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PubMed2000

Standard electrochemical behavior of high-quality, boron-doped polycrystalline diamond thin-film electrodes

Standard electrochemical data for high-quality, boron-doped diamond thin-film electrodes are presented. Films from two different sources were compared (NRL and USU) and both were highly conductive, hydrogen-terminated, and polycrystalline. The films are acid washed and hydrogen plasma treated prior to use to remove nondiamond carbon impurity phases and to hydrogen terminate the surface. The boron-doping level of the NRL film was estimated to be in the mid 1019 B/cm3 range, and the boron-doping level of the USU films was approximately 5 x 10(20) B/cm(-3) based on boron nuclear reaction analysis. The electrochemical response was evaluated using Fe-(CN)6(3-/4-), Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, dopamine, ascorbic acid, Fe(3+/2+), and chlorpromazine. Comparisons are made between the apparent heterogeneous electron-transfer rate constants, k0(app), observed at these high-quality diamond films and the rate constants reported in the literature for freshly activated glassy carbon. Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, and chlorpromazine all involve electron transfer that is insensitive to the diamond surface microstructure and chemistry with k0(app) in the 10(-2)-10(-1) cm/s range. The rate constants are mainly influenced by the electronic properites of the films. Fe(CN)6(3-/4-) undergoes electron transfer that is extremely sensitive to the surface chemistry with k0(app) in the range of 10(-2)-10(-1) cm/s at the hydrogen-terminated surface. An oxygen surface termination severely inhibits the rate of electron transfer. Fe(3+/2+) undergoes slow electron transfer at the hydrogen-terminated surface with k0(app) near 10(-5) cm/s. The rate of electron transfer at sp2 carbon electrodes is known to be mediated by surface carbonyl functionalities; however, this inner-sphere, catalytic pathway is absent on diamond due to the hydrogen termination. Dopamine, like other catechol and catecholamines, undergoes sluggish electron transfer with k0(app) between 10(-4) and 10(-5) cm/s. Converting the surface to an oxygen termination has little effect on k0(app). The slow kinetics may be related to weak adsorption of these analytes on the diamond surface. Ascorbic acid oxidation is very sensitive to the surface termination with the most negative Ep(ox) observed at the hydrogen-terminated surface. An oxygen surface termination shifts Ep(ox) positive by some 250 mV or more. An interfacial energy diagram is proposed to explain the electron transfer whereby the midgap density of states results primarily from the boron doping level and the lattice hydrogen. The films were additionally characterized by scanning electron microscopy and micro-Raman imaging spectroscopy. The cyclic voltammetric and kinetic data presented can serve as a benchmark for research groups evaluating the electrochemical properties of semimetallic (i.e., conductive), hydrogen-terminated, polycrystalline diamond.

Journal Article↗
PubMed2006

Characterizing pore-scale dissolution of organic immiscible liquid in natural porous media using synchrotron X-ray microtomography.

The objective of this study was to characterize the pore-scale dissolution of organic immiscible-liquid blobs residing within natural porous media. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of the aqueous, organic-liquid, and solid phases residing in columns packed with one of two porous media. Images of the packed columns were obtained after a stable, discontinuous distribution (e.g., residual saturation) of the organic liquid (trichloroethene) had been established, and three subsequent times during column flushing. These data were used to characterize the morphology of the organic-liquid blobs as a function of dissolution, and to quantify changes in total organic-liquid volume, surface area, and water-organic liquid interfacial area. The dissolution dynamics of individual blobs appeared to be influenced by the local pore configuration. In addition to dissolution-induced shrinkage, some blobs were observed to separate into multiple distinct subunits. The median blob size decreased by approximately a factor of 2 at the point where approximately 90% of the initial organic-liquid volume had been removed. The ratio of capillary associated interfacial area to total water-organic liquid interfacial area increased by 50% at the point where approximately 95% of the initial mass had been removed. A nearly linear relationship was observed between both total and capillary associated interfacial area and organic liquid volumetric fraction. Changes in the measured aqueous-phase trichloroethene effluent concentrations were well correlated with changes in the volume, surface area, and number of blobs. The effluent concentration data were adequately described by a first-order mass transfer expression employing a constant value of the mass-transfer coefficient, with values for the water-organic liquid interfacial area obtained independently from the microtomography data.

