Marcin Pisarek

Preparation of Superhydrophobic Coatings on Zinc, Silicon, and Steel by a Solution-Immersion Technique

Zinc, silicon, and steel superhydrophobic surfaces were prepared by a simple solution-immersion technique. In the case of zinc, the method consists of dipping of the substrate in a prehydrolyzed methanol solution of 1H,1H,2H,2H-(perfluorooctyl)trichlorosilane [CF(3)(CF(2))(5)(CH(2))(2)SiCl(3), PFTS] for 24 h at 50 degrees C. Micron-sized spheres (1.7-2 microm in diameter) were formed on the zinc substrate at 50 degrees C, while a featureless coating was obtained when the solution-immersion process was conducted at room temperature. When the reaction was performed at room temperature, the formation of superhydrophobic coatings took several days (up to 5 days). In contrast, immersion of silicon or steel substrates in the PFTS/methanol solution led to the formation of hydrophobic interfaces even for a prolonged immersion period at 50 degrees C. The formation of superhydrophobic surfaces on silicon and steel surfaces was only possible if a zinc foil was added in the PFTS/methanol solution containing the silicon or steel substrate. X-ray photoelectron spectroscopy analysis was used to characterize the resulting surfaces and to underline a plausible reaction mechanism.

Photopolymerized polypyrrole microvessels.

We report on the preparation of water-filled polymer microvessels through the photopolymerization of pyrrole in a water/chloroform emulsion. The resulting structures were characterized by complementary spectroscopic and microscopic techniques, including Raman spectroscopy, XPS, SEM, and TEM. The encapsulation of fluorescent, magnetic, and ionic species within the microvessels has been demonstrated. Confocal microscopy and fluorescence anisotropy measurements revealed that the encapsulated chromophore (Rhodamine 6G) resides within voids in the capsules; however, strong interaction of the dye with polypyrrole results in a measurable decrease in its rotational dynamics. Microvessels loaded with ferrofluid exhibit magnetic properties, and their structures can be directed with an external magnetic field. TEM measurements allowed imaging of individual nanoparticles entrapped within the vessels. The application of Cu(2+)-loaded microvessels as a transducer layer in all-solid-state ion-selective electrodes was also demonstrated.

Preparation and Characterization of Silver Substrates Coated with Antimony-Doped SnO2 Thin Films for Surface Plasmon Resonance Studies

This paper reports on the preparation of silver/antimony-doped tin oxide (Ag/SnO(2):Sb) hybrid interfaces using magnetron sputtering and their characterization. The influence of the Sn target composition (doping with 2 or 5% Sb) on the electrochemical and electrical characteristics of the hybrid interface was investigated using X-ray photoelectron spectroscopy (XPS), sheet resistance measurements, cyclic voltammetry, scanning tunneling microscopy (STM) and surface plasmon resonance (SPR). The best interface in terms of electrical conductivity and SPR signal is a hybrid interface with a 8.5 +/- 0.3 nm thick SnO(2):Sb layer obtained from a Sn target with 2% Sb deposited on 38 nm thick silver film. Different strategies to link functional groups onto the Ag/SnO(2):Sb interface are also presented.

Modification of surface activity of Cu-based amorphous alloys by chemical processes of metal degradation

Abstract Changes in morphology, local chemical composition, catalytic activity and local surface-enhanced Raman scattering (SERS) activity due to various methods of modification of surfaces of Cu–Zr, Cu–Hf and Cu–Ti amorphous alloys were investigated. Our recent investigations have shown that otherwise detrimental processes of material degradation may help to segregate clusters of Cu and to develop a large specific surface area of Cu on ZrOx or HfOx supports. This transforms the original Cu-based amorphous ribbons of low surface area into efficient and stable catalysts. The following methods of activation based on the degradation processes, and their combinations are presented: ageing/oxidation in air, anodic activation, and pre-treatment with hydrogen (hydrogenation under high hydrogen pressure, or cathodic hydrogen charging). Structural changes in the bulk of the amorphous alloys introduced by the above pre-treatments were examined by XRD. Morphological and chemical changes on the surface were followed microscopically (optical microscopy and high resolution SEM) and by using a high resolution scanning Auger microprobe (SAM) and an X-ray electron microprobe. The amount of segregated Cu on the surface was estimated by an electrochemical method. A test reaction of dehydrogenation of 2-propanol was used to compare the catalytic activity of the materials after different chemical pre-treatments. Proposed mechanisms of changes in the local adsorption properties, local enhancement of Raman spectra and the catalytic activities due to the above combined pre-treatments are discussed.

Microstructure of Haynes ® 282 ® Superalloy after Vacuum Induction Melting and Investment Casting of Thin-Walled Components

The aim of this work was to characterize the microstructure of the as-cast Haynes® 282® alloy. Observations and analyses were carried out using techniques such as X-ray diffraction (XRD), light microscopy (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray spectroscopy (EDS), wave length dispersive X-ray spectroscopy (WDS), auger electron spectroscopy (AES) and electron energy-loss spectrometry (EELS). The phases identified in the as-cast alloy include: γ (gamma matrix), γʹ (matrix strengthening phase), (TiMoCr)C (primary carbide), TiN (primary nitride), σ (sigma-TCP phase), (TiMo)2SC (carbosulphide) and a lamellar constituent consisting of molybdenum and chromium rich secondary carbide phase together with γ phase. Within the dendrites the γʹ appears mostly in the form of spherical, nanometric precipitates (74 nm), while coarser (113 nm) cubic γʹ precipitates are present in the interdendritic areas. Volume fraction content of the γʹ precipitates in the dendrites and interdendritic areas are 9.6% and 8.5%, respectively. Primary nitrides metallic nitrides (MN), are homogeneously dispersed in the as-cast microstructure, while primary carbides metallic carbides (MC), preferentially precipitate in interdendritic areas. Such preference is also observed in the case of globular σ phase. Lamellar constituents characterized as secondary carbides/γ phases were together with (TiMo)2SC phase always observed adjacent to σ phase precipitates. Crystallographic relations were established in-between the MC, σ, secondary carbides and γ/γʹ matrix.

