National Institute Of Materials Physics - Romania

This Special Issue was devoted to developments made in Physical Vapour Deposited (PVD) biomedical coatings for various healthcare applications. The scrutinized PVD methods were Radio-Frequency Magnetron Sputtering (RF-MS), Cathodic Arc Evaporation, Pulsed Electron Deposition and its variants, Pulsed Laser Deposition, and Matrix Assisted Pulsed Laser Evaporation (MAPLE), due to their great promise especially in the dentistry and orthopaedics. These methods have yet to gain traction for industrialization and large-scale application in biomedicine. A new generation of implant coatings can be made available by the (1) incorporation of organic moieties (e.g., proteins, peptides, enzymes) into thin films by innovative methods such as combinatorial MAPLE, (2) direct coupling of therapeutic agents with bioactive glasses or ceramics within substituted or composite layers via RF-MS, or (3) by innovation in high energy deposition methods such as arc evaporation or pulsed electron beam methods.

Tuning the intrinsic structural and stoichiometric properties by different means is used for increasing the green energy production efficiency of complex oxide materials. Here, we report on the formation of self-assembled nanodomains and their effects on the photoelectrochemical (PEC) properties of LaFeO3 (LFO) epitaxial thin films as a function of layer's thickness. The variation with the film's thickness of the structural parameters such as in-plane and out-of-plane crystalline coherence length and the coexistence of different epitaxial orientation-SrTiO3// LFO, SrTiO3// LFO and [110] LFO//[10] STO, as well as the appearance of self-assembled nanodomains for film's thicknesses higher than 14 nm, is presented. LFO thin films exhibit different epitaxial orientations depending on their thickness, and the appearance of self-assembled nanopyramids-like domains after a thickness threshold value has proven to have a detrimental effect on the PEC functional properties. Using Nb:SrTiO3 as conductive substrate and 0.5 M NaOH aqueous solution for PEC measurements, the dependence of the photocurrent density and the onset potential vs. RHE on the structural and stoichiometric features exhibited by the LFO photoelectrodes are unveiled by the X-ray diffraction, high-resolution transmission electron microscopy, ellipsometry, and Rutherford backscattering spectroscopy results. The potentiodynamic PEC analysis has revealed the highest photocurrent density J(photocurrent) values (up to 1.2 mA/cm(2)) with excellent stability over time, for the thinnest LFO/Nb:SrTiO3 sample, both cathodic and anodic behavior being noticed. Noticeably, the LFO thin film shows unbiased hydrogen evolution from water, as determined by gas chromatography in aqueous 0.5 M NaOH solution under constant illumination.

Peppers are consumed all over the world, have several benefits to human health, such as antioxidant properties that can prevent diseases related to free radicals such as cardiovascular, inflammatory diseases, cancer, among others. This work aimed to evaluate the antioxidant capacity (AOC) of 36 varieties of peppers through ABTS and DPPH radical scavenging, electroanalytical assays, and to verify the vasorelaxant properties of selected samples. The greater the amount of capsaicin found in the extracts, the higher the AOC the greater the vasorelaxation. Naga had the highest scoring for antioxidant capacity, pout showed the lowest antioxidant capacity, vase pyramid intermediate level, whereas the capsaicin content followed the same trend. Extracts from all pepper varieties studied presented vasorelaxant properties in independent and dependent endothelial pathways.

Magnetite (Fe3O4) and ferrite (MFe2O4, M = Mn, Zn) hydrophobic magnetic nanoparticles with various shapes and sizes were synthesized by high-temperature reaction of organic precursor solutions. Spherical, cubic, hexagonal, and octahedral shapes and sizes ranging from 10 to 100 nm were obtained. It has been proven that the reported high capability of tailoring the shape and the size of the surface-coated nanoparticles allows controlling a variety of properties that are relevant to many potential applications. Structurally well-formed hydrophobic magnetic nanoparticles with high saturation magnetization values are reported. The hydrophobic oleic acid shell was successfully transformed by a simple and environmentally friendly oxidative scission method into azelaic acid. The morphostructural characteristics, size distributions, chemical composition, and magnetic properties of the resulting hydrophilic nanoparticles were investigated by electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Mossbauer spectroscopy, superconducting quantum interference device, and vibrating sample magnetometry. Magnetic hyperthermia measurements have been performed in a specially designed sample holder placed in an inductor with copper windings assuring alternating magnetic fields of safely biological amplitude-frequency products. The optimal shape with a specific size range for nanoparticles dispersed in various carriers providing the best heating efficiency is reported.

Highly dispersed supported NbOx species were prepared via a deposition precipitation-carbonization (DPC)-like method. As precursors for niobium species and carrier ammonium niobate(V) oxalate hydrate and humins were used. Characterization of the resulted catalysts indicated bi-functional acid-base niobium species anchored onto a highly hydrophobic graphite-like carbon structure. These catalysts were investigated in the one-pot conversion of glucose to 5-hydroxymethylfurfural (HMF) in a biphasic system consisting of a mixture of a 20 wt% NaCl aqueous solution phase and an organic extracting phase (methyl-isobutyl-ketone (MIBK), 2-tert-butylphenol (TBP) or 2sec-butylphenol (SBP)). The optimization conditions afforded the highest yield to HMF (96 %) for the GHNb1.2 catalyst (with 2.5 wt%Nb), the base/acid sites ratio of 1.76, in biphasic TBP/water system, at 180 ?C after 8 h.