Chemistry, Organic↗
PubMed2004

Imaging the binding ability of proteins immobilized on surfaces with different orientations by using liquid crystals.

We report an investigation of the binding ability of a protein immobilized on surfaces with different orientations but in identical interfacial microenvironments. The surfaces present mixed self-assembled monolayers (SAMs) of 11-[19-carboxymethylhexa(ethylene glycol)]undecyl-1-thiol, 1, and 11-tetra(ethylene glycol) undecyl-1-thiol, 2. Whereas 2 is used to define an interfacial microenvironment that prevents nonspecific adsorption of proteins, 1 was activated by two different schemes to immobilize ribonuclease A (RNase A) in either a preferred orientation or random orientations. The binding of the ribonuclease inhibitor protein (RI) to RNase A on these surfaces was characterized by using ellipsometry and the orientational behavior of liquid crystals. Ellipsometric measurements indicate identical extents of immobilization of RNase A via the two schemes. Following incubation of both surfaces with RI, however, ellipsometric measurements indicate a 4-fold higher binding ability of the RNase A immobilized with a preferred orientation over RNase A immobilized with a random orientation. The higher binding ability of the oriented RNase A over the randomly oriented RNase A was also apparent in the orientational behavior of nematic liquid crystals of 4-cyano-4'-pentylcyanobiphenyl (5CB) overlayed on these surfaces. These results demonstrate that the orientations of proteins covalently immobilized in controlled interfacial microenvironments can influence the binding activities of the immobilized proteins. Results reported in this article also demonstrate that the orientational states of proteins immobilized at surfaces can be distinguished by examining the optical appearances of liquid crystals.

Adsorption↗
PubMed2001

Overproduction, purification, and characterization of the Trichoderma reesei hydrophobin HFBI.

Many characteristics of fungal hydrophobins, such as an ability to change hydrophobicity of different surfaces, have potential for several applications. The large-scale processes of production and isolation of these proteins susceptible to aggregation and attachment to interfacial surfaces still needs to be studied. We report for the first time on a method for a gram-scale production and purification of a hydrophobin, HFBI of Trichoderma reesei. A high production level of the class II hydrophobin (0.6 g l(-1)) was obtained by constructing a T. reesei HFBI-overproducing strain containing three copies of the hfb1 gene. The strain was cultivated on glucose-containing medium, which induces expression of hfb1. HFBI hydrophobin was purified from the cell walls of the fungus because most of the HFBI was cell-bound (80%). Purification was carried out with a simple three-step method involving extraction of the mycelium with 1% SDS at pH 9.0, followed by KCl precipitation to remove SDS, and hydrophobic interaction chromatography. The yield was 1.8 g HFBI from mycelium (419 g dw), derived from 15 l of culture. HFBI was shown to be rather unstable to N-terminal asparagine deamidation and also, to some extent, to non-specific proteases although its thermostability was excellent.

Chromatography, High Pressure Liquid↗
PubMed1991

Interfacial transfer kinetics of NO2 into pulmonary epithelial lining fluid.

Previous studies, both in intact lungs and epithelial lining fluid (ELF) (J. Appl. Physiol. 68: 594-603, 1990 and J. Appl: Physiol. 69: 523-531, 1990), have suggested that the steady-state absorption of inhaled NO2 is mediated by chemical reaction(s) between NO2 and ELF solute reactants. To characterize the kinetics of NO2 absorption into aqueous biological substrates across a gas-liquid interface, we utilized a closed system of known geometry and initial gas phase [NO2] [([NO2]g)0] to expose ELF (as bronchoalveolar lavage; BAL) and a biochemical model system (glutathione, GSH). Assessments of NO2 reactive uptake, into both GSH and ELF, indicated first-order NO2 kinetics [([NO2]g)0 less than or equal to 10.5 ppm] with effective rate constants of (kNO2)GSH = 4.8 and (kNO2)BAL = 2.9 ml.min-1.cm-2 (stirred). Above 10.5 ppm (1 mM GSH), zero-order kinetics were observed. Both (kNO2)GSH and (kNO2)BAL showed aqueous reactant dependence. The reaction order with respect to GSH and BAL was 0.47 and 0.64, respectively. We found no effect of interfacial surface area or bulk phase volume on kNO2. In unstirred systems, significant interfacial resistance was observed and was related to reactant concentration. These results indicate that NO2 reactive uptake follows first-order kinetics with respect to NO2 ([NO2]g less than or equal to 10.5 ppm) and displays aqueous substrate dependence. Furthermore the site of reactive absorption appears to be limited to near the aqueous surface interface. Unstirred conditions confine interfacial mass transfer kinetics in a dose-dependent manner. These phenomenological coefficients may provide the basis for direct extrapolation to environmentally relevant exposure concentrations.

