, Wei-Jing; Liu, Hong-Zhi; Shi, Ai-Min; Liu, Li; Wang, Qiang; Adhikari, Benu

    2015-10-01

    This study aimed at improving the mechanical properties and water solubility of peanut protein isolate (PPI) films by glycosylating with xylose (X). The modification process of glycosylation was optimized by using response surface methodology (RSM). The effects of pH, temperature and time on degrees of glycosylation (DG), tensile strength (TS), elongation (E), solubility and microstructure of xylose glycosylated PPI films (PPI-XF) were determined. The changes of DG in different conditions indicated that crosslinking should occur between PPI and xylose during the modification. Optimum glycosylation conditions were found to be pH 9.5, 91.5 °C and 95 min. Under these conditions, TS and E values of PPI-XF were 10.37 MPa and 96.47 %, respectively. Due to glycosylation, solubility of PPI-XF decreased from 96.64 to 35.94 % and these films remained intact in water for 24 h. The microstructure of PPI-XF was denser and more compact than the unmodified PPI films. These results suggest that the xylose glycosylated PPI films have potentiality of being used as biodegradable films in food packaging application. PMID:26396370

  3. Preparation of a porcine plasma protein composite film and its application.

    PubMed

    Lee, Ji-Hyun; Song, Kyung Bin

    2015-01-01

    To use blood released from slaughtering houses, a porcine plasma protein (PPP)/nanoclay composite film was prepared. The tensile strength and elongation at break values of the PPP composite film with 5% nanoclay were 10.01 MPa and 6.55%, respectively. The PPP composite film containing 1% grapefruit seed extract (GSE) was applied to pork meat, and the populations of inoculated Escherichia coli O157:H7 and Listeria monocytogenes in the pork meat packaged with the PPP composite film decreased by 0.8 and 1.0 log CFU/g, respectively, after 7 days of storage compared to the populations of the control. In addition, thiobarbituric acid values in the pork meat packaged with the PPP composite film were less than those of the control sample during storage. These results suggest that the PPP nanocomposite film containing 1% GSE can be used as a packaging material to maintain the quality of pork meat. PMID:25248798

  4. Adsorbent and adsorbent bed for materials capture and separation processes

    SciTech Connect

    Liu, Wei

    2011-01-25

    A method device and material for performing adsorption wherein a fluid mixture is passed through a channel in a structured adsorbent bed having a solid adsorbent comprised of adsorbent particles having a general diameter less than 100 um, loaded in a porous support matrix defining at least one straight flow channel. The adsorbent bed is configured to allow passage of a fluid through said channel and diffusion of a target material into said adsorbent under a pressure gradient driving force. The targeted molecular species in the fluid mixture diffuses across the porous support retaining layer, contacts the adsorbent, and adsorbs on the adsorbent, while the remaining species in the fluid mixture flows out of the channel.

  5. Recognition of dengue virus protein using epitope-mediated molecularly imprinted film.

    PubMed

    Tai, Dar-Fu; Lin, Chung-Yin; Wu, Tzong-Zeng; Chen, Li-Kuang

    2005-08-15

    Molecularly imprinted film was fabricated in the presence of a pentadecapeptide onto a quartz crystal microbalance (QCM) chip. This 15-mer peptide has been known as the linear epitope of the dengue virus NS1 protein. Imprinting resulted in an increased polymer affinity toward the corresponding templates but also to the virus protein. Direct detection of the dengue virus protein was achieved quantitatively. The QCM chip response to the NS1 protein was obtained using epitope-mediated imprinting demonstrating a comparable frequency shift in chips immobilized with monoclonal antibodies. The binding effect was further enhanced and confirmed using a monoclonal antibody to form a sandwich with the MIP-NS1 protein complex on the chip. No pretreatment was required. PMID:16097751

  6. Quantitative and epitope-specific antigenicity analysis of the human papillomavirus 6 capsid protein in aqueous solution or when adsorbed on particulate adjuvants.

    PubMed

    Li, Min; Wang, Xin; Cao, Lu; Lin, Zhijie; Wei, Minxi; Fang, Mujin; Li, Shaowei; Zhang, Jun; Xia, Ningshao; Zhao, Qinjian

    2016-08-17

    Human papillomavirus (HPV) 6 is a human pathogen which causes genital warts. Recombinant virus-like particle (VLP) based antigens are the active components in prophylactic vaccines to elicit functional antibodies. The binding and functional characteristics of a panel of 15 murine monoclonal antibodies (mAbs) against HPV6 was quantitatively assessed. Elite conformational indicators, recognizing the conformational epitopes, are also elite viral neutralizers as demonstrated with their viral neutralization efficiency (5 mAbs with neutralization titer below 4ng/mL) in a pseudovirion (PsV)-based system. The functionality of a given mAb is closely related to the nature of the corresponding epitope, rather than the apparent binding affinity to antigen. The epitope-specific antigenicity assays can be used to assess the binding activity of PsV or VLP preparations to neutralizing mAbs. These mAb-based assays can be used for process monitoring and for product release and characterization to confirm the existence of functional epitopes in purified antigen preparations. Due to the particulate nature of the alum adjuvants, the vaccine antigen adsorbed on adjuvants was considered largely as "a black box" due to the difficulty in analysis and visualization. Here, a novel method with fluorescence-based high content imaging for visualization and quantitating the immunoreactivity of adjuvant-adsorbed VLPs with neutralizing mAbs was developed, in which antigen desorption was not needed. The facile and quantitative in situ antigenicity analysis was amendable for automation. The integrity of a given epitope or two non-overlapping epitopes on the recombinant VLPs in their adjuvanted form can be assessed in a quantitative manner for cross-lot or cross-product comparative analysis with minimal manipulation of samples. PMID:27426626

  7. Exploring the Properties of Genetically Engineered Silk-Elastin-Like Protein Films.

    PubMed

    Machado, Raul; da Costa, André; Sencadas, Vitor; Pereira, Ana Margarida; Collins, Tony; Rodríguez-Cabello, José Carlos; Lanceros-Méndez, Senentxu; Casal, Margarida

    2015-12-01

    Free standing films of a genetically engineered silk-elastin-like protein (SELP) were prepared using water and formic acid as solvents. Exposure to methanol-saturated air promoted the formation of aggregated β-strands rendering aqueous insolubility and improved the mechanical properties leading to a 10-fold increase in strain-to-failure. The films were optically clear with resistivity values similar to natural rubber and thermally stable up to 180 °C. Addition of glycerol showed to enhance the flexibility of SELP/glycerol films by interacting with SELP molecules through hydrogen bonding, interpenetrating between the polymer chains and granting more conformational freedom. This detailed characterization provides cues for future and unique applications using SELP based biopolymers. PMID:26214274

  8. Improvement in physical and biological properties of chitosan/soy protein films by surface grafted heparin.

    PubMed

    Wang, Xiaomei; Hu, Ling; Li, Chen; Gan, Li; He, Meng; He, Xiaohua; Tian, Weiqun; Li, Mingming; Xu, Li; Li, Yinping; Chen, Yun

    2016-02-01

    A series of chitosan/soy protein isolate (SPI) composite films (CS-n, n=0, 10 and 30, corresponding to SPI content in the composites) were prepared. Heparin was grafted onto the surface of CS-n to fabricate a series of heparinized films (HCS-n). CS-n and HCS-n were characterized by ATR-Fourier transform infrared spectroscopy and water contact angle. The surface heparin density was measured by toluidine blue assay. The results showed that heparin has been successfully grafted onto the surface of CS-n. Heparin evenly distributed on the surface of the films and the heparin content increased with the increase of SPI content, and the hydrophilicity of the films was enhanced due to the grafted heparin. The cytocompatibility and hemocompatibility of CS-n and HCS-n were evaluated by cell culture (MTT assay, live/dead assay, cell morphology and cell density observation), platelet adhesion test, plasma recalcification time (PRT) measurement, hemolysis assay and thrombus formation test. HCS-n showed higher cell adhesion rate and improved cytocompatibility compared to the corresponding CS-n. HCS-n also exhibited lower platelet adhesion, longer PRT, higher blood anticoagulant indexes (BCI) and lower hemolysis rate than the corresponding CS-n. The improved cytocompatibility and hemocompatibility of HCS-n would shed light on the potential applications of chitosan/soy protein-based biomaterials that may come into contact with blood. PMID:26616450

  9. Effect of silk protein processing on drug delivery from silk films.

    PubMed

    Pritchard, Eleanor M; Hu, Xiao; Finley, Violet; Kuo, Catherine K; Kaplan, David L

    2013-03-01

    Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial-related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60, and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass-transition temperature, and increases the rate of degradation of a silk film by protease. Model compounds spanning a range of physical-chemical properties generally show an inverse relationship between degumming time and release rate through a varied degumming time silk coating. Degumming provides a useful control point to manipulate silk's material properties. PMID:23349062

  10. Ag island film-enhanced rare earth co-luminescence effect of Tb-Gd-protein-sodium dodecyl benzene sulfonate system and sensitive detection of protein.

    PubMed

    Sun, Chang Xia; Wu, Xia; Zhou, Hai Ping; Wang, Fei; Ding, Hong Hong; Zhao, Liang Liang; Yang, Jing He

    2008-09-15

    This paper reported the coupling technique of Ag island film-enhanced fluorescence with rare earth co-luminescence effect of Tb-Gd-sodium dodecyl benzene sulfonate (SDBS)-protein system. While the collagen is used as the separator between Ag island film and the fluorophore because it not only can decrease the fluorescence of the blank, but also can promote the adsorption of other proteins and change the conformation of the protein. The effects of Ag island film on both the fluorescence and resonance energy transfer process of Tb-Gd-SDBS-protein system are studied, finding that Ag island film can enhance the energy transfer efficiency of this system, resulting in fluorescence enhancement about tenfold compared with this system without Ag island film. Therefore, this technique is used for the detection of proteins as low as 0.72 ng/mL for BSA and 1.3 ng/mL for HSA. In addition, Ag island film can also change the energy transfer process of Tb-SDBS-protein system. PMID:18761153

  11. Interfacial hydrodynamic drag on nanowires embedded in thin oil films and protein layers.

    PubMed

    Lee, Myung Han; Lapointe, Clayton P; Reich, Daniel H; Stebe, Kathleen J; Leheny, Robert L

    2009-07-21

    We investigate the motion of ferromagnetic nanowires confined to nanometer-scale oil films at an air/aqueous interface in response to the application of external magnetic fields and field gradients. By varying the oil viscosity, film thickness, and wire length, we cover two regimes of response suggested by theory: one where the surface viscosity is expected to dominate the wire's motion and one where the subphase viscosity is expected to dominate [Levine, A. J.; Liverpool, T. B.; MacKintosh, F. C. Phys. Rev. E 2004, 69, 021503]. For wire motion parallel to the long axis of the wire, the observed drag agrees reasonably with theoretical predictions. However, the drag on wires moving perpendicular to their long axis or rotating about a short axis is unexpectedly insensitive to the film properties over the full range of measurements. This behavior is in contrast to the rotational and translational drag on nanowires in molecularly thin protein layers, which follow theoretical expectations. The observations in the oil films, which are explained in terms of the manner in which the wire immerses dynamically in the film and subphase, demonstrate how the effective drag viscosity of an aspherical particle confined to a fluid interface can depend on its direction of motion. PMID:19594180

  12. Langmuir-Blodgett film of hydrophobin protein from Pleurotus ostreatus at the air-water interface.

    PubMed

    Houmadi, S; Ciuchi, F; De Santo, M P; De Stefano, L; Rea, I; Giardina, P; Armenante, A; Lacaze, E; Giocondo, M

    2008-11-18

    We present results concerning the formation of Langmuir-Blodgett (LB) films of a class I hydrophobin from Pleurotus ostreatus at the air-water interface, and their structure as Langmuir-Blodgett (LB) films when deposited on silicon substrates. LB films of the hydrophobin were investigated by atomic force microscopy (AFM). We observed that the compressed film at the air-water interface exhibits a molecular depletion even at low surface pressure. In order to estimate the surface molecular concentration, we fit the experimental isotherm with Volmer's equation describing the equation of state for molecular monolayers. We found that about (1)/ 10 of the molecules contribute to the surface film formation. When transferred on silicon substrates, compact and uniform monomolecular layers about 2.5 nm thick, comparable to a typical molecular size, were observed. The monolayers coexist with protein aggregates, under the typical rodlet form with a uniform thickness of about 5.0 nm. The observed rodlets appear to be a hydrophilic bilayer and can then be responsible for the surface molecular depletion. PMID:18925762

  13. Corneal Cell Adhesion to Contact Lens Hydrogel Materials Enhanced via Tear Film Protein Deposition

    PubMed Central

    Elkins, Claire M.; Qi, Qin M.; Fuller, Gerald G.

    2014-01-01

    Tear film protein deposition on contact lens hydrogels has been well characterized from the perspective of bacterial adhesion and viability. However, the effect of protein deposition on lens interactions with the corneal epithelium remains largely unexplored. The current study employs a live cell rheometer to quantify human corneal epithelial cell adhesion to soft contact lenses fouled with the tear film protein lysozyme. PureVision balafilcon A and AirOptix lotrafilcon B lenses were soaked for five days in either phosphate buffered saline (PBS), borate buffered saline (BBS), or Sensitive Eyes Plus Saline Solution (Sensitive Eyes), either pure or in the presence of lysozyme. Treated contact lenses were then contacted to a live monolayer of corneal epithelial cells for two hours, after which the contact lens was sheared laterally. The apparent cell monolayer relaxation modulus was then used to quantify the extent of cell adhesion to the contact lens surface. For both lens types, lysozyme increased corneal cell adhesion to the contact lens, with the apparent cell monolayer relaxation modulus increasing up to an order of magnitude in the presence of protein. The magnitude of this increase depended on the identity of the soaking solution: lenses soaked in borate-buffered solutions (BBS, Sensitive Eyes) exhibited a much greater increase in cell attachment upon protein addition than those soaked in PBS. Significantly, all measurements were conducted while subjecting the cells to moderate surface pressures and shear rates, similar to those experienced by corneal cells in vivo. PMID:25144576

  14. Amaranth proteins foaming properties: Film rheology and foam stability - Part 2.

    PubMed

    Bolontrade, Agustín J; Scilingo, Adriana A; Añón, María C

    2016-05-01

    In this work the influence of pH and ionic strength on the stability of foams prepared with amaranth protein isolate was analyzed. The behaviour observed was related to the physico-chemical and structural changes undergone by amaranth protein as a result of those treatments. The results obtained show that foams prepared at acidic pH were more stable than the corresponding to alkaline pH. At pH 2.0 the foams presented higher times and more volumes of drainage. This behaviour is consistent with the characteristics of the interfacial film, which showed a higher viscoelasticity and a greater flexibility at acidic pH than alkaline pH value, which in turn increased by increasing the concentration of proteins in the foaming solution. It is also important to note that the presence of insoluble protein is not necessarily detrimental to the properties of the foam. Detected changes in the characteristics of the interfacial film as in the foam stability have been attributed to the increased unfolding, greater flexibility and net charge of amaranth proteins at acidic conditions. PMID:25497160

  15. 'All-solid-state' electrochemistry of a protein-confined polymer electrolyte film

    SciTech Connect

    Parthasarathy, Meera; Pillai, Vijayamohanan K. Mulla, Imtiaz S.; Shabab, Mohammed; Khan, M.I.

    2007-12-07

    Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique 'all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe{sup 2+}-form of the entrapped protein is found to bind molecular oxygen more strongly than the native protein. In the 'all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry.

  16. Novel adhesive properties of poly(ethylene-oxide) adsorbed nanolayers

    NASA Astrophysics Data System (ADS)

    Zeng, Wenduo

    Solid-polymer interfaces play crucial roles in the multidisciplinary field of nanotechnology and are the confluence of physics, chemistry, biology, and engineering. There is now growing evidence that polymer chains irreversibly adsorb even onto weakly attractive solid surfaces, forming a nanometer-thick adsorbed polymer layer ("adsorbed polymer nanolayers"). It has also been reported that the adsorbed layers greatly impact on local structures and properties of supported polymer thin films. In this thesis, I aim to clarify adhesive and tribological properties of adsorbed poly(ethylene-oxide) (PEO) nanolayers onto silicon (Si) substrates, which remain unsolved so far. The adsorbed nanolayers were prepared by the established protocol: one has to equilibrate the melt or dense solution against a solid surface; the unadsorbed chains can be then removed by a good solvent, while the adsorbed chains are assumed to maintain the same conformation due to the irreversible freezing through many physical solid-segment contacts. I firstly characterized the formation process and the surface/film structures of the adsorbed nanolayers by using X-ray reflectivity, grazing incidence X-ray diffraction, and atomic force microscopy. Secondly, to compare the surface energy of the adsorbed layers with the bulk, static contact angle measurements with two liquids (water and glycerol) were carried out using a optical contact angle meter equipped with a video camera. Thirdly, I designed and constructed a custom-built adhesion-testing device to quantify the adhesive property. The experimental results provide new insight into the microscopic structure - macroscopic property relationship at the solid-polymer interface.

  17. Properties of whey protein-based films containing organic acids and nisin to control Listeria monocytogenes.

    PubMed

    Pintado, Cristina M B S; Ferreira, Maria A S S; Sousa, Isabel

    2009-09-01

    Whey protein isolate and glycerol were mixed to form a matrix to incorporate antimicrobial agents and produce edible films with antimicrobial activity against Listeria monocytogenes strains isolated from cheeses. Various organic acids were used to decrease pH down to approximately 3. In a preliminary assay without nisin, the effect of each organic acid was evaluated with respect to the rheological properties of the film solutions and the inhibitory and mechanical properties of the films. Lactic, malic, and citric acids (3%, wt/vol), which were used in a subsequent study of their combined inhibitory effect with nisin (50 IU/ml), had significantly higher antilisterial activity (P < 0.05) compared with the control (2 N HCl, 3% [wt/vol], with nisin). The largest mean zone of inhibition was 4.00 +/- 0.92 mm for malic acid with nisin. Under small-amplitude oscillatory stress, the protein-glycerol-acid film solutions exhibited a predominantly viscous behavior or a weak gel behavior, with the storage modulus (G') slightly higher than the loss modulus (G"). The malic acid-based solution was the only one whose viscosity was not influenced by the addition of nisin. The addition of nisin resulted in a nonsignificant (P > 0.05) increase in the percentage of elongation at break. Results from tensile and puncture stress were variable, but in general no significant differences were found after the incorporation of nisin. The overall results support the use of malic acid with nisin to produce effective antimicrobial films to control L. monocytogenes growth. PMID:19777891

  18. Lubrication of metal-on-metal hip joints: the effect of protein content and load on film formation and wear.

    PubMed

    Myant, C; Underwood, R; Fan, J; Cann, P M

    2012-02-01

    Lubricant films were measured for a series of bovine serum and protein containing (albumin, globulin) saline solutions for CoCrMo femoral component sliding against a glass disc. Central film thickness was measured by optical interferometry as a function of time (constant mean speed: 0 and 10 mm/s) and variable mean speed (0-50 mm/s). The effect of load (5-20 N) on film thickness was also studied. The development of the wear scar on the CoCrMo surface was monitored by measuring the width of the contact zone during the film thickness tests. The results showed film thickness increased with time for both the static and sliding tests. Films formed in the static, loaded test were typically in the range of 3-40 nm. The globulin containing solutions formed the thickest films. In the sliding tests a wear scar rapidly formed on the implant component for the bovine serum and albumin fluids, negligible wear was observed for the globulin solutions. Film thickness increased with sliding time for all test solutions and was much greater than predicted by isoviscous EHL models. The film increase was found to correlate with increasing wear scar size and thus decreasing contact pressure. A new lubricating mechanism is proposed whereby during sliding the fluid undergoes bulk phase separation rheology, so that an elevated protein phase forms in the inlet zone. This protein phase is a high-viscosity biphasic matrix, which is periodically entrained into the contact forming a thick protective hydro-gel film. One of the main findings of this study is that film thickness was very sensitive to load; to a much greater extent than predicted by EHL models. Thus film formation in MoM hip joints is very susceptible to high contact pressures which might be due to implant misalignment and edge-loading. PMID:22301171

  19. Compositional and physicochemical factors governing the viability of Lactobacillus rhamnosus GG embedded in starch-protein based edible films

    PubMed Central

    Soukoulis, Christos; Singh, Poonam; Macnaughtan, William; Parmenter, Christopher; Fisk, Ian D.

    2016-01-01

    Probiotic incorporation in edible films and coatings has been shown recently to be an efficient strategy for the delivery of probiotics in foods. In the present work, the impact of the compositional, physicochemical and structural properties of binary starch-protein edible films on Lactobacillus rhamnosus GG viability and stability was evaluated. Native rice and corn starch, as well as bovine skin gelatine, sodium caseinate and soy protein concentrate were used for the fabrication of the probiotic edible films. Starch and protein type both impacted the structural, mechanical, optical and thermal properties of the films, and the process loss of L. rhamnosus GG during evaporation-dehydration was significantly lower in the presence of proteins (0.91–1.07 log CFU/g) compared to solely starch based systems (1.71 log CFU/g). A synergistic action between rice starch and proteins was detected when monitoring the viability of L. rhamnosus GG over four weeks at fridge and room temperature conditions. In particular, a 3- to 7-fold increase in the viability of L. rhamnosus GG was observed in the presence of proteins, with sodium caseinate – rice starch based films offering the most enhanced stability. The film's shelf-life (as calculated using the FAO/WHO (2011) basis of 6 log viable CFU/g) ranged between 27-96 and 15–24 days for systems stored at fridge or room temperature conditions respectively. PMID:26726280

  20. [Melting in adsorbed films]. Progress report 1992

    SciTech Connect

    Simon, M.I.

    1992-12-31

    Over the past several years we have been developing a new approach to cloning large fragments of mammalian DNA in E. coli. which will permit detailed analysis of complex genomes. In January 1992 we began construction of an arrayed total human genomic library prepared in our BAC vector. Our goal is to create a 4-5X library which will be accessible for screening both by colony hybridization and by PCR. Our efforts in 1992 have been focused on expanding this library, characterizing specific clones isolated from the library, and demonstrating the use of BACs and Fosmids in creating physical maps. As a Model for the use of BACs in physical mapping, we have begun mapping human chromosome 22. In addition to their stability and ease of handling, BACs and Fosniids offer the advantage of permitting isolation of relatively large amounts of pure DNA which should greatly facilitate contig construction. We have created a 7X chromosome 22-specific Fosmid library consisting of clones obtained from DNA from a hybrid cell line.

  1. Cell response to RGD density in cross-linked artificial extracellular matrix protein films.

    PubMed

    Liu, Julie C; Tirrell, David A

    2008-11-01

    This study examines the adhesion, spreading, and migration of human umbilical vein endothelial cells on cross-linked films of artificial extracellular matrix (aECM) proteins. The aECM proteins described here were designed for application in small-diameter grafts and are composed of elastin-like structural repeats and fibronectin cell-binding domains. aECM-RGD contains the RGD sequence derived from fibronectin; the negative control protein aECM-RDG contains a scrambled cell-binding domain. The covalent attachment of poly(ethylene glycol) (PEG) to aECM substrates reduced nonspecific cell adhesion to aECM-RDG-PEG but did not preclude sequence-specific adhesion of endothelial cells to aECM-RGD-PEG. Variation in ligand density was accomplished by the mixing of aECM-RGD-PEG and aECM-RDG-PEG prior to cross-linking. Increasing the density of RGD domains in cross-linked films resulted in more robust cell adhesion and spreading but did not affect cell migration speed. Control of cell-binding domain density in aECM proteins can thus be used to modulate cell adhesion and spreading and will serve as an important design tool as these materials are further developed for use in surgery, tissue engineering, and regenerative medicine. PMID:18826275

  2. Soluble Proteins Form Film by the Treatment of Low Temperature Plasma

    NASA Astrophysics Data System (ADS)

    Ikehara, Sanae; Sakakita, Hajime; Ishikawa, Kenji; Akimoto, Yoshihiro; Nakanishi, Hayao; Shimizu, Nobuyuki; Hori, Masaru; Ikehara, Yuzuru

    2015-09-01

    It has been pointed out that low temperature plasma in atmosphere was feasible to use for hemostasis without heat injury. Indeed, earlier studies demonstrated that low temperature plasma played an important role to stimulate platelets to aggregate and turned on the proteolytic activities of coagulation factors, resulting in the acceleration of the natural blood coagulation process. On the other hands, our developed equips could immediately form clots upon the contact with plasma flair, while the histological appearance was different from natural coagulation. Based on these findings in formed clots, we sought to determine if plasma flair supplied by our devices was capable of forming film using a series of soluble proteins Following plasma treatment, films were formed from bovine serum albumin, and the other plasma proteins at physiological concentration. Analysis of trans-electron microscope demonstrated that plasma treatment generated small protein particles and made them fuse to be larger aggregations The combined results demonstrated that plasma are capable of aggregating soluble proteins and that platelets and coagulation factors are not necessary for plasma induced blood coagulation. Supported in part by Grants-in-Aid for Scientific Research on Priority Area (21590454, 24590498, and 24108006 to Y. I.).

  3. Contact line of adsorbed colloid-polymer droplets in theory and experiment.

    PubMed

    Koning, Jesper; Hennequin, Yves; Bonn, Daniel; Indekeu, Joseph O

    2016-05-01

    The contact line between the colloid-rich bulk liquid and an adsorbed thin film in colloid-polymer mixtures (CPM) is studied by means of an interface displacement model. The interface displacement profiles are compared to laser scanning confocal microscopy (LSCM) images. The mixtures consist of poly(methylmetacrylate) (PMMA) colloids and polystyrene (PS) polymers with polymer-to-colloid size ratio q = 1.18. Based on the experimental parameters, the theoretical model predicts a contact angle for colloid-rich liquid droplets adsorbed on glass of θ∞ = 59°, assuming a contact line with infinite radius, R = ∞. When a contact-line curvature correction and a correction for the protein-limit character of the CPM are taken into account, a modest shift is obtained. The refined theory predicts θ≈ 56°. The contact angle determined visually from the LSCM images is θ≈ 30°. The model predicts a three-phase contact-line tension of τ = -1.2 × 10(-12) N (uncorrected) and τ = -2.3 × 10(-13) N (with protein-limit correction), which is physically sound both in sign and magnitude. The line tension influences the contact angle to a small extent due to the contact line curvature. The predicted width of the transition zone between the thin film and the droplet is about 2 μm. The effect of gravity is noticeable as a deformation near the middle of the droplet. PMID:27029605

  4. Construction of a functional S-layer fusion protein comprising an immunoglobulin G-binding domain for development of specific adsorbents for extracorporeal blood purification.

    PubMed

    Völlenkle, Christine; Weigert, Stefan; Ilk, Nicola; Egelseer, Eva; Weber, Viktoria; Loth, Fritz; Falkenhagen, Dieter; Sleytr, Uwe B; Sára, Margit

    2004-03-01

    The chimeric gene encoding a C-terminally-truncated form of the S-layer protein SbpA from Bacillus sphaericus CCM 2177 and two copies of the Fc-binding Z-domain was constructed, cloned, and heterologously expressed in Escherichia coli HMS174(DE3). The Z-domain is a synthetic analogue of the B-domain of protein A, capable of binding the Fc part of immunoglobulin G (IgG). The S-layer fusion protein rSbpA(31-1068)/ZZ retained the specific properties of the S-layer protein moiety to self-assemble in suspension and to recrystallize on supports precoated with secondary cell wall polymer (SCWP), which is the natural anchoring molecule for the S-layer protein in the bacterial cell wall. Due to the construction principle of the S-layer fusion protein, the ZZ-domains remained exposed on the outermost surface of the protein lattice. The binding capacity of the native or cross-linked monolayer for human IgG was determined by surface plasmon resonance measurements. For batch adsorption experiments, 3-microm-diameter, biocompatible cellulose-based, SCWP-coated microbeads were used for recrystallization of the S-layer fusion protein. In the case of the native monolayer, the binding capacity for human IgG was 5.1 ng/mm(2), whereas after cross-linking with dimethyl pimelimidate, 4.4 ng of IgG/mm(2) was bound. This corresponded to 78 and 65% of the theoretical saturation capacity of a planar surface for IgGs aligned in the upright position, respectively. Compared to commercial particles used as immunoadsorbents to remove autoantibodies from sera of patients suffering from an autoimmune disease, the IgG binding capacity of the S-layer fusion protein-coated microbeads was at least 20 times higher. For that reason, this novel type of microbeads should find application in the microsphere-based detoxification system. PMID:15006773

  5. Study of water vapour permeability of protein and gum-based edible films by a photothermal method

    NASA Astrophysics Data System (ADS)

    Tomás, S. A.; Saavedra, R.; Cruz, A.; Pedroza-Islas, R.; San Martín, E.

    2005-06-01

    The water vapour permeability of protein and gum-based edible films was studied by means of a photothermal method. The films were prepared with two basic ingredients, whey protein concentrate and mesquite gum, according to the proportions 75:25, 50:50, 25:75, and 0:100 (weight:weight). The water vapour diffusion coefficient of the analyzed films was found within the interval 0.37 × 10-6 to 2.04 × 10-6 cm^2/s, increasing linearly by increasing the mesquite gum composition in the films. The incorporation of mesquite gum in films produces less effective moisture barriers due to its highly hydrophilic property.

  6. Protein-modified shear mode film bulk acoustic resonator for bio-sensing applications

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Liu, Weihui; Xu, Yan; Chen, Da; Li, Dehua; Zhang, Luyin

    2014-09-01

    In this paper, we present a shear mode film bulk acoustic biosensor based on micro-electromechanical technology. The film bulk acoustic biosensor is a diaphragmatic structure consisting of a lateral field excited ZnO piezoelectric film piezoelectric stack built on an Si3N4 membrane. The device works at near 1.6 GHz with Q factors of 579 in water and 428 in glycerol. A frequency shift of 5.4 MHz and a small decline in the amplitude are found for the measurements in glycerol compared with those in water because of the viscous damping derived from the adjacent glycerol. For bio-sensing demonstration, the resonator was modified with biotin molecule to detect protein-ligand interactions in real-time and in situ. The resonant frequency of the biotin-modified device drops rapidly and gradually reaches equilibrium when exposed to the streptavidin solution due to the biotin-streptavidin interaction. The proposed film bulk acoustic biosensor shows promising applications for disease diagnostics, prognosis, and drug discovery.

  7. Properties of whey protein isolate nanocomposite films reinforced with nanocellulose isolated from oat husk.

    PubMed

    Qazanfarzadeh, Zeinab; Kadivar, Mahdi

    2016-10-01

    Whey protein isolate (WPI)-based composite films with varying proportions of oat husk nanocellulose (ONC) obtained from acid sulfuric hydrolysis were prepared using a solution casting method. The obtained material after each step of the isolating cellulose, morphological and crystallinity of the ONC were studied by Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The effect of ONC content (0, 2.5, 5 and 7.5wt% of WPI) on physical, mechanical and barrier properties of the nanocomposite were then evaluated. FTIR spectroscopy indicated the progressive removal of non-cellulosic components from the oat husk. SEM images showed the mean width of ONC was about 76nm and XRD analysis revealed the crystallinity increased after acid hydrolysis. The films prepared with up to 5wt% ONC showed the highest tensile strength, Young's modulus, solubility and the lowest elongation at break and moisture content. At high level (7.5wt%), tensile strength, Young's modulus and solubility of the films decreased and elongation at break and moisture content increased due to agglomeration of the fillers. Nevertheless, film transparency and water vapor permeability decreased with ONC incorporation. PMID:27349890

  8. Ascorbic Acid and BSA Protein in Solution and Films: Interaction and Surface Morphological Structure

    PubMed Central

    Maciel, Rafael R. G.; de Almeida, Adriele A.; Godinho, Odin G. C.; Gorza, Filipe D. S.; Pedro, Graciela C.; Trescher, Tarquin F.; Silva, Josmary R.; de Souza, Nara C.

    2013-01-01

    This paper reports on the study of the interactions between ascorbic acid (AA) and bovine serum albumin (BSA) in aqueous solution as well as in films (BSA/AA films) prepared by the layer-by-layer technique. Regarding to solution studies, a hyperchromism (in the range of ultraviolet) was found as a function of AA concentration, which suggested the formation of aggregates from AA and BSA. Binding constant, K, determined for aggregates from BSA and AA was found to be about 102 M−1, which indicated low affinity of AA with BSA. For the BSA/AA films, it was also noted that the AA adsorption process and surface morphological structures depended on AA concentration. By changing the contact time between the AA and BSA, a hypochromism was revealed, which was associated to decrease of accessibility of solvent to tryptophan due to formation of aggregates. Furthermore, different morphological structures of aggregates were observed, which were attributed to the diffusion-limited aggregation. Since most of studies of interactions of drugs and proteins are performed in solution, the analysis of these processes by using films can be very valuable because this kind of system is able to employ several techniques of investigation in solid state. PMID:23984366

  9. Ascorbic acid and BSA protein in solution and films: interaction and surface morphological structure.

    PubMed

    Maciel, Rafael R G; de Almeida, Adriele A; Godinho, Odin G C; Gorza, Filipe D S; Pedro, Graciela C; Trescher, Tarquin F; Silva, Josmary R; de Souza, Nara C

    2013-01-01

    This paper reports on the study of the interactions between ascorbic acid (AA) and bovine serum albumin (BSA) in aqueous solution as well as in films (BSA/AA films) prepared by the layer-by-layer technique. Regarding to solution studies, a hyperchromism (in the range of ultraviolet) was found as a function of AA concentration, which suggested the formation of aggregates from AA and BSA. Binding constant, K, determined for aggregates from BSA and AA was found to be about 10(2) M(-1), which indicated low affinity of AA with BSA. For the BSA/AA films, it was also noted that the AA adsorption process and surface morphological structures depended on AA concentration. By changing the contact time between the AA and BSA, a hypochromism was revealed, which was associated to decrease of accessibility of solvent to tryptophan due to formation of aggregates. Furthermore, different morphological structures of aggregates were observed, which were attributed to the diffusion-limited aggregation. Since most of studies of interactions of drugs and proteins are performed in solution, the analysis of these processes by using films can be very valuable because this kind of system is able to employ several techniques of investigation in solid state. PMID:23984366

  10. A hybrid multi-loop genetic-algorithm/simplex/spatial-grid method for locating the optimum orientation of an adsorbed protein on a solid surface

    NASA Astrophysics Data System (ADS)

    Wei, Tao; Mu, Shengjing; Nakano, Aiichiro; Shing, Katherine

    2009-05-01

    Atomistic simulation of protein adsorption on a solid surface in aqueous environment is computationally demanding, therefore the determination of preferred protein orientations on the solid surface usually serves as an initial step in simulation studies. We have developed a hybrid multi-loop genetic-algorithm/simplex/spatial-grid method to search for low adsorption-energy orientations of a protein molecule on a solid surface. In this method, the surface and the protein molecule are treated as rigid bodies, whereas the bulk fluid is represented by spatial grids. For each grid point, an effective interaction region in the surface is defined by a cutoff distance, and the possible interaction energy between an atom at the grid point and the surface is calculated and recorded in a database. In searching for the optimum position and orientation, the protein molecule is translated and rotated as a rigid body with the configuration obtained from a previous Molecular Dynamic simulation. The orientation-dependent protein-surface interaction energy is obtained using the generated database of grid energies. The hybrid search procedure consists of two interlinked loops. In the first loop A, a genetic algorithm (GA) is applied to identify promising regions for the global energy minimum and a local optimizer with the derivative-free Nelder-Mead simplex method is used to search for the lowest-energy orientation within the identified regions. In the second loop B, a new population for GA is generated and competitive solution from loop A is improved. Switching between the two loops is adaptively controlled by the use of similarity analysis. We test the method for lysozyme adsorption on a hydrophobic hydrogen-terminated silicon (110) surface in implicit water (i.e., a continuum distance-dependent dielectric constant). The results show that the hybrid search method has faster convergence and better solution accuracy compared with the conventional genetic algorithm.

