Silver-enriched ZnO:Ag thin films deposited by magnetron co-sputtering: Post annealing effects on structural and physical properties

The ZnO semiconductor is probably among the most mentioned compounds in the scientific literature during the last decade, which is mainly due to its wide spectrum of applications. Compounds based on ZnO (in doped or composite form) are of great relevance for the development of high-tech devices. In this work, we present the growth and characterization of samples deposited by DC Magnetron co-sputtering from two pure Zn and Ag targets in an O2 / Ar atmosphere. The samples were characterized as deposited and after an annealing treatment in a reducing atmosphere. We have used XRD, RBS, ellipsometry, UV visible photoluminescence, and electrical measurements for sample characterization. The results revealed the amorphization of ZnO when the Ag content increases and, after annealing, a mixture of crystalline phases was detected for the samples with higher Ag content. It is also demonstrated the strong effect of the presence of Ag atoms in the stimulated optical and electrical responses from ZnO:Ag compounds obtained in this wor

An Evaluation of Polyethylene-Glycol Films Stabilized by Plasma and Ion Beam Methods.

Abstract not availableJRC.I-Institute for Health and Consumer Protection (Ispra

Tailoring Surface Properties of Biomedical Polymers by Implantation of Ar and He Ions

Ion implantation at 25 and 100 keV has been used as a tool for the modification of the surface properties of two biomedical polymers. The modulation induced by the different energy dispersion mechanisms of Ar and He have allowed satisfactory modifications for both the activation of the surfaces of chemically functional polycaprolactone (PCL) and the stabilization of anti-fouling poly(ethylene glycol) (PEG). In both cases the implantations have been performed at doses of 1014 cm−2 by taking into account the effect of different current densities, which are shown to distinctly influence the fragmentation-crosslinking of the target polymers. The resultant films were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, time of flight secondary ion mass spectroscopy and atomic force microscopy. Both shifts in zeta potential versus pH curves and the alteration of the polar components of the surface free energy (contact angle measurements) were correlated with the composition analysis. The response of the modified surfaces towards biomolecular interaction is demonstrated by the induction of preferential adsorption on irradiated PCL and the inhibited adsorption onto implanted PEG regions for selected oligopeptides and proteins.JRC.I.4-Nanotechnology and Molecular Imagin

Acid/base Micropatterned Devices for pH-Dependent Biosensors

Micropatterned surfaces of poly(acrylic acid) (PAA) and poly(allylamine) (PAL) were prepared by the combination of plasma enhanced chemical vapour deposition (PE-CVD) and physical masking techniques. The deposition process for both polymers was optimized in order to obtain a good compromise between the stability and the specific chemical functionality of the surface. X-ray photoelectron spectroscopy, and secondary ion mass spectrometry were used to determine the chemical characteristics of the surfaces. The use of the imaging mode provided a determination of the chemical contrasts at the micrometre scale. The evaluation of the specific interaction forces, acting between the surfaces and the COOH-functionalized tips, as a function of the pH, was performed by chemical force microscopy. The force-distance curves provided the basis for a semi-quantitative calculation of the interaction forces between the tip and the surfaces. The repulsive or attractive nature of the interaction forces is due to the variation in the charge concentration on the surfaces. This allowed the determination of pH-dependent force maps where the PAA and PAL show a contrast in the adhesion force.JRC.I.4-Nanotechnology and Molecular Imagin

Plasma Functionalization, Surface Characterization and Protein Retention of Multiple-Sized Polymer Beads

The surfaces of several types of polymer beads used in solid-phase extraction processes were modified with functional groups. Porous polystyrene (PS) macrospheres and polyvinylchloride (PVC) microspheres were plasma-modified in a fluidized-bed reactor by functionalization with allylamine (AIA) or acrylic acid (AcA). The surface compositions, as measured by XPS, showed the successful incorporation of the functional groups, and the number of this groups were assayed by derivatization onto model planar substrates. Furthermore, the influence on the surface Zeta potential of the beads was measured, which showed shifts of +/- 10 mV at physiological pH by the immobilized amino or carboxylic groups, respectively. A bovine serum albumin-fluorescein conjugate was used in a liquid chromatography system to evaluate the protein retention capacity. The results indicate higher protein retention on plasma-treated beads with respect to the untreated materials, and on PS when compared to PVC. Particularly high retention is obtained with AlA functionalization at 100 W.JRC.I.4-Nanotechnology and Molecular Imagin

Green synthesized silver nanoparticles decorated on nanostructured porous silicon as an efficient platform for the removal of organic dye methylene blue

In the present work, nanostructured porous silicon (nPSi) thin films were used as a substrate for the deposition of green synthesized silver nanoparticles (AgNPs). Different kinds of AgNPs were green synthesized by using Peumo extract and changing AgNO3 concentration. UV-vis spectroscopy confirmed the success of the synthesis, and TEM characterization showed AgNPs with a like-spherical shape and an average diameter, which ranges from 4 to 25 nm, depending on the AgNO3 concentration used. Then, AgNPs were introduced into the nPSi layer with a mean pore diameter of 46 nm and 75% of porosity by capillary suction. Hybrid layers nPSi/AgNPs were characterized by SEM, XRD, and RBS, confirming that AgNPs were introduced into nPSi layers. The catalytic activity of the hybrid layer in the reduction of organic dyes in water was studied using methylene blue (MB) as a model dye. Experimental results showed a high catalytic activity in comparison with other hybrid systems. The kinetic reduction could be fitted to the first-order equation obtaining the best degradation rate of 8.6 min(-1) with AgNPs synthetized with 2 mM of AgNO3. In addition, the reusability of these layers was demonstrated after five cycles, showing promising results for their use in wastewater management