Absorption↗
PubMed2006

Langmuir and Langmuir-Blodgett films of proline-rich N-terminal domain peptide of gamma-zein.

The proline-rich N-Terminal domain peptides of gamma-zein (VHLPPP)(n) with n=1 and 3 (peptides I and II) are shown to form stable Langmuir films at air/water interface and the films have been characterized using surface pressure-molecular area (pi-A), surface potential-molecular area (DeltaV-A) isotherms, respectively. The longer peptide sequence does not show dramatic increase in surface or interfacial properties suggesting that the minimum length of n=1 is sufficient to achieve the necessary surface properties. Brewster angle micrographs also agreed with these results. The high surface-active nature of the peptide suggests a fairly non-polar character at air/water interface and at solid/air interface when coated expresses a high surface energy. Additives such as isopropyl alcohol (IPA) and polyvinyl alcohol (PVA) with the peptides showed more homogenous films at the air/water interface and also improved mechanical and tensile properties. The organized assembly of peptide I at the air/water and solid/air interface suggests that even thin layer of the peptide could play an important role in coating the inner surface of protein body membrane in storage proteins. Composite films of such short peptides with biocompatible polymers may find applications as surface coatings and in biomaterials.

Algorithms↗
PubMed2001

Application of double-impedance system and cyclic voltammetry to study the adsorption of fullerols (C60(OH)n) on biological peptide-adsorbed gold electrode.

The adsorption of fullerols (C60(OH)n) on glutathione-adsorbed gold electrode was characterized by using double-impedance system, i.e., electrochemical quartz crystal impedance and electrochemical impedance spectroscopy, and cyclic voltammetry. The time courses of piezoelectric parameters were used to reflect the changes of interfacial physical properties, such as mass, density-viscosity, and dielectric constant, during the adsorptions of peptide and fullerols onto electrode. The electrochemical impedance based on the simple equivalent electric network were also simultaneously measured and provided electrochemical interface information, e.g., double-layer capacitance and charge-transfer resistance. It was found that the double-impedance responses were varied with the forms of glutathione. It was also shown that the frequency curves due to the adsorption of oxidized (GSSG) and reduced (GSH) glutathione could be exhibited as different kinetic equations. The heterogeneous charge-transfer rate constants of ferricyanide/ferrocyanide before and after the peptide and fullerols adsorption were determined by CV and EIS methods. The results showed that the proposed method has potential applications in interfacial studies of biomaterials, since these combined techniques have advantages in real time providing multidimensional piezoelectric and electrochemical impedance information.

Adsorption↗
PubMed1998

Poly(arylazophosphonate)s: A New Polymer Class with Arylazophosphonate Units in the Main Chain.

Poly(arylazophosphonate)s are synthesized from bifunctional diazonium salts and bifunctional phosphoric diesters by interfacial polycondensation at the interface water/organic solvent. The azo unit is formed via N-P coupling during the polycondensation reaction in satisfying yield and selectivity. Fifteen new polymers were synthesized and characterized by common methods such as 1H, 13C, and 31P NMR, FTIR, UV/visible spectroscopy, and DSC and GPC measurements. According to first laser ablation experiments as well as film forming properties and thermal and photochemical behavior, poly(arylazophosphonate)s seem to be suitable materials for ablation with XeCl excimer lasers.

Journal Article↗
PubMed2001

Spray-dried diclofenac-loaded poly(epsilon-caprolactone) nanocapsules and nanospheres. Preparation and physicochemical characterization.