  11. One step physically adsorbed coating of silica capillary with excellent stability for the separation of basic proteins by capillary zone electrophoresis.

    PubMed

    Guo, Xiao-Feng; Guo, Xiao-Mei; Wang, Hong; Zhang, Hua-Shan

    2015-11-01

    The coating of capillary inner surface is considered to be an effective approach to suppress the adsorption of proteins on capillary inner surface in CE. However, most of coating materials reported are water-soluble, which may dissolve in BGE during the procedure of electrophoresis. In this study, a novel strategy for selection of physically coating materials has been illustrated to get coating layer with excellent stability using materials having poor solubility in commonly used solvents. Taking natural chitin as example (not hydrolyzed water soluble chitosan), a simple one step coating method using chitin solution in hexafluoroisopropanol was adopted within only 21 min with good coating reproducibility (RSDs of EOF for within-batch coated capillaries of 1.55% and between-batch coated capillaries of 2.31%), and a separation of four basic proteins on a chitin coated capillary was performed to evaluate the coating efficacy. Using chitin coating, the adsorption of proteins on capillary inner surface was successfully suppressed with reversed and stable EOF, and four basic proteins including lysozyme, cytochrome c, ribonuclease A and α-chymotrypsinogen A were baseline separated within 16 min with satisfied separation efficiency using 20 mM pH 2.0 H3PO4-Na2HPO4 as back ground electrolyte and 20 kV as separation voltage. What is more important, the chitin coating layer could be stable for more than two months during this study, which demonstrates that chitin is an ideal material for preparing semi-permanent coating on bare fused silica capillary inner wall and has hopeful potential in routine separation of proteins with CE. PMID:26452799

  12. Modification of functional properties of pullulan-whey protein bionanocomposite films with nanoclay.

    PubMed

    Hassannia-Kolaee, Mahbobeh; Khodaiyan, Faramarz; Shahabi-Ghahfarrokhi, Iman

    2016-02-01

    In this study, biodegradable nanocomposite film composed of pullulan - whey protein isolate (WPI) - montmorillonite (MMT) were developed and characterized as a function of incorporating various amounts of MMT nanoparticles (0, 1, 3 and 5 % wt). Results showed that the water-vapor permeability, moisture content, moisture absorption and water solubility decreased when the nano-MMT content was increased. Tensile strength improved and elongation at break simultaneously decreased with increasing MMT content. The glass transition temperature (Tg(and melting-point temperature (Tm) increased with increasing nano-MMT content. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis revealed uniform distribution of MMT into the polymer matrix. Atomic force microscopy (AFM) showed enhancement of films' roughness with increasing MMT content. PMID:27162410

  13. From adsorption to condensation: the role of adsorbed molecular clusters.

    PubMed

    Yaghoubian, Sima; Zandavi, Seyed Hadi; Ward, C A

    2016-08-01

    The adsorption of heptane vapour on a smooth silicon substrate with a lower temperature than the vapour is examined analytically and experimentally. An expression for the amount adsorbed under steady state conditions is derived from the molecular cluster model of the adsorbate that is similar to the one used to derive the equilibrium Zeta adsorption isotherm. The amount adsorbed in each of a series of steady experiments is measured using a UV-vis interferometer, and gives strong support to the amount predicted to be adsorbed. The cluster distribution is used to predict the subcooling temperature required for the adsorbed vapour to make a disorder-order phase transition to become an adsorbed liquid, and the subcooling temperature is found to be 2.7 ± 0.4 K. The continuum approach for predicting the thickness of the adsorbed liquid film originally developed by Nusselt is compared with that measured and is found to over-predict the thickness by three-orders of magnitude. PMID:27426944

  14. Resistance to protein adsorption and adhesion of fibroblasts on nanocrystalline diamond films: the role of topography and boron doping.

    PubMed

    Alcaide, María; Papaioannou, Stavros; Taylor, Andrew; Fekete, Ladislav; Gurevich, Leonid; Zachar, Vladimir; Pennisi, Cristian Pablo

    2016-05-01

    Boron-doped nanocrystalline diamond (BNCD) films exhibit outstanding electrochemical properties that make them very attractive for the fabrication of electrodes for novel neural interfaces and prosthetics. In these devices, the physicochemical properties of the electrode materials are critical to ensure an efficient long-term performance. The aim of this study was to investigate the relative contribution of topography and doping to the biological performance of BNCD films. For this purpose, undoped and boron-doped NCD films were deposited on low roughness (LR) and high roughness (HR) substrates, which were studied in vitro by means of protein adsorption and fibroblast growth assays. Our results show that BNCD films significantly reduce the adsorption of serum proteins, mostly on the LR substrates. As compared to fibroblasts cultured on LR BNCD films, cells grown on the HR BNCD films showed significantly reduced adhesion and lower growth rates. The mean length of fibronectin fibrils deposited by the cells was significantly increased in the BNCD coated substrates, mainly in the LR surfaces. Overall, the largest influence on protein adsorption, cell adhesion, proliferation, and fibronectin deposition was due to the underlying sub-micron topography, with little or no influence of boron doping. In perspective, BNCD films displaying surface roughness in the submicron range may be used as a strategy to reduce the fibroblast growth on the surface of neural electrodes. PMID:26975747

  15. Local retention of antibodies in vivo with an injectable film embedded with a fluorogen-activating protein.

    PubMed

    Liu, Wen; Saunders, Matthew J; Bagia, Christina; Freeman, Eric C; Fan, Yong; Gawalt, Ellen S; Waggoner, Alan S; Meng, Wilson S

    2016-05-28

    Herein we report an injectable film by which antibodies can be localized in vivo. The system builds upon a bifunctional polypeptide consisting of a fluorogen-activating protein (FAP) and a β-fibrillizing peptide (βFP). The FAP domain generates fluorescence that reflects IgG binding sites conferred by Protein A/G (pAG) conjugated with the fluorogen malachite green (MG). A film is generated by mixing these proteins with molar excess of EAK16-II, a βFP that forms β-sheet fibrils at high salt concentrations. The IgG-binding, fluorogenic film can be injected in vivo through conventional needled syringes. Confocal microscopic images and dose-response titration experiments showed that loading of IgG into the film was mediated by pAG(MG) bound to the FAP. Release of IgG in vitro was significantly delayed by the bioaffinity mechanism; 26% of the IgG were released from films embedded with pAG(MG) after five days, compared to close to 90% in films without pAG(MG). Computational simulations indicated that the release rate of IgG is governed by positive cooperativity due to pAG(MG). When injected into the subcutaneous space of mouse footpads, film-embedded IgG were retained locally, with distribution through the lymphatics impeded. The ability to track IgG binding sites and distribution simultaneously will aid the optimization of local antibody delivery systems. PMID:27038493

  16. Orbital tomography for highly symmetric adsorbate systems

    NASA Astrophysics Data System (ADS)

    Stadtmüller, B.; Willenbockel, M.; Reinisch, E. M.; Ules, T.; Bocquet, F. C.; Soubatch, S.; Puschnig, P.; Koller, G.; Ramsey, M. G.; Tautz, F. S.; Kumpf, C.

    2012-10-01

    Orbital tomography is a new and very powerful tool to analyze the angular distribution of a photoemission spectroscopy experiment. It was successfully used for organic adsorbate systems to identify (and consequently deconvolute) the contributions of specific molecular orbitals to the photoemission data. The technique was so far limited to surfaces with low symmetry like fcc(110) oriented surfaces, owing to the small number of rotational domains that occur on such surfaces. In this letter we overcome this limitation and present an orbital tomography study of a 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) monolayer film adsorbed on Ag(111). Although this system exhibits twelve differently oriented molecules, the angular resolved photoemission data still allow a meaningful analysis of the different local density of states and reveal different electronic structures for symmetrically inequivalent molecules. We also discuss the precision of the orbital tomography technique in terms of counting statistics and linear regression fitting algorithm. Our results demonstrate that orbital tomography is not limited to low-symmetry surfaces, a finding which makes a broad field of complex adsorbate systems accessible to this powerful technique.

  17. Resistance to moist conditions of whey protein isolate and pea starch biodegradable films and low density polyethylene nondegradable films: a comparative study

    NASA Astrophysics Data System (ADS)

    Mehyar, G. F.; Bawab, A. Al

    2015-10-01

    Biodegradable packaging materials are degraded under the natural environmental conditions. Therefore using them could alleviate the problem of plastics accumulation in nature. For effective replacement of plastics, with biodegradable materials, biodegradable packages should keep their properties under the high relative humidity (RH) conditions. Therefore the objectives of the study were to develop biodegradable packaging material based on whey protein isolate (WPI) and pea starch (PS). To study their mechanical, oxygen barrier and solubility properties under different RHs compared with those of low density polyethylene (LDPE), the most used plastic in packaging. Films of WPI and PS were prepared separately and conditioned at different RH (30-90%) then their properties were studied. At low RHs (<50%), WPI films had 2-3 times lower elongation at break (E or stretchability) than PS and LDPE. Increasing RH to 90% significantly (P<0.01) increased the elongation of PS but not WPI and LDPE films. LDPE and WPI films kept significantly (P<0.01) higher tensile strength (TS) than PS films at high RH (90%). Oxygen permeability (OP) of all films was very low (<0.5 cm3 μm m-2 d-1 kPa-1) below 40% RH but increased for PS films and became significantly (P<0.01) different than that of LDPE and WPI at > 40% RH. Oxygen permeability of WPI and LDPE did not adversely affected by increasing RH to 65%. Furthermore, WPI and LDPE films had lower degree of hydration at 50% and 90% RH and total soluble matter than PS films. These results suggest that WPI could be successfully replacing LDPE in packaging of moist products.

  18. Layer-by-Layer Deposition with Polymers Containing Nitrilotriacetate, A Convenient Route to Fabricate Metal- and Protein-Binding Films.

    PubMed

    Wijeratne, Salinda; Liu, Weijing; Dong, Jinlan; Ning, Wenjing; Ratnayake, Nishanka Dilini; Walker, Kevin D; Bruening, Merlin L

    2016-04-27

    This paper describes a convenient synthesis of nitrilotriacetate (NTA)-containing polymers and subsequent layer-by-layer adsorption of these polymers on flat surfaces and in membrane pores. The resulting films form NTA-metal-ion complexes and capture 2-3 mmol of metal ions per mL of film. Moreover, these coatings bind multilayers of polyhistidine-tagged proteins through association with NTA-metal-ion complexes. Inclusion of acrylic acid repeat units in NTA-containing copolymers promotes swelling to increase protein binding in films on Au-coated wafers. Adsorption of NTA-containing films in porous nylon membranes gives materials that capture ∼46 mg of His-tagged ubiquitin per mL. However, the binding capacity decreases with the protein molecular weight. Due to the high affinity of NTA for metal ions, the modified membranes show modest leaching of Ni(2+) in binding and rinsing buffers. Adsorption of NTA-containing polymers is a simple method to create metal- and protein-binding films and may, with future enhancement of stability, facilitate development of disposable membranes that rapidly purify tagged proteins. PMID:27042860

  19. Antimicrobial activity and hydrophobicity of edible whey protein isolate films formulated with nisin and/or glucose oxidase.

    PubMed

    Murillo-Martínez, María M; Tello-Solís, Salvador R; García-Sánchez, Miguel A; Ponce-Alquicira, Edith

    2013-04-01

    The use of edible antimicrobial films has been reported as a means to improve food shelf life through gradual releasing of antimicrobial compounds on the food surface. This work reports the study on the incorporation of 2 antimicrobial agents, nisin (N), and/or glucose oxidase (GO), into the matrix of Whey protein isolate (WPI) films at pH 5.5 and 8.5. The antimicrobial activity of the edible films was evaluated against Listeria innocua (ATCC 33090), Brochothrix thermosphacta (NCIB10018), Escherichia coli (JMP101), and Enterococcus faecalis (MXVK22). In addition, the antimicrobial activity was related to the hydrophobicity and water solubility of the WPI films. The greatest antibacterial activity was observed in WPI films containing only GO. The combined addition of N and GO resulted in films with lower antimicrobial activity than films with N or GO alone. In most cases, a pH effect was observed as greater antimicrobial response at pH 5.5 as well as higher film matrix hydrophobicity. WPI films supplemented with GO can be used in coating systems suitable for food preservation. PMID:23488765

  20. Novel layer-by-layer structured nanofibrous mats coated by protein films for dermal regeneration.

    PubMed

    Xin, Shangjing; Li, Xueyong; Wang, Qun; Huang, Rong; Xu, Xiaoli; Lei, Zhanjun; Deng, Hongbing

    2014-05-01

    Layer-by-layer coating technique is effective in modifying the surface of nanofibrous mats, but overmuch film-coating makes the mats less porous to hardly suit the condition for tissue engineering. We developed novel nanofibrous mats layer-by-layer coated by silk fibroin and lysozyme on the cellulose electrospun template via electrostatic interaction. The film-coating assembled on the mats was not excessive because the charge of the proteins varied in the coating process due to different pH value. In addition, pure nature materials made the mats nontoxic, biodegradable and low-cost. The morphology and composition variation during layer-by-layer coating process was investigated and the results showed that the structure and thickness of film-coatings could be well-controlled. The antibacterial assay and in vitro cell experiments indicated that the mats could actively inhibit bacteria and exhibit excellent biocompatibility. In vivo implant assay further verified the mats cultured with human epidermal cells could promote wound healing and avoid wound infection. Therefore, these mats showed promising prospects when performed for dermal reconstruction. PMID:24734533

  1. Protein UTLC-MALDI-MS using thin films of submicrometer silica particles

    PubMed Central

    Zhang, Zhaorui; Ratnayaka, Saliya N.; Wirth, Mary J.

    2011-01-01

    Slides for ultra thin-layer chromatography (UTLC) slides were made by coating nonporous silica particles, chemically modified with polyacrylamide, as 15 μm films on glass or silicon. Three proteins, myoglobin, cytochrome c and lysozyme, are nearly baseline resolved by the mechanism of hydrophilic interaction chromatography. A plate height as low as 3 μm, with 3,900 plates, are observed in 14 mm. Varying silica particle diameter among 900, 700 and 350 nm showed that decreasing particle diameter slightly improves resolution but slows the separation. Matrix-assisted laser desorption/ionization (MALDI)-MS of the proteins after separation is demonstrated by wicking sufficient sinapinic acid into the separation medium. PMID:21890140

  2. Nanoporous membrane based on block copolymer thin film for protein drug delivery

    NASA Astrophysics Data System (ADS)

    Yang, Seung Yun; Yang, Jeong-A.; Kim, Eung-Sam; Jeon, Gumhye; Oh, Eun Ju; Choi, Kwan Yong; Hahn, Sei Kwang; Kim, Jin Kon

    2010-03-01

    We studied long term and controlled release of protein drugs by using nanoporous membranes with various pore sizes. Nanoporous membrane consists of the separation layer prepared by polystyrene-block-poly(methylmethacrylate) copolymer thin film and conventional microfiltration membrane as a support. We demonstrate a long-term constant in vitro release of bovine serum albumin (BSA)and human growth hormone ) (hGH) without their denaturation up to 2 months. A nearly constant serum concentration of hGH was maintained up to 3 weeks in SD rats. The long-term constant delivery based on this membrane for protein drugs within the therapeutic range can be highly appreciated for the patients with hormone- deficiency.

  3. Block copolymer adsorbed layers on solids

    NASA Astrophysics Data System (ADS)

    Sen, Mani; Jiang, Naisheng; Gowd, Bhoje; Endoh, Maya; Koga, Tadanori

    Block copolymer thin films offer a simple and effective route to fabricate highly ordered periodic microdomain structures. The fundamental, yet unsolved question is whether these highly oriented microdomain structures persist even near an impenetrable solid wall. We here report the adsorbed structures of polystyrene-block-poly (4-vinylpyridine) (PS-block-P4VP, Mw = 41,000, PS (weight fraction =0.81) formed on planar silicon substrates. Perpendicularly aligned cylindrical microdomains were created by solvent vapor annealing (Gowd et al., Soft Matter, 2014, 10, 7753), and the adsorbed layer was derived by solvent leaching with chloroform, a good solvent for the polymers and thereafter characterized by using atomic force microscopy, scanning electron microscopy, grazing incidence small angle x-ray scattering, and x-ray reflectivity. The results showed that both PS and P4VP chains lie flat on the substrate, forming a microphase-separated structure (MSS) without long-range order. Moreover, a spin-coated PS-block-P4VP thin film annealed under vacuum at 190 °C showed similar MSS on the substrate, indicating the generality of the interfacial polymer structure. Details will be discussed in the presentation. NSF Grant No. CMMI-1332499.

  4. Antimicrobial and antioxidant effects of milk protein-based film containing essential oils for the preservation of whole beef muscle.

    PubMed

    Oussalah, Mounia; Caillet, Stéphane; Salmiéri, Stéphane; Saucier, Linda; Lacroix, Monique

    2004-09-01

    Milk protein-based edible films containing 1.0% (w/v) oregano, 1.0% (w/v) pimento, or 1.0% oregano-pimento (1:1) essential oils mix were applied on beef muscle slices to control the growth of pathogenic bacteria and increase the shelf life during storage at 4 degrees C. Meat and film were periodically tested during 7 days for microbial and biochemical analysis. The lipid oxidation potential of meat was evaluated by the determination of thiobarbituric reactive substances (TBARS). The availability of phenolic compounds from essential oils was evaluated by the determination of total phenolic compounds present in the films during storage. Antioxidant properties of films during storage were also evaluated following a modified procedure of the N,N-diethyl-p-phenylenediamine colorimetric method. Oregano-based films stabilized lipid oxidation in beef muscle samples, whereas pimento-based films presented the highest antioxidant activity. The application of bioactive films on meat surfaces containing 10(3) colony-forming units/cm2 of Escherichia coli O157:H7 or Pseudomonas spp. showed that film containing oregano was the most effective against both bacteria, whereas film containing pimento oils seems to be the least effective against these two bacteria. A 0.95 log reduction of Pseudomonas spp. level, as compared to samples without film, was observed at the end of storage in the presence of films containing oregano extracts. A 1.12 log reduction of E. coli O157:H7 level was noted in samples coated with oregano-based films. PMID:15373399

  5. Fabrication and Protein Conjugation of Aligned Polypyrrole-Poly(L-lactic acid) Fibers Film with the Conductivity and Stability.

    PubMed

    Qin, Jiabang; Huang, Zhongbing; Yin, Guangfu; Yang, Anneng; Han, Wei

    2016-03-01

    The conducting composite scaffold, including fiber-cores of aligned poly(L-lactic acid) (PLLA) and shell-layer of polypyrrole (PPy), was fabricated, and then bovine serum albumin (BSA) was conjugated on the PPy shell-layer. Aligned PLLA fibers (about 300 nm diameter) were obtained by electrospinning and rotating drum collection, and then coated by PPy nanoparticles (NPs, about 50 nm diameter) via chemical oxidation. The surface resistivity of PPy-PLLA fibers film were 0.971, 0.874 kΩ. cm at the fiber's vertical and parallel directions, respectively. The results of PPy-PLLA fibers film immersed in phosphate buffer saline for 8 d indicated that the fibers morphology and the film conductivity were not significantly changed, and the fluorescent images showed that FITC-labeled BSA (FITC-BSA) were successfully conjugated in the fibers film with carbodiimide chemistry, and the largest amount of FITC-BSA conjugated in the fibers film from 100 μg/mL proteins solution was 31.31 μg/cm2 due to lots of poly(glutamic acid) in surface-nanogrooves of the fibers surface. Under electrical stimulation of 100 mV, the fibers film was accompanied the release of all conjugated FITC-BSA with the detachment of some PPy NPs. These results suggested that PPy-PLLA fibers film would be potentially applied in the construction of degradable tissue engineering scaffold with protein factors, especially neurotrophic factors for nerve tissue repair. PMID:27455643

  6. Mechanical and water barrier properties of isolated soy protein composite edible films as affected by carvacrol and cinnamaldehyde micro and nanoemulsions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edible films may be used in food packaging, for which they must deliver good barrier and mechanical properties. Films based on proteins have good gas barrier and mechanical properties, but poor water barrier properties. Films made from lipids have good water barrier properties, but poor mechanical p...

  7. Kinetics of Protein Adsorption at liquid/solid interfaces

    NASA Astrophysics Data System (ADS)

    Bellion, Markus; Santen, Ludger; Nagel, Armin; Mantz, Hubert; Quinn, Anthony; Jacobs, Karin

    2006-03-01

    Protein adsorption processes are of crucial importance in many biomedical processes. From a physical point of view these processes raise a number of challenging questions, e.g.: How does the surface influence the conformation of proteins at the surface? What are the characteristics of the protein film at the liquid/solid interface? In this work we investigate the adsorption kinetics of salivary proteins on different kinds of surfaces in a liquid environment. The adsorbed protein layers are analyzed by means of ellipsometry, plasmon resonance, and SPM. It turns out that the adsorbed amount of proteins is sensitive to the long ranged interactions of the solid surface. The experimental data are compared to extensive Monte Carlo simulation of a colloidal protein model. The Monte Carlo results strongly suggest that induced conformal changes lead to the experimentally observed three step kinetics of amylase.

  8. Adsorbed water and CO on Pt electrode modified with Ru

    NASA Astrophysics Data System (ADS)

    Futamata, Masayuki; Luo, Liqiang

    Highly sensitive ATR-SEIRA spectroscopy was exploited to elucidate water, CO and electrolyte anions adsorbed on the Ru modified Pt film electrode. CO on Ru domains was oxidized below ca. +0.3 V, followed by pronounced water adsorption. Since the oxidation potential of CO on Pt domain was significantly reduced compared to bare Pt, these water molecules on Ru obviously prompt CO oxidation on adjacent Pt surface as consistent with the bifunctional mechanism. Diffusion of adsorbate from Ru to Pt surfaces was indicated in dilute CH 3OH solution by spectral changes with potential.

  9. Larger red-shift in optical emissions obtained from the thin films of globular proteins (BSA, lysozyme) - polyelectrolyte (PAA) complexes

    NASA Astrophysics Data System (ADS)

    Talukdar, Hrishikesh; Kundu, Sarathi; Basu, Saibal

    2016-09-01

    Globular proteins (lysozyme and BSA) and polyelectrolyte (sodium polyacrylic acid) are used to form protein-polyelectrolyte complexes (PPC). Out-of-plane structures of ≈30-60 nm thick PPC films and their surface morphologies have been studied by using X-ray reflectivity and atomic force microscopy, whereas optical behaviors of PPC and protein conformations have been studied by using UV-vis, photoluminescence and FTIR spectroscopy respectively. Our study reveals that thin films of PPC show a larger red-shift of 23 and 16 nm in the optical emissions in comparison to that of pure protein whereas bulk PPC show a small blue-shift of ≈3 nm. A small amount of peak-shift is found to occur due to the heat treatment or concentration variation of the polyelectrolyte/protein in bulk solution but cannot produce such film thickness independent larger red-shift. Position of the emission peak remains nearly unchanged with the film thickness. Mechanism for such larger red-shift has been proposed.

  10. Multilayered Graphene Nano-Film for Controlled Protein Delivery by Desired Electro-Stimuli

    PubMed Central

    Choi, Moonhyun; Kim, Kyung-Geun; Heo, Jiwoong; Jeong, Hyejoong; Kim, Sung Yeol; Hong, Jinkee

    2015-01-01

    Recent research has highlighted the potential use of “smart” films, such as graphene sheets, that would allow for the controlled release of a variety of therapeutic drugs. Taking full advantage of these versatile conducting sheets, we investigated the novel concept of applying graphene oxide (GO) and reduced graphene oxide (rGO) materials as both barrier and conducting layers that afford controlled entrapment and release of any molecules of interest. We fabricated multilayered nanofilm architectures using a hydrolytically degradable cationic poly(β-amino ester) (PAE), a model protein antigen, ovalbumin (OVA) as a building block along with the GO and rGO. We successfully showed that these multilayer films are capable of blocking the initial burst release of OVA, and they can be triggered to precisely control the release upon the application of electrochemical potential. This new drug delivery platform will find its usefulness in various transdermal drug delivery devices where on-demand control of drug release from the surface is necessary. PMID:26621344

  11. A comparison of adsorbed and grafted fibronectin coatings under static and dynamic conditions.

    PubMed

    Montaño-Machado, Vanessa; Hugoni, Ludivine; Díaz-Rodríguez, Sergio; Tolouei, Ranna; Chevallier, Pascale; Pauthe, Emmanuel; Mantovani, Diego

    2016-09-21

    Coatings for medical devices are expected to improve their surface biocompatibility mainly by being bioactive, i.e. stimulating healing-oriented interactions with living cells, tissues and organs. In particular, for stent applications, coatings are often designed to enhance the endothelialization process. The coating strategy will be primarily responsible for the interfacial properties between the substrate and the coating, which must show high stability. Therefore, the present work aims at comparing the stability of adsorbed and grafted fibronectin, a protein well-known to promote endothelialization. Fibronectin coatings were deposited on fluorocarbon films generated by a plasma-based process on stainless steel substrates. Then, deformation tests were performed in order to simulate the stenting procedure and stability tests were completed under static and under-flow conditions. Coatings were characterized by XPS, AFM, water contact angle, immunostaining and ToF-SIMS analyses. The results show higher stability for the grafted coatings; indeed, the integrity of the protein simply adsorbed was strongly compromised especially after under-flow tests. Both coatings exhibited similar behavior after deformation and static tests. These results clearly show the impact of the coating strategy on the overall stability of the coatings as well as the importance of under-flow investigations. PMID:27546569

  12. Plasma-treated polystyrene film that enhances binding efficiency for sensitive and label-free protein biosensing

    NASA Astrophysics Data System (ADS)

    Guo, Bihong; Li, Shaopeng; Song, Lusheng; Yang, Mo; Zhou, Wenfei; Tyagi, Deependra; Zhu, Jinsong

    2015-08-01

    A plasma-treated ultrathin polystyrene (PS) film surface was explored as a simple, robust, and low-cost surface chemistry solution for protein biosensing applications. This surface could dramatically improve the binding efficiency of the protein-protein interactions, which is defined as the binding signal per immobilized ligand. The PS-modified protein biosensor was readily fabricated by spin coating and plasma treatment. Various parameters for fabrication, including the concentration of the PS solution, rate of spin coating, and duration of plasma treatment, were systematically optimized based on the improvement of fluorescence signal yielded by the microfluidic network-aided fluorescence immunoassay. The performance of the label-free protein detection on the optimized surfaces was further evaluated by surface plasmon resonance imaging (SPRi). PS surfaces with optimal fabrication parameters exhibited up to an 620% enhancement of the protein binding response and approximately 210% of the protein binding per immobilized protein ligand compared with a self-assembled monolayer (SAM) surface of 11-mercapto undecanoic acid (MUA). The relationship between the fabrication parameters used and changes to the surface chemistry and the morphological properties were characterized with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). It was revealed that the morphological changes observed in the plasma-treated PS film were the dominant factor for the improvement of the protein bioassay performance, rather than the chemical changes.

  13. Enhancement of Colorimetric Response of Enzymatic Reactions by Thermally Evaporated Plasmonic Thin Films: Application to Glial Fibrillary Acidic Protein

    PubMed Central

    Abel, Biebele; Kabir, Tabassum S.; Odukoya, Babatunde; Mohammed, Muzaffer; Aslan, Kadir

    2015-01-01

    We report the enhancement of the colorimetric response of horseradish peroxidase (HRP) and alkaline phosphatase (AP) in bioassays by thermally evaporated silver, gold, copper and nickel thin films. In this regard, a model bioassay based on biotin-avidin interactions was employed. Biotin groups and enzymes were introduced to all surfaces using a biotinylated linker molecule and avidin, respectively. The colorimetric response of HRP in the model bioassay carried out on the plasmonic thin films were up to 4.4-fold larger as compared to control samples (i.e., no plasmonic thin films), where the largest enhancement of colorimetric response was observed on silver thin films. The colorimetric response of AP on plasmonic thin films was found to be similar to those observed on control samples, which was attributed to the loss of enzymes from the surface during the bioassay steps. The extent of enzymes immobilized on to plasmonic thin films was found to affect the colorimetric response of the model bioassay. These findings allowed us to demonstrate the use of silver thin films for the detection of glial fibrillary acidic protein (GFAP), where the colorimetric response of the standard bioassays for GFAP was enhanced up to 67% as compared to bioassays on glass slides. PMID:25663850

  14. Controllable degradation of medical magnesium by electrodeposited composite films of mussel adhesive protein (Mefp-1) and chitosan.

    PubMed

    Jiang, Ping-Li; Hou, Rui-Qing; Chen, Cheng-Dong; Sun, Lan; Dong, Shi-Gang; Pan, Jin-Shan; Lin, Chang-Jian

    2016-09-15

    To control the degradation rate of medical magnesium in body fluid environment, biocompatible films composed of Mussel Adhesive Protein (Mefp-1) and chitosan were electrodeposited on magnesium surface in cathodic constant current mode. The compositions and structures of the films were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and infrared reflection absorption spectroscopy (IRAS). And the corrosion protection performance was investigated using electrochemical measurements and immersion tests in simulated body fluid (Hanks' solution). The results revealed that Mefp-1 and chitosan successfully adhered on the magnesium surface and formed a protective film. Compared with either single Mefp-1 or single chitosan film, the composite film of chitosan/Mefp-1/chitosan (CPC (chitosan/Mefp-1/chitosan)) exhibited lower corrosion current density, higher polarization resistance and more homogenous corrosion morphology and thus was able to effectively control the degradation rate of magnesium in simulated body environment. In addition, the active attachment and spreading of MC3T3-E1 cells on the CPC film coated magnesium indicated that the CPC film was significantly able to improve the biocompatibility of the medical magnesium. PMID:27309944

  15. Preparation and characterization of soy protein films with a durable water resistance-adjustable and antimicrobial surface.

    PubMed

    Li, Shuzhao; Donner, Elizabeth; Xiao, Huining; Thompson, Michael; Zhang, Yachuan; Rempel, Curtis; Liu, Qiang

    2016-12-01

    A water resistant surface was first obtained by immobilizing hydrophobic copolymers, poly (styrene-co-glycidyl methacrylate) (PSG), with functional groups on soy protein isolate (SPI) films. XPS and AFM results showed that PSG copolymers were immobilized on the film by chemical bonding, and formed a rough surface with some bumps because of the segregation of two different phases on PSG copolymers. Water resistance of the modified films could be adjusted dramatically by further immobilizing different amounts of guanidine-based antimicrobial polymers, poly (hexamethylene guanidine hydrochloride) (PHMG) on the resulting hydrophobic surface. The introduction of hydrophilic PHMG on the resulting surface generated many micropores, which potentially increased the water uptake of the modified films. Furthermore, the modified SPI films showed higher thermostability compared to native SPI film and broad-spectrum antimicrobial activity by contact killing, attributed to the presence of PHMG on the surface. The modified SPI film with a multi-functional surface showed potential for applications in the packaging and medical fields. PMID:27612790

  16. Antioxidant activities of distiller dried grains with solubles as protein films containing tea extracts and their application in the packaging of pork meat.

    PubMed

    Yang, Hyun-Ju; Lee, Ji-Hyeon; Won, Misun; Song, Kyung Bin

    2016-04-01

    Distiller dried grains with solubles (DDGS) as protein (DP) films were prepared. Additionally, to prepare anti-oxidant films, green tea extract (GTE), oolong tea extract (OTE), and black tea extract (BTE) were incorporated into the DP films. Consequently, the incorporation of the tea extracts did not alter the physical properties of the films much, whereas the antioxidant activities, such as ABTS and DPPH radical scavenging activities were observed. To apply the DP films containing tea extracts to food packaging, pork meat was wrapped with the films and stored at 4 °C for 10 d. During storage, the pork meat wrapped with the DP films containing GTE, OTE, and BTE had less lipid oxidation than did the control. Among the tea extracts, the DP film containing GTE had the greatest antioxidant activity. These results indicate that the DP films containing green tea extracts can be utilized as an anti-oxidative packaging material for pork meat. PMID:26593480

  17. Preparation and characterization of bio-nanocomposite films based on soy protein isolate and montmorillonite using melt extrusion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and montmorillo...

  18. Human Pulmonary Surfactant Protein SP-A1 Provides Maximal Efficiency of Lung Interfacial Films.

    PubMed

    Lopez-Rodriguez, Elena; Pascual, Alicia; Arroyo, Raquel; Floros, Joanna; Perez-Gil, Jesus

    2016-08-01

    Pulmonary surfactant is a lipoprotein complex that reduces surface tension to prevent alveolar collapse and contributes to the protection of the respiratory surface from the entry of pathogens. Surfactant protein A (SP-A) is a hydrophilic glycoprotein of the collectin family, and its main function is related to host defense. However, previous studies have shown that SP-A also aids in the formation and biophysical properties of pulmonary surfactant films at the air-water interface. Humans, unlike rodents, have two genes, SFTPA1 and SFTPA2. The encoded proteins, SP-A1 and SP-A2, differ quantitatively or qualitatively in function. It has been shown that both gene products are necessary for tubular myelin formation, an extracellular structural form of lung surfactant. The goal of this study was to investigate potential differences in the biophysical properties of surfactants containing human SP-A1, SP-A2, or both. For this purpose, we have studied for the first time, to our knowledge, the biophysical properties of pulmonary surfactant from individual humanized transgenic mice expressing human SP-A1, SP-A2, or both SP-A1 and SP-A2, in the captive bubble surfactometer. We observed that pulmonary surfactant containing SP-A1 reaches lower surface tension after postexpansion interfacial adsorption than surfactants containing no SP-A or only SP-A2. Under interfacial compression-expansion cycling conditions, surfactant films containing SP-A1 also performed better, particularly with respect to the reorganization of the films that takes place during compression. On the other hand, addition of recombinant SP-A1 to a surfactant preparation reconstituted from the hydrophobic fraction of a porcine surfactant made it more resistant to inhibition by serum than the addition of equivalent amounts of SP-A2. We conclude that the presence of SP-A1 allows pulmonary surfactant to adopt a particularly favorable structure with optimal biophysical properties. PMID:27508436

  19. A simultaneous electrochemical multianalyte immunoassay of high sensitivity C-reactive protein and soluble CD40 ligand based on reduced graphene oxide-tetraethylene pentamine that directly adsorb metal ions as labels.