The 20S proteasome enzyme complex is involved in the proteolytic degradation of misfolded and oxidatively damaged proteins and is a focus of medical research for the development of compounds with pharmaceutical properties, which are active in cancer cells and/or neurodegenerative diseases. The present study aims to develop a biosensor for investigating the 20S proteasome activity and inhibition by means of electrochemical methods. The 20S proteasome is best immobilized at the electrode surface through bio-affinity interactions with antibodies that target different subunits on the 20S proteasome, enabling the investigation of the effect of an enzyme's orientation on biosensor response. The enzymatic activity is analyzed by fixed potential amperometry with the highest sensitivity of 24 mu A cm(-2) mM(-1) and a LOD of 0.4 mu M. The detection principle involves the oxidation of an electroactive probe that is released from the enzyme's substrates upon proteolysis. The most sensitive biosensor is then used to study the multicatalytic activity of the 20S proteasome, i.e. the caspase-, trypsin- and chymotrypsin-like activity, by analyzing the biosensor's sensitivity towards different substrates. The behavior of the immobilized 20S proteasome is investigated as a function of substrate concentration. The kinetic parameters are derived and compared with those obtained when the enzyme was free in solution, with K-0.5 values being one to two orders of magnitude lower in the present case. Two 20S inhibitors, epoxomicin and bortezomib, are investigated by analyzing their influence on the 20S biosensor response. The proposed analytical method for proteasome activity and inhibitor screening has the main advantage of being cost-effective compared to the ones typically employed.

The 20S proteasome enzyme complex is involved in the proteolytic degradation of misfolded and oxidatively damaged proteins and is a focus of medical research for the development of compounds with pharmaceutical properties, which are active in cancer cells and/or neurodegenerative diseases. The present study aims to develop a biosensor for investigating the 20S proteasome activity and inhibition by means of electrochemical methods. The 20S proteasome is best immobilized at the electrode surface through bio-affinity interactions with antibodies that target different subunits on the 20S proteasome, enabling the investigation of the effect of an enzyme's orientation on biosensor response. The enzymatic activity is analyzed by fixed potential amperometry with the highest sensitivity of 24 mu A cm(-2) mM(-1) and a LOD of 0.4 mu M. The detection principle involves the oxidation of an electroactive probe that is released from the enzyme's substrates upon proteolysis. The most sensitive biosensor is then used to study the multicatalytic activity of the 20S proteasome, i.e. the caspase-, trypsin- and chymotrypsin-like activity, by analyzing the biosensor's sensitivity towards different substrates. The behavior of the immobilized 20S proteasome is investigated as a function of substrate concentration. The kinetic parameters are derived and compared with those obtained when the enzyme was free in solution, with K-0.5 values being one to two orders of magnitude lower in the present case. Two 20S inhibitors, epoxomicin and bortezomib, are investigated by analyzing their influence on the 20S biosensor response. The proposed analytical method for proteasome activity and inhibitor screening has the main advantage of being cost-effective compared to the ones typically employed.

Three commercial powders of MgB2 were tested in vitro by MTS and LDH cytotoxicity tests on the HS27 dermal cell line. Depending on powders, the toxicity concentrations were established in the range of 8.3-33.2 mu g/ml. The powder with the lowest toxicity limit was embedded into polyvinylpyrrolidone (PVP), a biocompatible and biodegradable polymer, for two different concentrations. The self-replenishing MgB2-PVP composite materials were coated on substrate materials (plastic foil of the reservoir and silicon tubes) composing a commercial urinary catheter. The influence of the PVP-reference and MgB2-PVP novel coatings on the bacterial growth of Staphylococcus aureus ATCC 25923, Enterococcus faecium DMS 13590, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, in planktonic and biofilm state was assessed in vitro at 6, 24, and 48 h of incubation time. The MgB2-PVP coatings are efficient both against planktonic microbes and microbial biofilms. Results open promising applications for the use of MgB2 in the design of anti-infective strategies for different biomedical devices and systems.

Amorphous metal chalcogenides have good switching properties for resistive memories, but have low thermal stability. In this work, the response to rapid thermal stress, as high as 550 degrees C, of amorphous Cu-GeSe, Ag-GeSe, Cu-GeTe, Ag-GeTe thin films, is investigated. Metal-GeTe films, which are amorphous up to 280 degrees C, are the most stable. Metal-GeSe films start to crystallize at 190 degrees C and a Cu1.59Se phase, with 20.5% Cu vacancies and a structure similar to the c-Cu2-xSe superionic conductor, is formed. This might boost the performance of memory devices. Silver atoms migration is facilitated in Ag-GeSe by poor crystallization (below 5%, at all temperatures). Difussion of Ag is enhanced in Ag-GeTe, due to the crystallization of the cubic (Ag2Te)(4)-GeTe2 (Ag8GeTe6) phase, which has Ag+ vacancies. In Cu-GeTe, the formation of stoichiometric polycrystalline Cu0.67Ge0.33 Te might hinder diffusion. An unusual anisotropic behaviour (increase in thickness, simultaneously with contraction of surface) is observed at 100 degrees C in Cu-GeSe and Cu-GeTe thin films, which suggests the orientation of the amorphous clusters package along a preferential direction.

In the present study, a new low-cost bioceramic nanocomposite based on porous hydroxyapatite (HAp) and cetyl trimethyl ammonium bromide (CTAB) as surfactant was successfully obtained by a simple chemical co-precipitation. The composition and structure of the HAp-CTAB were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer, and N-2 adsorption/desorption analysis. The capacity of HAp-CTAB nanocomposites to remove the lead ions from aqueous solutions was studied by adsorption batch experiments and proved by Langmuir and Freundlich models. The Pb2+ removal efficiency of HAp-CTAB biocomposite was also confirmed by non-destructive ultrasound studies. The cytotoxicity assays showed that the HAp-CTAB nanocomposites did not induce any significant morphological changes of HeLa cells after 24 h of incubation or other toxic effects. Taken together, our results suggests that the obtained porous HAp-CTAB powder could be used for the decontamination of water polluted with heavy metals, such as Pb2+.