The aims of the present study were to prepare spray-dried polymeric nanocapsules (NC) and nanospheres (NS) from poly(epsilon-caprolactone) (P epsilon C) suspensions containing diclofenac (DIC) and to determine the physicochemical properties of the formulations. NC or NS suspensions were prepared by interfacial deposition of the polymer. DSC-thermograms of raw materials and NC or NS suspensions (evaporated or spray-dried) were obtained using a PL-DSC. Spray-dried powders were prepared by addition of 3% (w/v) Aerosil 200 into suspensions of NC or NS. These mixtures were fed into a spray-dryer. DIC was assayed by HPLC. NC and NS spray-dried powders were examined under SEM (Jeol Scanning Microscope, JSM-5800). NC and NS suspensions had acceptable diameter, 340 and 247 nm respectively. The yields of NC and NS spray-dried powders were 80% and 75% and the recovery of the DIC was 99% and 93%, respectively. The melting peak of P epsilon C in NC and NS was observed at a temperature about 10 degrees C lower than in the raw material. In the NC thermograms the maximum of the oil (Miglyol 810) melting peak (+1.6 degrees C) was lowered about 7 degrees C. For spray-dried NC formulations, the SEM analyses of powders showed spherical microparticles of silicon dioxide, covered by nanoparticles (300 nm), while for spray-dried NS formulations the microparticles presented a rugged surface at the same magnification.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

The crystal structure of a triacylglycerol lipase from Pseudomonas cepacia reveals a highly open conformation in the absence of a bound inhibitor.

BACKGROUND: . Lipases, a family of enzymes which catalyze the hydrolysis of triglycerides, are widely distributed in many organisms. True lipases are distinguished from esterases by the characteristic interfacial activation they exhibit at an oil-water interface. Lipases are one of the most frequently used biocatalysts for organic reactions performed under mild conditions. Their biotechnological applications include food and oil processing and the preparation of chiral intermediates for the synthesis of enantiomerically pure pharmaceuticals. Recent structural studies on several lipases have provided some clues towards understanding the mechanisms of hydrolytic activity, interfacial activation, and stereoselectivity. This study was undertaken in order to provide structural information on bacterial lipases, which is relatively limited in comparison to that on the enzymes from other sources. RESULTS: . We have determined the crystal structure of a triacylglycerol lipase from Pseudomonas cepacia (PcL) in the absence of a bound inhibitor using X-ray crystallography. The structure shows the lipase to contain an alpha/beta-hydrolase fold and a catalytic triad comprising of residues Ser87, His286 and Asp264. The enzyme shares several structural features with homologous lipases from Pseudomonas glumae (PgL) and Chromobacterium viscosum (CvL), including a calcium-binding site. The present structure of PcL reveals a highly open conformation with a solvent-accessible active site. This is in contrast to the structures of PgL and PcL in which the active site is buried under a closed or partially opened 'lid', respectively. CONCLUSIONS: . PcL exhibits some structural features found in other lipases. The presence of the Ser-His-Asp catalytic triad, an oxyanion hole, and the opening of a helical lid suggest that this enzyme shares the same mechanisms of catalysis and interfacial activation as other lipases. The highly open conformation observed in this study is likely to reflect the activated form of the lipase at an oil-water interface. The structure suggests that the interfacial activation of bacterial lipases involves the reorganization of secondary structures and a large movement of the lid to expose the active site. This is similar to the mechanism described for other well characterized fungal and mammalian lipases.

Amino Acid Sequence↗
PubMed1994

Spontaneous injection in microcolumn separations.

The phenomenon of spontaneous (ubiquitous) injection in microcolumn separations has been characterized to improve quantitative precision for ultramicrosampling and to enhance separation efficiency. By combining fluorescence imaging, video microscopy, and measurements from capillary electrophoresis, we demonstrate that spontaneous injection is caused primarily by an interfacial pressure difference formed at the inlet of the capillary. This complex injection mechanism has been modeled with some simple assumptions based on fluid dynamics. In particular, studies showed that extraneous injection is reduced up to 12-fold by etching the capillary inlet or by using a thin-walled capillary. Variations by a factor of 2 in the injection length can result from delays between sample introduction and reinsertion into the inlet vial if the timing is not controlled precisely. Evidence is presented that evaporation of buffer from the inlet can reduce the injection length by more than 1 order of magnitude.

Image Processing, Computer-Assisted↗
PubMed2003

Effects of geometric confinement on the adhesive debonding of soft elastic solids.