    PubMed

    Yuan, Guolin; Yu, Chao; Xia, Chunyong; Gao, Liuliu; Xu, Wailan; Li, Wenjuan; He, Junlin

    2015-10-15

    A simplified electrochemical multianalyte immunosensor for the simultaneous detection of high sensitivity C-reactive protein (hsCRP) and soluble CD40 ligand (sCD40L) that uses reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) that directly adsorbs metal ions as labels is reported. rGO-TEPA contains a large number of amino groups and has excellent conductivity, making it an ideal template for the loading of Pb(2+) and Cu(2+), which greatly amplifies the detection signals. The signals could be directly detected in a single run through differential pulse voltammetry (DPV), and each biorecognition event produces a distinct voltammetric peak. The position and size of each peak reflects the identity and the level of the corresponding antigen. Primarily designed for an application in a sandwich-type immunoassay based on Pb(2+) and Cu(2+) labels, two main challenges are accomplished with the herein presented nanosheets: fabrication of the template and the amination process for Pb(2+) and Cu(2+) adsorption. To further improve the analytical performance of the immunosensor, Au@bovine serum albumin (BSA) nanospheres synthesized through a "green" synthesis route were used as a sensor platform, which not only provides a biocompatible microenvironment for the immobilization of antibodies but also amplifies the electrochemical signals. Under optimal conditions, hsCRP and sCD40L could be assayed in the range of 0.05 to 100 ng mL(-1) with detection limits of 16.7 and 13.1 pg mL(-1) (S/N=3), respectively. The assay results on clinical serum samples with the proposed immunosensor were in acceptable agreement with those using the standard single-analyte test of the enzyme-linked immunosorbent assay (ELISA). This novel immunosensing system provides a simple, sensitive and low-cost approach for a multianalyte immunoassay. PMID:25985199

  20. Effect of surface charge distribution on the adsorption orientation of proteins to lipid monolayers.

    PubMed

    Tiemeyer, Sebastian; Paulus, Michael; Tolan, Metin

    2010-09-01

    The adsorption orientation of the proteins lysozyme and ribonuclease A (RNase A) to a neutral 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a negatively charged stearic acid lipid film was investigated by means of X-ray reflectivity. Both proteins adsorbed to the negatively charged lipid monolayer, whereas at the neutral monolayer, no adsorption was observed. For acquiring comprehensive information on the proteins' adsorption, X-ray reflectivity data were combined with electron densities obtained from crystallographic data. With this method, it is possible to determine the orientation of adsorbed proteins in solution underneath lipid monolayers. While RNase A specifically coupled with its positively charged active site to the negatively charged lipid monolayer, lysozyme prefers an orientation with its long axis parallel to the Langmuir film. In comparison to the electrostatic maps of the proteins, our results can be explained by the discriminative surface charge distribution of lysozyme and RNase A. PMID:20707324

  1. Molecularly imprinted polymer film interfaced with Surface Acoustic Wave technology as a sensing platform for label-free protein detection.

    PubMed

    Tretjakov, Aleksei; Syritski, Vitali; Reut, Jekaterina; Boroznjak, Roman; Öpik, Andres

    2016-01-01

    Molecularly imprinted polymer (MIP)-based synthetic receptors integrated with Surface Acoustic Wave (SAW) sensing platform were applied for the first time for label-free protein detection. The ultrathin polymeric films with surface imprints of immunoglobulin G (IgG-MIP) were fabricated onto the multiplexed SAW chips using an electrosynthesis approach. The films were characterized by analyzing the binding kinetics recorded by SAW system. It was revealed that the capability of IgG-MIP to specifically recognize the target protein was greatly influenced by the polymer film thickness that could be easily optimized by the amount of the electrical charge consumed during the electrodeposition. The thickness-optimized IgG-MIPs demonstrated imprinting factors towards IgG in the range of 2.8-4, while their recognition efficiencies were about 4 and 10 times lower toward the interfering proteins, IgA and HSA, respectively. Additionally, IgG-MIP preserved its capability to recognize selectively the template after up to four regeneration cycles. The presented approach of the facile integration of the protein-MIP sensing layer with SAW technology allowed observing the real-time binding events of the target protein at relevant sensitivity levels and can be potentially suitable for cost effective fabrication of a biosensor for analysis of biological samples in multiplexed manner. PMID:26703269

  2. Design and characterization of controlled-release edible packaging films prepared with synergistic whey-protein polysaccharide complexes.

    PubMed

    Liu, Fei; Jiang, Yanfeng; Du, Bingjian; Chai, Zhi; Jiao, Tong; Zhang, Chunyue; Ren, Fazheng; Leng, Xiaojing

    2013-06-19

    This paper describes an investigation into the properties of a doubly emulsified film incorporated with protein-polysaccharide microcapsules, which serves as a multifunctional food packaging film prepared using common edible materials in place of petroleum--based plastics. The relationships between the microstructural properties and controlled release features of a series of water-in-oil-in-water (W/O/W) microcapsulated edible films prepared in thermodynamically incompatible conditions were analyzed. The hydrophilic riboflavin (V(B2)) nano-droplets (13-50 nm) dispersed in α-tocopherol (V(E)) oil phase were embedded in whey protein-polysaccharide (WPs) microcapsules with a shell thickness of 20-56 nm. These microcapsules were then integrated in 103 μm thick WPs films. Different polysaccharides, including gum arabic (GA), low-methoxyl pectin (LMP), and κ-carrageenan (KCG), exhibited different in vitro synergistic effects on the ability of both films to effect enteric controlled release of both vitamins. GA, which showed a strong emulsifying ability, also showed better control of V(E) than other polysaccharides, and the highly charged KCG showed better control of V(B2) than GA did. PMID:23718814

  3. Imparting Nonfouling Properties to Chemically Distinct Surfaces with a Single Adsorbing Polymer: A Multimodal Binding Approach.

    PubMed

    Serrano, Ângela; Zürcher, Stefan; Tosatti, Samuele; Spencer, Nicholas D

    2016-04-01

    Surface-active polymers that display nonfouling properties and carry binding groups that can adsorb onto different substrates are highly desirable. We present a postmodification protocol of an active-ester-containing polymer that allows the creation of such a versatile platform. Poly(pentafluorophenyl acrylate) has been postmodified with a fixed grafting ratio of a nonfouling function (mPEG) and various combinations of functional groups, such as amine, silane and catechol, which can provide strong affinity to two model substrates: SiO2 and TiO2 . Adsorption, stability and resistance to nonspecific protein adsorption of the polymer films were studied. A polymer was obtained that maintained its surface functionality under a variety of harsh conditions. EG surface-density calculations show that this strategy generates a denser packing when both negatively and positively charged groups are present within the backbone, and readily allows the fabrication of a broad combinatorial matrix. PMID:26858017

  4. A high-capacity hydrophobic adsorbent for human serum albumin.

    PubMed

    Belew, M; Peterson, E A; Porath, J

    1985-12-01

    A simple method, based on salting out hydrophobic interaction chromatography, for the efficient removal of trace amounts of serum albumin from partially purified protein preparations is described. The method is also successfully applied for the purification of albumin from Cohn fraction IV, a by-product obtained from the commercial fractionation of human serum proteins by the ethanol precipitation procedure. About 70% of the adsorbed albumin can be eluted by buffer of low ionic strength and can thus be lyophilized directly, if required. The adsorbent can be used for several cycles of adsorption and desorption without affecting its selectivity or capacity. Its adsorption properties and capacity for serum albumin are compared with those of the commercially available adsorbent Blue Sepharose CL-6B. PMID:3879424

  5. Allantoin as a solid phase adsorbent for removing endotoxins.

    PubMed

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Gagnon, Pete

    2013-10-01

    In this study we present a simple and robust method for removing endotoxins from protein solutions by using crystals of the small-molecule compound 2,5-dioxo-4-imidazolidinyl urea (allantoin) as a solid phase adsorbent. Allantoin crystalline powder is added to a protein solution at supersaturated concentrations, endotoxins bind and undissolved allantoin crystals with bound endotoxins are removed by filtration or centrifugation. This method removes an average of 99.98% endotoxin for 20 test proteins. The average protein recovery is ∼80%. Endotoxin binding is largely independent of pH, conductivity, reducing agent and various organic solvents. This is consistent with a hydrogen-bond based binding mechanism. Allantoin does not affect protein activity and stability, and the use of allantoin as a solid phase adsorbent provides better endotoxin removal than anion exchange, polymixin affinity and biological affinity methods for endotoxin clearance. PMID:24001944

  6. Nanosize electropositive fibrous adsorbent

    DOEpatents

    Tepper, Frederick; Kaledin, Leonid

    2005-01-04

    Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2 /g have been fount to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of mirobes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolicules such as proteins may be separated from each other based on their electronegative charges.

  7. Nuclear spin heat capacity of 3He adsorbed on graphite

    NASA Astrophysics Data System (ADS)

    Greywall, Dennis S.

    1989-10-01

    The heat capacity of 3He adsorbed on graphite has been measured for films between one and five atomic layers and for temperatures between 2 and 200 mK. These results are compared with recent magnetization data which also show several anomalies in this coverage regime. Prior to third layer promotion the second layer is found to solidify into a registered structure with unusual propertis. This contradicts the model proposed to explain the NMR measurements.

  8. Dynamic interfacial properties of human tear-lipid films and their interactions with model-tear proteins in vitro.

    PubMed

    Svitova, Tatyana F; Lin, Meng C

    2016-07-01

    This review summarizes the current state of knowledge regarding interfacial properties of very complex biological colloids, specifically, human meibum and tear lipids, and their interactions with proteins similar to the proteins found in aqueous part of human tears. Tear lipids spread as thin films over the surface of tear-film aqueous and play crucial roles in tear-film stability and overall ocular-surface health. The vast majority of papers published to date report interfacial properties of meibum-lipid monolayers spread on various aqueous sub-phases, often containing model proteins, in Langmuir trough. However, it is well established that natural human ocular tear lipids exist as multilayered films with a thickness between 30 and 100nm, that is very much disparate from 1 to 2nm thick meibum monolayers. We employed sessile-bubble tensiometry to study the dynamic interfacial and rheological properties of reconstituted multilayered human tear-lipid films. Small amounts (0.5-1μg) of human tear lipids were deposited on an air-bubble surface to produce tear-lipid films in thickness range 30-100nm corresponding to ocular lipid films. Thus, we were able to overcome major Langmuir-trough method limitations because ocular tear lipids can be safely harvested only in minute, sub-milligram quantities, insufficient for Langmuir through studies. Sessile-bubble method is demonstrated to be a versatile tool for assessing conventional synthetic surfactants adsorption/desorption dynamics at an air-aqueous solution interface. (Svitova T., Weatherbee M., Radke C.J. Dynamics of surfactant sorption at the air/water interface: continuous-flow tensiometry. J. Colloid Interf. Sci. 2003;261:1170-179). The augmented flow-sessile-bubble setup, with step-strain relaxation module for dynamic interfacial rheological properties and high-precision syringe pump to generate larger and slow interfacial area expansions-contractions, was developed and employed in our studies. We established that

  9. Formation of intermolecular beta-sheet structures: a phenomenon relevant to protein film structure at oil-water interfaces of emulsions.

    PubMed

    Lefèvre, Thierry; Subirade, Muriel

    2003-07-01

    Oil-in-water emulsions stabilized with beta-lactoglobulin (beta-lg) were made using a homogenizer or a high-speed blender. The protein was studied by Fourier transform infrared (FTIR) spectroscopy in the raw emulsion, in the bulk phase, and at the interface, as a function of pH, oil content, and homogenizing pressure. Results show that the amount of adsorbed protein varies with the available interfacial area. The protein that remains in the aqueous phase exhibit no spectral change, which suggests that homogenization causes no conformational modification or reversible ones. Strong and irreversible changes were observed in the adsorbed protein. Our findings reveal the formation of intermolecular antiparallel beta-sheets upon adsorption due to the protein self-aggregation. As deduced from transmission electronic microscopy, this surface aggregation leads to the formation of continuous and homogeneous membranes coating the globules. The structure of the adsorbed proteins is unaffected by the homogenizing pressures used in our study and slightly modified by the pH. FTIR spectroscopy allows to characterize the type of aggregates formed at the interface. An analysis of the spectra of beta-lg heat-induced gels shows that the aggregates at the interface are very close at a molecular scale to those that constitute particulate gels near the protein's isoelectric point. Since the type of aggregates is similar when the emulsion water phase is pure D(2)O and D(2)O at pD 4.4, the interface not only seems to induce aggregation, but seems to determine the type of aggregation as well. The mechanism that drives the formation of particulate aggregates (rather than fine-stranded ones) may reside in strong protein-protein interactions that are promoted by adverse oil-protein interactions. PMID:12804885

  10. Long-Wavelength Infrared Sensing by Cytochrome C Protein Thin Film Deposited by the Spin Coating Method

    PubMed Central

    Lai, Bo-Yu; Chu, Chung-Hao; Su, Guo-Dung John

    2013-01-01

    High infrared absorption, large temperature coefficient of resistance (TCR) and small 1/f noise are preferred characteristics for sensing materials used in bolometers. In this paper, we discuss a cytochrome c protein as a potential sensing material for long-wavelength bolometers. We simulated and experimentally proved high infrared absorption of cytochrome c in the wavelength between 8 μm and 14 μm. Cytochrome c thin films were deposited on a hydrophilic surface using the spin coating method. The resistance variation with temperature is measured and we show that the TCR of cytochrome c thin films is consistently higher than 20%. The measured values of 1/f noise were as low as 2.33 × 10−13 V2/Hz at 60 Hz. Finally, we test the reliability of cytochrome c by measuring the resistance changes over time under varying conditions. We found that cytochrome c thin films deteriorated significantly without appropriate packaging. PMID:24264331

  11. Multilayer structures in lipid monolayer films containing surfactant protein C: effects of cholesterol and POPE.

    PubMed

    Malcharek, Stefan; Hinz, Andreas; Hilterhaus, Lutz; Galla, Hans-Joachim

    2005-04-01

    The influence of cholesterol and POPE on lung surfactant model systems consisting of DPPC/DPPG (80:20) and DPPC/DPPG/surfactant protein C (80:20:0.4) has been investigated. Cholesterol leads to a condensation of the monolayers, whereas the isotherms of model lung surfactant films containing POPE exhibit a slight expansion combined with an increased compressibility at medium surface pressure (10-30 mN/m). An increasing amount of liquid-expanded domains can be visualized by means of fluorescence light microscopy in lung surfactant monolayers after addition of either cholesterol or POPE. At surface pressures of 50 mN/m, protrusions are formed which differ in size and shape as a function of the content of cholesterol or POPE, but only if SP-C is present. Low amounts of cholesterol (10 mol %) lead to an increasing number of protrusions, which also grow in size. This is interpreted as a stabilizing effect of cholesterol on bilayers formed underneath the monolayer. Extreme amounts of cholesterol (30 mol %), however, cause an increased monolayer rigidity, thus preventing reversible multilayer formation. In contrast, POPE, as a nonbilayer lipid thought to stabilize the edges of protrusions, leads to more narrow protrusions. The lateral extension of the protrusions is thereby more influenced than their height. PMID:15653721

  12. Size-dependent denaturing kinetics of bovine serum albumin adsorbed onto gold nanospheres

    NASA Astrophysics Data System (ADS)

    Teichroeb, J. H.; Forrest, J. A.; Jones, L. W.

    2008-08-01

    We have used localized surface plasmon resonance (LSPR) to monitor the kinetics of thermal denaturing of bovine serum albumin (BSA) adsorbed onto gold nanospheres of size 5nm-100nm. The effect of the protein on the LSPR was monitored by visible extinction spectroscopy. The wavelength of the peak extinction (resonance) is affected by the conformation of the adsorbed protein layer, and as such can be used as a very sensitive probe of thermal denaturing that is specific to the adsorbed (as opposed to free) protein. The time dependence of the denaturing is measured in the temperature range 60 °C - 70 °C , and the lifetimes are used to calculate an activation barrier for thermal denaturing. The results show that thermally activated denaturing of proteins adsorbed onto nanoparticles has a nanoparticle-size-dependent activation barrier, and this barrier increases for decreasing particle size. This may have important implications for other protein-nanoparticle interactions.

  13. Deoxynivalenol Impairs Hepatic and Intestinal Gene Expression of Selected Oxidative Stress, Tight Junction and Inflammation Proteins in Broiler Chickens, but Addition of an Adsorbing Agent Shifts the Effects to the Distal Parts of the Small Intestine

    PubMed Central

    Osselaere, Ann; Santos, Regiane; Hautekiet, Veerle; De Backer, Patrick; Chiers, Koen; Ducatelle, Richard; Croubels, Siska

    2013-01-01

    Broiler chickens are rather resistant to deoxynivalenol and thus, clinical signs are rarely seen. However, effects of subclinical concentrations of deoxynivalenol on both the intestine and the liver are less frequently studied at the molecular level. During our study, we investigated the effects of three weeks of feeding deoxynivalenol on the gut wall morphology, intestinal barrier function and inflammation in broiler chickens. In addition, oxidative stress was evaluated in both the liver and intestine. Besides, the effect of a clay-based mycotoxin adsorbing agent on these different aspects was also studied. Our results show that feeding deoxynivalenol affects the gut wall morphology both in duodenum and jejenum of broiler chickens. A qRT-PCR analysis revealed that deoxynivalenol acts in a very specific way on the intestinal barrier, since only an up-regulation in mRNA expression of claudin 5 in jejunum was observed, while no effects were seen on claudin 1, zona occludens 1 and 2. Addition of an adsorbing agent resulted in an up-regulation of all the investigated genes coding for the intestinal barrier in the ileum. Up-regulation of Toll-like receptor 4 and two markers of oxidative stress (heme-oxigenase or HMOX and xanthine oxidoreductase or XOR) were mainly seen in the jejunum and to a lesser extent in the ileum in response to deoxynivalenol, while in combination with an adsorbing agent main effect was seen in the ileum. These results suggest that an adsorbing agent may lead to higher concentrations of deoxynivalenol in the more distal parts of the small intestine. In the liver, XOR was up-regulated due to DON exposure. HMOX and HIF-1α (hypoxia-inducible factor 1α) were down-regulated due to feeding DON but also due to feeding the adsorbing agent alone or in combination with DON. PMID:23922676

  14. Fabricating electrospun cellulose nanofibre adsorbents for ion-exchange chromatography

    PubMed Central

    Dods, Stewart R.; Hardick, Oliver; Stevens, Bob; Bracewell, Daniel G.

    2015-01-01

    Protein separation is an integral step in biopharmaceutical manufacture with diffusion-limited packed bed chromatography remaining the default choice for industry. Rapid bind-elute separation using convective mass transfer media offers advantages in productivity by operating at high flowrates. Electrospun nanofibre adsorbents are a non-woven fibre matrix of high surface area and porosity previously investigated as a bioseparation medium. The effects of compression and bed layers, and subsequent heat treatment after electrospinning cellulose acetate nanofibres were investigated using diethylaminoethyl (DEAE) or carboxylate (COO) functionalisations. Transbed pressures were measured and compared by compression load, COO adsorbents were 30%, 70% and 90% higher than DEAE for compressions 1, 5 and 10 MPa, respectively, which was attributed to the swelling effect of hydrophilic COO groups. Dynamic binding capacities (DBCs) at 10% breakthrough were measured between 2000 and 12,000 CV/h (2 s and 0.3 s residence times) under normal binding conditions, and DBCs increased with reactant concentration from 4 to 12 mg BSA/mL for DEAE and from 10 to 21 mg lysozyme/mL for COO adsorbents. Comparing capacities of compression loads applied after electrospinning showed that the lowest load tested, 1 MPa, yielded the highest DBCs for DEAE and COO adsorbents at 20 mg BSA/mL and 27 mg lysozyme/mL, respectively. At 1 MPa, DBCs were the highest for the lowest flowrate tested but stabilised for flowrates above 2000 CV/h. For compression loads of 5 MPa and 10 MPa, adsorbents recorded lower DBCs than 1 MPa as a result of nanofibre packing and reduced surface area. Increasing the number of bed layers from 4 to 12 showed decreasing DBCs for both adsorbents. Tensile strengths were recorded to indicate the mechanical robustness of the adsorbent and be related to packing the nanofibre adsorbents in large scale configurations such as pleated cartridges. Compared with an

  15. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    NASA Astrophysics Data System (ADS)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D < 6 nm do not change during HA synthesis, while the volume of pores with diameters of 6 nm < D < 9 nm shrinks slightly due to the adsorption of albumin in the pore orifices. It is established that the volume of pores with diameters D > 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  16. Nitric oxide releasing material adsorbs more fibrinogen.

    PubMed

    Lantvit, Sarah M; Barrett, Brittany J; Reynolds, Melissa M

    2013-11-01

    One mechanism of the failure of blood-contacting devices is clotting. Nitric oxide (NO) releasing materials are seen as a viable solution to the mediation of surface clotting by preventing platelet activation; however, NO's involvement in preventing clot formation extends beyond controlling platelet function. In this study, we evaluate NO's effect on factor XII (fibrinogen) adsorption and activation, which causes the initiation of the intrinsic arm of the coagulation cascade. This is done by utilizing a model plasticized poly(vinyl) chloride (PVC), N-diazeniumdiolate system and looking at the adsorption of fibrinogen, an important clotting protein, to these surfaces. The materials have been prepared in such a way to eliminate changes in surface properties between the control (plasticized PVC) and composite (NO-releasing) materials. This allows us to isolate NO release and determine the effect on the adsorption of fibrinogen, to the material surface. Surprisingly, it was found that an NO releasing material with a surface flux of 17.4 ± 0.5 × 10(-10) mol NO cm(-2) min(-1) showed a significant increase in the amount of fibrinogen adsorbed to the material surface compared to one with a flux of 13.0 ± 1.6 × 10(-10) mol NO cm(-2) min(-1) and the control (2334 ± 496, 226 ± 99, and 103 ±31% fibrinogen adsorbed of control, respectively). This study suggests that NO's role in controlling clotting is extended beyond platelet activation. PMID:23554300

  17. Innovative bionanocomposite films of edible proteins containing liposome-encapsulated nisin and halloysite nanoclay.

    PubMed

    Boelter, Juliana Ferreira; Brandelli, Adriano

    2016-09-01

    Films and coatings based on natural polymers have gained increased interest for food packaging applications. In this work, halloysite and phosphatidylcholine liposomes encapsulating nisin were used to develop nanocomposite films of gelatin and casein. Liposomes prepared with either soybean lecithin or Phospholipon(®) showed particle size ranging from 124 to 178nm and high entrapment efficiency (94-100%). Considering their stability, Phospholipon(®) liposomes with 1.0mg/ml nisin were selected for incorporation into nanocomposite films containing 0.5g/l halloysite. The films presented antimicrobial activity against Listeria monocytogenes, Clostridium perfringens and Bacillus cereus. Scanning electron microscopy revealed that the films had a smooth surface, but showed increased roughness with addition of liposomes and halloysite. Casein films were thinner and slightly yellowish, less rigid and very elastic as compared with gelatin films. Thermogravimetric analysis showed a decrease of the degradation temperature for casein films added with liposomes. The glass transition temperature decreased with addition of liposomes and halloysite. Gelatin and casein films containing nisin-loaded liposomes and halloysite represent an interesting alternative for development of active food packaging. PMID:27289315

  18. Solution-based Syntheses of Iron Pyrite Thin Films for Photovoltaic and Protein Foot-printing Applications

    NASA Astrophysics Data System (ADS)

    El Makkaoui, Mohammed

    Iron pyrite (cubic FeS2) is a non-toxic, earth abundant semiconductor possessing a set of excellent optical/electronic properties for serving as an absorber layer in PV devices. Additionally, pyrite is a very efficient hydroxyl radical generator via Fenton chemistry and has shown promise in oxidative protein and DNA foot-printing application. The main focus of this thesis is on fabricating phase and elementally pure iron pyrite thin films using a solution-based approach that employs hydrazine as a solvent. A precursor ink is formed at room temperature by mixing elemental iron and sulfur in anhydrous hydrazine and then deposited on Mo-coated glass substrates, via spin coating, to yield amorphous iron sulfide films that are then annealed in H2S (340°C) and sulfur gas (≤ 500 °C) to form uniform, polycrystalline and phase pure pyrite films with densely packed grains. This approach is likely to yield the most elementally pure pyrite thin films made to date, through a very simple and scalable process. The ink has shown to be very sensitive to environmental conditions and has a very short shelf life (˜1 day). Additionally, the film microstructure is greatly influenced by the S:Fe concentration ratio that when tuned to 3:1, yielded uniform, robust and optically flat iron sulfide thin films with an optimal thickness (˜320 nm) for PV application. The results however were not reproducible, mainly due to failure in applying multiple layers without compromising film morphology. Thinner (< 100 nm) iron sulfide films, on the other hand, are reproducibly produced, but are too thin to be employed in PV devices. Direct annealing in sulfur gas at 475°C for 4 hours, bypassing the > 12 hour H2S annealing step, yielded phase pure pyrite films, with good morphology, at lower processing time and annealing temperatures (< 500°C). The latter part of this thesis regards the use of pyrite nano-crystals in conjunction with high surface area polymer laminates for protein foot

  19. [DSC and FTIR study of adsorbed lysozyme on hydrophobic surface].

    PubMed

    Lei, Zu-meng; Geng, Xin-peng; Dai, Li; Geng, Xin-du

    2008-09-01

    During a process of hen egg white lysozyme adsorption and folding on a moderately hydrophobic surface (PEG-600), the effects of salt((NH4)2SO4) concentrations, surface coverage and denaturant (guanidine hydrochloride, GuHCl) concentrations on thermal stability and the changes in the molecular conformation of adsorbed native and denatured lysozyme without aqueous solution were studied with a combination of differential scanning calorimetry (DSC) with FTIR spectroscopy. The results showed that temperature due to endothermic peaks was reduced and the disturbance increased at higher temperature with the increase in salt concentration and surface coverage of adsorbed protein. beta-Sheet and beta-Turn stucture increased while alpha-Helix structure decreased after the adsorption. The peaks corresponding to both C-C stretching frequency in 1400-1425 cm(-1) and amide I band frequency in 1650-1670 cm(-1) of adsorbed denatured lysozyme can be detected in FTIR spectra while that due to amide I band frequency of adsorbed native lysozyme almost can't be observed. Adsorption resulted in structural loss of adsorbed native lysozyme, whose performance was less stable. PMID:19093560

  20. Interactions of organic contaminants with mineral-adsorbed surfactants

    USGS Publications Warehouse

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  1. Supercritical fluid regeneration of adsorbents

    NASA Astrophysics Data System (ADS)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  2. Attachment of Listeria innocua to polystyrene: effects of ionic strength and conditioning films from culture media and milk proteins.

    PubMed

    Robitaille, Gilles; Choinière, Sébastien; Ells, Timothy; Deschènes, Louise; Mafu, Akier Assanta

    2014-03-01

    It is recognized that bacterial adhesion usually occurs on conditioning films made of organic macromolecules absorbed to abiotic surfaces. The objectives of this study were to determine the extent to which milk protein-coated polystyrene (PS) pegs interfere with biofilm formation and the synergistic effect of this conditioning and hypertonic growth media on the bacterial adhesion and biofilm formation of Listeria innocua, used as a nonpathogenic surrogate for Listeria monocytogenes. PS pegs were uncoated (bare PS) or individually coated with whey proteins isolate (WPI), β-lactoglobulin, bovine serum albumin, or tryptic soy broth (TSB) and were incubated in bacterial suspensions in modified Welshimer's broth. After 4 h, the number of adherent cells was dependent on the coating, as follows: TSB (10(7) CFU/ml) > bare PS > β-lactoglobulin > bovine serum albumin ∼ WPI (10(4) CFU/ml). The sessile cell counts increased up to 24 h, reaching > 10(7) CFU per peg for all surfaces (P > 0.1), except for WPI-coated PS; this indicates that the inhibitory effects of milk protein conditioning films are transient, slowing down the adhesion process. The 4-h bacterial adhesion on milk protein-coated PS in modified Welshimer's broth supplemented with salt (0 to 10% [wt/vol]) did not vary (P > 0.1), indicating that conditioning with milk proteins was the major determinant for inhibition of bacterial adhesion and that the synergetic effect of salt and milk proteins on adhesion was minimal. Moreover, the presence of 5 to 10% salt significantly inhibited 24-h biofilm formation on the TSB-coated and bare PS, with a decrease of >3 log at 10% (wt/vol) NaCl and almost completely depleted viable sessile bacteria on the milk protein-coated PS. PMID:24674434

  3. Robust Maleimide-Functionalized Gold Surfaces and Nanoparticles Generated Using Custom-Designed Bidentate Adsorbates.

    PubMed

    Park, Chul Soon; Lee, Han Ju; Jamison, Andrew C; Lee, T Randall

    2016-07-26

    A series of custom-designed alkanethioacetate ligands were synthesized to provide a facile method of attaching maleimide-terminated adsorbates to gold nanostructures via thiolate bonds. Monolayers on flat gold substrates derived from both mono- and dithioacetates, with and without oligo(ethylene glycol) (OEG) moieties in their alkyl spacers, were characterized using X-ray photoelectron spectroscopy, polarization modulation infrared reflection-absorption spectroscopy, ellipsometry, and contact angle goniometry. For all adsorbates, the resulting monolayers revealed that a higher packing density and more homogeneous surface were generated when the film was formed in EtOH, but a higher percentage of bound thiolate was obtained in THF. A series of gold nanoparticles (AuNPs) capped with each adsorbate were prepared to explore how adsorbate structure influences aqueous colloidal stability under extreme conditions, as examined visually and spectroscopically. The AuNPs coated with adsorbates that include OEG moieties exhibited enhanced stability under high salt concentration, and AuNPs capped with dithioacetate adsorbates exhibited improved stability against ligand exchange in competition with dithiothreitol (DTT). Overall, the best results were obtained with a chelating dithioacetate adsorbate that included OEG moieties in its alkyl spacer, imparting improved stability via enhanced solubility in water and superior adsorbate attachment owing to the chelate effect. PMID:27385466

  4. Enhanced physicochemical properties of chitosan/whey protein isolate composite film by sodium laurate-modified TiO2 nanoparticles.

    PubMed

    Zhang, Wei; Chen, Jiwang; Chen, Yue; Xia, Wenshui; Xiong, Youling L; Wang, Hongxun

    2016-03-15

    Chitosan/whey protein isolate film incorporated with sodium laurate-modified TiO2 nanoparticles was developed. The nanocomposite film was characterized by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry, and investigated in physicochemical properties as color, tensile strength, elongation at break, water vapor permeability and water adsorption isotherm. Our results showed that the nanoparticles improved the compatibility of whey protein isolate and chitosan. Addition of nanoparticles increased the whiteness of chitosan/whey protein isolate film, but decreased its transparency. Compared with binary film, the tensile strength and elongation at break of nanocomposite film were increased by 11.51% and 12.01%, respectively, and water vapor permeability was decreased by 7.60%. The equilibrium moisture of nanocomposite film was lower than binary film, and its water sorption isotherm of the nanocomposite film fitted well to Guggenheim-Anderson-deBoer model. The findings contributed to the development of novel food packaging materials. PMID:26794738

  5. Method And Apparatus For Regenerating Nox Adsorbers

    DOEpatents

    Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten

    2006-03-28

    Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

  6. Rupture force of adsorbed self-assembled surfactant layers. Effect of the dielectric exchange force

    NASA Astrophysics Data System (ADS)

    Teschke, O.; Ceotto, G.; de Souza, E. F.

    2001-08-01

    The tip applied force necessary to obtain tip/substrate contact, i.e., rupture force between adsorbed layers of self-assembled surfactant films and atomic force microscope (AFM) tips in water has been measured. A substantial contribution of this rupture force is due to the dielectric exchange force (DEF). The DEF model is in agreement with the observation that the surfactant layer rupture forces are smaller in the thickest layers, where the compactness of the adsorbed film results in the smallest values of the dielectric permittivity. Within experimental accuracy a dielectric permittivity value of ˜4 for bilayers and of ˜36 for monolayers is found.

  7. Monte Carlo lattice models for adsorbed polymer conformation

    NASA Technical Reports Server (NTRS)

    Good, B. S.

    1985-01-01

    The adhesion between a polymer film and a metal surface is of great technological interest. However, the prediction of adhesion and wear properties of polymer coated metals is quite difficult because a fundamental understanding of the polymer surface interaction does not yet exist. A computer model for the conformation of a polymer molecule adsorbed on a surface is discussed. The chain conformation is assumed to be described by a partially directed random walk on a three dimensional simple cubic lattice. An attractive surface potential is incorporated into the model through the use of a random walk step probability distribution that is anisotropic in the direction normal to the attractive surface. The effects of variations in potential characteristics are qualitatively included by varying both the degree of anisotropy of the step distribution and the range of the anisotropy. Polymer conformation is characterized by the average end to end distance, average radius of gyration, and average number of chain segments adsorbed on the surface.

  8. SPR-MS: from identifying adsorbed molecules to image tissues

    NASA Astrophysics Data System (ADS)

    Masson, Jean-François; Breault-Turcot, Julien; Forest, Simon; Chaurand, Pierre

    2015-03-01

    Surface plasmon resonance (SPR) sensors have become valuable analytical sensors for biomolecule detection. While SPR is heralded with high sensitivity, label-free and real-time detection, nonspecific adsorption and detection of ultralow concentrations remain issues. Nonspecific adsorption can be minimized using adequate surface chemistry. For example, we have employed peptide monolayers to reduce nonspecific adsorption of crude serum or cell lysate. It is important to uncover the nature of molecules nonspecifically adsorbing to surfaces in these biofluids, to further improve understanding of the nonspecific adsorption processes. Mass spectrometry (MS) provides a complementary tool to SPR to identify biomolecule adsorbed to surface. Trypsic digestion of the proteins adsorbed to surfaces led to identification of characteristic peptides from the proteins involved in nonspecific adsorption. Nonspecific adsorption in crude cell lysate results mainly from lipids, as confirmed with SPR and MS but proteins were observed on some surfaces. In another application of SPR and MS, imaging SPR can be used in combination to imaging MS to image tissue sections. Thin sections of mouse liver were inserted in the fluidic chamber of a SPRi instrument and proteins were transferred to the SPRi chip. The SPR chip was then imaged using MALDI imaging MS to identify the biomolecules that were transferred to the SPRi chip.

  9. Use of /γ-irradiation cross-linking to improve the water vapor permeability and the chemical stability of milk protein films

    NASA Astrophysics Data System (ADS)

    Ouattara, B.; Canh, L. T.; Vachon, C.; Mateescu, M. A.; Lacroix, M.

    2002-03-01

    γ-irradiation was used to produce free-standing cross-linked milk proteins. Film forming solutions were prepared according to a method previously developed in our laboratory using calcium caseinate (cas) with various proportions of whey protein isolate (wpi) or whey protein concentrate (wpc). The following caseinate-whey protein (cas:wp) ratio were prepared: 100:0, 75:25, 50:50, 25:75, and 0:100. The WVP of the films was determined gravimetrically at 23°C using a modified ASTM procedure. Molecular properties characterization was performed by size exclusion chromatography (SEC). Results showed significant ( p⩽0.05) reduction of the WVP of protein films for the following formulations: cas:wpi or cas:wpc (100:0); cas:wpi (25:75); cas:wpc (25:75); and cas:wpc (0:100). Mixture of cas and wpi produced a synergistic effect. The strongest combined effect was obtained for cas:wpi (25:75) formulation with permeability values of 2.07 and 1.38 g mm/m 2 d mm Hg for unirradiated and irradiated samples, respectively. γ-irradiation also induced a substantial increase of high molecular weight protein components in film forming solutions. The predominant fraction was ⩾10×10 6 Da for irradiated film forming solutions, compared to less than 0.2×10 6 Da for native unirradiated solutions.