Plasma Fabrication and SERS Functionality of Gold Crowned Silicon Submicrometer Pillars

Sequential plasma processes combined with specific lithographic methods allow for the fabrication of advanced material structures. In the present work, we used self-assembled colloidal monolayers as lithographic structures for the conformation of ordered Si submicrometer pillars by reactive ion etching. We explored different discharge conditions to optimize the Si pillar geometry. Selected structures were further decorated with gold by conventional sputtering, prior to colloidal monolayer lift-off. The resulting structures consist of a gold crown, that is, a cylindrical coating on the edge of the Si pillar and a cavity on top. We analysed the Au structures in terms of electronic properties by using X-ray absorption spectroscopy (XAS) prior to and after post-processing with thermal annealing at 300 °C and/or interaction with a gold etchant solution (KI). The angular dependent analysis of the plasmonic properties was studied with Fourier transformed UV-vis measurements. Certain conditions were selected to perform a surface enhanced Raman spectroscopy (SERS) evaluation of these platforms with two model dyes, prior to confirming the potential interest for a well-resolved analysis of filtered blood plasma.Ministry of Science, Innovation and Universities of Spain - grant SPECTRASENSE (RTC-2017-6311-1)Spline (Spanish CRG beamline at the ESRF) (25-01/986)3.623 JCR (2020) Q2, 79/162 Chemistry, Physical0.682 SJR (2020) Q2, 180/638 Materials Science (miscellaneous)No data IDR 2020UE

Microanalysis of Ar and He Bombarded Biomedical Polymer Films

Implantations onto polyethyleneglycol, polycaprolactone and polymethylmethacrylate, carried out with Ar and He ions at 25 and 100 KeV with fluences of 5 x10(13) cm-2, have been made with identical ion currents (20 uA) but different sweep areas in order to take into account the effect of the ion flux on the composition and structure of these biopolymers. Vibrational (Fourier transformed infrared spectroscopy), microanalytical (Rutherford backscattering and energy recoil detection) and microscopic techniques (atomic force microscopy) confirm that, even in this low fluence regime, the ion flux effect is responsible of scaled modifications. More interestingly, these techniques indicate that the damage seems to be higher for He. All these factors suggest that He could be preferentially used to engineer biomedical polymers exploiting the tailoring opportunities offered by ion flux effects.JRC.I.4-Nanotechnology and Molecular Imagin

Coatings of Cyclodextrin/Citric-Acid Biopolymer as Drug Delivery Systems: A Review

In the early 2000s, a method for cross-linking cyclodextrins (CDs) with citric acid (CTR) was developed. This method was nontoxic, environmentally friendly, and inexpensive compared to the others previously proposed in the literature. Since then, the CD/CTR biopolymers have been widely used as a coating on implants and other materials for biomedical applications. The present review aims to cover the chemical properties of CDs, the synthesis routes of CD/CTR, and their applications as drug-delivery systems when coated on different substrates. Likewise, the molecules released and other pharmaceutical aspects involved are addressed. Moreover, the different methods of pretreatment applied on the substrates before the in situ polymerization of CD/CTR are also reviewed as a key element in the final functionality. This process is not trivial because it depends on the surface chemistry, geometry, and physical properties of the material to be coated. The biocompatibility of the polymer was also highlighted. Finally, the mechanisms of release generated in the CD/CTR coatings were analyzed, including the mathematical model of Korsmeyer-Peppas, which has been dominantly used to explain the release kinetics of drug-delivery systems based on these biopolymers. The flexibility of CD/CTR to host a wide variety of drugs, of the in situ polymerization to integrate with diverse implantable materials, and the controllable release kinetics provide a set of advantages, thereby ensuring a wide range of future uses

TiNxOy/TiN dielectric contrasts obtained by ion implantation of O+2 ; structural, optical and electrical properties

The properties of TiN can be gradually transformed by O+2 implantations in the 10–40 keV range and fluences in the 5 × 1013–5 × 1016 cm−2 range. The resulting structure consists of shallow TiNxOy(TiNO)/TiN contrasts with increased resistivity on the top layer. In fact, oxygen actively replaces nitrogen in the implanted TiN region as illustrated by Rutherford backscattering spectrometry. N substitutions and vacancies in the lattice induce structural distortions and strain generation as illustrated by x-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy. The influence of these modifications in the optical and electrical properties was characterized by spectroscopic ellipsometry and four probe resistivity measurements. The proposed process, especially at the lower energy, is liable to help in the creation of electrical/photonic structures based in shallow TiNO/TiN electric/dielectric contrasts.JRC.DG.I.5-Nanobioscience