The effect of increasing confinement on soft elastic gel layers has been investigated and a means of analyzing the behavior of such systems has been developed. A probe tack test was used to study the behavior of thin elastic layers during interfacial debonding from a cylindrical glass indenter. For this gel-indenter system, confinement is defined as the ratio of a(0), the radius of the indenter, to h, the thickness of the elastic layer. In order to investigate geometric effects, the adhesion energy of the gel was kept constant while the thickness and modulus of the gels were varied. A fracture mechanics approach, based on the compliance of the layer, has been employed in analyzing the experimental data. It is shown that a fracture mechanics analysis is appropriate for these systems, allowing quantitative results to be obtained, despite very irregular contacts. It has also been shown that the interfacial instabilities observed during debonding maximize the compliance of the elastic layer. Additionally, four dimensionless parameters that dictate the behavior of confined systems have been defined, offering a general guide to understanding and characterizing the mechanical behavior of thin elastic layers.

Journal Article↗
PubMed1986

Preparation and characterization of thin film surface coatings for biological environments.

An approach to the problem of selecting synthetic materials for use in biological media is presented. Firstly, a surface energetic criterion of biocompatibility of foreign surfaces is suggested. This criterion, which is based on an analysis of the surface interactions between a typical biological fluid (i.e. blood) and synthetic surfaces, is founded on the premise that a sufficiently low (but not very low) solid-biological fluid interfacial free energy of the order of 1-3 dyne/cm, is necessary in order to fulfil the dual requirements of maintaining a low thermodynamic driving force for the adsorption of fluid components on the solid surface as well as a mechanically stable solid-fluid interface. In the second part of this investigation, an experimental approach involving the radio frequency (rf) sputter deposition of thin solid films of tightly adhering polymeric compounds on materials with the desired bulk characteristics, is shown to be a promising method of tailoring the surface properties of many types of synthetic materials for use in biological environments. The preparation and surface characterization of thin, solid films of oxidized fluorocarbon coatings (from a Teflon FEP target) by rf sputtering is illustrated. The deposited polymer films were characterized for their surface morphology, thickness, elemental surface chemical composition and their wetting properties in a biological environment, by the techniques of scanning electron microscopy (SEM), ellipsometry, electron spectroscopy for chemical analysis (ESCA) and contact angle measurements, respectively. Based on the ESCA and contact angle results, it emerges that the surfaces of such polymeric coatings possess sufficient mobility to considerably alter their structures between different environments (such as air and water) and thereby present different wetting characters to these environments. The contact angle procedure developed in this investigation permitted the estimation of the relevant wetting properties of such mobile surfaces in an aqueous environment (which is the environment encountered in most biological fluids). In the final part of this investigation, the possibility of effecting a drastic reduction in the solid-water interfacial free energy of the sputtered polymer surfaces by physical and or chemical modification of their surfaces and thereby improving their biocompatibility is illustrated.

Biocompatible Materials↗
PubMed2005

The effect of slow interfacial kinetics on the chronoamperometric response of composite lithiated graphite electrodes and on the calculation of the chemical diffusion coefficient of Li ions in graphite.

This paper deals with a study of the shape of the chronoamperometric response (current, I, vs time, t) and, eventually, the mechanism of Li-ions insertion and deinsertion to/from composite graphite electrodes obtained by a small-amplitude (incremental) technique, such as potentiostatic intermittent titration (PITT). The dependences of log I, the Cottrell parameter It(1/2), and the differential parameter d log I/d log t on the process duration (vs log t) were carefully examined both for single- and two-phase coexistence domains. log I vs log t curves for single-phase domains were characterized by a single monotonic curve with a gradually increasing slope. In contrast, the same curves for two-phase domains consist of two sequential downward concave lines. Both types of response were explained by using the cell-impedance-control model. To separate the contributions of solid-state diffusion, Ohmic drops, and slow interfacial charge-transfer kinetics to the chronoamperometric response, the data were presented in the form of the inverse Cottrell parameter, (It(1/2))(-1) vs t(-1/2), from which the chemical diffusion coefficient (D) could be obtained. Refined values of D for Li insertion into graphite obtained herein agree very well with values of the component diffusion coefficient obtained from quasielastic neutron scattering for Li insertion into HOPG, reported in the literature.

Journal Article↗
PubMed2006

A novel real-time confocal imaging technique for examining host-implant interfacial shear failure patterns.