  10. Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films

    PubMed Central

    Millar, Thomas J.; Mudgil, Poonam; Butovich, Igor A.; Palaniappan, Chendur K.

    2009-01-01

    Purpose Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. Methods Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (∏-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. Results The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37°C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in ∏-T profiles and the microscopic appearance of the films. Conclusions It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film. PMID:18757516

  11. Analysis and modeling of moisture sorption behavior for antimicrobial composite protein films.

    PubMed

    Lei, Qiao; Pan, Jiazhen; Bao, Jianqiang; Huang, Zhiying; Zhang, Yuting

    2014-01-01

    The WPI-NaCas-GLY antimicrobial film takes full advantage of the controlled release of active or antimicrobial agents as well as demonstrates a great potential for functioning as an alternative biodegradable polymer in practical applications. The moisture sorption kinetics of the film as an important carrier of active agents was investigated at various relative humidities (RH). The results indicated that the moisture sorption characterization and procedure of this film can be described well by the empirical Peleg model with higher confidence and concordance. The model could predict the film's moisture content at any time (Mt), the time to reach any given level of R (tR), the equilibrium moisture at any RH condition (Me), and isotherm trend based upon experimental data and modeled constants k(1), k(2), a, b, c, and d without giving consideration to their physical meaning. The water vapor transmission rate of the WPI-NaCas-GLY antimicrobial film increased exponentially with increasing RH due to its hydrophilicity, which was primarily caused by the presence of glycerol in a higher content. The results also suggested that aw predominately affects the film's Me values compared with the temperature factor by fixed nonlinear multiple regression analyses. PMID:25226893

  12. Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films.

    PubMed

    Chinma, C E; Ariahu, C C; Alakali, J S

    2015-04-01

    The effect of temperature and relative humidity on the water vapour permeability (WVP) and mechanical properties of cassava starch and soy protein concentrate (SPC) based edible films containing 20 % glycerol level were studied. Tensile strength and elastic modulus of edible films increased with increase in temperature and decreased with increase in relative humidity, while elongation at break decreased. Water vapour permeability of the films increased (2.6-4.3 g.mm/m(2).day.kPa) with increase in temperature and relative humidity. The temperature dependence of water vapour permeation of cassava starch-soy protein concentrate films followed Arrhenius relationship. Activation energy (Ea) of water vapour permeation of cassava starch-soy protein concentrate edible films ranged from 1.9 to 5.3 kJ/mol (R (2)  ≥ 0.93) and increased with increase in SPC addition. The Ea values were lower for the bio-films than for polyvinylidene chloride, polypropylene and polyethylene which are an indication of low water vapour permeability of the developed biofilms compared to those synthetic films. PMID:25829623

  13. Contact and friction of nanoasperities: effects of adsorbed monolayers.

    PubMed

    Cheng, Shengfeng; Luan, Binquan; Robbins, Mark O

    2010-01-01

    Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, and spherical tip with radius of order 30 nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare surfaces showed that the atomic scale deviations from a sphere that are present on any tip constructed from discrete atoms lead to significant deviations from continuum theory and dramatic variability in friction forces. Introducing an adsorbed monolayer leads to larger deviations from continuum theory but decreases the variations between tips with different atomic structure. Although the film is fluid, it remains in the contact and behaves qualitatively like a thin elastic coating except for certain tips at high loads. Measures of the contact area based on the moments or outer limits of the pressure distribution and on counting contacting atoms are compared. The number of tip atoms making contact during a time interval Deltat grows as a power of Deltat when the film is present and as the logarithm of Deltat for bare surfaces. Friction is measured by displacing the tip at a constant velocity or pulling the tip with a spring. Both static and kinetic friction rise linearly with load at small loads. Transitions in the state of the film lead to nonlinear behavior at large loads. The friction is less clearly correlated with contact area than load. PMID:20365427

  14. In vitro investigation of protein adsorption and platelet adhesion on inorganic biomaterial surfaces

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Lü, Xiaoying; Jingwu, Ma; Huang, Nan

    2008-11-01

    The aim of this paper was to study the surface properties, protein adsorption and platelet adhesion behaviors of diamond-like carbon (DLC) and titanium (Ti) films. The surface energy and microstructures of these films were characterized by contact angle measurement and atomic force microscopy (AFM). A modified Coomassie brilliant blue (CBB) protein assay was used to study the amount of adsorbed proteins. Platelet adhesion was assessed by scanning electron microscopy (SEM). The AFM results show that the DLC film is smoother than Ti. Protein adsorption results from CBB protein assay show that the ratio of adsorbed albumin (Alb) to IgG ( RA/I) on DLC is larger than Ti, which coincide with the sequence of the ratio of interfacial tension between solid surface and Alb ( γS,Alb) to interfacial tension between surface and IgG ( γS,IgG) ( γS,Alb/ γS,IgG). The DLC film has a preferential adsorption for Alb. The results suggest that the ratio of γS,Alb/ γS,IgG may indicate an Alb/IgG affinity ratio of materials. More platelets adhere on Ti film than on DLC, which may correspond to the surface roughness of materials. The conclusion is the blood compatibility of DLC seems to be better than Ti.

  15. Protein adsorption on surfaces: dynamic contact-angle (DCA) and quartz-crystal microbalance (QCM) measurements.

    PubMed

    Stadler, H; Mondon, M; Ziegler, C

    2003-01-01

    Adsorption of the protein bovine serum albumin (BSA) on gold has been tested at various concentrations in aqueous solution by dynamic contact-angle analysis (DCA) and quartz-crystal microbalance (QCM) measurements. With the Wilhelmy plate technique advancing and receding contact angles and the corresponding hysteresis were measured and correlated with the hydrophilicity and the homogeneity of the surface. With electrical admittance measurements of a gold-coated piezoelectrical quartz crystal, layer mass and viscoelastic contributions to the resonator's frequency shift during adsorption could be separated. A correlation was found between the adsorbed mass and the homogeneity and hydrophilicity of the adsorbed film. PMID:12520439

  16. Effect of film thickness on the antifouling performance of poly(hydroxy-functional methacrylates) grafted surfaces.

    PubMed

    Zhao, Chao; Li, Lingyan; Wang, Qiuming; Yu, Qiuming; Zheng, Jie

    2011-04-19

    The development of nonfouling biomaterials to prevent nonspecific protein adsorption and cell/bacterial adhesion is critical for many biomedical applications, such as antithrombogenic implants and biosensors. In this work, we polymerize two types of hydroxy-functional methacrylates monomers of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA) into polymer brushes on the gold substrate via surface-initiated atom transfer radical polymerization (SI-ATRP). We systematically examine the effect of the film thickness of polyHEMA and polyHPMA brushes on their antifouling performance in a wide range of biological media including single-protein solution, both diluted and undiluted human blood serum and plasma, and bacteria culture. Surface plasmon resonance (SPR) results show a strong correlation between antifouling property and film thickness. Too thin or too thick polymer brushes lead to large protein adsorption. Surfaces with the appropriate film thickness of ∼25-45 nm for polyHPMA and ∼20-45 nm for polyHEMA can achieve almost zero protein adsorption (<0.3 ng/cm(2)) from single-protein solution and diluted human blood plasma and serum. For undiluted human blood serum and plasma, polyHEMA brushes at a film thickness of ∼20-30 nm adsorb only ∼3.0 and ∼3.5 ng/cm(2) proteins, respectively, while polyHPMA brushes at a film thickness of ∼30 nm adsorb more proteins of ∼13.5 and ∼50.0 ng/cm(2), respectively. Moreover, both polyHEMA and polyHPMA brushes with optimal film thickness exhibit very low bacteria adhesion. The excellent antifouling ability and long-term stability of polyHEMA and polyHPMA brushes make them, especially for polyHEMA, effective and stable antifouling materials for usage in blood-contacting devices. PMID:21405141

  17. Measuring interactions between polydimethylsiloxane and serum proteins at the air-water interface.

    PubMed

    Liao, Zhengzheng; Hsieh, Wan-Ting; Baumgart, Tobias; Dmochowski, Ivan J

    2013-07-30

    The interaction between synthetic polymers and proteins at interfaces is relevant to basic science as well as a wide range of applications in biotechnology and medicine. One particularly common and important interface is the air-water interface (AWI). Due to the special energetics and dynamics of molecules at the AWI, the interplay between synthetic polymer and protein can be very different from that in bulk solution. In this paper, we applied the Langmuir-Blodgett technique and fluorescence microscopy to investigate how the compression state of polydimethylsiloxane (PDMS) film at the AWI affects the subsequent adsorption of serum protein [e.g., human serum albumin (HSA) or immunoglobulin G (IgG)] and the interaction between PDMS and protein. Of particular note is our observation of circular PDMS domains with micrometer diameters that form at the AWI in the highly compressed state of the surface film: proteins were shown to adsorb preferentially to the surface of these circular PDMS domains, accompanied by a greater than 4-fold increase in protein found in the interfacial film. The PDMS-only film and the PDMS-IgG composite film were transferred to cover glass, and platinum-carbon replicas of the transferred films were further characterized by scanning electron microscopy and atomic force microscopy. We conclude that the structure of the PDMS film greatly affects the amount and distribution of protein at the interface. PMID:23819833

  18. Multi-Layered Films Containing a Biomimetic Stimuli-Responsive Recombinant Protein

    NASA Astrophysics Data System (ADS)

    Barbosa, J. S.; Costa, R. R.; Testera, A. M.; Alonso, M.; Rodríguez-Cabello, J. C.; Mano, J. F.

    2009-10-01

    Electrostatic self-assembly was used to fabricate new smart multi-layer coatings, using a recombinant elastin-like polymer (ELP) and chitosan as the counterion macromolecule. The ELP was bioproduced, purified and its purity and expected molecular weight were assessed. Aggregate size measurements, obtained by light scattering of dissolved ELP, were performed as a function of temperature and pH to assess the smart properties of the polymer. The build-up of multi-layered films containing ELP and chitosan, using a layer-by-layer methodology, was followed by quartz-crystal microbalance with dissipation monitoring. Atomic force microscopy analysis permitted to demonstrate that the topography of the multi-layered films could respond to temperature. This work opens new possibilities for the use of ELPs in the fabrication of biodegradable smart coatings and films, offering new platforms in biotechnology and in the biomedical area.

  19. Multi-Layered Films Containing a Biomimetic Stimuli-Responsive Recombinant Protein

    PubMed Central

    2009-01-01

    Electrostatic self-assembly was used to fabricate new smart multi-layer coatings, using a recombinant elastin-like polymer (ELP) and chitosan as the counterion macromolecule. The ELP was bioproduced, purified and its purity and expected molecular weight were assessed. Aggregate size measurements, obtained by light scattering of dissolved ELP, were performed as a function of temperature and pH to assess the smart properties of the polymer. The build-up of multi-layered films containing ELP and chitosan, using a layer-by-layer methodology, was followed by quartz-crystal microbalance with dissipation monitoring. Atomic force microscopy analysis permitted to demonstrate that the topography of the multi-layered films could respond to temperature. This work opens new possibilities for the use of ELPs in the fabrication of biodegradable smart coatings and films, offering new platforms in biotechnology and in the biomedical area. PMID:20596391

  20. Preparation and characterization of protein-doped sol-gel derived nanocomposite films for biosensor development

    NASA Astrophysics Data System (ADS)

    Goring, Gillian Louise Grace

    The entrapment of biomolecules within TEOS-based sol-gel derived organic/inorganic nanocomposite materials has proven to be a viable platform for the development of biosensors and solid-phase biocatalysts. In this thesis, a series of organically modified silica materials were prepared by a two-step aqueous processing method that was suitable for biomolecule entrapment, and were formed as submicron thick films by dipcasting. Dispersed additives, such as polymers (Class I materials) and covalently bound additives, such as organically modified silanes (Class II materials), were used to modify the internal environment compared to the undoped matrices and to correlate the properties of entrapped enzymes. The morphology of organically modified silica materials could be modified through the use of either separate or co-hydrolysis of the silane precursors, with the later method generating optically transparent materials. Fluorescence microscopy revealed chemical heterogeneity in materials that appeared to be homogeneous by brightfield or SEM. Fluorescence emission studies of a solvatochromic dye entrapped within the film continued that the internal chemical environment of the films was strongly affected by doping with polymers and organosilanes. The films showed a rapid initial change in chemical properties owing to solvent evaporation, followed by a much slower evolution over several months owing to continued condensation reactions within the film. A reagentless biosensor was designed based on co-entrapment of an enzyme and a fluorescently labeled polymer. The enzymes urease and lipase were selected for this study as both catalyze reactions that alter the local pH. By co-entrapping pH sensitive fluorophores (SNARF-1 and fluorescein) bound to a high molecular weight polymer, it was possible to detect the analytes urea and glyceryl tributyrate using changes in the fluorescence intensity (fluorescein) or emission ratio (SNARF-1). By tuning the polarity of the matrix it was

  1. A novel fiber-based adsorbent technology

    SciTech Connect

    Reynolds, T.A.

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  2. Structure of collagen adsorbed on a model implant surface resolved by polarization modulation infrared reflection-absorption spectroscopy.

    PubMed

    Brand, Izabella; Habecker, Florian; Ahlers, Michael; Klüner, Thorsten

    2015-03-01

    The polarization modulation infrared reflection-absorption spectra of collagen adsorbed on a titania surface and quantum chemical calculations are used to describe components of the amide I mode to the protein structure at a sub-molecular level. In this study, imino acid rich and poor fragments, representing the entire collagen molecule, are taken into account. The amide I mode of the collagen triple helix is composed of three absorption bands which involve: (i) (∼1690cm(-1)) the CO stretching modes at unhydrated groups, (ii) (1655-1673cm(-1)) the CO stretching at carbonyl groups at imino acids and glycine forming intramolecular hydrogen bonds with H atoms at both NH2 and, unusual for proteins, CH2 groups at glycine at a neighbouring chain and (iii) (∼1640cm(-1)) the CO stretching at carbonyl groups forming hydrogen bonds between two, often charged, amino acids as well as hydrogen bonds to water along the entire helix. The IR spectrum of films prepared from diluted solutions (c<50μgml(-1)) corresponds to solution spectra indicating that native collagen molecules interact with water adsorbed on the titania surface. In films prepared from solutions (c⩾50μgml(-1)) collagen multilayers are formed. The amide I mode is blue-shifted by 18cm(-1), indicating that intramolecular hydrogen bonds at imino acid rich fragments are weakened. Simultaneous red-shift of the amide A mode implies that the strength of hydrogen bonds at the imino acid poor fragments increases. Theoretically predicted distortion of the collagen structure upon adsorption on the titania surface is experimentally confirmed. PMID:25498816

  3. Quasiparticle excitations of adsorbates on doped graphene

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Wickenburg, Sebastian; Wong, Dillon; Karrasch, Christoph; Wang, Yang; Lu, Jiong; Omrani, Arash A.; Brar, Victor; Tsai, Hsin-Zon; Wu, Qiong; Corsetti, Fabiano; Mostofi, Arash; Kawakami, Roland K.; Moore, Joel; Zettl, Alex; Louie, Steven G.; Crommie, Mike

    Adsorbed atoms and molecules can modify the electronic structure of graphene, but in turn it is also possible to control the properties of adsorbates via the graphene substrate. In my talk, I will discuss the electronic structure of F4-TCNQ molecules on doped graphene and present a first-principles based theory of quasiparticle excitations that captures the interplay of doping-dependent image charge interactions between substrate and adsorbate and electron-electron interaction effects on the molecule. The resulting doping-dependent quasiparticle energies will be compared to experimental scanning tunnelling spectra. Finally, I will also discuss the effects of charged adsorbates on the electronic structure of doped graphene.

  4. Physical properties of emulsion-based hydroxypropyl methylcellulose/whey protein isolate (HPMC/WPI) edible films.

    PubMed

    Rubilar, Javiera F; Zúñiga, Rommy N; Osorio, Fernando; Pedreschi, Franco

    2015-06-01

    The objective of this research was to study the effect of the film microstructure of oil-in-water emulsions stabilized by hydroxypropyl methyl cellulose/whey protein isolate (HPMC/WPI) with or without sodium dodecyl sulfate (SDS) over physical properties of HPMC/WPI emulsion-based films. The films were prepared with different HPMC/WPI-oil-SDS combinations (%w/w for 100g of dispersion): HPMC; WPI; HPMC/1WPI-0.5-SDS; HPMC/1WPI-1; HPMC/2WPI-0.5; HPMC/2WPI-1-SDS. Physical properties of films were evaluated. The results showed no statistical differences (p>0.05) between the thicknesses of EFs (0.156 ± 0.004 mm). The effect of oil content and incorporation of SDS showed the inverse trend for WI and ΔE, the increasing order of change, for WI and ΔE, among the formulation evaluated was: HPMC/1WPI-1>HPMC/2WPI-0.5>HPMC/2WPI-1.0-SDS≈HPMC/1WPI-0.5-SDS≈WPI>HPMC for WI and HPMC/1WPI-0.5-SDS>HPMC/2WPI-1.0-SDS>HPMC/2WPI-0.5>HPMC/1WPI-1 for ΔE, respectively. The addition of oil and SDS decreased the TS and EB, because oil addition into EF induces the development of structural discontinuities, producing an EF with less chain mobility, and consequently, with less flexibility and resistance to fracture. PMID:25843831

  5. Field effect of screened charges: electrical detection of peptides and proteins by a thin-film resistor.

    PubMed

    Lud, Simon Q; Nikolaides, Michael G; Haase, Ilka; Fischer, Markus; Bausch, Andreas R

    2006-02-13

    For many biotechnological applications the label-free detection of biomolecular interactions is becoming of outstanding importance. In this Article we report the direct electrical detection of small peptides and proteins by their intrinsic charges using a biofunctionalized thin-film resistor. The label-free selective and quantitative detection of small peptides and proteins is achieved using hydrophobized silicon-on-insulator (SOI) substrates functionalized with lipid membranes that incorporate metal-chelating lipids. The response of the nanometer-thin conducting silicon film to electrolyte screening effects is taken into account to determine quantitatively the charges of peptides. It is even possible to detect peptides with a single charge and to distinguish single charge variations of the analytes even in physiological electrolyte solutions. As the device is based on standard semiconductor technologies, parallelization and miniaturization of the SOI-based biosensor is achievable by standard CMOS technologies and thus a promising basis for high-throughput screening or biotechnological applications. PMID:16404758

  6. Guiding Principles of Hydrogenase Catalysis Instigated and Clarified by Protein Film Electrochemistry.

    PubMed

    Armstrong, Fraser A; Evans, Rhiannon M; Hexter, Suzannah V; Murphy, Bonnie J; Roessler, Maxie M; Wulff, Philip

    2016-05-17

    Protein film electrochemistry (PFE) is providing cutting-edge insight into the chemical principles underpinning biological hydrogen. Attached to an electrode, many enzymes exhibit "reversible" electrocatalytic behavior, meaning that a catalyzed redox reaction appears reversible or quasi-reversible when viewed by cyclic voltammetry. This efficiency is most relevant for enzymes that are inspiring advances in renewable energy, such as hydrogen-activating and CO2-reducing enzymes. Exploiting the rich repertoire of available instrumental methods, PFE experiments yield both a general snapshot and fine detail, all from tiny samples of enzyme. The dynamic electrochemical investigations blaze new trails and add exquisite detail to the information gained from structural and spectroscopic studies. This Account describes recent investigations of hydrogenases carried out in Oxford, including ideas initiated with PFE and followed through with complementary techniques, all contributing to an eventual complete picture of fast and efficient H2 activation without Pt. By immobilization of an enzyme on an electrode, catalytic electron flow and the chemistry controlling it can be addressed at the touch of a button. The buried nature of the active site means that structures that have been determined by crystallography or spectroscopy are likely to be protected, retained, and fully relevant in a PFE experiment. An electrocatalysis model formulated for the PFE of immobilized enzymes predicts interesting behavior and gives insight into why some hydrogenases are H2 producers and others are H2 oxidizers. Immobilization also allows for easy addition and removal of inhibitors along with precise potential control, one interesting outcome being that formaldehyde forms a reversible complex with reduced [FeFe]-hydrogenases, thereby providing insight into the order of electron and proton transfers. Experiments on O2-tolerant [NiFe]-hydrogenases show that O2 behaves like a reversible inhibitor: it

  7. Physicochemical properties of soy protein isolate/carboxymethyl cellulose blend films crosslinked by Maillard reactions: color, transparency and heat-sealing ability.

    PubMed

    Su, Jun-Feng; Yuan, Xiao-Yan; Huang, Zhen; Wang, Xin-Yu; Lu, Xu-Zhen; Zhang, Li-Dan; Wang, Sheng-Bao

    2012-01-01

    Soy protein isolate (SPI) films have many potential applications in the biomaterial field as surgical dressings for burns, films for reduction of wound inflammation, and facial masks. The appearance and the sealing ability are important physicochemical properties that greatly influence consumer acceptance of such protein-based films. The aim of the present work was to investigate the chemical structure and the physical properties associated with color, transparency and heat-sealing ability for SPI/carboxymethyl cellulose (CMC) blend films prepared by solution casting, with weight proportions 90/10, 80/20, 70/30 and 60/40. Fourier transform infra-red (FTIR) and solid-state (13)C nuclear magnetic resonance (NMR) spectra confirmed that Maillard reactions occurred between SPI and CMC. The Hunter color value (L, a, b) and transparency of films were affected by varying the proportions of SPI and CMC. With increasing degree of crosslinking of SPI and CMC, the yellow color of the films was diluted and transparency was improved. Peel strength and tensile strength measurements showed that the Maillard reactions had the main effect of enhancing the heat-sealing ability above the melting temperature. These results indicated that the structure and properties of SPI-based films could be modified and improved by blending with CMC. PMID:23177770

  8. Protein nanorings organized by poly(styrene-block-ethylene oxide) self-assembled thin films

    NASA Astrophysics Data System (ADS)

    Malmström, Jenny; Wason, Akshita; Roache, Fergus; Yewdall, N. Amy; Radjainia, Mazdak; Wei, Shanghai; Higgins, Michael J.; Williams, David E.; Gerrard, Juliet A.; Travas-Sejdic, Jadranka

    2015-11-01

    This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures.This study explores the use of block copolymer self-assembly to organize Lsmα, a protein which forms stable doughnut-shaped heptameric structures. Here, we have explored the idea that 2-D crystalline arrays of protein filaments can be prepared by stacking doughnut shaped Lsmα protein into the poly(ethylene oxide) blocks of a hexagonal microphase-separated polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer. We were able to demonstrate the coordinated assembly of such a complex hierarchical nanostructure. The key to success was the choice of solvent systems and protein functionalization that achieved sufficient compatibility whilst still promoting assembly. Unambiguous characterisation of these structures is difficult; however AFM and TEM measurements confirmed that the protein was sequestered into the PEO blocks. The use of a protein that assembles into stackable doughnuts offers the possibility of assembling nanoscale optical, magnetic and electronic structures. Electronic supplementary

  9. The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    DOE PAGESBeta

    Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; Park, Jiyeon; Jeters, Robert T.; Bonheyo, George T.; Pan, Horng -Bin; Wai, Chien; Khangaonkar, Tarang P.; Bianucci, Laura; et al

    2016-02-07

    The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

  10. The Uranium from Seawater Program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    SciTech Connect

    Gill, Gary; Kuo, Li-Jung; Janke, Christopher James; Park, Jiyeon; Jeters, Robert T; Bonheyo, George; Pan, Horng-Bin; Wai, Chien; Khangaonkar, Tarang P; Bianucci, Laura; Wood, Jordana; Warner, Marvin G; Peterson, Sonja; Abrecht, David; Mayes, Richard T; Tsouris, Costas; Oyola, Yatsandra; Strivens, Jonathan E.; Schlafer, Nicholas; Addleman, Shane R; Chouyyok, Wilaiwan; Das, Sadananda; Kim, Jungseung; Buesseler, Dr. Ken; Breier, Crystalline; D'Alessandro, Dr. Evan

    2016-01-01

    The Pacific Northwest National Laboratory s (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacity and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing at Woods Hole

  11. Capillary-Channeled Polymer (C-CP) Films as Processing Platforms for Protein Analysis by Matrix-Assisted Laser/Desorption Ionization Mass Spectrometry (MALDI-MS)

    NASA Astrophysics Data System (ADS)

    Pittman, Jennifer J.; Manard, Benjamin T.; Kowalski, Paul J.; Marcus, R. Kenneth

    2012-01-01

    Polypropylene (PP) capillary-channeled polymer (C-CP) films have parallel, μm-sized channels that induce solution wicking via capillary action. Efficient mass transport from the solution phase to the channel surface leads to adsorption of hydrophobic protein solutes. The basic premise by which C-CP films can be used as media to manipulate analyte solutions (e.g., proteins in buffer), for the purpose of desalting or chromatographic separation prior to MALDI-MS analysis is presented here. Cytochrome c and myoglobin prepared in a Tris-HCl buffer, and ribonuclease A, lysozyme, and transferrin prepared in phosphate buffered saline (PBS), are used as the test solutions to demonstrate the desalting concept. Protein analysis is performed after deposition on a C-CP film with and without a water washing step, followed by spray deposition of a typical sinapinic acid matrix. Extracted MALDI mass spectra exhibit much improved signal-to-noise characteristics after water washing. A mixture of cytochrome c and myoglobin (2 μL of 2.5 μM each in Tris-HCl buffer) was applied, washed with water and spatially separated via simple capillary action (wicking) using a reversed-phase solvent composition of 0.1% trifluoroacetic acid (TFA) in 50:50 acetonitrile (ACN):H2O. Subsequent application of sinapinic acid followed by imaging of the film using MALDI-MS reveals that as the protein solution is wicked down the film, separation occurs.

  12. Capillary-channeled polymer (C-CP) films as processing platforms for protein analysis by matrix-assisted laser/desorption ionization mass spectrometry (MALDI-MS).

    PubMed

    Pittman, Jennifer J; Manard, Benjamin T; Kowalski, Paul J; Marcus, R Kenneth

    2012-01-01

    Polypropylene (PP) capillary-channeled polymer (C-CP) films have parallel, μm-sized channels that induce solution wicking via capillary action. Efficient mass transport from the solution phase to the channel surface leads to adsorption of hydrophobic protein solutes. The basic premise by which C-CP films can be used as media to manipulate analyte solutions (e.g., proteins in buffer), for the purpose of desalting or chromatographic separation prior to MALDI-MS analysis is presented here. Cytochrome c and myoglobin prepared in a Tris-HCl buffer, and ribonuclease A, lysozyme, and transferrin prepared in phosphate buffered saline (PBS), are used as the test solutions to demonstrate the desalting concept. Protein analysis is performed after deposition on a C-CP film with and without a water washing step, followed by spray deposition of a typical sinapinic acid matrix. Extracted MALDI mass spectra exhibit much improved signal-to-noise characteristics after water washing. A mixture of cytochrome c and myoglobin (2 μL of 2.5 μM each in Tris-HCl buffer) was applied, washed with water and spatially separated via simple capillary action (wicking) using a reversed-phase solvent composition of 0.1% trifluoroacetic acid (TFA) in 50:50 acetonitrile (ACN):H(2)O. Subsequent application of sinapinic acid followed by imaging of the film using MALDI-MS reveals that as the protein solution is wicked down the film, separation occurs. PMID:22012690

  13. Combined and Independent Action of Proteins SP-B and SP-C in the Surface Behavior and Mechanical Stability of Pulmonary Surfactant Films

    PubMed Central

    Schürch, David; Ospina, Olga L.; Cruz, Antonio; Pérez-Gil, Jesús

    2010-01-01

    The hydrophobic proteins SP-B and SP-C are essential for pulmonary surfactant function, even though they are a relatively minor component (<2% of surfactant dry mass). Despite countless studies, their specific differential action and their possible concerted role to optimize the surface properties of surfactant films have not been completely elucidated. Under conditions kept as physiologically relevant as possible, we tested the surface activity and mechanical stability of several surfactant films of varying protein composition in vitro using a captive bubble surfactometer and a novel (to our knowledge) stability test. We found that in the naturally derived surfactant lipid mixtures, surfactant protein SP-B promoted film formation and reextension to lower surface tensions than SP-C, and in particular played a vital role in sustaining film stability at the most compressed states, whereas SP-C produced no stabilization. Preparations containing both proteins together revealed a slight combined effect in enhancing film formation. These results provide a qualitative and quantitative framework for the development of future synthetic therapeutic surfactants, and illustrate the crucial need to include SP-B or an efficient SP-B analog for optimal function. PMID:21081077

  14. Protein adsorption on piezoelectric poly(L-lactic) acid thin films by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Barroca, Nathalie; Vilarinho, Paula M.; Daniel-da-Silva, Ana Luisa; Wu, Aiying; Fernandes, Maria Helena; Gruverman, Alexei

    2011-03-01

    Up until now, no direct evidence of protein adsorption processes associated with polar activity of a piezoelectric has been reported. This work presents the experimental evidence of the protein adsorption process' dependence on the surface polarization of a piezoelectric by showing at the local scale that the process of protein adsorption is highly favored in the poled areas of a piezoelectric polymer such as poly(L-lactic) acid.

  15. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    SciTech Connect

    Janke, Chris; Yatsandra, Oyola; Mayes, Richard; none,; Gill, Gary; Li-Jung, Kuo; Wood, Jordana; Sadananda, Das

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  16. Heterogeneous Reactions of Surface-Adsorbed Catechol: A Comparison of Tropospheric Aerosol Surrogates

    NASA Astrophysics Data System (ADS)

    Hinrichs, R. Z.; Woodill, L. A.

    2009-12-01

    reactivity of surface-adsorbed catechol contrasts prior observations which found thin films of pure catechol unreactive with NO2, indicating that thin films do not always serve as reliable models for surface-adsorbed species.

  17. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  18. Nanovalved Adsorbents for CH4 Storage.

    PubMed

    Song, Zhuonan; Nambo, Apolo; Tate, Kirby L; Bao, Ainan; Zhu, Minqi; Jasinski, Jacek B; Zhou, Shaojun J; Meyer, Howard S; Carreon, Moises A; Li, Shiguang; Yu, Miao

    2016-05-11

    A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications. PMID:27124722

  19. NOx adsorber and method of regenerating same

    SciTech Connect

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  20. Protein-lipid interactions in zein films investigated by surface plasmon resonance.

    PubMed

    Wang, Qin; Crofts, Antony R; Padua, Graciela W

    2003-12-01

    Experiments on the adsorption of alpha-zein (characterized by SDS-PAGE) from aqueous ethanol and 2-propanol solutions onto hydrophilic and hydrophobic surfaces are reported. Zein adsorption onto self-assembled monolayers (SAMs) was detected by surface plasmon resonance (SPR). Gold substrates were prepared by thermal evaporation on glass slides. Gold-coated surfaces were modified by depositing SAMs of either a long-chain carboxylic acid terminated thiol [COOH(CH2)(10)SH] or a methyl-terminated alkanethiol [CH3(CH2)(7)SH]. Experimental measurements indicated that zein interacted with both hydrophilic and hydrophobic surfaces. Zein concentration affected the thickness of bound zein layers. The estimated thickness of the zein monolayer deposited on hydrophilic surfaces was 4.7 nm. Zein monolayer thickness on hydrophobic surfaces was estimated at 4.6 nm. The topography of zein layers was examined by atomic force microscopy (AFM) after solvent was evaporated. Surface features of zein deposits depended on the adsorbing surface. On hydrophilic surfaces, roughness values were high and distinct ring-shaped structures were observed. On hydrophobic surfaces, zein formed a uniform and featureless coverage. PMID:14640596

  1. Formation, disruption and mechanical properties of a rigid hydrophobin film at an air-water interface

    NASA Astrophysics Data System (ADS)

    Walker, Lynn; Kirby, Stephanie; Anna, Shelley; CMU Team

    Hydrophobins are small, globular proteins with distinct hydrophilic and hydrophobic regions that make them extremely surface active. The behavior of hydrophobins at surfaces has raised interest in their potential industrial applications, including use in surface coatings, food foams and emulsions, and as dispersants. Practical use of hydrophobins requires an improved understanding of the interfacial behavior of these proteins, both individually and in the presence of surfactants. Cerato-ulmin (CU) is a hydrophobin that has been shown to strongly stabilize air bubbles and oil droplets through the formation of a persistent protein film at the interface. In this work, we characterize the adsorption behavior of CU at air/water interfaces by measuring the surface tension and interfacial rheology as a function of adsorption time. CU is found to strongly, irreversibly adsorb at air/water interfaces; the magnitude of the dilatational modulus increases with adsorption time and surface pressure, until the CU eventually forms a rigid film. The persistence of this film is tested through the addition of SDS, a strong surfactant, to the bulk. SDS is found to co-adsorb to interfaces pre-coated with a CU film. At high concentrations, the addition of SDS significantly decreases the dilatational modulus, indicating disruption and displacement of CU. These results lend insight into the complex interfacial interactions between hydrophobins and surfactants. Funding from GoMRI.

  2. Separation of the attractive and repulsive contributions to the adsorbate-adsorbate interactions of polar adsorbates on Si(100)

    NASA Astrophysics Data System (ADS)

    Lin, Ying-Hsiu; Jeng, Horng-Tay; Lin, Deng-Sung

    2015-11-01

    Dissociative adsorption of H2O, NH3, CH3OH and CH3NH2 polar molecules on the Si(100) surface results in a 1:1 mixture of two adsorbates (H and multi-atomic fragment A = OH, NH2, CH3O, CH3NH, respectively) on the surface. By using density functional theory (DFT) calculations, the adsorption geometry, the total energies and the charge densities for various possible ordered structures of the mixed adsorbate layer have been found. Analyzing the systematic trends in the total energies unveils concurrently the nearest-neighbor interactions ENN and the next nearest-neighbor interactions ENNN between two polar adsorbates A. In going from small to large polar adsorbates, ENN's exhibit an attractive-to-repulsive crossover behavior, indicating that they include competing attractive and repulsive contributions. Exploration of the charge density distributions allows the estimation of the degree of charge overlapping between immediately neighboring A's, the resulting contribution of the steric repulsions, and that of the attractive interactions to the corresponding ENN's. The attractive contributions to nearest neighboring adsorbate-adsorbate interactions between the polar adsorbates under study are shown to result from hydrogen bonds or dipole-dipole interactions.

