An innovative aluminium foil electrode modified with Al nanoparticles and EDTA for lead detection in biological samples.

This study presents a novel Aluminium foil-based electrode characterized by its affordability, flexibility, and ease of modification with carboxylic moiety-containing organic molecules. Upon foil modification with Aluminium nanoparticles and EDTA (AlNP-EDTA/AlE), the modified electrode exhibits remarkable activity in the oxidation of lead at potentials around -0.4 V. The lead signal is derived from the oxidation of lead deposited on the electrode surface using anodic stripping voltammetry (ASV). The addition of EDTA to AlNP/AlE increased the anodic peak current of lead by more than 500 %. The surface characterization of the electrode was performed by scanning electron microscopy (SEM) and infrared spectroscopy (IR), while its electroactive properties were evaluated by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Optimal operating parameters include pH 2.1, square-wave voltammetry (SWV) with an accumulation time of 60 s and an accumulation potential of -0.8 V. A low detection limit of 0.20 µmol/L and a relative standard deviation (RSD) of 3.0 % were achieved using five different electrodes. The effectiveness of AlNP-EDTA/AlE was further demonstrated with consistent results in biological samples spiked with Pb.

Antimicrobial activity of graphite oxide doped with silver against Bacillus subtilis, Candida albicans, Escherichia coli, and Staphylococcus aureus by agar well diffusion test: Synthesis and characterization.

In the present study, graphite oxide, graphite oxide doped with 0.8 g AgNO3 named GrO-0.5Ag, and graphite oxide doped with 1.25 g AgNO3 named GrO-1.0Ag (silver-doped graphitic materials) were synthesized by the modified Hummers and chemical doping methods. Subsequently, its antimicrobial activity against Bacillus subtilis, Candida albicans, Escherichia coli, and Staphylococcus aureus microorganisms was evaluated by agar well diffusion test with 1 and 2 mg·ml-1 of material concentrations. The silver-doped graphitic materials were characterized by X-Ray Diffraction, Fourier-Transform Infrared, Raman, X-Ray Photoelectron spectroscopies, and Scanning Electron Microscopy. The GrO-0.5Ag material showed a percentage of inhibition effect of 86, 82, 48, and 45% with respect to the positive control for Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Candida albicans microorganisms, respectively. Otherwise, the GrO-1.0Ag material showed a percentage of inhibition effect of 54% with respect to the positive control for Bacillus subtilis and less than 50% for the other microorganisms. The material concentrations showed a slight change in the percentage of inhibition effect for all microorganisms. Graphite oxide functional groups, small crystal size, free silver ions, and silver carbonate formation in silver-doped graphitic materials presented a viable alternative to inhibit bacterial growth.

Synthesis, characterization and photocatalytic activity of 1D TiO2 nanostructures.

Nanowire/nanorod TiO(2) structures of approximately 8 nm in diameter and around 1,000 nm long were synthesized by alkaline hydrothermal treatment of two different TiO(2) nanopowders. The first precursor was TiO(2) obtained by the sol-gel process (SG-TiO(2)); the second was the well-known commercial TiO(2) P-25 (P25-TiO(2)). Anatase-like 1D TiO(2) nanostructures were obtained in both cases. The one-dimensional (1D) nanostructures synthesized from SG-TiO(2) powders turned into rod-like nanostructures after annealing at 400 °C for 2 h. Conversely, the nanostructures synthesized from P25-TiO(2) preserved the tubular structure after annealing, displaying a higher Brunauer-Emmett-Teller surface area than the first system (279 and 97 m²/g, respectively). Despite the higher surface area shown by the 1D nanostructures, in both cases the photocatalytic activity was lower than for the P25-TiO(2) powder. However, the rod-like nanostructures obtained from SG-TiO(2) displayed slightly higher efficiency than the sol-gel prepared powders. The lower photocatalytic activity of the nanostructures with respect to P-25 can be associated with the lower crystallinity of 1D TiO(2) in both materials.

Indium Doped Zinc Oxide Thin Films Deposited by Ultrasonic Chemical Spray Technique, Starting from Zinc Acetylacetonate and Indium Chloride.

The physical characteristics of ultrasonically sprayed indium-doped zinc oxide (ZnO:In) thin films, with electrical resistivity as low as 3.42 × 10-3 Ω·cm and high optical transmittance, in the visible range, of 50%-70% is presented. Zinc acetylacetonate and indium chloride were used as the organometallic zinc precursor and the doping source, respectively, achieving ZnO:In thin films with growth rate in the order of 100 nm/min. The effects of both indium concentration and the substrate temperature on the structural, morphological, optical, and electrical characteristics were measured. All the films were polycrystalline, fitting well with hexagonal wurtzite type ZnO. A switching in preferential growth, from (002) to (101) planes for indium doped samples were observed. The surface morphology of the films showed a change from hexagonal slices to triangle shaped grains as the indium concentration increases. Potential applications as transparent conductive electrodes based on the resulting low electrical resistance and high optical transparency of the studied samples are considered.

Chromium and ruthenium-doped zinc oxide thin films for propane sensing applications.

Chromium and ruthenium-doped zinc oxide (ZnO:Cr) and (ZnO:Ru) thin solid films were deposited on soda-lime glass substrates by the sol-gel dip-coating method. A 0.6 M solution of zinc acetate dihydrate dissolved in 2-methoxyethanol and monoethanolamine was used as basic solution. Chromium (III) acetylacetonate and Ruthenium (III) trichloride were used as doping sources. The Ru incorporation and its distribution profile into the films were proved by the SIMS technique. The morphology and structure of the films were studied by SEM microscopy and X-ray diffraction measurements, respectively. The SEM images show porous surfaces covered by small grains with different grain size, depending on the doping element, and the immersions number into the doping solutions. The sensing properties of ZnO:Cr and ZnO:Ru films in a propane (C3H8) atmosphere, as a function of the immersions number in the doping solution, have been studied in the present work. The highest sensitivity values were obtained for films doped from five immersions, 5.8 and 900, for ZnO:Cr and ZnO:Ru films, respectively. In order to evidence the catalytic effect of the chromium (Cr) and ruthenium (Ru), the sensing characteristics of undoped ZnO films are reported as well.