In clinical practice, implant failure usually occurs at the biomaterial-host tissue interface, typically involving both biomechanical and biochemical mechanisms. By definition, any new 'bioactive' material will bond to living bone but, prior to clinical use, interface formation, performance, longevity and failure pattern characterizations are necessary. The common missing link in many biomaterial interface investigations is imaging at the point of presumed loaded failure. The novel real-time confocal technique described here allows bond strength, formation rate, longevity and bone-material interface failure pattern characterization for a wide range of biomaterials capable of forming tissue interfaces, in one real-time imaged microshear stress process, conducted using imaging frame matched load/displacement data acquisition under relatively normal near in vivo environmental conditions. The technique, validated by post-failure scanning electron microscopy imaging, revealed that more slowly reacting melt-derived 45S5 glass materials produced stronger and more stable long-term interfaces than faster reacting microporous bioactive sol-gel glasses.

Biocompatible Materials↗
PubMed1999

Characterization of the interface between prefabricated gold copings and cast dental alloy in implant restorations.

The objective of this study was to analyse the characteristics of the metal interface between the casting of a dental noble alloy and prefabricated gold copings (OCTA-ITI Implant System) after the fabrication procedures of a prosthetic implant-retained superstructure. The microscopical investigation, performed by optical microscopy (OM) and scanning electron microscopy (SEM), of the region around the cylinder after the casting process and the subsequent porcelain firing procedures showed the presence of an ideal interface, including: i) maintenance of coping and casting alloy microstructures up to the interface, and ii) absence of interfacial reaction products. A low content of porosity (less than 3% by volume in average) was observed in the casting alloy bulk as well as at interface. The investigation by energy-dispersive spectroscopy (EDS) of the alloy composition close to the interface showed the presence of a minimal elemental interdiffusion, suggesting that an adequate compatibility between alloy and coping characterized the materials used. A small decrease of the prefabricated coping hardness was also observed after the casting and porcelain firing procedures.

Dental Abutments↗
PubMed2006

Mechanical properties of porous, electrosprayed calcium phosphate coatings.

Mechanical properties of calcium phosphate coatings (CaP), deposited using the electrostatic spray deposition (ESD) technique, have been characterized using a range of analytical techniques, including tensile testing (ASTM C633), fatigue testing (ASTM E855), and scratch testing using blunt and sharp scratch styli. Moreover, a simple explantation procedure was successfully introduced using ESD-coated, threaded dental implants to characterize the mechanical performance of CaP coatings qualitatively under conditions that mimic clinical situations as close as possible. Generally, all analysis techniques revealed that ESD coatings need to be crystallized in order to ensure interfacial adhesion to the substrate and sufficient mechanical strength of the superficial reticular structure. Crystalline carbonated hydroxyapatite coatings (CHA, heat-treated at 700 degrees C) were resistant to fatigue as well as to plastic ploughing deformation by means of various scratch styli, and the fragile surface structure of ESD coatings was maintained to a large extent after unscrewing CHA-coated dental implants from femoral condyles of goat cadavers. From these experiments, it was concluded that interfacial adhesion of crystalline CHA ESD coatings to the titanium substrate was sufficient, but that mechanical strength of the superficial architecture of ESD coatings need to be optimized for applications where high shear and compressive stresses are imposed onto the rather fragile coating surface of reticular ESD morphologies.

Animals↗
PubMed2005

Plasmonic nanoparticle chains via a morphological, sphere-to-string transition.

Au nanoparticles encapsulated within polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles assemble into regular, one-dimensional arrays when they are exposed to solvent conditions that relax interfacial curvature in the micellar shell. Nanoparticle chaining was induced by adding salt, acid, or cationic carbodiimide to the suspension of purified encapsulated Au nanoparticles (Au@PS-b-PAA). The resulting assemblies were characterized by scanning and transmission electron microscopies, by dark-field optical microscopy, and by visible absorption spectroscopy. The length of the chains was modulated by varying the concentration of additive. More importantly, the spacing between Au nanoparticles was dictated entirely by the shell thickness of the Au@PS-b-PAA starting material. Far-field polarization microspectroscopy demonstrated directional surface plasmon coupling in a straightened nanoparticle chain, which is a basic requirement for the use of these assemblies as plasmon waveguides.

Acrylic Resins↗