  3. Controlling Protein Oligomerization with Surface Curvature on the Nanoscale

    NASA Astrophysics Data System (ADS)

    Kurylowicz, Marty; Dutcher, John

    2011-03-01

    We investigate the effect of surface curvature on the conformation of beta-lactoglobulin (β LG) using Single Molecule Force Spectroscopy. β LG is a model interfacial protein which stabilizes oil droplets in milk and is known to undergo structural rearrangement when adsorbed onto a surface. We reliably control nanoscale surface curvature by creating close-packed monolayers of monodisperse polystyrene (PS) nanoparticles with diameters of 20, 40, 60, 80 and 140 nm, which are stable in aqueous buffer. By adsorbing β LG onto these hydrophobic surfaces and collecting force-extension curves in the fluid phase we can compare the conformation of β LG on 5 different surface curvatures with that on a flat PS film. We demonstrate a transition from oligomeric to monomeric β LG as the surface curvature is increased. Histograms of contour length from fits to peaks in the force-extension curves show a single maximum near 30 nm for β LG adsorbed onto nanoparticles with diameters less than 80 nm. For the larger nanoparticles, the histogram approaches that observed for β LG adsorbed onto a flat PS film, with maxima indicative of β LG dimers and trimers.

  4. Immobilization-stabilization of proteins on nanofibrillated cellulose derivatives and their bioactive film formation.

    PubMed

    Arola, Suvi; Tammelin, Tekla; Setälä, Harri; Tullila, Antti; Linder, Markus B

    2012-03-12

    In a number of different applications for enzymes and specific binding proteins a key technology is the immobilization of these proteins to different types of supports. In this work we describe a concept for protein immobilization that is based on nanofibrillated cellulose (NFC). NFC is a form of cellulose where fibers have been disintegrated into fibrils that are only a few nanometers in diameter and have a very large aspect ratio. Proteins were conjugated through three different strategies using amine, epoxy, and carboxylic acid functionalized NFC. The conjugation chemistries were chosen according to the reactive groups on the NFC derivatives; epoxy amination, heterobifunctional modification of amino groups, and EDC/s-NHS activation of carboxylic acid groups. The conjugation reactions were performed in solution and immobilization was performed by spin coating the protein-NCF conjugates. The structure of NFC was shown to be advantageous for both protein performance and stability. The use of NFC allows all covalent chemistry to be performed in solution, while the immobilization is achieved by a simple spin coating or spreading of the protein-NFC conjugates on a support. This allows more scalable methods and better control of conditions compared to the traditional methods that depend on surface reactions. PMID:22248303

  5. Molecular mobility in the monolayers of foam films stabilized by porcine lung surfactant.

    PubMed Central

    Lalchev, Z I; Todorov, R K; Christova, Y T; Wilde, P J; Mackie, A R; Clark, D C

    1996-01-01

    Certain physical properties of a range of foam film types that are believed to exist in vivo in the lung have been investigated. The contribution of different lung surfactant components found in porcine lung surfactant to molecular surface diffusion in the plane of foam films has been investigated for the first time. The influence of the type and thickness of black foam films, temperature, electrolyte concentration, and extract composition on surface diffusion has been studied using the fluorescence recovery after photobleaching technique. Fluorescent phospholipid probe molecules in foam films stabilized by porcine lung surfactant samples or their hydrophobic extracts consisting of surfactant lipids and hydrophobic lung surfactant proteins, SP-B and SP-C, exhibited more rapid diffusion than observed in films of its principal lipid component alone, L-alpha-phosphatidylcholine dipalmitoyl. This effect appears to be due to contributions from minor lipid components present in the total surfactant lipid extracts. The minor lipid components influence the surface diffusion in foam films both by their negative charge and by lowering the phase transition temperature of lung surfactant samples. In contrast, the presence of high concentrations of the hydrophillic surfactant protein A (SP-A) and non-lung-surfactant proteins in the sample reduced the diffusion coefficient (D) of the lipid analog in the adsorbed layer of the films. Hysteresis behavior of D was observed during temperature cycling, with the cooling curve lying above the heating curve. However, in cases where some surface molecular aggregation and surface heterogeneity were observed during cooling, the films became more rigid and molecules at the interfaces became immobilized. The thickness, size, capillary pressure, configuration, and composition of foam films of lung surfactant prepared in vitro support their investigation as realistic structural analogs of the surface films that exist in vivo in the lung

  6. Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

    PubMed

    Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

    2015-12-21

    A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. PMID:26538339

  7. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  8. The low-temperature loss tangent of adsorbed water in alumina

    NASA Astrophysics Data System (ADS)

    Khasawneh, Mazin; Sarabi, Bahman; Khalil, M. S.; Stoutimore, M. J. A.; Gladchenko, Sergiy; Wellstood, F. C.; Lobb, C. J.; Osborn, Kevin

    2012-02-01

    Superconducting quantum information circuits use various amorphous dielectrics for capacitors, and alumina is the ubiquitous barrier material for Josephson junctions within these devices. The exposure of the devices to air allows water molecules to penetrate the dielectric films along grain boundaries, and become adsorbed onto internal surfaces. In this study we plan to use ALD-grown alumina and titanium oxide to study the penetration of water through films. Using blocking layers to selectively prevent water penetration, we then plan to measure the difference in the low-temperature loss tangent between an alumina film which is exposed to air and one which is not.

  9. Site blocking effects on adsorbed polyacrylamide conformation

    NASA Astrophysics Data System (ADS)

    Brotherson, Brett A.

    The use of polymers as flocculating additives is a common practice in many manufacturing environments. However, exactly how these polymers interact with surfaces is relatively unknown. One specific topic which is thought to be very important to flocculation is an adsorbed polymer's conformation. Substantial amounts of previous work, mainly using simulations, have been performed to elucidate the theory surrounding adsorbed polymer conformations. Yet, there is little experimental work which directly verifies current theory. In order to optimize the use of polymer flocculants in industrial applications, a better understanding of an adsorbed polymer's conformation on a surface beyond theoretical simulations is necessary. This work looks specifically at site blocking, which has a broad impact on flocculation, adsorption, and surface modification, and investigated its effects on the resulting adsorbed polymer conformation. Experimental methods which would allow direct determination of adsorbed polymer conformational details and be comparable with previous experimental results were first determined or developed. Characterization of an adsorbed polymer's conformation was then evaluated using dynamic light scattering, a currently accepted experimental technique to examine this. This commonly used technique was performed to allow the comparison of this works results with past literature. Next, a new technique using atomic force microscopy was developed, building on previous experimental techniques, to allow the direct determination of an adsorbed polymer's loop lengths. This method also was able to quantify changes in the length of adsorbed polymer tails. Finally, mesoscopic simulation was attempted using dissipative particle dynamics. In order to determine more information about an adsorbed polymer's conformation, three different environmental factors were analyzed: an adsorbed polymer on a surface in water, an adsorbed polymer on a surface in aqueous solutions of varying

  10. Fabrication of PP-g-PEGMA-g-heparin and its hemocompatibility: From protein adsorption to anticoagulant tendency

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Jiang, Wei; shi, Qiang; Zhao, Jie; Yin, Jinghua; Stagnaro, Paola

    2012-05-01

    We described a two-step process to fabricate the heparinized polypropylene (PP) film using cyanuric chloride (CC) as a trifunctional reagent and poly (ethylene glycol) methacrylate (PEGMA) as a spacer. The modified PP films were characterized by attenuated total reflectance FT-IR and X-ray photoelectron spectroscopy; the content of PEGMA and heparin were determined by gravimetric method and a toluidine blue assay, respectively. For the PP-g-PEGMA films, it was found that small size protein BSA tended to adsorb on the surface of low molecular weight monomer grafted PP, whereas big spindle-shaped fibrinogen tended to adsorb on the surface of high molecular weight monomer grafted PP. We gave a definition of anti-protein adsorptive factor r with two model proteins, albumin and fibrinogen. The results by platelet adhesion and plasma recalcification time (PRT) experiments indicated that the factor r could be used to quantitatively evaluate the anticoagulant tendency of PP-g-PEGMA modified films. For the PP-g-PEGMA-g-heparin modified films, the surface was proved to have a high bioactivity by the adsorption of AT III assay and very low platelet adhesion. It indicated that immobilization of heparin on the PP film with PEGMA as a spacer was an effective way to improve the hemocompatibility of PP.

  11. Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified mo...

  12. Low-Friction Adsorbed Layers of a Triblock Copolymer Additive in Oil-Based Lubrication.

    PubMed

    Yamada, Shinji; Fujihara, Ami; Yusa, Shin-ichi; Tanabe, Tadao; Kurihara, Kazue

    2015-11-10

    The tribological properties of the dilute solution of an ABA triblock copolymer, poly(11-acrylamidoundecanoic acid)-block-poly(stearyl methacrylate)-block-poly(11-acrylamidoundecanoic acid (A5S992A5), in poly(α-olefin) (PAO) confined between mica surfaces were investigated using the surface forces apparatus (SFA). Friction force was measured as a function of applied load and sliding velocity, and the film thickness and contact geometry during sliding were analyzed using the fringes of equal chromatic order (FECO) in the SFA. The results were contrasted with those of confined PAO films; the effects of the addition of A5S992A5 on the tribological properties were discussed. The thickness of the A5S992A5/PAO system varied with time after surface preparation and with repetitive sliding motions. The thickness was within the range from 40 to 70 nm 1 day after preparation (the Day1 film), and was about 20 nm on the following day (the Day2 film). The thickness of the confined PAO film was thinner than 1.4 nm, indicating that the A5S992A5/PAO system formed thick adsorbed layers on mica surfaces. The friction coefficient was about 0.03 to 0.04 for the Day1 film and well below 0.01 for the Day2 film, which were 1 or 2 orders of magnitude lower than the values for the confined PAO films. The time dependent changes of the adsorbed layer thickness and friction properties should be caused by the relatively low solubility of A5S992A5 in PAO. The detailed analysis of the contact geometry and friction behaviors implies that the particularly low friction of the Day2 film originates from the following factors: (i) shrinkage of the A5S992A5 molecules (mainly the poly(stearyl methacrylate) blocks) that leads to a viscoelastic properties of the adsorbed layers; and (ii) the intervening PAO layer between the adsorbed polymer layers that constitutes a high-fluidity sliding interface. Our results suggest that the block copolymer having relatively low solubility in a lubricant base oil is

  13. Mechanical properties of hexadecane-water interfaces with adsorbed hydrophobic bacteria

    NASA Astrophysics Data System (ADS)

    Kang, Zhewen

    Certain strains of hydrophobic bacteria are known to play critical roles in petroleum-related applications. The aim of this study was to investigate how hydrophobic bacteria in their stationary phase could adsorb onto the hexadecane-water interface and alter its mechanical properties. The two strains of bacteria used in forming the interfacial films were Acinetobacter venetianus RAG-1 (a Gram-negative bacterium) and Rhodococcus erythropolis 20S-E1-c (Gram-positive). Experiments at two different length scales (millimetre and micrometre) were conducted and the results were compared. In addition, a simple flow experiment was designed in a constricted channel and the results were related to the intrinsic mechanical properties of bacteria-adsorbed films. On the millimetre scale, using the pendant drop technique, the film interfacial tension was monitored as the surface area was made to undergo changes. Under static conditions, both types of bacteria showed no significant effect on the interfacial tension. When subjected to transient excitations, the two bacterial films exhibited qualitatively similar, yet quantitative distinct rheological properties (including film elasticities and relaxation times). Under continuous reduction of surface area, the RAG-1 system showed a "paper-like" interface, while the interface of the 20S-E1-c system was "soap film-like." These macroscopic observations could be explained by the surface ultrastructures of the two cell strains. On the micrometre scale, using the micropipette technique, colloidal stability of the bacteria-coated oil droplets was examined through direct-contact experiments. Both types of bacteria were seen to function as effective stabilizers. In addition, the adsorbed bacteria also interacted with one another at the interface, giving rise to higher order 2-D rheological properties. A technique of directly probing the mechanical properties of the emulsion drop surfaces revealed that (a) the films behaved as purely elastic

  14. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  15. States of water adsorbed on perindopril crystals

    NASA Astrophysics Data System (ADS)

    Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

    2011-10-01

    The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

  16. Single Molecular Film for Recognizing Biological Molecular Interaction: DNA-Protein Interaction and Enzyme Reaction

    NASA Astrophysics Data System (ADS)

    Kurihara, Kazue

    Protein-protein and protein-substrate interactions play essential roles in biological functions. Surface forces measurement and atomic force microscopy, which directly measure the interaction forces as a function of the surface separation, enable us to quantitatively evaluate these interactions [1-3]. We have employed the surface forces measurement [4] and colloidal probe atomic force microscopy [5] to study interactions involved in specific molecular recognition of DNA-protein and enzyme-substrate reaction. Studied are interactions between nucleic acid bases (adenine and thymine) [6], Spo0A-DB (the DNA-binding site of a transcription factor Spo0A), and DNA [7,8], those between subunits I and II of heptaprenyl diphosphate (HepPP) synthase in the presence of a substrate ((E,E)-farnesyl diphosphate, FPP) and a cofactor (Mg2+) [9-11], and the selectivity of the substrates in this enzymatic reaction [12]. Keys of our approach are the preparation of well-defined samples and the appropriate analysis. We have modified he substrate surfaces with these proteins using the Langmuir-Blodgett (LB) method. This chapter reviews the LB modification method and subsequent demonstrations of biological specific interactions employing this approach.

  17. Lubrication and load-bearing properties of human salivary pellicles adsorbed ex vivo on molecularly smooth substrata.

    PubMed

    Harvey, Neale M; Yakubov, Gleb E; Stokes, Jason R; Klein, Jacob

    2012-01-01

    In a series of Surface Force Balance experiments, material from human whole saliva was adsorbed to molecularly smooth mica substrata (to form an 'adsorbed salivary film'). Measurements were taken of normal (load bearing, F (n)) and shear (frictional, F (s)*) forces between two interacting surfaces. One investigation involved a salivary film formed by overnight adsorption from undiluted, centrifuged saliva, with the adsorbed film rinsed with pure water before measurement. Measurements were taken under pure water and 70 mM NaNO(3). In a second investigation, a film was formed from and measured under a solution of 7% filtered saliva in 10 mM NaNO(3). F (n) results for both systems showed purely repulsive layers, with an uncompressed thickness of 35-70 nm for the diluted saliva investigation and, prior to the application of shear, 11 nm for the rinsed system. F (s)* was essentially proportional to F (n) for all systems and independent of shear speed (in the range 100-2000 nm s(-1)), with coefficients of friction μ ≈ 0.24 and μ ≈ 0.46 for the unrinsed and rinsed systems, respectively. All properties of the rinsed system remained similar when the pure water measurement environment was changed to 70 mM NaNO(3). For all systems studied, shear gave rise to an approximately threefold increase in the range of normal forces, attributed to the ploughing up of adsorbed material during shear to form debris that stood proud of the adsorbed layer. The results provide a microscopic demonstration of the wear process for a salivary film under shear and may be of particular interest for understanding the implications for in vivo oral lubrication under conditions such as rinsing of the mouth cavity. The work is interpreted in light of earlier studies that showed a structural collapse and increase in friction for an adsorbed salivary film in an environment of low ionic strength. PMID:22881290

  18. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  19. Performance of a membrane adsorber for trace impurity removal in biotechnology manufacturing.

    PubMed

    Phillips, Michael; Cormier, Jason; Ferrence, Jennifer; Dowd, Chris; Kiss, Robert; Lutz, Herbert; Carter, Jeffrey

    2005-06-17

    Membrane adsorbers provide an attractive alternative to traditional bead-based chromatography columns used to remove trace impurities in downstream applications. A linearly scalable novel membrane adsorber family designed for the efficient removal of trace impurities from biotherapeutics, are capable of reproducibly achieving greater than 4 log removal of mammalian viruses, 3 log removal of endotoxin and DNA, and greater than 1 log removal of host cell protein. Single use, disposable membrane adsorbers eliminate the need for costly and time consuming column packing and cleaning validation associated with bead-based chromatography systems, and minimize the required number and volume of buffers. A membrane adsorber step reduces process time, floor space, buffer usage, labor cost, and improves manufacturing flexibility. This "process compression" effect is commonly associated with reducing the number of processing steps. The rigid microporous structure of the membrane layers allows for high process flux operation and uniform bed consistency at all processing scales. PMID:16007984

  20. IR investigations of surfaces and adsorbates

    SciTech Connect

    Gwyn Williams

    2001-12-10

    Synchrotron infrared reflection-absorption measurements on single crystal metal surfaces with adsorbates have led to the determination of many key parameters related to the bonding vibrational modes and the dynamics of adsorbates. In particular, energy couplings between electrons and adsorbate motion have been shown to be a dominant mechanism on metal surfaces. Excellent agreement has been obtained with calculations for many of the observations, and the synergy between theory and experiment has led to a deeper understanding of the roles of electrons and phonons in determining the properties of interfaces and their roles in phenomena as diverse as friction, lubrication, catalysis and adhesion. Nonetheless, as the experiments are pushed harder, to describe such effects as co-adsorbed systems, disagreements continue to challenge the theory and our comprehension also is still evolving.

  1. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    EPA Science Inventory

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  2. Examining Adsorbed Polymer Conformations with Fluorescence Imaging

    NASA Astrophysics Data System (ADS)

    Parkes, Maria; Chennaoui, Mourad; Wong, Janet; Tribology Group, Dept. of Mechanical Engineering Team

    2011-03-01

    The conformation of adsorbed polymers can have significant impact on their properties such as dynamics and elasticity as well as their ability to take part in reactions with other molecules. Experimental research to determine adsorbed polymer conformation has relied mainly on atomic force microscopy (AFM) studies. During an AFM scan, the contact between the scanning probe and the polymer could affect the polymer conformation, particularly where parts of the polymer might have formed projected loops and tails. In this work, conformations of model polymers are examined with total internal reflection fluorescence microscopy (TIRFM). The advantage of TIRFM over AFM is that TIRFM is a non contact technique. Lambda DNA labelled along its length with fluorescent probes was adsorbed in a projected 2D -- 3D state. With TIRFM, the relationship between intensity and depth was used as a basis to determine how the conformation of the adsorbed polymers evolved with time using our custom algorithm.

  3. Dispersed-phase adsorbents for biotechnology applications

    SciTech Connect

    Scott, C.D.

    1987-01-01

    A new type of adsorbent material has been developed in which very small adsorbent particles are entrapped in a hydrocolloidal gel matrix that is formed into small, monodisperse spherical beads. Examples of applications of this type of material include dispersed, hydrous transition metal oxides that can be used for the retention of biocatalysts, such as enzymes, and certain microorganisms or microbial fragments that can be dispersed into the gel matrix to accumulate and isolate various dissolved metals. 7 refs., 2 figs., 2 tabs.

  4. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  5. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  6. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  7. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  8. X-ray fluorescence studies for the elemental composition and molecular organization of protein films on the surface of the liquid subphase

    SciTech Connect

    Zheludeva, S. I.; Novikova, N. N. Kovalchuk, M. V.; Stepina, N. D.; Konovalov, O. V.; Yurieva, E. A.

    2009-11-15

    This paper reports on the results of the investigation of protein films that are based on alkaline phosphatase and glucose oxidase enzymes and formed on the surface of the liquid subphase. The experimental studies have been performed using total external reflection X-ray fluorescence spectrometry at the European Synchrotron Radiation Facility (Grenoble, France). The self-organization processes that occur in protein systems on the surface of the liquid subphase under the conditions where the protein molecules retain their mobility have been investigated using X-ray fluorescence measurements for the first time.

  9. Photochemistry of Nitrate Adsorbed on Mineral Dust

    NASA Astrophysics Data System (ADS)

    Gankanda, A.; Grassian, V. H.

    2013-12-01

    Mineral dust particles in the atmosphere are often associated with adsorbed nitrate from heterogeneous reactions with nitrogen oxides including HNO3 and NO2. Although nitrate ion is a well-studied chromophore in natural waters, the photochemistry of adsorbed nitrate on mineral dust particles is yet to be fully explored. In this study, wavelength dependence of the photochemistry of adsorbed nitrate on different model components of mineral dust aerosol has been investigated using transmission FTIR spectroscopy. Al2O3, TiO2 and NaY zeolite were used as model systems to represent non-photoactive oxides, photoactive semiconductor oxides and porous materials respectively, present in mineral dust aerosol. In this study, adsorbed nitrate is irradiated with 254 nm, 310 nm and 350 nm narrow band light. In the irradiation with narrow band light, NO2 is the only detectable gas-phase product formed from nitrate adsorbed on Al2O3 and TiO2. The NO2 yield is highest at 310 nm for both Al2O3 and TiO2. Unlike Al2O3 and TiO2, in zeolite, adsorbed nitrate photolysis to nitrite is observed only at 310 nm during narrow band irradiation. Moreover gas phase products were not detected during nitrate photolysis in zeolite at all three wavelengths. The significance of these differences as related to nitrate photochemistry on different mineral dust components will be highlighted.

  10. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation.

    PubMed

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  11. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation

    PubMed Central

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  12. Amphiphilic agarose-based adsorbents for chromatography. Comparative study of adsorption capacities and desorption efficiencies.

    PubMed

    Oscarsson, S; Angulo-Tatis, D; Chaga, G; Porath, J

    1995-01-01

    A number of hydrophobic derivatives attached to cross-linked agarose were studied as protein adsorbents. Differences in the adsorption and desorption behaviour were determined as functions of type and concentration of selected salts. Whereas octyl- and phenyl-Sepharose adsorb serum albumin preferentially, pyridyl-S-agarose shows a much stronger preferential affinity for IgG in the presence of high concentrations of lyotropic salts, such as sulphates. In contrast to pyridyl-S-agarose, a large portion of proteins remained fixed to octyl- and phenyl-Sepharose after extensive washing with 1 M NaOH. PMID:7881534

  13. Bombyx mori silk protein films microprocessing with a nanosecond ultraviolet laser and a femtosecond laser workstation: theory and experiments

    NASA Astrophysics Data System (ADS)

    Lazare, S.; Sionkowska, A.; Zaborowicz, M.; Planecka, A.; Lopez, J.; Dijoux, M.; Louména, C.; Hernandez, M.-C.

    2012-01-01

    Laser microprocessing of several biopolymers from renewable resources is studied. Three proteinic materials were either extracted from the extracellular matrix like Silk Fibroin/Sericin and collagen, or coming from a commercial source like gelatin. All can find future applications in biomedical experimentation, in particular for cell scaffolding. Films of ˜hundred of microns thick were made by aqueous solution drying and laser irradiation. Attention is paid to the properties making them processable with two laser sources: the ultraviolet and nanosecond (ns) KrF (248 nm) excimer and the infrared and femtosecond (fs) Yb:KGW laser. The UV radiation is absorbed in a one-photon resonant process to yield ablation and the surface foaming characteristics of a laser-induced pressure wave. To the contrary, resonant absorption of the IR photons of the fs laser is not possible and does not take place. However, the high field of the intense I>˜1012 W/cm2 femtosecond laser pulse ionizes the film by the multiphoton absorption followed by the electron impact mechanism, yielding a dense plasma capable to further absorb the incident radiation of the end of the pulse. The theoretical model of this absorption is described in detail, and used to discuss the presented experimental effects (cutting, ablation and foaming) of the fs laser. The ultraviolet laser was used to perform simultaneous multiple spots experiments in which energetic foaming yields melt ejection and filament spinning. Airborne nanosize filaments "horizontally suspended by both ends" (0.25 μm diameter and 10 μm length) of silk biopolymer were observed upon irradiation with large fluences.

  14. Fabrication of Nanometer- and Micrometer-Scale Protein Structures by Site-Specific Immobilization of Histidine-Tagged Proteins to Aminosiloxane Films with Photoremovable Protein-Resistant Protecting Groups.

    PubMed

    Xia, Sijing; Cartron, Michaël; Morby, James; Bryant, Donald A; Hunter, C Neil; Leggett, Graham J

    2016-02-23

    The site-specific immobilization of histidine-tagged proteins to patterns formed by far-field and near-field exposure of films of aminosilanes with protein-resistant photolabile protecting groups is demonstrated. After deprotection of the aminosilane, either through a mask or using a scanning near-field optical microscope, the amine terminal groups are derivatized first with glutaraldehyde and then with N-(5-amino-1-carboxypentyl)iminodiacetic acid to yield a nitrilo-triacetic-acid-terminated surface. After complexation with Ni(2+), this surface binds histidine-tagged GFP and CpcA-PEB in a site-specific fashion. The chemistry is simple and reliable and leads to extensive surface functionalization. Bright fluorescence is observed in fluorescence microscopy images of micrometer- and nanometer-scale patterns. X-ray photoelectron spectroscopy is used to study quantitatively the efficiency of photodeprotection and the reactivity of the modified surfaces. The efficiency of the protein binding process is investigated quantitatively by ellipsometry and by fluorescence microscopy. We find that regions of the surface not exposed to UV light bind negligible amounts of His-tagged proteins, indicating that the oligo(ethylene glycol) adduct on the nitrophenyl protecting group confers excellent protein resistance; in contrast, exposed regions bind His-GFP very effectively, yielding strong fluorescence that is almost completely removed on treatment of the surface with imidazole, confirming a degree of site-specific binding in excess of 90%. This simple strategy offers a versatile generic route to the spatially selective site-specific immobilization of proteins at surfaces. PMID:26820378

  15. Fabrication of Nanometer- and Micrometer-Scale Protein Structures by Site-Specific Immobilization of Histidine-Tagged Proteins to Aminosiloxane Films with Photoremovable Protein-Resistant Protecting Groups

    PubMed Central

    2016-01-01

    The site-specific immobilization of histidine-tagged proteins to patterns formed by far-field and near-field exposure of films of aminosilanes with protein-resistant photolabile protecting groups is demonstrated. After deprotection of the aminosilane, either through a mask or using a scanning near-field optical microscope, the amine terminal groups are derivatized first with glutaraldehyde and then with N-(5-amino-1-carboxypentyl)iminodiacetic acid to yield a nitrilo-triacetic-acid-terminated surface. After complexation with Ni2+, this surface binds histidine-tagged GFP and CpcA-PEB in a site-specific fashion. The chemistry is simple and reliable and leads to extensive surface functionalization. Bright fluorescence is observed in fluorescence microscopy images of micrometer- and nanometer-scale patterns. X-ray photoelectron spectroscopy is used to study quantitatively the efficiency of photodeprotection and the reactivity of the modified surfaces. The efficiency of the protein binding process is investigated quantitatively by ellipsometry and by fluorescence microscopy. We find that regions of the surface not exposed to UV light bind negligible amounts of His-tagged proteins, indicating that the oligo(ethylene glycol) adduct on the nitrophenyl protecting group confers excellent protein resistance; in contrast, exposed regions bind His-GFP very effectively, yielding strong fluorescence that is almost completely removed on treatment of the surface with imidazole, confirming a degree of site-specific binding in excess of 90%. This simple strategy offers a versatile generic route to the spatially selective site-specific immobilization of proteins at surfaces. PMID:26820378

  16. Protein adsorption and biomimetic mineralization behaviors of PLL-DNA multilayered films assembled onto titanium

    NASA Astrophysics Data System (ADS)

    Gao, Wenli; Feng, Bo; Ni, Yuxiang; Yang, Yongli; Lu, Xiong; Weng, Jie

    2010-11-01

    Titanium and its alloys are frequently used as surgical implants in load bearing situations, such as hip prostheses and dental implants, owing to their biocompatibility, mechanical and physical properties. In this paper, a layer-by-layer (LBL) self-assembly technique, based on the polyelectrolyte-mediated electrostatic adsorption of poly-L-lysine (PLL) and DNA, was used to the formation of multilayer on titanium surfaces. Then bovine serum albumin (BSA) adsorption and biomimetic mineralization of modified surfaces were studied. The chemical composition and wettability of assembled substrates were investigated by X-ray photoelectron spectroscopy (XPS), fluorescence microscopy and water contact angle measurement, respectively. The XPS analysis indicated that the layers were assembled successfully through electrostatic attractions. The measurement with ultraviolet (UV) spectrophotometer revealed that the LBL films enhanced ability of BSA adsorption onto titanium. The adsorption quantity of BSA on the surface terminated with PLL was higher than that of the surface terminated with DNA, and the samples of TiOH/P/D/P absorbed BSA most. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that samples of assembled PLL or/and DNA had better bioactivity in inducing HA formation. Thus the assembling of PLL and DNA onto the surface of titanium in turn via a layer-by-layer self-assembly technology can improve the bioactivity of titanium.

  17. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    PubMed

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications. PMID:27131811

  18. Grafting of a model protein on lactide and caprolactone based biodegradable films for biomedical applications

    PubMed Central

    Larrañaga, Aitor; Guay-Bégin, Andrée-Anne; Chevallier, Pascale; Sabbatier, Gad; Fernández, Jorge; Laroche, Gaétan; Sarasua, Jose-Ramon

    2014-01-01

    Thermoplastic biodegradable polymers displaying elastomeric behavior and mechanical consistency are greatly appreciated for the regeneration of soft tissues and for various medical devices. However, while the selection of a suitable base material is determined by mechanical and biodegradation considerations, it is the surface properties of the biomaterial that are responsible for the biological response. In order to improve the interaction with cells and modulate their behavior, biologically active molecules can be incorporated onto the surface of the material. With this aim, the surface of a lactide and caprolactone based biodegradable elastomeric terpolymer was modified in two stages. First, the biodegradable polymer surface was aminated by atmospheric pressure plasma treatment and second a crosslinker was grafted in order to covalently bind the biomolecule. In this study, albumin was used as a model protein. According to X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), albumin was efficiently immobilized on the surface of the terpolymer, the degree of albumin surface coverage (ΓBSA) reached ~35%. Moreover, gel permeation chromatography (GPC) studies showed that the hydrolytic degradation kinetic of the synthesized polymer was slightly delayed when albumin was grafted. However, the degradation process in the bulk of the material was unaffected, as demonstrated by Fourier transform infrared (FTIR) analyses. Furthermore, XPS analyses showed that the protein was still present on the surface after 28 days of degradation, meaning that the surface modification was stable, and that there had been enough time for the biological environment to interact with the modified material. PMID:24509417

  19. Grafting of a model protein on lactide and caprolactone based biodegradable films for biomedical applications.

    PubMed

    Larrañaga, Aitor; Guay-Bégin, Andrée-Anne; Chevallier, Pascale; Sabbatier, Gad; Fernández, Jorge; Laroche, Gaétan; Sarasua, Jose-Ramon

    2014-01-01

    Thermoplastic biodegradable polymers displaying elastomeric behavior and mechanical consistency are greatly appreciated for the regeneration of soft tissues and for various medical devices. However, while the selection of a suitable base material is determined by mechanical and biodegradation considerations, it is the surface properties of the biomaterial that are responsible for the biological response. In order to improve the interaction with cells and modulate their behavior, biologically active molecules can be incorporated onto the surface of the material. With this aim, the surface of a lactide and caprolactone based biodegradable elastomeric terpolymer was modified in two stages. First, the biodegradable polymer surface was aminated by atmospheric pressure plasma treatment and second a crosslinker was grafted in order to covalently bind the biomolecule. In this study, albumin was used as a model protein. According to X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), albumin was efficiently immobilized on the surface of the terpolymer, the degree of albumin surface coverage (ΓBSA) reached ~35%. Moreover, gel permeation chromatography (GPC) studies showed that the hydrolytic degradation kinetic of the synthesized polymer was slightly delayed when albumin was grafted. However, the degradation process in the bulk of the material was unaffected, as demonstrated by Fourier transform infrared (FTIR) analyses. Furthermore, XPS analyses showed that the protein was still present on the surface after 28 days of degradation, meaning that the surface modification was stable, and that there had been enough time for the biological environment to interact with the modified material. PMID:24509417

  20. Improving biocompatibility by controlling protein adsorption: Modification and design of biomaterials using poly(ethylene glycol) microgels and microspheres

    NASA Astrophysics Data System (ADS)

    Scott, Evan Alexander

    2009-12-01

    Guided by the clinical needs of patients and developments in biology and materials science, the primary focus of the biomaterials field remains at the solid/liquid interface between biomaterial surfaces and biological fluids. For blood-contacting devices, biological responses are initially elicited and directed by proteins that adsorb from this multicomponent solution to form thin films on their surfaces. The identity, conformation, and quantity of adsorbed proteins are related to the properties of a material's surface. For example, hydrophobic surfaces tend to be thrombotic via interactions between platelets and adsorbed fibrinogen, while surface-activation of specific enzymes initiates the coagulation cascade on hydrophilic surfaces. The objective of this thesis is to improve the design of biomaterials through the analysis and control of adsorbing protein layers. This goal is approached through three separate strategies. First, a proteomics-based methodology is presented for the assessment of protein conformation at the residue level after adsorption to biomaterial surfaces. A quantitative mass spectrometric technique is additionally suggested for the identification and quantification of proteins within adsorbed protein layers. Second, a method is described for the covalent attachment of poly(ethylene glycol) (PEG)-based hydrogel coatings onto biomaterials surfaces for the minimization of protein adsorption. The coatings are applied using partially crosslinked PEG solutions containing polymer and protein oligomers and microgels that can be designed to control cell adhesion. Finally, a modular strategy is proposed for the assembly of bioactive PEG-based hydrogel scaffolds. This was accomplished using novel PEG microspheres with diverse characteristics that individually contribute to the ability of the scaffold to direct cellular infiltration. The methodologies proposed by this thesis contribute to the recent shift in biomaterials and tissue engineering strategies

  1. Controlling spins in adsorbed molecules by a chemical switch

    PubMed Central

    Wäckerlin, Christian; Chylarecka, Dorota; Kleibert, Armin; Müller, Kathrin; Iacovita, Cristian; Nolting, Frithjof; Jung, Thomas A.; Ballav, Nirmalya

    2010-01-01

    The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co2+ is modified and a NO–CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off–on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect. PMID:20975713

  2. Synthetic Polypeptide Adsorption to Cu-IDA Containing Lipid Films: A Model for Protein-Membrane Interactions

    PubMed Central

    Yim, H.; Murton, J. K.; Sasaki, D. Y.; Polizzotti, B. D.; Charati, M. B.; Kiick, K. L.; Kuzmenko, I.; Satija, S.

    2010-01-01

    Adsorption of synthetic alanine-rich peptides to lipid monolayers was studied by X-ray and neutron reflectivity, grazing incidence X-ray diffraction (GIXD), and circular dichroic spectroscopy. The peptides contained histidine residues to drive adsorption to Langmuir monolayers of lipids with iminodiacetate headgroups loaded with Cu2+. Adsorption was found to be irreversible with respect to bulk peptide concentration. The peptides were partially helical in solution at room temperature, the temperature of the adsorption assays. Comparisons of the rate of binding and the structure of the adsorbed layer were made as a function of the number of histidines (from 0 to 2) and also as a function of the positioning of the histidines along the backbone. For peptides containing two histidines on the same side of the helical backbone, large differences were observed in the structure of the adsorbed layer as a function of the spacing of the histidines. With a spacing of 6 Å, there was a substantial increase in helicity upon binding (from 17% to 31%), and the peptides adsorbed to a final density approaching that of a nearly completed monolayer of α-helices adsorbed side-on. The thickness of the adsorbed layer (17 ± 2.5 Å) was slightly greater than the diameter of α-helices, suggesting that the free, unstructured ends extended into solution. With a spacing of 30 Å between histidines, a far weaker increase in helicity upon binding was observed (from 13% to 19%) and a much lower packing density resulted. The thickness of the adsorbed layer (10 ± 4 Å) was smaller, consistent with the ends being bound to the monolayer. Striking differences were observed in the interaction of the two types of peptide with the lipid membrane by GIXD, consistent with binding by two correlated sites only for the case of 6 Å spacing. All these results are attributed to differences in spatial correlation between the histidines as a function of separation distance along the backbone for these

  3. Black Molecular Adsorber Coatings for Spaceflight Applications

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  4. Size selective hydrophobic adsorbent for organic molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  5. Spread Films of Human Serum Albumin at the Air-Water Interface: Optimization, Morphology, and Durability.