Development of new localized surface plasmon resonance interfaces based on gold nanostructures sandwiched between tin-doped indium oxide films.

This article reports on the fabrication and characterization of plasmonic interfaces composed of a sandwiched structure comprising a tin-doped indium oxide (ITO) substrate, gold nanostructures (Au NSs), and a thin ITO film overcoating. The change in the optical characteristics of the ITO/Au NSs/ITO interfaces as a function of the ITO overlayer thickness (d(ITO) = 0-200 nm) was followed by recording UV-vis transmission spectra. The influence of the thickness of the ITO overcoating on the position and shape of the plasmonic signal is discussed. The possibility to functionalize the ITO/Au NSs/ITO interfaces chemically is demonstrated by covalently linking ethynyl ferrocene to azide-terminated ITO/Au NSs/ITO interfaces. The resulting interfaces were characterized using X-ray photoelectron spectroscopy (XPS), electrochemical (cyclic voltammetry and differential pulse voltammetry) techniques, and UV-vis transmission spectroscopy.

Magnetic-nanoparticle-decorated polypyrrole microvessels: toward encapsulation of mRNA cap analogues.

Many phosphorylated nucleoside derivatives have therapeutic potential, but their application is limited by problems with membrane permeability and with intracellular delivery. Here, we prepared polypyrrole microvessel structures modified with superparamagnetic nanoparticles for use as potential carriers of nucleotides. The microvessels were prepared via the photochemical polymerization of the monomer onto the surface of aqueous ferrofluidic droplets. A complementary physicochemical analysis revealed that a fraction of the nanoparticles was embedded in the microvessel walls, while the other nanoparticles were in the core of the vessel. SQUID (superconducting quantum interference device) measurements indicated that the incorporated nanoparticles retained their superparamagnetic properties; thus, the resulting nanoparticle-modified microvessels can be directed by an external magnetic field. As a result of these features, these microvessels may be useful as drug carriers in biomedical applications. To demonstrate the encapsulation of drug molecules, two labeled mRNA cap analogues, nucleotide-derived potential anticancer agents, were used. It was shown that the cap analogues are located in the aqueous core of the microvessels and can be released to the external solution by spontaneous permeation through the polymer walls. Mass spectrometry analysis confirmed that the cap analogues were preserved during encapsulation, storage, and release. This finding provides a foundation for the future development of anticancer therapies and for the delivery of nucleotide-based therapeutics.

TiO2 nanotube composite layers as delivery system for ZnO and Ag nanoparticles — An unexpected overdose effect decreasing their antibacterial efficacy

Enhancement of biocompatibility and antibacterial properties of implant materials is potentially beneficial for their practical value. Therefore, the use of metallic and metallic oxide nanoparticles as antimicrobial coatings components which induce minimized antibacterial resistance receives currently particular attention. In this work, TiO2 nanotubes layers loaded with ZnO and Ag nanoparticles were designed for biomedical coatings and delivery systems and evaluated for antimicrobial activity. TiO2 nanotubes themselves exhibited considerable and diameter-dependent antibacterial activity against planktonic Staphylococcus epidermidis cells but favored bacterial adhesion. Loading of nanotubes with moderate amount of ZnO nanoparticles significantly diminished S. epidermidis cell adhesion and viability just after 1.5h contact with modified surfaces. However, an increase of loaded ZnO amount unexpectedly altered the structure of nanoparticle-nanolayer, caused partial closure of nanotube interior and significantly reduced ZnO solubility and antibacterial efficacy. Co-deposition of Ag nanoparticles enhanced the antibacterial properties of synthesized coatings. However, the increase of ZnO quantity on Ag nanoparticles co-deposited surfaces favored the adhesion of bacterial cells. Thus, ZnO/Ag/TiO2 nanotube composite layers may be promising delivery systems for combating post-operative infections in hard tissue replacement procedures. However, the amount of loaded antibacterial agents must be carefully balanced to avoid the overdose and reduced efficacy.

Local characterisation of inhomogeneous Cu surfaces by surface-enhanced Raman scattering

Abstract An attempt was made to compare surface-enhanced Raman spectra (SERS) of the probe molecules adsorbed on highly dispersed Cu surfaces of both real catalyst and various model systems produced from pure Cu. In particular, we searched for the Cu clusters with adsorption properties significantly differing from the properties of the clusters produced from pure copper on the surface of highly active copper-containing catalysts. The SERS spectra of pyridine used as a probe molecule were collected with a Raman spectrometer connected to a microscope having a focal radius of less than 10−6 m. It was found, for example, that for the very active catalyst produced from 50Cu–50Zr amorphous precursor by high-pressure hydrogen charging, the relative intensities of pyridine bands are considerably different at some places to those observed for copper. At other areas on the sample, however, the spectrum is similar to that observed for pure Cu. This indicates that the local SERS technique has the potential to investigate adsorbate properties that are usually hidden by averaging if the signal is collected from a larger surface area.

Biomimetic and Electrodeposited Calcium-Phosphates Coatings on Ti - Formation, Surface Characterization, Biological Response

© 2012 Pisarek et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biomimetic and Electrodeposited Calcium-Phosphates Coatings on Ti – Formation, Surface Characterization, Biological Response