Mn-tetratolylporphyrin-Nano-Au complex sensitive to 4-aminosalicylic acid

Porphyrins and metalloporphyrins provide recognition sites for amino acids both through their cationic central metal ion and due to various functional groups at the four mesoand the eight β-positions of pyrolles. Immobilized metallo-phenylporphyrins can be used as sensitive and selective sensors for different analytes as they provide two ways of interaction via the metallic center of porphyrin and between the electrons of the macrocycles and the solute [1]. The purpose of this study was to establish an easy way to determine low concentrations of 4-aminosalycilic acid (PAS) using hybrid materials obtained from porphyrins, namely: Mn(III)-tetratolylporphyrin chloride (MnTTPCl) and gold nanoparticles (n-Au). During the adding of 4-aminosalycilic acid to the MnTTPCl-nAu hybrid it can be observed that the intensity of the plasmonic band is continuously decreasing with the increase in 4-aminosalycilic acid concentration. Another notable feature is the bathochromic shift of the major peak to higher wavelengths from 619 nm to 622 nm. Equilibria processes are involved and accompanied by an isosbestic point around 725 nm. The dependence between the absorption intensity of the plasmonic complex and the concentration of 4-aminosalicylic acid is linear, with an excellent corelation coefficient of 99.31% in a wide range of 4- aminosalicylic acid concentrations: 2.88x10-5M - 8.89x10-4M

Electrodeposition and corrosion behavior of hydroxyapatite onto titanium

The present study includes the results of the hydroxyapatite electrochemical deposition on titanium substrate from 3 solutions of different concentrations of precursors. The deposited HA layers and the substrate were studied by means of x-ray diffraction and scanning electron microscopy, and also corrosion resistance tests have been performed. Results confirmed the formation of low crystallinity hydroxyapatite coatings, displaying fine layers of feathery crystals and other structures resulted from agglomeration phenomena. Corrosion tests, performed in artificial saliva solution, showed that the corrosion resistance of the hydroxyapatite coated Ti sample obtained from 0.875M Ca and 0.525M P precursors solutions was higher than that of the other samples

Electrochemical synthesis of poly-3-aminophenylboronic acid in sulfuric acid solution

Sensors based on the complexation of boron groups with diols are an attractive alternative to detection of biologic compounds in particular dopamine. The electropolymerisation of 3- aminophenylboronic acid (APBA) in aqueous solutions on Pt electrodes has been investigated. The obtained poly-3-aminophenylboronic acid is used for the potentiometric detection of dopamine

Electrochemical behaviour of LaMnO3-modified graphite electrodes

The electrochemical behaviour of LaMnO3-modified graphite electrodes was studied using cyclic voltammetry. Potassium ferricyanide was employed as a probe to determine the electroactive surface area of LaMnO3 modified electrodes and their diffusion coefficient. The electroactive surface area and the diffusion coefficient were calculated using the RandlesSevcik equation

Hydroxyapatite coatings on TI substrates by simultaneous precipitation and electrodeposition

This paper presents the results obtained by analyzing hydroxyapatite (HA) coatings electrodeposited onto titanium plates. Instead of using a solution containing both calcium and phosphorus ions, the present approach starts with just one precursor in the electrolysis cell, and the other precursor is being added while an electrochemical potential of -1500 mV is simultaneously applied. By alternating the order of precursor addition, the Ti substrate surface was modified and the differences were evidenced using XRD, SEM, Raman and AFM. For all samples, needle-like crystals of HA grouped as hemispheres on the substrate surface. There is no significant difference, regarding morphology and hemisphere size, between the samples prepared at 1h deposition time, regardless of the precursor addition order; by contrast, the sample deposited for 4h presented a higher density

TEM, EDX and raman study of nickel oxide micro- and nanophases obtained by thermal decomposition of an organometallic precursor

Nickel(II) polyoxalate was thermally decomposed to nickel oxide in both oxidative and inert atmospheres and the products were investigated using TEM-EDX and Raman spectroscopy. The resulting micro- and nanoparticles were compared regarding their size, morphology and composition. In dynamic aerobic conditions, the product obtained at 1000 °C shows better crystallinity and presents more well defined shapes than the one obtained at 400 °C. The 1000 °C product obtained in argon is a mixture of NiO and metallic Ni

Effect of PD addition in lanthanum manganite : morpho-structural and electrical properties

LaMnO3 is an inorganic compound with perovskite structure and partial substitution of lanthanum ions [1] or manganese ions [2] has an effect on the physical properties of materials. In the present work we report the synthesis of LaMn1−x PdxO3 (with x = 0.2 and 0.3) materials at low temperature. The doping was performed in order to improve the electrical properties by changing the crystalline structure and prevent ordering of the oxygen vacancies in these materials. The obtained materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), BET analysis, energy-dispersive X-ray spectroscopy (EDX) and electrical measurements. Structural analysis shows that the obtained materials crystallize in cubic structure and have a homogeneous composition, without secondary compounds