    PubMed

    Campbell, Richard A; Ang, Joo Chuan; Sebastiani, Federica; Tummino, Andrea; White, John W

    2015-12-22

    It has been known for almost one hundred years that a lower surface tension can be achieved at the air-water interface by spreading protein from a concentrated solution than by adsorption from an equivalent total bulk concentration. Nevertheless, the factors that control this nonequilibrium process have not been fully understood. In the present work, we apply ellipsometry, neutron reflectometry, X-ray reflectometry, and Brewster angle microscopy to elaborate the surface loading of human serum albumin in terms of both the macroscopic film morphology and the spreading dynamics. We show that the dominant contribution to the surface loading mechanism is the Marangoni spreading of protein from the bulk of the droplets rather than the direct transfer of their surface films. The films can be spread on a dilute subphase if the concentration of the spreading solution is sufficient; if not, dissolution of the protein occurs, and only a textured adsorbed layer slowly forms. The morphology of the spread protein films comprises an extended network with regions of less textured material or gaps. Further, mechanical cycling of the surface area of the spread films anneals the network into a membrane that approach constant compressibility and has increased durability. Our work provides a new perspective on an old problem in colloid and interface science. The scope for optimization of the surface loading mechanism in a range of systems leading to its exploitation in deposition-based technologies in the future is discussed. PMID:26607026

  6. Observing single protein binding by optical transmission through a double nanohole aperture in a metal film

    PubMed Central

    Al Balushi, Ahmed A.; Zehtabi-Oskuie, Ana; Gordon, Reuven

    2013-01-01

    We experimentally demonstrate protein binding at the single particle level. A double nanohole (DNH) optical trap was used to hold onto a 20 nm biotin-coated polystyrene (PS) particle which subsequently is bound to streptavidin. Biotin-streptavidin binding has been detected by an increase in the optical transmission through the DNH. Similar optical transmission behavior was not observed when streptavidin binding sites where blocked by mixing streptavidin with excess biotin. Furthermore, interaction of non-functionalized PS particles with streptavidin did not induce a change in the optical transmission through the DNH. These results are promising as the DNH trap can make an excellent single molecule resolution sensor which would enable studying biomolecular interactions and dynamics at a single particle/molecule level. PMID:24049672

  7. Method for modifying trigger level for adsorber regeneration

    DOEpatents

    Ruth, Michael J.; Cunningham, Michael J.

    2010-05-25

    A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

  8. Dimensionally Frustrated Diffusion towards Fractal Adsorbers

    NASA Astrophysics Data System (ADS)

    Nair, Pradeep R.; Alam, Muhammad A.

    2007-12-01

    Diffusion towards a fractal adsorber is a well-researched problem with many applications. While the steady-state flux towards such adsorbers is known to be characterized by the fractal dimension (DF) of the surface, the more general problem of time-dependent adsorption kinetics of fractal surfaces remains poorly understood. In this Letter, we show that the time-dependent flux to fractal adsorbers (1

  9. Standoff Spectroscopy of Surface Adsorbed Chemicals

    SciTech Connect

    Van Neste, Charles W; Senesac, Larry R; Thundat, Thomas George

    2009-01-01

    Despite its immediate applications, selective detection of trace quantities of surface adsorbed chemicals, such as explosives, without physically collecting the sample molecules is a challenging task. Standoff spectroscopic techniques offer an ideal method of detecting chemicals without using a sample collection step. Though standoff spectroscopic techniques are capable of providing high selectivity, their demonstrated sensitivities are poor. Here we describe standoff detection of trace quantities of surface adsorbed chemicals using two quantum cascade lasers operated simultaneously, with tunable wavelength windows that match with absorption peaks of the analytes. This standoff method is a variation of photoacoustic spectroscopy, where scattered light from the sample surface is used for exciting acoustic resonance of the detector. We demonstrate a sensitivity of 100 ng/cm{sup 2} and a standoff detection distance of 20 m for surface adsorbed analytes such as explosives and tributyl phosphate.

  10. Real-time measurement of protein adsorption on electrophoretically deposited hydroxyapatite coatings and magnetron sputtered metallic films using the surface acoustic wave technique.

    PubMed

    Meininger, M; Schmitz, T; Wagner, T; Ewald, A; Gbureck, U; Groll, J; Moseke, C

    2016-04-01

    Surface acoustic wave (SAW) biosensors are highly sensitive for mass binding and are therefore used to detect protein-protein and protein-antibody interactions. Whilst the standard surface of the chips is a thin gold film, measurements on implant- or bone-like surfaces could significantly enhance the range of possible applications for this technique. The aim of this study was to establish methods to coat biosensor chips with Ti, TiN, and silver-doped TiN using physical vapor deposition as well as with hydroxyapatite by electrophoresis. To demonstrate that protein adsorption can be detected on these surfaces, binding experiments with fibronectin and fibronectin-specific antibodies have been performed with the coatings, which successfully proved the applicability of PVD and EPD for SAW biosensor functionalization. PMID:26838860

  11. The biogeochemical cycle of the adsorbed template. II - Selective adsorption of mononucleotides on adsorbed polynucleotide templates

    NASA Technical Reports Server (NTRS)

    Lazard, Daniel; Lahav, Noam; Orenberg, James B.

    1988-01-01

    Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and (5-prime)-AMP, (5-prime)-GMP, (5-prime)-CMP and (5-prime)-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, (5-prime)-GMP and (5-prime)-AMP, respectively, were observed to be the most strongly adsorbed species.

  12. Unoccupied electronic states in adsorbate systems

    NASA Astrophysics Data System (ADS)

    Bertel, E.

    1991-11-01

    Experimental work on unoccupied electronic states in adsorbate systems on metallic substrates is reviewed with emphasis on recent developments. The first part is devoted to molecular adsorbates. Weakly chemisorbed hydrocarbons are briefly discussed. An exhaustive inverse photoemission (IPE) study of the CO bond to the transition metals Ni, Pb, and Pt is presented. Adsorbed NO is taken as an example to demonstrate the persisting discrepancies in the interpretation of IPE spectra. Atomic adsorbates are discussed in the second part. The quantum well state model is applied to interpret the surface states in reconstructing and non-reconstructing adsorption systems of alkali metals and hydrogen. A recent controversy on the unoccupied electronic states of the Cu(110)/O p(2×1) surface is critically reviewed. The quantum well state model is then compared to tight binding and local-density-functional calculations of the unoccupied bands and the deficiencies of the various approaches are pointed out. Finally, the relation between the surface state model and more chemically oriented models of surface bonding is briefly discussed.

  13. Use of immobilized metal ions as a negative adsorbent for purification of enzymes: application to phosphoglycerate mutase from chicken muscle extract and horseradish peroxidase.

    PubMed

    Chaga, G; Andersson, L; Ersson, B; Berg, M

    1992-01-01

    Two enzymes, phosphoglycerate mutase and peroxidase, were purified by using an immobilized metal ion adsorbent for the removal of unwanted proteins. The mutase was obtained pure from a single column, whereas the purification of peroxidase required the use of a thiophilic adsorbent in a tandem. The capacity was 2.5 mg pure peroxidase per mL gel. PMID:1386542

  14. Cleaning of biomaterial surfaces: protein removal by different solvents.

    PubMed

    Kratz, Fabian; Grass, Simone; Umanskaya, Natalia; Scheibe, Christian; Müller-Renno, Christine; Davoudi, Neda; Hannig, Matthias; Ziegler, Christiane

    2015-04-01

    The removal of biofilms or protein films from biomaterials is still a challenging task. In particular, for research investigations on real (applied) surfaces the reuse of samples is of high importance, because reuse allows the comparison of the same sample in different experiments. The aim of the present study was to evaluate the cleaning efficiency of different solvents (SDS, water, acetone, isopropanol, RIPA-buffer and Tween-20) on five different biomaterials (titanium, gold, PMMA (no acetone used), ceramic, and PTFE) with different wettability which were covered by layers of two different adsorbed proteins (BSA and lysozyme). The presence of a protein film after adsorption was confirmed by transmission electron microscopy (TEM). After treatment of the surfaces with the different solvents, the residual proteins on the surface were determined by BCA-assay (bicinchoninic acid assay). Data of the present study indicate that SDS is an effective solvent, but for several protein-substrate combinations it does not show the cleaning efficiency often mentioned in literature. RIPA-buffer and Tween-20 were more effective. They showed very low residual protein amounts after cleaning on all examined material surfaces and for both proteins, however, with small differences for the respective substrate-protein combinations. RIPA-buffer in combination with ultrasonication completely removed the protein layer as confirmed by TEM. PMID:25725311

  15. Development and Testing of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

    2012-01-01

    The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

  16. In situ modification of chromatography adsorbents using cold atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Olszewski, P.; Willett, T. C.; Theodosiou, E.; Thomas, O. R. T.; Walsh, J. L.

    2013-05-01

    Efficient manufacturing of increasingly sophisticated biopharmaceuticals requires the development of new breeds of chromatographic materials featuring two or more layers, with each layer affording different functions. This letter reports the in situ modification of a commercial beaded anion exchange adsorbent using atmospheric pressure plasma generated within gas bubbles. The results show that exposure to He-O2 plasma in this way yields significant reductions in the surface binding of plasmid DNA to the adsorbent exterior, with minimal loss of core protein binding capacity; thus, a bi-layered chromatography material exhibiting both size excluding and anion exchange functionalities within the same bead is produced.

  17. Molecular Factors in Dendritic Cell Responses to Adsorbed Glycoconjugates

    PubMed Central

    Hotaling, Nathan A.; Cummings, Richard D.; Ratner, Daniel M.; Babensee, Julia E.

    2014-01-01

    Carbohydrates and glycoconjugates have been shown to exert pro-inflammatory effects on the dendritic cell (DC), supporting pathogen-induced innate immunity and antigen processing, as well as immunosuppressive effects in the tolerance to self-proteins. Additionally, the innate inflammatory response to implanted biomaterials has been hypothesized to be mediated by inflammatory cells interacting with adsorbed proteins, many of which are glycosylated. However, the molecular factors relevant for surface displayed glycoconjugate modulation of DC phenotype are unknown. Thus, in this study, a model system was developed to establish the role of glycan composition, density, and carrier cationization state on DC response. Thiol modified glycans were covalently bound to a model protein carrier, maleimide functionalized bovine serum albumin (BSA), and the number of glycans per BSA modulated. Additionally, the carrier isoelectric point was scaled from a pI of ~4.0 to ~10.0 using ethylenediamine (EDA). The DC response to the neoglycoconjugates adsorbed to wells of a 384 well plate was determined via a high throughput assay. The underlying trends in DC phenotype in relation to conjugate properties were elucidated via multivariate general linear models. It was found that glycoconjugates with more than 20 glycans per carrier had the greatest impact on the pro-inflammatory response from DCs, followed by conjugates having an isoelectric point above 9.5. Surfaces displaying terminal α1–2 linked mannose structures were able to increase the inflammatory DC response to a greater extent than did any other terminal glycan structure. The results herein can be applied to inform the design of the next generation of combination products and biomaterials for use in future vaccines and implanted materials. PMID:24746228

  18. Mechanisms of liquid crystal and biopolymer alignment on highly-oriented polymer thin films

    NASA Astrophysics Data System (ADS)

    Dennis, John Raymond

    1998-12-01

    Molecular order can strongly enhance material properties, or produce materials which perform advanced functions. Many materials, from small crystals to large macromolecules, may be aligned on highly-oriented poly(tetrafluoroethylene) (PTFE) or high-density polyethylene (HDPE) thin films, prepared by a simple shear deposition procedure. Here, processes by which these films produce order are examined, first in a well- characterized liquid crystal, then in two more complex polymer liquid crystals, and finally in an adsorbed motor protein system. Optical second harmonic generation (SHG) was used to study surface molecular order in the liquid crystal 4'-n-octyl-4-cyano-biphenyl (8CB) on PTFE and HDPE films. In nematic 8CB cells with bulk alignment along the polymer orientation axis, the surface monolayers of 8CB were also aligned, and showed C2ν symmetry. In the isotropic phase, the surface monolayer alignment was lost. Monolayers of 8CB evaporated onto either polymer showed little or no alignment. The bulk 8CB alignment appears to be primarily caused by surface ridges through an elastic, bulk- mediated mechanism, unlike the epitaxy-like alignment found on some cloth-rubbed polymer surfaces. For the polymer liquid crystal poly-γ-benzyl- glutamate (PBG), uniform homogeneous surface alignment was observed on PTFE films; this is the first report of PBG surface alignment. However, liquid crystalline samples of microtubules were not aligned. PTFE films show promise for aligning some other polymer liquid crystals via elastic interactions. The motor protein kinesin, adsorbed to PTFE films, transported fluorescently labeled microtubules predominantly in straight lines along the films' orientation axis, not in random directions as observed on glass surfaces. As the kinesin surface density was increased, the degree of alignment peaked and then declined. The results indicate that directed motion occurs because active kinesin preferentially adsorbs to surface sites along linear

  19. Natural Transformation of Azotobacter vinelandii by Adsorbed Chromosomal DNA: Role of Adsorbed DNA Conformation

    NASA Astrophysics Data System (ADS)

    Lv, N.; Zilles, J.; Nguyen, H.

    2008-12-01

    Recent increases in antibiotic resistance among pathogenic microorganisms and the accompanying public health concerns result both from the widespread use of antibiotics and from the transfer of antibiotic resistance genes among microorganisms. To understand the transfer of antibiotic resistance genes and identify efficient measures to minimize these transfers, an interdisciplinary approach was used to identify physical and chemical factors that control the fate and biological availability of extracellular DNA. Quartz crystal microbalance with dissipation (QCM-D) was used to study extracellular DNA adsorption and the conformation of the adsorbed DNA on silica and natural organic matter (NOM) surfaces. Solution chemistry was varied systematically to investigate the role of adsorbed DNA conformation on transformation. Gene transfer was assessed under the same conditions using natural transformation of chromosomal DNA into the soil bacteria Azotobacter vinelandii. DNA adsorbed to both silica and NOM surfaces has a more compact and rigid conformation in the presence of Ca2+ compared to Na+. Extracellular DNA adsorbed on silica and NOM surfaces transformed A. vinelandii. The transformation efficiency of adsorbed DNA was up to 4 orders of magnitude lower than that of dissolved DNA. Preliminary results suggest that the presence of Ca2+ in groundwater (e.g. hardness) reduces the availability of adsorbed DNA for transformation.

  20. Correlation of average hydrophobicity, water/air interface surface rheological properties and foaming properties of proteins.

    PubMed

    Medrano, A; Abirached, C; Araujo, A C; Panizzolo, L A; Moyna, P; Añón, M C

    2012-04-01

    A comparative study on the behavior in the air-water interface of β-lactoglobulin, α-lactoalbumin, glycinin and β-conglycinin was performed. The behavior at the interface was evaluated by equilibrium surface tension and surface rheological properties of adsorbed films. There were significant differences (α ≤ 0.05) in the values of the constants of adsorption to the interface of the four proteins. The glycinin had the slowest rate of adsorption, due to its low average hydrophobicity, low molecular flexibility and large molecular size. Smaller proteins like β-lactoglobulin and α-lactoalbumin tended to greater equilibrium pressure values than the larger proteins because of its higher rate of adsorption to the interface. The foam capacity of proteins showed a positive correlation with the average hydrophobicity; the maximal retained liquid volume or the initial rate of passage of liquid to foam were significantly lower (α ≤ 0.05) when protein was glycinin. The dilatational modulus of glycinin was the lowest, which implies lowest resistance to disruption of the film. Glycinin protein has lower proportion of gravitational drainage and higher disproportionation having perhaps a less resistant film. In conclusion, β-conglycinin and whey proteins showed a similar behavior, so β-conglycinin might be the best soybean protein to replace milk proteins in food formulations. PMID:22414931

  1. Nanohardness, corrosion and protein adsorption properties of CuAlO2 films deposited on 316L stainless steel for biomedical applications

    NASA Astrophysics Data System (ADS)

    Chang, Shih-Hang; Chen, Jian-Zhang; Hsiao, Sou-Hui; Lin, Guan-Wei

    2014-01-01

    This study preliminarily assesses the biomedical applications of CuAlO2 coatings according to nanoindentation, electrochemical, and protein adsorption tests. Nanoindentation results revealed that the surface hardness of 316L stainless steel increased markedly after coating with CuAlO2 films. Electrochemical tests of corrosion potential, breakdown potential, and corrosion current density showed that the corrosion resistance properties of 316L stainless steel are considerably improved by CuAlO2 coatings. Bicinchoninic acid (BCA) protein assay results revealed that the protein adsorption behavior of 316L stainless steel did not exhibit notable differences with or without CuAlO2 coatings. A CuAlO2 coating of 100 nm thickness improved the surface nanohardness and corrosion resistance ability of 316L stainless steel. CuAlO2 is a potential candidate for biomaterial coating applications, particularly for surface modification of fine, delicate implants.

  2. Hemoglobin-mimetic oxygen adsorbent prepared via self-assembly of cysteinyl bolaamphiphiles.

    PubMed

    Lee, Chaemyeong; Kim, Min-Chul; Lee, Sang-Yup

    2016-06-01

    In this study, a novel cysteinyl bolaamphiphilic molecule was synthesized and its self-assembled planar suprastructure was applied as a biomimetic matrix to create a hemoglobin-mimetic oxygen adsorbent that exploits the ability of cysteine thiols to bind hemin. Self-assembly of the cysteinyl bolaamphiphilic molecule exposed cysteine thiols on its surface in the presence of β-mercaptoethanol, known to reduce disulfide bonds, without which, helically coiled structures were generated. The self-assembled planar structure was used as a soft matrix to create a hemoglobin-mimetic oxygen adsorbent. The surface-exposed cysteine thiols were used to attach hemin, producing a hemin-bound, planar structure mimicking hemoglobin. This hemoglobin mimic strongly adsorbed oxygen and remained stable up to 50°C. The cysteinyl bolaamphiphile self-assembled structure provided a biomimetic platform that allowed for the association of biological substances in a manner similar to natural proteins. PMID:26970824

  3. An adsorbent monolith device to augment the removal of uraemic toxins during haemodialysis.

    PubMed

    Sandeman, Susan R; Howell, Carol A; Phillips, Gary J; Zheng, Yishan; Standen, Guy; Pletzenauer, Robert; Davenport, Andrew; Basnayake, Kolitha; Boyd, Owen; Holt, Stephen; Mikhalovsky, Sergey V

    2014-06-01

    Adsorbents designed with porosity which allows the removal of protein bound and high molecular weight uraemic toxins may improve the effectiveness of haemodialysis treatment of chronic kidney disease (CKD). A nanoporous activated carbon monolith prototype designed for direct blood contact was first assessed for its capacity to remove albumin bound marker toxins indoxyl sulphate (IS), p-cresyl sulphate (p-CS) and high molecular weight cytokine interleukin-6 in spiked healthy donor studies. Haemodialysis patient blood samples were then used to measure the presence of these markers in pre- and post-dialysis blood and their removal by adsorbent recirculation of post-dialysis blood samples. Nanopores (20-100 nm) were necessary for marker uraemic toxin removal during in vitro studies. Limited removal of IS and p-CS occurred during haemodialysis, whereas almost complete removal occurred following perfusion through the carbon monoliths suggesting a key role for such adsorbent therapies in CKD patient care. PMID:24573455

  4. EMERGING TECHNOLOGY SUMMARY: DEMONSTRATION OF AMBERSORB 563 ADSORBENT TECHNOLOGY

    EPA Science Inventory

    A field pilot study was conducted to demonstrate the technical feasibility and cost-effectiveness of Ambersorb® 5631 carbonaceous adsorbent for remediating groundwater contaminated with volatile organic compounds (VOCs). The Ambersorb adsorbent technology demonstration consist...

  5. New paradigm for stabilization of liquid polymer films on solids

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Jiang, Naisheng; Wang, Jiaxun; di, Xiaoyu; Cheung, Justin; Endoh, Maya

    2015-03-01

    We report that wetting/dewetting behavior of liquid polymer films on solids can be controlled by nanoscale architectures of polymer chains irreversibly adsorbed on the impenetrable surfaces. Monodisperse polystyrene (PS) ultrathin films (20 nm in thickness) with different molecular weights on silicon (Si) substrates with a natural amorphous Si dioxide layer were used as models. The PS thin films were annealed at high temperatures at T>Tg (Tg is the bulk glass transition temperature) for several days, and the surface structures were studied by using optical and atomic force microscopes. At the same time, the annealed PS films were further leached with a good solvent and the residue films (i.e., irreversibly adsorbed layers) were characterized by x-ray reflectivity. The experimental data reveals a strong correlation between the conformations of the adsorbed polymer chains and the stability of the liquid films on top. T. K. acknowledges the partial financial support from NSF Grant No. CMMI-1332499.

  6. Investigation of interparticle forces in natural waters: effects of adsorbed humic acids on iron oxide and alumina surface properties.

    PubMed

    Sander, Sylvia; Mosley, Luke M; Hunter, Keith A

    2004-09-15

    The nature of interparticle forces acting on colloid particle surfaces with adsorbed surface films of the internationally used humic acid standard material, Suwannee River Humic Acid (SHA), has been investigated using an atomic force microscope (AFM). Two particle surfaces were used, alumina and a hydrous iron oxide film coated onto silica particles. Adsorbed SHA dominated the interactive forces for both surface types when present. At low ionic strength and pH > 4, the force curves were dominated by electrostatic repulsion of the electrical double layers, with the extent of repulsion decreasing as electrolyte (NaCl) concentration increased, scaling with the Debye length (kappa(-1)) of the electrolyte according to classical theory. At pH approximately 4, electrostatic forces were largely absent, indicating almost complete protonation of carboxylic acid (-COOH) functional groups on the adsorbed SHA. Under these conditions and also at high electrolyte concentration ([NaCl] > 0.1 M), the absence of electrostatic forces allowed observation of repulsion forces arising from steric interaction of adsorbed SHA as the oxide surfaces approached closely to each other (separation < 10 nm). This steric barrier shrank as electrolyte concentration increased, implying tighter coiling of the adsorbed SHA molecules. In addition, adhesive bridging between surfaces was observed only in the presence of SHA films, implying a strong energy barrier to spontaneous detachment of the surfaces from each other once joined. This adhesion was especially strong in the presence of Ca2+ which appears to bridge SHA layers on each surface. Overall, our results show that SHA is a good model for the NOM adsorbed on colloids. PMID:15487789

  7. Lysozyme fractionation from egg white at pilot scale by means of tangential flow membrane adsorbers: Investigation of the flow conditions.

    PubMed

    Brand, Janina; Voigt, Katharina; Zochowski, Bianca; Kulozik, Ulrich

    2016-03-18

    The application of membrane adsorbers instead of classical packed bed columns for protein fractionation is still a growing field. In the case of egg white protein fractionation, the application of classical chromatography is additionally limited due to its high viscosity that impairs filtration. By using tangential flow membrane adsorbers as stationary phase this limiting factor can be left out, as they can be loaded with particle containing substrates. The flow conditions existing in tangential flow membrane adsorbers are not fully understood yet. Thus, the aim of the present study was to gain a deeper understanding of the transport mechanisms in tangential flow membrane adsorbers. It was found that loading in recirculation mode instead of single pass mode increased the binding capacity (0.39 vs. 0.52mgcm(-2)). Further, it was shown that either higher flow rates (0.39mgcm(-2) vs. 0.57mgcm(-2) at 1CVmin(-1) or 20CVmin(-1), respectively) or higher amounts of the target protein in the feed (0.24mgcm(-2) vs. 0.85mgcm(-2) for 2.5 or 39.0g lysozyme, respectively) led to more protein binding. These results show that, in contrast to radial flow or flat sheet membrane adsorbers, the transport in tangential flow membrane adsorbers is not purely based on convection, but on a mix of convection and diffusion. Additionally, investigations concerning the influence of fouling formation were performed that can lead to transport limitations. It was found that this impact is neglectable. It can be concluded that the usage of tangential flow membrane adsorbers is very recommendable for egg white protein fractionations, although the transport is partly diffusion-limited. PMID:26898148

  8. Analysis of Adsorbed Natural Gas Tank Technology

    NASA Astrophysics Data System (ADS)

    Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

    With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

  9. Gas storage using fullerene based adsorbents

    NASA Technical Reports Server (NTRS)

    Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

    2000-01-01

    This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

  10. Adsorption at the air-water interface and emulsification properties of grain legume protein derivatives from pea and broad bean.

    PubMed

    Tsoukala, A; Papalamprou, E; Makri, E; Doxastakis, G; Braudo, E E

    2006-12-01

    Functional properties of native and modified (through induced autolysis) pea (Pisum sativum L.) and broad bean (Vicia faba L.) protein derivatives are studied. In specific, protein solubility and behavior at the air-water interface through surface pressure measurements are investigated. Furthermore the ability of the protein products to act as emulsifying agents and to stabilize emulsions is studied through oil droplet size distribution measurements and by the protein adsorbed at the oil-water interface. The data reveal that the ability of the proteins to act as surfactants and build up a rigid film around the oil droplets, mainly depends on their suitable molecular configuration and structure. Hydrolysis did not promote the functionality of the legume proteins. Broad bean exhibited better functionality than pea, before and after hydrolysis. Some comparisons were also made with lupin (Lupinus albus L.) protein isolate. PMID:17049437

  11. Antifouling surfaces for proteins labeled with dye-doped silica nanoparticles.

    PubMed

    Wang, Hui; Tong, Qi; Yan, Mingdi

    2013-01-01

    We report that proteins labeled with fluorescein-doped silica nanoparticles (FSNPs) showed drastically different fouling behavior than those labeled with the fluorescein dye. Arrays of polymer films were covalently immobilized on silicon wafers and were treated with protein conjugated on FSNPs. Fluorescence imaging showed that the protein-FSNP conjugate adsorbed strongly on hydrophilic polymers such as poly(ethylene oxide) (PEO) and weakly on hydrophobic polymers such as polystyrene (PS), and the extent of adsorption decreased with increasing hydrophobicity of the polymer film. Thus, carbohydrate microarrays probed with FSNP-labeled lectin showed significantly enhanced signals when PS was used as the antifouling coating than when PEO was used, or when using bovine serum albumin as the blocking agent. PMID:23236953

  12. Antifouling Surfaces for Proteins Labeled with Dye-Doped Silica Nanoparticles

    PubMed Central

    Wang, Hui; Tong, Qi; Yan, Mingdi

    2012-01-01

    We report that proteins labeled with fluorescein-doped silica nanoparticles (FSNPs) showed drastically different fouling behavior than those labeled with the fluorescein dye. Arrays of polymer films were covalently immobilized on silicon wafers, and were treated with protein conjugated on FSNPs. Fluorescence imaging showed that the protein-FSNP conjugate adsorbed strongly on hydrophilic polymers such as poly(ethylene oxide) (PEO) and weakly on hydrophobic polymers such as polystyrene (PS), and the extent of adsorption decreased with increasing hydrophobicity of the polymer film. Thus, carbohydrate microarrays probed with FSNP-labeled lectin showed significantly enhanced signals when PS was used as the antifouling coating than PEO as well as when bovine serum albumin was used as the blocking agent. PMID:23236953

  13. Simulations of noble gases adsorbed on graphene

    NASA Astrophysics Data System (ADS)

    Maiga, Sidi; Gatica, Silvina

    2014-03-01

    We present results of Grand Canonical Monte Carlo simulations of adsorption of Kr, Ar and Xe on a suspended graphene sheet. We compute the adsorbate-adsorbate interaction by a Lennard-Jones potential. We adopt a hybrid model for the graphene-adsorbate force; in the hybrid model, the potential interaction with the nearest carbon atoms (within a distance rnn) is computed with an atomistic pair potential Ua; for the atoms at r>rnn, we compute the interaction energy as a continuous integration over a carbon uniform sheet with the density of graphene. For the atomistic potential Ua, we assume the anisotropic LJ potential adapted from the graphite-He interaction proposed by Cole et.al. This interaction includes the anisotropy of the C atoms on graphene, which originates in the anisotropic π-bonds. The adsorption isotherms, energy and structure of the layer are obtained and compared with experimental results. We also compare with the adsorption on graphite and carbon nanotubes. This research was supported by NSF/PRDM (Howard University) and NSF (DMR 1006010).

  14. Functionalized-MnO2/chitosan nanocomposites: A promising adsorbent for the removal of lead ions.

    PubMed

    Mallakpour, Shadpour; Madani, Maryam

    2016-08-20

    In the current study, the surface of alpha manganese dioxide nanorod (α-MnO2) functionalized with γ-aminopropyltriethoxysilane (APTS). The α-MnO2-APTS was used as filler for preparation of chitosan (CS) nanocomposites (NCs). The α-MnO2-APTS/CS NCs were crosslinked with different amount of glutaraldehyde (GA). The effects of the GA content on the morphology, thermal properties and adsorption of NC films were studied. The Fourier transform infrared (FT-IR) results verified the grafting of APTS onto α-MnO2. The amount of APTS grafted onto α-MnO2 was found to be 20wt% by thermo gravimetric analysis. Presented results also show that with increasing crosslinker agent concentration, the thermal stability of CS films were increased. The α-MnO2-APTS/CS NCs were tested and evaluated as a potential adsorbent for the removal of lead ions. The results showed that the adsorbent exhibited a favorable performance for the removal of lead ions. Therefore, α-MnO2-APTS/CS NCs could serve as promising adsorbents. PMID:27178908

  15. Neutron Reflection Study of Bovine β-Casein Adsorbed on OTS Self- Assembled Monolayers

    NASA Astrophysics Data System (ADS)

    Fragneto, Giovanna; Thomas, Robert K.; Rennie, Adrian R.; Penfold, Jeffrey

    1995-02-01

    Specular neutron reflection has been used to determine the structure and composition of bovine β-casein adsorbed on a solid surface from an aqueous phosphate-buffered solution at pH 7. The protein was adsorbed on a hydrophobic monolayer self-assembled from deuterated octadecyltrichlorosilane solution on a silicon (111) surface. A two-layer structure formed consisting of one dense layer of thickness 23 ± 1 angstroms and a surface coverage of 1.9 milligrams per square meter adjacent to the surface and an external layer protruding into the solution of thickness 35 ± 1 angstroms and 12 percent protein volume fraction. The structure of the (β-casein) layer is explained in terms of the charge distribution in the protein.

  16. Protein and polysaccharide-composite sol-gel silicate film for an interference-free amperometric glucose biosensor.

    PubMed

    Matsuhisa, Hironori; Tsuchiya, Munenori; Hasebe, Yasushi

    2013-11-01

    A novel permselective, organic-inorganic-hybrid, sol-gel silicate-film was chemically modified on an anodized platinum (Pt) electrode surface to form a selective, sensitive and interference-free amperometric glucose biosensor. This permselective hybrid sol-gel film consists of three organo-silanes [i.e., 3-aminopropyltriethoxysilane (APTES); tetraethoxysilane (TEOS); triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (FAS)] and two biomacromolecules [i.e., bovine serum albumin (BSA) and a chitosan (CHIT)]. After the addition of the film to the Pt electrode, glucose oxidase (GOx) was covalently immobilized within the film with glutaraldehyde. The incorporation of the BSA and CHIT not only enhanced the permselectivity of H2O2 but also improved the activity of the immobilized GOx. The CHIT effectively suppressed any swelling of the film. Moreover, the conjugation of the FAS was especially effective in reducing the interference currents of AA and UA to levels less than 1/400 and 1/300 of the current of H2O2. The resulting organic-inorganic-hybrid sol-gel-film-based amperometric glucose biosensor exhibited rapid and sensitive responses to glucose (100% response in <3s, sensitivity: 1.84 μA mM(-1), detection limit: 0.032 mM), and the highly selective determination of glucose was possible, even in the presence of 0.1mM AA and UA. PMID:23886787

  17. Characterization and protein-adsorption behavior of deposited organic thin film onto titanium by plasma polymerization with hexamethyldisiloxane.

    PubMed

    Hayakawa, Tohru; Yoshinari, Masao; Nemoto, Kimiya

    2004-01-01

    Plasma polymerized hexamethyldisiloxane (HMDSO) thin film was deposited onto titanium using a radio-frequency apparatus for the surface modification of titanium. A titanium disk was first polished using colloidal silica at pH=9.8. Plasma-polymerized HMDSO films were firmly attached to the titanium by heating the titanium to a temperature of approximately 250 degrees C. The thickness of the deposited film was 0.07-0.35mum after 10-60min of plasma polymerization. The contact angle with respect to double distilled water significantly increased after HMDSO coating. X-ray photoelectron spectroscopy revealed that the deposited thin film consisted of Si, C, and O atoms. No Ti peaks were observed on the deposited surface. The deposited HMDSO film was stable during 2-weeks immersion in phosphate buffer saline solution. Fourier transform reflection-absorption spectroscopy showed the formation of Si-H, Si-C, C-H, and Cz.dbnd6;O bonds in addition to Si-O-Si bonds. Quartz crystal microbalance-dissipation measurement demonstrated that the deposition of HMDSO thin films on titanium has a benefit for fibronectin adsorption at the early stage. In conclusion, plasma polymerization is a promising technique for the surface modification of titanium. HMDSO-coated titanium has potential application as a dental implant material. PMID:14580915

  18. Structure and Dynamics of Proteins Adsorbed to Biomaterial Interfaces

    SciTech Connect

    Drobny, Gary P.; Long, Joanna R.; Shaw, Wendy J.; Cotten, Myriam L.; Stayton, Partick S.

    2002-10-31

    Biomineralization, defined as the organized deposition of inorganic materials in the cellular or extracellular matrix, may be as simple a process as the formation of an iron oxide crystal in the vesicle of a magnetobacterium, or as complex a process as the formation of the intricate calcium carbonate and calcium phosphate structures found in marine coccoliths, invertebrate shells, vertebrate skeletons and teeth. The phenomenon of Biomineralization has attracted a great deal of attention recently from the materials science community, which seeks to understand the way in which inorganic biological composites are synthesized and processed in nature.

  19. Shelf-life extension of refrigerated sea bass slices wrapped with fish protein isolate/fish skin gelatin-ZnO nanocomposite film incorporated with basil leaf essential oil.

    PubMed

    Arfat, Yasir Ali; Benjakul, Soottawat; Vongkamjan, Kitiya; Sumpavapol, Punnanee; Yarnpakdee, Suthasinee

    2015-10-01

    Microbiological, chemical and sensory changes of sea bass slices wrapped with fish protein isolate (FPI)/fish skin gelatin (FSG) films incorporated with 3 % ZnO nanoparticles (ZnONP) (w/w, based on protein content) and 100 % basil leaf essential oil (BEO) (w/w, based on protein content) during storage of 12 days at 4 °C were investigated. Sea bass slices wrapped with FPI/FSG-ZnONP-BEO film had the lowest growth of psychrophilic bacteria, lactic acid bacteria and spoilage microorganisms including Pseudomonas , H2S-producing bacteria and Enterobacteriaceae throughout storage of 12 days in comparison with those wrapped with FPI/FSG-BEO, FPI/FSG-ZnONP, FPI/FSG film, polypropylene film (PP film) and the control (without wrapping), respectively (P < 0.05). Lowered increases in pH, total volatile base, peroxide value and TBARS value were found in FPI/FSG-ZnO-BEO film wrapped samples, compared with others (P < 0.05). Sensory evaluation revealed that shelf-life of sea bass slices was longest for samples wrapped with FPI/FSG-ZnONP-BEO film (12 days), as compared to the control (6 days) (P < 0.05). PMID:26396365

  20. Fabrication of Self-Cleaning, Reusable Titania Templates for Nanometer and Micrometer Scale Protein Patterning.

    PubMed

    Moxey, Mark; Johnson, Alexander; El-Zubir, Osama; Cartron, Michael; Dinachali, Saman Safari; Hunter, C Neil; Saifullah, Mohammad S M; Chong, Karen S L; Leggett, Graham J

    2015-06-23

    The photocatalytic self-cleaning characteristics of titania facilitate the fabrication of reuseable templates for protein nanopatterning. Titania nanostructures were fabricated over square centimeter areas by interferometric lithography (IL) and nanoimprint lithography (NIL). With the use of a Lloyd's mirror two-beam interferometer, self-assembled monolayers of alkylphosphonates adsorbed on the native oxide of a Ti film were patterned by photocatalytic nanolithography. In regions exposed to a maximum in the interferogram, the monolayer was removed by photocatalytic oxidation. In regions exposed to an intensity minimum, the monolayer remained intact. After exposure, the sample was etched in piranha solution to yield Ti nanostructures with widths as small as 30 nm. NIL was performed by using a silicon stamp to imprint a spin-cast film of titanium dioxide resin; after calcination and reactive ion etching, TiO2 nanopillars were formed. For both fabrication techniques, subsequent adsorption of an oligo(ethylene glycol) functionalized trichlorosilane yielded an entirely passive, protein-resistant surface. Near-UV exposure caused removal of this protein-resistant film from the titania regions by photocatalytic degradation, leaving the passivating silane film intact on the silicon dioxide regions. Proteins labeled with fluorescent dyes were adsorbed to the titanium dioxide regions, yielding nanopatterns with bright fluorescence. Subsequent near-UV irradiation of the samples removed the protein from the titanium dioxide nanostructures by photocatalytic degradation facilitating the adsorption of a different protein. The process was repeated multiple times. These simple methods appear to yield durable, reuseable samples that may be of value to laboratories that require nanostructured biological interfaces but do not have access to the infrastructure required for nanofabrication. PMID:26042335

  1. Effect of Milk Proteins on Adhesion of Bacteria to Stainless Steel Surfaces

    PubMed Central

    Barnes, L.-M.; Lo, M. F.; Adams, M. R.; Chamberlain, A. H. L.

    1999-01-01

    Stainless steel coupons were treated with skim milk and subsequently challenged with individual bacterial suspensions of Staphylococcus aureus, Pseudomonas fragi, Escherichia coli, Listeria monocytogenes, and Serratia marcescens. The numbers of attached bacteria were determined by direct epifluorescence microscopy and compared with the attachment levels on clean stainless steel with two different surface finishes. Skim milk was found to reduce adhesion of S. aureus, L. monocytogenes, and S. marcescens. P. fragi and E. coli attached in very small numbers to the clear surfaces, making the effect of any adsorbed protein layer difficult to assess. Individual milk proteins α-casein, β-casein, κ-casein, and α-lactalbumin were also found to reduce the adhesion of S. aureus and L. monocytogenes. The adhesion of bacteria to samples treated with milk dilutions up to 0.001% was investigated. X-ray photoelectron spectroscopy was used to determine the proportion of nitrogen in the adsorbed films. Attached bacterial numbers were inversely related to the relative atomic percentage of nitrogen on the surface. A comparison of two types of stainless steel surface, a 2B and a no. 8 mirror finish, indicated that the difference in these levels of surface roughness did not greatly affect bacterial attachment, and reduction in adhesion to a milk-treated surface was still observed. Cross-linking of adsorbed proteins partially reversed the inhibition of bacterial attachment, indicating that protein chain mobility and steric exclusion may be important in this phenomenon. PMID:10508087

  2. Protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins are the major structural and functional components of all cells in the body. They are macromolecules that comprise 1 or more chains of amino acids that vary in their sequence and length and are folded into specific 3-dimensional structures. The sizes and conformations of proteins, therefor...

  3. Proteins.

    ERIC Educational Resources Information Center

    Doolittle, Russell F.

    1985-01-01

    Examines proteins which give rise to structure and, by virtue of selective binding to other molecules, make genes. Binding sites, amino acids, protein evolution, and molecular paleontology are discussed. Work with encoding segments of deoxyribonucleic acid (exons) and noncoding stretches (introns) provides new information for hypotheses. (DH)

  4. Adsorbed Natural Gas Storage in Optimized High Surface Area Microporous Carbon

    NASA Astrophysics Data System (ADS)

    Romanos, Jimmy; Rash, Tyler; Nordwald, Erik; Shocklee, Joshua Shawn; Wexler, Carlos; Pfeifer, Peter

    2011-03-01

    Adsorbed natural gas (ANG) is an attractive alternative technology to compressed natural gas (CNG) or liquefied natural gas (LNG) for the efficient storage of natural gas, in particular for vehicular applications. In adsorbants engineered to have pores of a few molecular diameters, a strong van der Walls force allows reversible physisorption of methane at low pressures and room temperature. Activated carbons were optimized for storage by varying KOH:C ratio and activation temperature. We also consider the effect of mechanical compression of powders to further enhance the volumetric storage capacity. We will present standard porous material characterization (BET surface area and pore-size distribution from subcritical N2 adsorption) and methane isotherms up to 250 bar at 293K. At sufficiently high pressure, specific surface area, methane binding energy and film density can be extracted from supercritical methane adsorption isotherms. Research supported by the California Energy Commission (500-08-022).

  5. Spectral Inspections on Molecular Configurations of Nile Blue A Adsorbed on the Elementary Clay Sheets.

    PubMed

    Huang, Mei; He, Shuai; Liu, Wenhong; Yao, Yunjin; Miao, Shiding

    2015-10-22

    Studies on the configuration of dye molecules are of great importance in revealing origins of the electronic bands as well as understanding their transitions. In this work, we utilized dye molecules named Nile blue A, which are a type of oxazine dyes, to study the molecular configurations when they are transferred from solutions to a solid surface. The Langmuir-Blodgett (LB) technique was employed to construct such an interface where the interaction between the dye molecules and solid supports can be pursued. Hybrid films were prepared via the LB depositions, and the dye molecules were assembled on the elementary clay sheets (laponite, saponite). The configuration of Nb reflected by the molecular orientation, packing density, phase behavior, and variances of the surface tension has been derived. The ex situ spectroscopy characterizations such as UV-vis absorption, fluorescence emission, and excitation spectra were carried out on these LB films to reveal the fact that the adsorbed Nb molecules are mainly assembled in two types of configurations. Adsorbed state I was found to be achieved at high concentrations (1-10 ppm) of clay dispersions and low surface pressure (∼5 mN/m). In this state the anionic oxazine rings of Nb are adsorbed on clay sheets sharing a large lift-off area. This configuration gives allowable fluorescence (λ = 550 nm). Lower clay concentration (<1 ppm) and high surface pressure (10-30 mN/m) yield the adsorbed state II in which the oxazine chromophores were arranged in a side-by-side style, and the dye molecules stand perpendicularly to the clay sheets. This conformation exhibits no photoluminescence. PMID:26436823

  6. Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

    2015-06-01

    The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation. PMID:25978089

  7. Adsorbed serum albumin is permissive to macrophage attachment to perfluorocarbon polymer surfaces in culture

    PubMed Central

    Godek, M.L.; Michel, R.; Chamberlain, L. M.; Castner, D. G.; Grainger, D.W.

    2013-01-01

    Monocyte/macrophage adhesion to biomaterials, correlated with foreign body response, occurs through protein-mediated surface interactions. Albumin-selective perfluorocarbon (FC) biomaterials are generally poorly cell-conducive due to insufficient receptor-mediated surface interactions, but macrophages bind to albumin-coated substrates and also preferentially to highly hydrophobic fluorinated surfaces. Bone marrow macrophages (BMMO) and IC-21, RAW 264.7 and J774A.1 monocyte/macrophage cells were cultured on FC surfaces. Protein deposition onto two distinct FC surfaces from complex and single-component solutions was tracked using fluorescence and time-of-flight secondary ion mass spectrometry (ToF-SIMS) methods. Cell adhesion and growth on protein pre-treated substrates were compared by light microscopy. Flow cytometry and integrin-directed antibody receptor blocking assessed integrins critical for monocyte/macrophage adhesion in vitro. Albumin predominantly adsorbs onto both FC surfaces from 10% serum. In cultures pre-adsorbed with albumin or serum-dilutions, BMMO responded similar to IC-21 at early time points. Compared to Teflon® AF, plasma-polymerized FC was less permissive to extended cell proliferation. The β2 integrins play major roles in macrophage adhesion to FC surfaces: antibody blocking significantly disrupted cell adhesion. Albumin-mediated cell adhesion mechanisms to FC surfaces could not be clarified. Primary BMMO and secondary IC-21 macrophages behave similarly on FC surfaces, regardless of pre-adsorbed protein biasing, with respect to adhesion, cell morphology, motility and proliferation. PMID:18306309

  8. Thin films, asphaltenes, and reservoir wettability

    SciTech Connect

    Kaminsky, R.; Bergeron, V.; Radke, C.J. |

    1993-04-01

    Reservoir wettability impacts the success of oil recovery by waterflooding and other methods. To understand wettability and its alteration, thin-film forces in solid-aqueous-oil systems must be elucidated. Upon rupture of thick aqueous films separating the oil and rock phases, asphaltene components in the crude oil adsorb irreversibly on the solid surface, changing it from water-wet to oil-wet. Conditions of wettability alteration can be found by performing adhesion tests, in which an oil droplet is brought into contact with a solid surface. Exceeding a critical capillary pressure destabilizes the film, causing spontaneous film rupture to a molecularly adsorbed layer and oil adhesion accompanied by pinning at the three-phase contact line. The authors conduct adhesion experiments similar to those of Buckley and Morrow and simultaneously examine the state of the underlying thin film using optical microscopy and microinterferometry. Aqueous thin films between an asphaltic Orcutt crude oil and glass surfaces are studied as a function of aqueous pH and salinity. For the first time, they prove experimentally that strongly water-wet to strongly oil-wet wettability alteration and contact-angle pinning occur when thick aqueous films thin to molecularly adsorbed films and when the oil phase contains asphaltene molecules.

  9. Conformational properties of an adsorbed charged polymer.

    PubMed

    Cheng, Chi-Ho; Lai, Pik-Yin

    2005-06-01

    The behavior of a strongly charged polymer adsorbed on an oppositely charged surface of a low-dielectric constant is formulated by the functional integral method. By separating the translational, conformational, and fluctuational degrees of freedom, the scaling behaviors for both the height of the polymer and the thickness of the diffusion layer are determined. Unlike the results predicted by scaling theory, we identified the continuous crossover from the weak compression to the compression regime. All the analytical results are found to be consistent with Monte Carlo simulations. Finally, an alternative (operational) definition of a charged polymer adsorption is proposed. PMID:16089715

  10. Recovery of Technetium Adsorbed on Charcoal

    SciTech Connect

    Engelmann, Mark D.; Metz, Lori A.; Ballou, Nathan E.

    2006-05-01

    Two methods capable of near complete recovery of technetium adsorbed on charcoal are presented. The first involves liquid extraction of the technetium from the charcoal by hot 4M nitric acid. An average recovery of 98% (n=3) is obtained after three rounds of extraction. The second method involves dry ashing with air in a quartz combustion tube at 400-450 C. This method yields an average recovery of 96% (n=5). Other thermal methods were attempted, but resulted in reduced recovery and incomplete material balance

  11. Lead removal with adsorbing colloid flotation

    SciTech Connect

    Thackston, E.L.; Wilson, D.J.; Hanson, J.S.; Miller, D.L. Jr.

    1980-02-01

    A process that removes lead from industrial waste by adsorbing colloid foam flotation has been designed and demonstrated. A system of ferric chloride and sodium lauryl sulfate, both relatively inexpensive chemicals, gave good performance with optimum dosages of sodium lauryl sulfate at 40 mg/l and trivalent iron at 150 mg/l. With optimum chemical and hydraulic conditions, the pilot plant was able to produce effluents with lead concentrations of less than 0.5 mg/l. The process may be especially attractive where space for heavy metals removal equipment is extremely limited.

  12. Raman fingerprint of doping due to metal adsorbates on graphene.

    PubMed

    Iqbal, M W; Singh, Arun Kumar; Iqbal, M Z; Eom, Jonghwa

    2012-08-22

    The properties of single-layer graphene are strongly affected by metal adsorbates and clusters on graphene. Here, we study the effect of a thin layer of chromium (Cr) and titanium (Ti) metals on chemical vapor deposition (CVD)-grown graphene by using Raman spectroscopy and transport measurements. The Raman spectra and transport measurements show that both Cr and Ti metals affect the structure as well as the electronic properties of the CVD-grown graphene. The shift of peak frequencies, intensities and widths of the Raman bands are analyzed after the deposition of metal films of different thickness on CVD-grown graphene. The shifts in G and 2D peak positions indicate the doping effect of graphene by Cr and Ti metals. While p-type doping was observed for Cr-coated graphene, n-type doping was observed for Ti-coated graphene. The doping effect is also confirmed by measuring the gate voltage dependent resistivity of graphene. We have also found that annealing in Ar atmosphere induces a p-type doping effect on Cr- or Ti-coated CVD-grown graphene. PMID:22814217

  13. Raman fingerprint of doping due to metal adsorbates on graphene

    NASA Astrophysics Data System (ADS)

    Iqbal, M. W.; Singh, Arun Kumar; Iqbal, M. Z.; Eom, Jonghwa

    2012-08-01

    The properties of single-layer graphene are strongly affected by metal adsorbates and clusters on graphene. Here, we study the effect of a thin layer of chromium (Cr) and titanium (Ti) metals on chemical vapor deposition (CVD)-grown graphene by using Raman spectroscopy and transport measurements. The Raman spectra and transport measurements show that both Cr and Ti metals affect the structure as well as the electronic properties of the CVD-grown graphene. The shift of peak frequencies, intensities and widths of the Raman bands are analyzed after the deposition of metal films of different thickness on CVD-grown graphene. The shifts in G and 2D peak positions indicate the doping effect of graphene by Cr and Ti metals. While p-type doping was observed for Cr-coated graphene, n-type doping was observed for Ti-coated graphene. The doping effect is also confirmed by measuring the gate voltage dependent resistivity of graphene. We have also found that annealing in Ar atmosphere induces a p-type doping effect on Cr- or Ti-coated CVD-grown graphene.

  14. Label-free optical detection of C-reactive protein by nanoimprint lithography-based 2D-photonic crystal film.

    PubMed

    Endo, Tatsuro; Kajita, Hiroshi; Kawaguchi, Yukio; Kosaka, Terumasa; Himi, Toshiyuki

    2016-06-01

    The development of high-sensitive, and cost-effective novel biosensors have been strongly desired for future medical diagnostics. To develop novel biosensor, the authors focused on the specific optical characteristics of photonic crystal. In this study, a label-free optical biosensor, polymer-based two-dimensional photonic crystal (2D-PhC) film fabricated using nanoimprint lithography (NIL), was developed for detection of C-reactive protein (CRP) in human serum. The nano-hole array constructed NIL-based 2D-PhC (hole diameter: 230 nm, distance: 230, depth: 200 nm) was fabricated on a cyclo-olefin polymer (COP) film (100 µm) using thermal NIL and required surface modifications to reduce nonspecific adsorption of target proteins. Antigen-antibody reactions on the NIL-based 2D-PhC caused changes to the surrounding refractive index, which was monitored as reflection spectrum changes in the visible region. By using surface modified 2D-PhC, the calculated detection limit for CRP was 12.24 pg/mL at an extremely short reaction time (5 min) without the need for additional labeling procedures and secondary antibody. Furthermore, using the dual-functional random copolymer, CRP could be detected in a pooled blood serum diluted 100× with dramatic reduction of nonspecific adsorption. From these results, the NIL-based 2D-PhC film has great potential for development of an on-site, high-sensitivity, cost-effective, label-free biosensor for medical diagnostics applications. PMID:27150702

  15. Adsorbents as antiendotoxin agents in experimental colitis.

    PubMed Central

    Gardiner, K R; Anderson, N H; McCaigue, M D; Erwin, P J; Halliday, M I; Rowlands, B J

    1993-01-01

    The intestinal mucosa protects the body from a large reservoir of intraluminal pathogenic bacteria and endotoxins. This mucosal barrier is disrupted by the inflammation and ulceration of inflammatory bowel disease and may permit the absorption of toxic bacterial products. Systemic endotoxaemia has been demonstrated in ulcerative colitis and Crohn's disease and correlates with the extent and activity of disease. In this study the efficacy of absorbents as antiendotoxin agents in a hapten induced rat model of colitis is investigated. Induction of colitis was associated with systemic endotoxaemia. Enteral administration of terra fullonica and kaolin, but not of charcoal, significantly reduced systemic endotoxaemia (terra fullonica 4.2 (1.40) pg/ml; kaolin 5.29 (1.86) pg/ml; charcoal 32.7 (16.6) pg/ml; water 39.8 (12.6) pg/ml). Data expressed as mean (SE). With increasing severity of colitis, there was a decreasing ability of adsorbent therapy (terra fullonica) to control systemic endotoxaemia. Enteral administration of adsorbents controls gut derived systemic endotoxaemia in experimental colitis in animals and may be a useful antiendotoxin treatment in patients with inflammatory bowel disease. PMID:8432452

  16. Mimetite Formation from Goethite-Adsorbed Ions.

    PubMed

    Kleszczewska-Zębala, Anna; Manecki, Maciej; Bajda, Tomasz; Rakovan, John; Borkiewicz, Olaf J

    2016-06-01

    Bioavailability of arsenic in contaminated soils and wastes can be reduced to insignificant levels by precipitation of mimetite Pb5(AsO4)3Cl. The objective of this study is to elucidate mechanisms of the reaction between solution containing lead ions and arsenates adsorbed on synthetic goethite (AsO4-goethite), or arsenate ions in the solution and goethite saturated with adsorbed Pb (Pb-goethite). These reactions, in the presence of Cl, result in rapid crystallization of mimetite. Formation of mimetite is faster than desorption of AsO4 but slower than desorption of Pb from the goethite surface. Slow desorption of arsenates from AsO4-goethite results in heterogeneous precipitation and formation of mimetite incrustation on goethite crystals. Desorption of lead from Pb-goethite is at least as fast as diffusion and advection of AsO4 and Cl in suspension allowing for homogeneous crystallization of mimetite in intergranular solution. Therefore, the mechanism of nucleation is primarily driven by the kinetics of constituent supply to the saturation front, rather than by the thermodynamics of nucleation. The products of the reactions are well documented using microscopy methods such as scanning electron microscopy, electron backscattered diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy. PMID:27329315

  17. The persistence length of adsorbed dendronized polymers.

    PubMed

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-21

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role. PMID:27353115

  18. Photodecomposition of chloromethanes adsorbed on silica surfaces

    NASA Technical Reports Server (NTRS)

    Ausloos, P.; Rebbert, R. E.; Glasgow, L.

    1977-01-01

    Irradiation of CCl4, CFCl3, and CF2Cl2 in the presence of C2H6 in vessels containing silica sand or fused quartz tubing results in the formation of chlorine-containing products. The formation of these compounds occurs at wavelengths extending up to approximately 400 nm, that is, at wavelengths well beyond the absorption threshold of the chloromethanes in the gas phase. It is suggested that CCl4 adsorbed on silica surfaces photodissociates to yield CCl3 and CCl2 species. The poor material balance obtained in these experiments indicates that several of the chlorine-containing fragments are strongly adsorbed on the surface. At a CCl4 pressure of 13 Pa (0.1 torr), photolysis with 366 nm light in the presence of sand results in the decomposition of one molecule for every 10,000 photons striking the surface. Under otherwise identical conditions, the photon-induced breadkdown of CFCl3 and CF2Cl2 is respectively only 10% or 3% as efficient.

  19. Investigation of drug-porous adsorbent interactions in drug mixtures with selected porous adsorbents.

    PubMed

    Madieh, Shadi; Simone, Michael; Wilson, Wendy; Mehra, Dev; Augsburger, Larry

    2007-04-01

    The adsorption of drugs onto porous substrates may prove to be a convenient method by which to enhance the dissolution rate of certain poorly water-soluble drugs in body fluids. The purpose of this research is to provide a better understanding of the type of interactions occurring between drugs and certain pharmaceutically acceptable porous adsorbents that leads to enhanced drug dissolution rates. The interactions between ibuprofen (acidic drug), acetaminophen (acidic drug), dipyridamole (basic drug), and the porous adsorbents used (calcium silicate and silica gel) were investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier Transform infrared spectroscopy (FTIR). DSC and PXRD results indicated a significant loss of crystallinity of both ibuprofen and acetaminophen but not dipyridamole. In the case of ibuprofen, FTIR results indicated the ionization of the carboxylic group based on the shift in the FTIR carboxylic band. Dissolution of ibuprofen from its mixtures with porous adsorbents was found to be significantly higher compared to the neat drug, whereas dipyridamole dissolution from its mixtures with porous adsorbents was not significantly different from that of the neat drug. PMID:17221849

  20. Equilibrium molecular theory of two-dimensional adsorbate drops on surfaces of heterogeneous adsorbents

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2016-08-01

    A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor-fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

  1. Simple synthesis of smart magnetically driven fibrous films for remote controllable oil removal

    NASA Astrophysics Data System (ADS)

    Wu, Jing; Wang, Nü; Zhao, Yong; Jiang, Lei

    2015-01-01

    Inspired by the marine mussel adhesive protein, smart, magnetically controllable, oil adsorption nanofibrous materials were successfully fabricated in this research. Taking advantage of the properties of dopamine whose molecular structure mimics the single unit of the marine mussel adhesive protein and can be polymerized in alkaline solution forming a ``glue'' layer on many kinds of material surfaces, magnetic iron(ii, iii) oxide (Fe3O4) nanoparticles were easily and robustly anchored on to electrospun poly(vinylidene fluoride) fibrous films. After fluorination, the as-prepared hierarchical structured films exhibited superhydrophobicity, superoleophilicity and an excellent oil adsorption capacity from water. Importantly, because of the magnetically controllable property endowed by the Fe3O4 nanoparticles, such fibrous films act as a ``smart magnetically controlled oil removal carrier'', which effectively overcome the drawbacks of other in situ oil adsorbant materials and can also be easily recovered. This work provides a simple strategy to fabricate magnetic responsive intelligent oil removal materials, which will find broad applications in complex environment oil-water separation.Inspired by the marine mussel adhesive protein, smart, magnetically controllable, oil adsorption nanofibrous materials were successfully fabricated in this research. Taking advantage of the properties of dopamine whose molecular structure mimics the single unit of the marine mussel adhesive protein and can be polymerized in alkaline solution forming a ``glue'' layer on many kinds of material surfaces, magnetic iron(ii, iii) oxide (Fe3O4) nanoparticles were easily and robustly anchored on to electrospun poly(vinylidene fluoride) fibrous films. After fluorination, the as-prepared hierarchical structured films exhibited superhydrophobicity, superoleophilicity and an excellent oil adsorption capacity from water. Importantly, because of the magnetically controllable property endowed by the Fe3

  2. Fabrication of Micro-Lens Array using a Chemically Adsorbed Monomolecular Layer

    NASA Astrophysics Data System (ADS)

    Okada, Kazushi; Oohira, Fumikazu; Hosogi, Maho; Hashiguchi, Gen; Mihara, Yutaka; Ogawa, Kazufumi; Shiwaku, Kazuya

    We proposed a new method of patterning a chemically adsorbed monomolecular layer on the substrate and then dropping UV cure material to form a lens shape using oil repellent effect of this film. The curvature radius of the lens was controlled by the amount of the dropped UV cure material. Using this method, a micro-lens array of various radiuses was fabricated. The formed micro-lens array shapes are transferred by the electro-plating and then the micro dies are fabricated, which are used for molding the plastic lens array. The optical characteristic of the molded micro-lens was evaluated.

  3. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    SciTech Connect

    Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W. -P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  4. Bioaffinity sensor based on nanoarchitectonic films: control of the specific adsorption of proteins through the dual role of an ethylene oxide spacer.

    PubMed

    Davila, Johanna; Toulemon, Delphine; Garnier, Tony; Garnier, Aurélie; Senger, Bernard; Voegel, Jean-Claude; Mésini, Philippe J; Schaaf, Pierre; Boulmedais, Fouzia; Jierry, Loïc

    2013-06-18

    The identification and quantification of biomarkers or proteins is a real challenge in allowing the early detection of diseases. The functionalization of the biosensor surface has to be properly designed to prevent nonspecific interactions and to detect the biomolecule of interest specifically. A multilayered nanoarchitecture, based on polyelectrolyte multilayers (PEM) and the sequential immobilization of streptavidin and a biotinylated antibody, was elaborated as a promising platform for the label-free sensing of targeted proteins. We choose ovalbumin as an example. Thanks to the versatility of PEM films, the platform was built on two types of sensor surface and was evaluated using both optical- and viscoelastic-based techniques, namely, optical waveguide lightmode spectroscopy and the quartz crystal microbalance, respectively. A library of biotinylated poly(acrylic acids) (PAAs) was synthesized by grafting biotin moieties at different grafting ratios (GR). The biotin moieties were linked to the PAA chains through ethylene oxide (EO) spacers of different lengths. The adsorption of the PAA-EOn-biotin (GR) layer on a PEM precursor film allows tuning the surface density in biotin and thus the streptavidin adsorption mainly through the grafting ratio. The nonspecific adsorption of serum was reduced and even suppressed depending on the length of the EO arms. We showed that to obtain an antifouling polyelectrolyte the grafting of EO9 or EO19 chains at 25% in GR is sufficient. Thus, the spacer has a dual role: ensuring the antifouling property and allowing the accessibility of biotin moieties. Finally, an optimized platform based on the PAA-EO9-biotin (25%)/streptavidin/biotinylated-antibody architecture was built and demonstrated promising performance as interface architecture for bioaffinity sensing of a targeted protein, in our case, ovalbumin. PMID:23346932

  5. pH-dependent immobilization of proteins on surfaces functionalized by plasma-enhanced chemical vapor deposition of poly(acrylic acid)- and poly(ethylene oxide)-like films.

    PubMed

    Belegrinou, Serena; Mannelli, Ilaria; Lisboa, Patricia; Bretagnol, Frederic; Valsesia, Andrea; Ceccone, Giacomo; Colpo, Pascal; Rauscher, Hubert; Rossi, François

    2008-07-15

    The interaction of the proteins bovine serum albumin (BSA), lysozyme (Lys), lactoferrin (Lf), and fibronectin (Fn) with surfaces of protein-resistant poly(ethylene oxide) (PEO) and protein-adsorbing poly(acrylic acid) (PAA) fabricated by plasma-enhanced chemical vapor deposition has been studied with quartz crystal microbalance with dissipation monitoring (QCM-D). We focus on several parameters which are crucial for protein adsorption, i.e., the isoelectric point (pI) of the proteins, the pH of the solution, and the charge density of the sorbent surfaces, with the zeta-potential as a measure for the latter. The measurements reveal adsorption stages characterized by different segments in the plots of the dissipation vs frequency change. PEO remains protein-repellent for BSA, Lys, and Lf at pH 4-8.5, while weak adsorption of Fn was observed. On PAA, different stages of protein adsorption processes could be distinguished under most experimental conditions. BSA, Lys, Lf, and Fn generally exhibit a rapid initial adsorption phase on PAA, often followed by slower processes. The evaluation of the adsorption kinetics also reveals different adsorption stages, whereas the number of these stages does not always correspond to the structurally different phases as revealed by the D- f plots. The results presented here, together with information obtained in previous studies by other groups on the properties of these proteins and their interaction with surfaces, allow us to develop an adsorption scenario for each of these proteins, which takes into account electrostatic protein-surface and protein-protein interaction, but also the pH-dependent properties of the proteins, such as shape and exposure of specific domains. PMID:18549295

  6. Adsorption and conformational modification of fibronectin and fibrinogen adsorbed on hydroxyapatite. A QCM-D study.

    PubMed

    Fernández-Montes Moraleda, Belén; San Román, Julio; Rodríguez-Lorenzo, Luís M

    2016-10-01

    Hydroxyapatite is a bioactive ceramic frequently used for bone engineering/replacement. One of the parameters that influence the biological response to implanted materials is the conformation of the first adsorbed protein layer. In this work, the adsorption and conformational changes of two fibroid serum proteins; fibronectin and fibrinogen adsorbed onto four different hydroxyapatite powders are studied with a Quartz Crystal Microbalance with Dissipation (QCM-D). Each of the calcined apatites adsorbs less protein than their corresponding synthesized samples. Adsorption on synthesized samples yields always an extended conformation whereas a reorganization of the layer is observed for the calcined samples. Fg acquires a "Side on" conformation in all the samples at the beginning of the experiment except for one of the synthesized samples where an "End-on" conformation is obtained during the whole experiment. The Extended conformation is the active conformation for Fn. This conformation is favored by apatites with large specific surface area (SSA) and on highly concentrated media. Apatite surface features should be considered in the selection or design of materials for bone regeneration, since it is possible to control the conformation mode of attachment of Fn and Fg by an appropriate selection of them. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2585-2594, 2016. PMID:27254464

  7. Solution- and Adsorbed-State Structural Ensembles Predicted for the Statherin-Hydroxyapatite System

    PubMed Central

    Masica, David L.; Gray, Jeffrey J.

    2009-01-01

    Abstract We have developed a multiscale structure prediction technique to study solution- and adsorbed-state ensembles of biomineralization proteins. The algorithm employs a Metropolis Monte Carlo-plus-minimization strategy that varies all torsional and rigid-body protein degrees of freedom. We applied the technique to fold statherin, starting from a fully extended peptide chain in solution, in the presence of hydroxyapatite (HAp) (001), (010), and (100) monoclinic crystals. Blind (unbiased) predictions capture experimentally observed macroscopic and high-resolution structural features and show minimal statherin structural change upon adsorption. The dominant structural difference between solution and adsorbed states is an experimentally observed folding event in statherin's helical binding domain. Whereas predicted statherin conformers vary slightly at three different HAp crystal faces, geometric and chemical similarities of the surfaces allow structurally promiscuous binding. Finally, we compare blind predictions with those obtained from simulation biased to satisfy all previously published solid-state NMR (ssNMR) distance and angle measurements (acquired from HAp-adsorbed statherin). Atomic clashes in these structures suggest a plausible, alternative interpretation of some ssNMR measurements as intermolecular rather than intramolecular. This work demonstrates that a combination of ssNMR and structure prediction could effectively determine high-resolution protein structures at biomineral interfaces. PMID:19383454

  8. Fundamental characteristics of synthetic adsorbents intended for industrial chromatographic separations.

    PubMed

    Adachi, Tadashi; Isobe, Eiji

    2004-05-14

    With the aim of obtaining comprehensive information on the selection of synthetic adsorbents for industrial applications, effect of pore and chemical structure of industrial-grade synthetic adsorbents on adsorption capacity of several pharmaceutical compounds was investigated. For relatively low molecular mass compounds, such as cephalexin, berberine chloride and tetracycline hydrochloride, surface area per unit volume of polystyrenic adsorbents dominated the equilibrium adsorption capacity. On the contrary, effect of pore size of the polystyrenic adsorbents on the equilibrium adsorption capacity was observed for relatively high molecular mass compounds, such as rifampicin, Vitamin B12 and insulin. Polystyrenic adsorbent with high surface area and small pore size showed small adsorption capacity for relatively high molecular mass compounds, whereas polystyrenic adsorbent with relatively small surface area but with large pore size showed large adsorption capacity. Effect of chemical structure on the equilibrium adsorption capacity of several pharmaceutical compounds was also studied among polystyrenic, modified polystyrenic and polymethacrylic adsorbents. The modified polystyrenic adsorbent showed larger adsorption capacity for all compounds tested in this study due to enhanced hydrophobicity. The polymethacrylic adsorbent possessed high adsorption capacity for rifampicin and insulin, but it showed lower adsorption capacity for the other compounds studied. This result may be attributed to hydrogen bonding playing major role for the adsorption of compounds on polymethacrylic adsorbent. Furthermore, column adsorption experiments were operated to estimate the effect of pore characteristics of the polystyrenic adsorbents on dynamic adsorption behavior, and it is found that both surface area and pore size of the polystyrenic adsorbents significantly affect the dynamic adsorption capacity as well as flow rate. PMID:15139411

  9. Improved photocatalytic activity of zeolite- and silica-incorporated TiO2 film.

    PubMed

    Tanaka, K; Fukuyoshi, J; Segawa, H; Yoshida, K

    2006-09-21

    Porous TiO2 film was prepared by sol-gel method from TiO2 sol containing polyvinylpyrolidone (PVP). Photocatalytic activity of the film was evaluated by the elimination rate of ethylene. Several adsorbents including zeolite and silica powders were incorporated into the TiO2 film. All the adsorbents enhanced the activity. The optimum adsorbent content was 0.005-0.01 g/ml of the coating sol solution. Silica provided better activity than zeolite. At high humidity and in dry air the activity decreased. PMID:16704899

  10. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, G.I.; Dietz, R.N.

    1994-04-05

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons. 8 figures.

  11. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, Gunnar I.; Dietz, Russell N.

    1994-01-01

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons.

  12. Video STM Studies of Adsorbate Diffusion at Electrochemical Interfaces

    NASA Astrophysics Data System (ADS)

    Tansel, T.; Magnussen, O. M.

    2006-01-01

    Direct in situ studies of the surface diffusion of isolated adsorbates at an electrochemical interface by high-speed scanning tunneling microscopy (video STM) are presented for sulfide adsorbates on Cu(100) in HCl solution. As revealed by a quantitative statistical analysis, the adsorbate motion can be described by thermally activated hopping between neighboring adsorption sites with an activation energy that increases linearly with electrode potential by 0.50 eV per V. This can be explained by changes in the adsorbate dipole moment during the hopping process and contributions from coadsorbates.

  13. Stability of aqueous films between bubbles. Part 2. Effects of trace impurities and evaporation.

    PubMed

    Yaminsky, Vassili V; Ohnishi, Satomi; Vogler, Erwin A; Horn, Roger G

    2010-06-01

    The stability of water films has been investigated with a Mysels-Scheludko type film balance. Minor trace impurities in water do not affect the lifetime of water films under vapor saturation, but significantly influence the stability in free evaporation. Trace amounts of positively adsorbed contaminants induce Marangoni-driven flow that destabilizes films under evaporation conditions whereas negatively adsorbed electrolytes actually prolong stability by reversing interfacial tension gradients and driving a steady circulation within the film. At high thinning rates, pure-water films develop exotic-appearing flow patterns and break due to a strong coupling between hydrodynamic and interfacial tension-gradient adsorption stresses. The most dominant factor of transient film stabilization in dynamic conditions under evaporation is a surface tension gradient created in the film. We discuss surface tension gradients in transient films created by temperature differences, impurity concentration, and expansion of the films. PMID:20146432

  14. Linear dichroism of microalgae, developing thylakoids and isolated pigment-protein complexes in stretched poly(vinyl alcohol) films at 77 K.

    PubMed

    Biggins, J; Svejkovský, J

    1980-10-01

    A variety of unicellular algae, thylakoids from higher plants in different stages of maturity and isolated pigment-protein complexes were oriented in stretched polyvinyl alcohol films. Low temperature linear dichroism (LD) spectra of Chlorella pyrenoidosa and higher plant thylakoids in the films were very similar to those obtained after orientation of similar samples using magnetic or electric fields. Positive LD bands corresponding to Chl a (670) and (682) and negative bands due to Chl a (658) and Chl b(648) were resolved in spectra of the light harvesting Chl a/b protein. Chl b (648) and Chl a (658) and (670) were not seen in the LD spectrum of thylakoids from plants grown in intermittent light, the Chl b-less mutant of barley, Euglena gracilis or the cyanobacteria, Phormidium luridum and Anacystis nidulans, but did appear upon chloroplast maturation in Romaine lettuce and during the greening of etiolated and intermittent light plants. The highly oriented long wavelength Chl a (682) in the light-harvesting complex may represent residual PS II whose peak dichroism is centered at 681 nm. The PS I preparation had a Chl a/b ratio of approx. 6 and the LD spectrum was positive with a maximum at 690-694 nm and a band of lower amplitude at 652 nm. The minor LD band was not observed in PS I preparations from organisms that lack chl b such as the cyanobacteria, intermittent light plants and the Chl b-less mutant of barley. We suggest that the 652 nm band is due to Chl b molecules associated with the antenna of PS I and are distinct from those on the light harvesting complex whose orientation is different. We also conclude that all the Chl a forms are oriented and that the long geometric axes of the pigment-protein complexes, as deduced from the configuration they assume in the stretched films, are axes that normally lie parallel to the plane of the native thylakoid. PMID:6774749

  15. Linear transport models for adsorbing solutes

    NASA Astrophysics Data System (ADS)

    Roth, K.; Jury, W. A.

    1993-04-01

    A unified linear theory for the transport of adsorbing solutes through soils is presented and applied to analyze movement of napropamide through undisturbed soil columns. The transport characteristics of the soil are expressed in terms of the travel time distribution of the mobile phase which is then used to incorporate local interaction processes. This approach permits the analysis of all linear transport processes, not only the small subset for which a differential description is known. From a practical point of view, it allows the direct use of measured concentrations or fluxes of conservative solutes to characterize the mobile phase without first subjecting them to any model. For complicated flow regimes, this may vastly improve the identification of models and estimation of their parameters for the local adsorption processes.

  16. The persistence length of adsorbed dendronized polymers

    NASA Astrophysics Data System (ADS)

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A. Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-01

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role.The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth

  17. Removal of aqueous nickel (II) using laterite as a low-cost adsorbent.

    PubMed

    Mukherjee, Somnath; Kumar, Sunil; Misra, A K; Acharya, P C

    2006-10-01

    The present paper describes the laboratory study of laterite as a low-cost adsorbent for removal of aqueous nickel (II). At pH 7 and a temperature of 30 degrees C, a sorbent dose of 15 mg/L resulted in approximately 90% removal of nickel (II) from its initial concentration of 10 mg/L. A maximum removal of 98% of the adsorbate was observed with an adsorbent particle size of 210 micro with the above conditions. Batch kinetics results were described by fitting in a Langmuir isotherm. Helffrich's half-time equation (Helffrich, 1962) has been applied to evaluate the adsorption process. It appears that film diffusion would be the rate-limiting step. The effect of pH on the sorption process was carried out to a value of 8.0. The removal rate of nickel was found to be the function of pH of the reaction mixture. The rate of nickel uptake by laterite with the decrease in pH value has been explained on the basis of aqueous-complex formation and the subsequent acid-base dissociation at the solid-solution interface. PMID:17120446

  18. Hydrodynamic thickness of petroleum oil adsorbed layers in the pores of reservoir rocks.

    PubMed

    Alkafeef, Saad F; Algharaib, Meshal K; Alajmi, Abdullah F

    2006-06-01

    The hydrodynamic thickness delta of adsorbed petroleum (crude) oil layers into the pores of sandstone rocks, through which the liquid flows, has been studied by Poiseuille's flow law and the evolution of (electrical) streaming current. The adsorption of petroleum oil is accompanied by a numerical reduction in the (negative) surface potential of the pore walls, eventually stabilizing at a small positive potential, attributed to the oil macromolecules themselves. After increasing to around 30% of the pore radius, the adsorbed layer thickness delta stopped growing either with time or with concentrations of asphaltene in the flowing liquid. The adsorption thickness is confirmed with the blockage value of the rock pores' area determined by the combination of streaming current and streaming potential measurements. This behavior is attributed to the effect on the disjoining pressure across the adsorbed layer, as described by Derjaguin and Churaev, of which the polymolecular adsorption films lose their stability long before their thickness has approached the radius of the rock pore. PMID:16414057

  19. Vibrational Spectra of Vinyltriethoxysilane (vtes) Monolayers Adsorbed on Germania and Alumina

    NASA Astrophysics Data System (ADS)

    Craig, Ronald; Mallik, Robert R.

    1997-05-01

    VTES is used as a coupling agent to improve the adhesion of various coatings especially to glass, but also to minerals, metal oxides and other substrates. It has been studied extensively in this context by Infrared, Raman, and other spectroscopic methods; however, few of these methods have the sensitivity to probe effectively the first adsorbed monolayer on the above substrates. Inelastic Electron Tunneling Spectroscopy (IETS), however, is intrinsically capable of detecting fractional monolayer coverage, but, until recently, studies have been limited primarily to the adsorption of monolayers on aluminum oxide which forms the insulating barrier in most metal/insulator/metal IET junctions. IETS has not been used to investigate adorbates on other barriers because it is difficult to make the barriers suitably thin and physically continuous. We are now able to fabricate viable IETS barriers by radio-frequency sputtering, and we present spectra of VTES adsorbed on thermally grown alumina, and sputtered germania films. Germania is chosen as a model for glass to avoid any ambiguity in assigning Si-O related vibrational modes to either the adsorband or adsorbate.

  20. Adsorption of Polyethylene from Solution onto Starch Film Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since starch adsorbs onto polyethylene (PE) surfaces from cooled solutions of jet cooked starch, this study was carried out to determine whether adsorption of PE onto hydrophilic starch film surfaces would also take place if starch films were placed in hot solutions of PE in organic solvents, and th...

  1. Neutron Reflectometry Studies of the Adsorbed Structure of the Amelogenin, LRAP

    SciTech Connect

    Tarasevich, Barbara J.; Perez-Salas, Ursula; Masica, David L.; Philo, John; Krueger, Susan; Majkrzak, Charles F.; Gray, Jeffrey J.; Shaw, Wendy J.

    2013-03-21

    Amelogenins make up over 90 percent of the protein present during enamel formation and have been demonstrated to be critical in proper enamel development, but the mechanism governing this control is not well understood. Leucine-rich amelogenin peptide (LRAP) is a 59-residue splice variant of amelogenin and contains the charged regions from the full protein thought to control crystal regulation. In this work, we utilized neutron reflectivity (NR) to investigate the structure and orientation of LRAP adsorbed from solutions onto molecularly smooth COOH-terminated self-assembled monolayers (SAMs) surfaces. Sedimentation velocity experiments revealed that LRAP is primarily a monomer in saturated calcium phosphate (SCP) solutions (0.15 M NaCl) at pH 7.4. LRAP adsorbed as ~33 Å thick layers at ~70% coverage as determined by NR. Rosetta simulations of the dimensions of LRAP in solution (37 Å diameter) indicate that the NR determined z dimension is consistent with an LRAP monomer. Sedimentation velocity experiments and Rosetta simulation show that the LRAP monomer has an extended, asymmetric shape in solution. The NR data suggests that the protein is not completely extended on the surface, having some degree of structure away from the surface. A protein orientation with the C-terminal and inner N-terminal region (~8-24)) located near the surface is consistent with the higher scattering length density (SLD) and higher protein hydration found near the surface by NR. This work presents new information on the tertiary and quaternary structure of LRAP in solution and adsorbed onto surfaces. It also presents further evidence that the monomeric species may be an important functional form of amelogenin proteins.

  2. A self-assembled polydopamine film on the surface of magnetic nanoparticles for specific capture of protein

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Zhang, Xihao; He, Xiwen; Chen, Langxing; Zhang, Yukui

    2012-05-01

    In this study, we report a facile method for the preparation of core-shell magnetic molecularly imprinted polymers (MIPs) for protein recognition. Uniform carboxyl group functionalized Fe3O4 nanoparticles (NPs) were synthesized using a solvothermal method. Magnetic MIPs were synthesized by self-polymerization of dopamine in the presence of template protein on the surface of the Fe3O4 NPs. A thin layer of polydopamine can be coated on Fe3O4 NPs via dopamine self-polymerization and the imprinted polydopamine shells can be controlled by the mass ratio of Fe3O4 NPs and dopamine. More importantly, there is a critical value of polydopamine shell thickness for the maximum rebinding capacity. The as-prepared lysozyme-imprinted Fe3O4@polydopamine NPs show high binding capacity and acceptable specific recognition behavior towards template proteins. This method provides the possibility for the separation and enrichment of abundant proteins in proteomic analysis.

  3. Probing interactions between TiO 2 photocatalyst and adsorbing species using quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Morand, R.; Noworyta, K.; Augustynski, J.

    2002-10-01

    Photoactivity of nanocrystalline TiO 2 films is shown to be strongly affected by the presence in aqueous solution of salicylic acid, known to form Ti(IV)salicylate surface complexes. In particular, the photooxidation of methanol - an effective hole scavenger - at TiO 2 appears to be in part, or even completely inhibited by the additions of increasing amounts of salicylic acid. The chemisorption of salicylic and also phthalic acid on TiO 2 was followed using quartz crystal microbalance, QCM. The observed resonant frequency changes of the quartz crystal bearing TiO 2 films, accompanying increasing additions of the benzoic acids to the contacting solutions, indicate large displacement of water as a consequence of the adsorbent-imparted hydrophobicity of the interface.

  4. Sensitive detection and prevention of protein adsorption on biomaterial (lipid bilayer) surfaces

    NASA Astrophysics Data System (ADS)

    Xu, Zhong

    2000-10-01

    The adsorption of proteins on biomaterial surfaces is recognized as the first and the most important event that determines or directs consequent host responses. The amount, composition, conformation, and binding affinity of the adsorbed proteins are critical in determining events leading to blood coagulation, platelet adhesion and activation, mammalian and bacterial cell adhesion, and complement activation. This thesis is concerned with the non-specific adsorption of plasma proteins on self-assembled phospholipid surfaces. To examine molecular events in detail, adsorption of plasma proteins on lipid bilayers was studied on both supported planar bilayer and liposomes (phospholipid vesicles) systems. Monolayers of mixed distearoylphosphatidlcholine (DSPC) and PEO (MW. 2000)-grafted distearoylphosphatidylethanolanane (PEO2k-DSPE) were deposited on DSPE-coated quartz substrates by Langmuir-Blodgett (LB) deposition technique. A sensitive total internal reflection fluorescence (TIRF) method, capable of detecting the adsorption of <0.3 ng/cm2 of fluorescein-labeled fibrinogen at a temporal resolution of 0.2 sec, was utilized to study adsorption kinetics of plasma proteins on the supported lipid bilayers. All supported lipid bilayers exhibited over a magnitude reduction in adsorbed plasma proteins compared with the quartz substrate. The increase of PEO2k-DSPE density in the mixed bilayers slightly increased the amount of adsorbed proteins on the bilayers. Plasma proteins adsorbed on liposomes (composed of DSPC and cholesterol) were studied using a spin column procedure for liposome isolation, and SDS-polyacrylamide gel electrophoresis and immunoanalysis for protein separation, quantification and identification. Plasma proteins isolated from liposome surfaces showed distinct and complex profiles. Albumin and fibrinogen were identified as two major plasma proteins that undergo non-specific adsorption on liposomes. Incorporating (PEO2k-DSPE) into liposomes reduced the amount

  5. Protein-resistant cross-linked poly(vinyl alcohol) micropatterns via photolithography using removable polyoxometalate photocatalyst.

    PubMed

    Pavli, Pagona; Petrou, Panagiota S; Douvas, Antonios M; Dimotikali, Dimitra; Kakabakos, Sotirios E; Argitis, Panagiotis

    2014-10-22

    In the last years, there has been an increasing interest in controlling the protein adsorption properties of surfaces because this control is crucial for the design of biomaterials. On the other hand, controlled immobilization of proteins is also important for their application as solid surfaces in immunodiagnostics and biosensors. Herein we report a new protein patterning method where regions of the substrate are covered by a hydrophilic film that minimizes protein adsorption. Particularly, poly(vinyl alcohol) (PVA) cross-linked structures created by an especially developed photolithographic process are proved to prevent protein physisorption and they are used as a guide for selective protein adsorption on the uncovered areas of a protein adsorbing substrate such as polystyrene. The PVA cross-linking is induced by photo-oxidation using, as a catalyst, polyoxometalate (H3PW12O40 or α-(NH4)6P2W18O62), which is removed using a methyl alcohol/water mixed solvent as the developer. We demonstrate that the polystyrene and the cross-linked PVA exhibit dramatically different performances in terms of protein physisorption. In particular, the polystyrene areas presented up to 130 times higher protein binding capacity than the PVA ones, whereas the patterning resolution could easily reach dimensions of a few micrometers. The proposed approach can be applied on any substrate where PVA films can be coated for controlling protein adsorption onto surface areas custom defined by the user. PMID:25212665

  6. Emulsion-templated fully reversible protein-in-oil gels.

    PubMed

    Romoscanu, Alexandre I; Mezzenga, Raffaele

    2006-08-29

    We have developed a new method allowing us to transform low-viscous apolar fluids into elastic solids with a shear elastic modulus of the order of 10(3)-10(5) Pa. The elasticity of the elastic solid is provided by a percolating 3D network of proteins, which are originally adsorbed at the interface of an oil-in-water emulsion template. By cross-linking the protein films at the interface and upon removal of water, the template is driven into a structure resembling a dry foam where the protein interfaces constitute the walls of the foam and the air is replaced by oil confined within polyhedral, closely packed droplets. Depending on the density of the protein network, the final material consists of chemically unmodified oil in a proportion of 95 to 99.9%. The physical properties of the elastic solid obtained can be tuned by changing either the average diameter size of the emulsion template or the cross-linking process of the protein film. However, the original low-viscosity emulsion can be restored by simply rehydrating the solidified fluid. Therefore, the present procedure offers an appealing strategy to build up solid properties for hydrophobic liquids while preserving the low viscosity and ease of manufacturing. PMID:16922568

  7. SORPTION PROPERTIES OF MODEL COMPOUNDS ON C18 ADSORBENTS

    EPA Science Inventory

    The bonded silica adsorbent Bondapak-C18 was evaluated for removing organic matter from secondary sewage effluents and from solutions of pure organic compounds. The adsorbent is hydrophobic and its behavior with water samples may be erratic unless first wet with a solvent. Howeve...

  8. Development of a Desulfurization Strategy for a NOx Adsorber Catalyst

    SciTech Connect

    Tomazic, Dean

    2000-08-20

    Improve NOx regeneration calibration developed in DECSE Phase I project to understand full potential of NOx adsorber catalyst over a range of operating temperatures. Develop and demonstrate a desulfurization process to restore NOx conversion efficiency lost to sulfur contamination. Investigate effect of desulfurization process on long-term performance of the NOx adsorber catalyst.

  9. Formation of a Rigid Hydrophobin Film and Disruption by an Anionic Surfactant at an Air/Water Interface.

    PubMed

    Kirby, Stephanie M; Zhang, Xujun; Russo, Paul S; Anna, Shelley L; Walker, Lynn M

    2016-06-01

    Hydrophobins are amphiphilic proteins produced by fungi. Cerato-ulmin (CU) is a hydrophobin that has been associated with Dutch elm disease. Like other hydrophobins, CU stabilizes air bubbles and oil droplets through the formation of a persistent protein film at the interface. The behavior of hydrophobins at surfaces has raised interest in their potential applications, including use in surface coatings, food foams, and emulsions and as dispersants. The practical use of hydrophobins requires an improved understanding of the interfacial behavior of these proteins, alone and in the presence of added surfactants. In this study, the adsorption behavior of CU at air/water interfaces is characterized by measuring the surface tension and interfacial rheology as a function of adsorption time. CU is found to adsorb irreversibly at air/water interfaces. The magnitude of the dilatational modulus increases with adsorption time and surface pressure until CU eventually forms a rigid film. The persistence of this film is tested through the sequential addition of strong surfactant sodium dodecyl sulfate (SDS) to the bulk liquid adjacent to the interface. SDS is found to coadsorb to interfaces precoated with a CU film. At high concentrations, the addition of SDS significantly decreases the dilatational modulus, indicating disruption and displacement of CU by SDS. Sequential adsorption results in mixed layers with properties not observed in interfaces generated from complexes formed in the bulk. These results lend insight to the complex interfacial interactions between hydrophobins and surfactants. PMID:27164189

  10. Polydopamine Thin Films as Protein Linker Layer for Sensitive Detection of Interleukin-6 by Surface Plasmon Enhanced Fluorescence Spectroscopy.

    PubMed

    Toma, Mana; Tawa, Keiko

    2016-08-31

    Polydopamine (PDA) thin films are introduced to the surface modification of biosensor surfaces utilizing surface plasmon enhanced fluorescence spectroscopy (SPFS) as the linker layer of capture antibody on to the sensor surfaces. The capture antibody can be directly attached to the sensor surface without using any coupling agent by functionalizing the gold sensor surface with PDA thin films. The PDA coating is performed by a single-step preparation process by applying the dopamine solution on the sensor surface, which requires an extremely short incubation time (10 min). The real-time in situ measurement of the adsorption kinetics of the capture antibody onto the PDA-coated sensor surface is studied by surface plasmon resonance (SPR) spectroscopy. It reveals that the immobilization of capture antibody immediately occurs after introduction of a solution containing capture antibody, and the sensor surface is fully covered with the capture antibody. The sensitive detection of the cytokine marker interleukin-6 (IL-6) is performed by SPFS using a sandwich assay format with fluorescently labeled detection antibody. The sensor chips functionalized by PDA chemistry exhibited sensitive sensor responses with low nonspecific adsorption of the detection antibody onto the sensor surface. The detection limit of IL-6 with the developed SPFS biosensor is determined to be 2 pg/mL (100 fM), which is within the range of the diagnostic criteria. Our observation elucidates the remarkable utility of PDA coatings for chemical modification of the metallic sensor surfaces by a simple, brief, and inexpensive manner. PMID:27484114

  11. Kinetic study of lead adsorption to composite biopolymer adsorbent

    SciTech Connect

    Seki, H.; Suzuki, A.

    1999-03-15

    A kinetic study of lead adsorption to composite biopolymer adsorbents was carried out. Spherical and membranous adsorbents containing two biopolymers, humic acid and alginic acid, were used for lead adsorption in dilute acidic solutions. The shrinking core model derived by M.G. Rao and A.K. Gupta was applied to describe the rate process of lead adsorption to spherical adsorbents (average radii of 0.12, 0.15, and 0.16 cm). Furthermore, the shrinking core model was modified and adapted for description of the rate process of lead adsorption to membranous adsorbent (average thickness of 0.0216 cm). The adsorption rate process for both the cases was well described and average apparent lead diffusion coefficients of about 6 {times} 10{sup {minus}6} and 7 {times} 10{sup {minus}6} cm{sup 2}/s were found for the spherical and membranous adsorbents, respectively.

  12. Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent.

    PubMed

    Seki; Suzuki

    1999-03-15

    A kinetic study of lead adsorption to composite biopolymer adsorbents was carried out. Spherical and membranous adsorbents containing two biopolymers, humic acid and alginic acid, were used for lead adsorption in dilute acidic solutions. The shrinking core model derived by M. G. Rao and A. K. Gupta (Chem. Eng. J. 24, 181, 1982) was applied to describe the rate process of lead adsorption to spherical adsorbents (average radii of 0.12, 0.15, and 0.16 cm). Furthermore, the shrinking core model was modified and adapted for description of the rate process of lead adsorption to membranous adsorbent (average thickness of 0.0216 cm). The adsorption rate process for the both cases was well described and average apparent lead diffusion coefficients of about 6 x 10(-6) and 7 x 10(-6) cm2 s-1 were found for the spherical and membranous adsorbents, respectively. Copyright 1999 Academic Press. PMID:10049553

  13. Neutron Reflectometry Studies of the Adsorbed Structure of the Amelogenin, LRAP

    PubMed Central

    Tarasevich, Barbara J.; Perez-Salas, Ursula; Masica, David L.; Philo, John; Kienzle, Paul; Krueger, Susan; Majkrzak, Charles F.; Gray, Jeffrey L.; Shaw, Wendy J.

    2013-01-01

    Amelogenins make up over 90 percent of the protein present during enamel formation and have been demonstrated to be critical in proper enamel development, but the mechanism governing this control is not well understood. Leucine-rich amelogenin peptide (LRAP) is a 59-residue splice variant of amelogenin and contains the charged regions from the full protein thought to control crystal regulation. In this work, we utilized neutron reflectivity (NR) to investigate the structure and orientation of LRAP adsorbed from solutions onto molecularly smooth COOH-terminated self-assembled monolayers (SAMs) surfaces. Sedimentation velocity (SV) experiments revealed that LRAP is primarily a monomer in saturated calcium phosphate (SCP) solutions (0.15 M NaCl) at pH 7.4. LRAP adsorbed as ~32 Å thick layers at ~70% coverage as determined by NR. Rosetta simulations of the dimensions of LRAP in solution (37 Å diameter) indicate that the NR determined z dimension is consistent with an LRAP monomer. SV experiments and Rosetta simulation show that the LRAP monomer has an extended, asymmetric shape in solution. The NR data suggests that the protein is not completely extended on the surface, having some degree of structure away from the surface. A protein orientation with the C-terminal and inner N-terminal region (residues ~8–24) located near the surface is consistent with the higher scattering length density (SLD) found near the surface by NR. This work presents new information on the tertiary and quaternary structure of LRAP in solution and adsorbed onto surfaces. It also presents further evidence that the monomeric species may be an important functional form of amelogenin proteins. PMID:23477285

  14. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    SciTech Connect

    Janke, Christopher James; Das, Sadananda; Oyola, Yatsandra; Mayes, Richard T.; Saito, Tomonori; Brown, Suree; Gill, Gary; Kuo, Li-Jung; Wood, Jordana

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  15. Imaging the wave functions of adsorbed molecules

    PubMed Central

    Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter

    2014-01-01

    The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust. PMID:24344291

  16. Mesoporous carbon nanomaterials as environmental adsorbents.

    PubMed

    Tripathi, Pranav K; Gan, Lihua; Liu, Mingxian; Rao, Nageswara N

    2014-02-01

    The transportation and diffusion of the guest objects or molecules in the porous carbon nanomaterials can be facilitated by reducing the pathway and resistance. The reduced pathway depends on the porous nature of carbon nanomaterials. Classification of porous carbon materials by the International Union of Pure and Applied Chemistry (IUPAC) has given a new opportunity to design the pores as per their applicability and to understand the mobility of ions, atoms, and molecules in the porous network of carbon materials and also advanced their countless applicability. However, synthesis of carbon nanomaterials with a desired porous network is still a great challenge. Although, remarkable developments have taken place in the recent years, control over the pores size and/or hierarchical porous architectures, especially in the synthesis of carbon nanospheres (CNSs) and ordered mesoporous carbon (OMCs) is still intriguing. The micro and mesoporous CNSs and OMCs have been prepared by a variety of procedures and over a wide range of compositions using various different surfactant templates and carbon precursors etc. The mechanisms of formation of micromesopore in the CNSs and OMCs are still evolving. On the other hand, the urge for adsorbents with very high adsorption capacities for removing contaminants from water is growing steadily. In this review, we address the state-of-the-art synthesis of micro and mesoporous CNSs and OMCs, giving examples of their applications for adsorptive removals of contaminants including our own research studies. PMID:24749459

  17. NASA Applications of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin S.

    2015-01-01

    The Molecular Adsorber Coating (MAC) is a new, innovative technology that was developed to reduce the risk of molecular contamination on spaceflight applications. Outgassing from materials, such as plastics, adhesives, lubricants, silicones, epoxies, and potting compounds, pose a significant threat to the spacecraft and the lifetime of missions. As a coating made of highly porous inorganic materials, MAC offers impressive adsorptive capabilities that help capture and trap contaminants. Past research efforts have demonstrated the coating's promising adhesion performance, optical properties, acoustic durability, and thermal stability. These results advocate its use near or on surfaces that are targeted by outgassed materials, such as internal optics, electronics, detectors, baffles, sensitive instruments, thermal control coatings, and vacuum chamber test environments. The MAC technology has significantly progressed in development over the recent years. This presentation summarizes the many NASA spaceflight applications of MAC and how the coatings technology has been integrated as a mitigation tool for outgassed contaminants. For example, this sprayable paint technology has been beneficial for use in various vacuum chambers for contamination control and hardware bake-outs. The coating has also been used in small instrument cavities within spaceflight instrument for NASA missions.

  18. Morphological characterization of furfuraldehyde resins adsorbents

    SciTech Connect

    Sanchez, R.; Monteiro, S.N.; D`Almeida, J.R.

    1996-12-31

    Sugar cane is one of the most traditional plantation cultivated crops in large areas in Brazil. The State University of the North of Rio de Janeiro, UENF, is currently engaged in a program aimed to exploit the potentialities of sugar cane industry as a self sustained non-polluting enterprise. One of the projects being carried out at the UENF is the transformation of sugar cane bagasse in precursor materials for the industry of furan derivatives such as the furfuraldehyde resins obtained by acid catalysis. The possibility of employing acid catalyzed furfuraldehyde resins as selective adsorbents has arisen during a comprehensive study of physical-chemical adsorption properties of these materials. The morphology of these resins depend on the synthesis method. Scanning Electron Microscopic studies of these materials which were synthesized, in bulk (FH-M) and solution (FH-D), showed differences in surface density and particle size. Using mercury porosimeter techniques and BET adsorption methods, it was found different pore size distributions and a decrement in surface area when solvent was employed in the synthesis process. By thermogravimetric analysis it was found similar weight losses (6%) of water adsorption and a small differences in thermal stabilities.

  19. Multicolor surface plasmon resonance imaging of ink jet-printed protein microarrays.

    PubMed

    Singh, Bipin K; Hillier, Andrew C

    2007-07-15

    We report a technique that utilizes surface plasmon resonance dispersion as a mechanism to provide multicolor contrast for imaging thin molecular films. Illumination of gold surfaces with p-polarized white light in the Kretschmann configuration produces distinct reflected colors due to excitation of surface plasmons and the resulting absorption of specific wavelengths from the source light. In addition, these colors transform in response to the formation of thin molecular films. This process represents a simple detection method for distinguishing between films of varying thickness in sensor applications. As an example, we interrogated a protein microarray formed by a commercial drop-on-demand chemical ink jet printer. Submonolayer films of a test protein (bovine serum albumin) were readily detected by this method. Analysis of the dispersion relations and absorbance sensitivities illustrate the performance and characteristics of this system. Higher detection sensitivity was achieved at angles where red wavelengths coupled to surface plasmons. However, improved contrast and spatial resolution occurred when the angle of incidence was such that shorter wavelengths coupled to the surface plasmons. Simplified optics combined with the robust microarray printing platform are used to demonstrate the applicability of this technique as a rapid and versatile, high-throughput tool for label-free detection of adsorbed films and macromolecules. PMID:17569506

  20. Chitosan/whey Protein (CWP) Edible Films Efficiency for Controlling Mould Growth and on Microbiological, Chemical and Sensory Properties During Storage of Göbek Kashar Cheese

    PubMed Central

    2015-01-01

    The objective of present study was to evaluate the effects of the application of chitosan and chitosan/whey protein on the chemical, microbial and organoleptic properties of Göbek Kashar cheese during ripening time (on 3rd, 30th, 60th and 90th d). Difference in microbiological and chemical changes between samples was found to be significant (p<0.05) during ripening period. Cheese samples with edible coating had statistically lower mould counts compared to the uncoated samples. Furthermore the highest and lowest mould counts were determined in control (4.20 Log CFU/g) and other samples (<1 Log CFU/g) at 60th and 90th d of storage. All samples exhibited higher levels of water soluble nitrogen and ripening index at the end of storage process. At the end of 90 day storage period, no signicant dierences in salt and fat values were observed among the cheeses studied. The edible coatings had a beneficial effect on the sensory quality of cheese samples. In the result of sensory analysis, while cheese C and the chitosan coated cheese samples were more preferred by the panellists, the chitosan/whey protein film-coated cheese samples received the lowest scores. This study shows coating suggests could be used to improve the quality of cheese during ripening time. PMID:26761831

  1. Chitosan/whey Protein (CWP) Edible Films Efficiency for Controlling Mould Growth and on Microbiological, Chemical and Sensory Properties During Storage of Göbek Kashar Cheese.

    PubMed

    Yangılar, Filiz

    2015-01-01

    The objective of present study was to evaluate the effects of the application of chitosan and chitosan/whey protein on the chemical, microbial and organoleptic properties of Göbek Kashar cheese during ripening time (on 3(rd), 30(th), 60(th) and 90(th) d). Difference in microbiological and chemical changes between samples was found to be significant (p<0.05) during ripening period. Cheese samples with edible coating had statistically lower mould counts compared to the uncoated samples. Furthermore the highest and lowest mould counts were determined in control (4.20 Log CFU/g) and other samples (<1 Log CFU/g) at 60(th) and 90(th) d of storage. All samples exhibited higher levels of water soluble nitrogen and ripening index at the end of storage process. At the end of 90 day storage period, no signicant dierences in salt and fat values were observed among the cheeses studied. The edible coatings had a beneficial effect on the sensory quality of cheese samples. In the result of sensory analysis, while cheese C and the chitosan coated cheese samples were more preferred by the panellists, the chitosan/whey protein film-coated cheese samples received the lowest scores. This study shows coating suggests could be used to improve the quality of cheese during ripening time. PMID:26761831

  2. Pyrolyzed feather fibers for adsorbent and high temperature applications

    NASA Astrophysics Data System (ADS)

    Senoz, Erman

    Chicken feather fibers (CFF) are problematic and costly for the poultry industry in terms of managing maintenance and disposal. Considering their great availability, low cost, and unique protein structure, CFF can be an environmentally friendly and bio-renewable candidate to replace petroleum products. CFF's low degradation and melting temperature render them useless at high temperatures. Pyrolysis methods were developed for CFF by using two temperature steps to convert them into high temperature resistant and adsorbent fibers while retaining their original physical appearance and affine dimensions. An intermolecular crosslinking mechanism in the first step of pyrolysis at 215 ºC for 24 h provided an intact fibrous structure with no subsequent melting. The evidence obtained from the thermal, bulk, and surface analysis techniques was indication of the simultaneous side chain degradation, polypeptide backbone scission, disulfide bond cleavage, and isopeptide crosslinking. The variation in the reaction kinetics of disulfide bond cleavage and isopeptide crosslinking played an important role in the melting transition. Consequently, long-lasting heat treatments below the melting point provided sufficient crosslinks in the protein matrix to keep the fibrous structure intact. Water-insoluble and crosslinked CFF reinforced the triglyceride-fatty acid based composites by providing a 15 fold increase in storage and tensile modulus at room temperature. These thermally stable fibers can be used instead of CFF in composites which may require high temperature compounding and molding processes. The second step of pyrolysis at 400--450 ºC for 1 h resulted in microporous fibers with a micropore volume of ˜0.18 cm3/g STP and with a narrower pore size distribution than commercial activated carbons through thermal degradation. Nearly all accessible pores in the microporous pyrolyzed chicken feather fibers (PCFF) had diameters less than 1 nm and therefore, showed a potential to be

  3. Equilibrium flattening process of irreversibly adsorbed polymer chains on a solid

    NASA Astrophysics Data System (ADS)

    Sen, Mani; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori; Kawaguchi, Daisuke; Tanaka, Keiji

    We here report the equilibrium process of adsorbed polymer chains on a solid by sum frequency generation (SFG) spectroscopy. Polystyrene (PS,Mw = 290 kDa) thin films prepared onto quartz prisms (a weakly attractive system) were used as a model system. Spin-cast PS 50 nm films on quartz surface (QS) were annealed at 150 °C >Tg for up to 100 h and subsequently rinsed with chloroform to derive the ``flattened chains'' that lie flat onto the substrate surface. The SFG results for the ``matured'' flattened chains after annealing for 96 h revealed the strong interfacial orientation of the backbone chains and weak orientation of PS phenyl rings at the QS which is in contrast to a PS spin-cast film annealed at 150 °C for 1 h: the phenyl rings were strongly directed toward the QS, while the backbone chains were weakly orientated at the QS. We postulate that the increase in the number of solid/segment contacts of the backbone chains is the driving force for this equilibrium flattening process. We will also discuss the generality of this flattening process by using solvent-cast PS thin films where the chains are randomly oriented near the QS. Acknowledgement: NSF Grant No. CMMI-1332499.

  4. Film Reviews.

    ERIC Educational Resources Information Center

    Lance, Larry M.; Atwater, Lynn

    1987-01-01

    Reviews four Human Sexuality films and videos. These are: "Personal Decisions" (Planned Parenthood Federation of America, 1985); "The Touch Film" (Sterling Production, 1986); "Rethinking Rape" (Film Distribution Center, 1985); "Not A Love Story" (National Film Board of Canada, 1981). (AEM)

  5. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, Thomas Richard; Golden, Timothy Christopher; Mayorga, Steven Gerard; Brzozowski, Jeffrey Richard; Taylor, Fred William

    1999-01-01

    A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

  6. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, T.R.; Golden, T.C.; Mayorga, S.G.; Brzozowski, J.R.; Taylor, F.W.

    1999-06-29

    A pressure swing adsorption process for absorbing CO[sub 2] from a gaseous mixture containing CO[sub 2] comprises introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100 C and 500 C to adsorb CO[sub 2] to provide a CO[sub 2] laden alumina adsorbent and a CO[sub 2] depleted gaseous mixture and contacting the CO[sub 2] laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO[sub 2] from the CO[sub 2] laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100 C and 600 C, is not degraded by high concentrations of water under process operating conditions. 1 fig.