Laboratorio Interdisciplinar Of Materiais Avancados

Teresina, Brazil

Laboratorio Interdisciplinar Of Materiais Avancados

Teresina, Brazil
Time filter
Source Type

Bittencourt C.R.,Federal University of Piauí | De Oliveira Farias E.A.,Federal University of Piauí | Bezerra K.C.,Federal University of Piauí | Veras L.M.C.,Federal University of Piauí | And 9 more authors.
Materials Science and Engineering C | Year: 2016

This report details the development of thin films containing an antimicrobial peptide, specifically, dermaseptin 01 (GLWSTIKQKGKEAAIAAA-KAAGQAALGAL-NH2, [DRS 01]), and a natural polysaccharide, for a novel application in detecting the presence of Leishmania cells and maintaining anti-leishmanial activity. The peptide DRS 01 was immobilized in conjunction with natural cashew gum (CG) onto an indium tin oxide (ITO) substrate using the Layer-by-Layer (LbL) deposition technique. The LbL film ITO/CG/DRS 01, containing DRS 01 as the outer layer, was capable of detecting the presence of Leishmania cells and acting as an anti-leishmanial system. Detection was performed using cyclic voltammetry (CV) in phosphate buffer (pH 7.2) in the presence of promastigote cells (0-107 cells/mL). The results showed a linear and inversely proportional relation between the concentration of Leishmania infantum protozoan cells and the measured current values obtained for the films, which was attributed to the effect of peptide-induced lysis of the cell membrane, and resulted in freed residues that were adsorbed on the electrode surface. With this, the paper shows a method using thin films with this new material to demonstrate the anti-leishmanial activity in vitro models of carpet-like mechanisms. © 2015 Elsevier B.V. All rights reserved.

Sousa R.B.,Laboratorio Interdisciplinar Of Materiais Avancados | Nascimento V.A.,Laboratorio Interdisciplinar Of Materiais Avancados | Matos J.M.E.,Laboratorio Interdisciplinar Of Materiais Avancados | Lima C.L.,Federal University of Piauí | And 2 more authors.
Ceramica | Year: 2015

Barium tungstate (BaWO4) is an important ceramic material belonging to the family of scheelites, which is applied as photoluminescent material, as scintillator, light-emitting diodes (LEDs), solid-state lasers, among other, being a host matrix for lanthanide ions, due to its chemical and mechanical stability. This research aims to synthetize, characterize structurally and evaluate photoluminescent properties of barium tungstate powders and Ho3+-doped barium tungstate. Powders of Ba1-xHo2x/3WO4 (x= 0, 0.01 and 0.02) were obtained by coprecipitation and characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier-Transformed Infrared spectroscopy (FTIR), UV-Vis spectroscopy, scanning electron microscopy (SEM) and photoluminescent spectroscopy. XRD and Raman spectroscopy analyses revealed crystalline ordering for these materials. Their morphology was characterized by the presence of octahedral grains with heterogeneous distribution of grain size. A broad band centered at 475 nm was identified for BaWO4 at 350,7 nm excitation in emission spectrum. The addiction of holmium ions into the BaWO4 matrix promoted a significant reduction of the optical gap and characteristic transitions (f-f transitions) of ions Ho3+ were identified.

Nunes Pauli G.E.,Federal University of Santa Catarina | Araruna F.B.,Federal University of Piauí | Eiras C.,Federal University of Piauí | Eiras C.,Laboratorio Interdisciplinar Of Materiais Avancados | And 7 more authors.
Materials Science and Engineering C | Year: 2014

This paper reports the study and characterization of a new platform for practical applications, where the use of phaeophytin-b (phaeo-b), a compound derived from chlorophyll, was characterized and investigated for sensing purposes. Modified electrodes with nanostructured phaeo-b films were fabricated via the layer-by-layer (LbL) technique, where phaeo-b was assembled with cashew gum, a polysaccharide, or with poly(allylamine) hydrochloride (PAH). The multilayer formation was investigated with UV-Vis spectroscopy by monitoring the absorption band associated to phaeo-b at approximately 410 nm, where distinct molecular interactions between the materials were verified. The morphology of the films was analyzed by atomic force microscopy (AFM). The electrochemical properties through redox behavior of phaeo-b were studied with cyclic voltammetry. The produced films were applied as sensors for hydrogen peroxide (H2O2) detection. In terms of sensing, the cashew/phaeo-b film exhibited the most promising result, with a fast response and broad linear range upon the addition of H2O2. This approach provides a simple and inexpensive method for development of a nonenzymatic electrochemical sensor for H2O2. © 2014 Elsevier B.V. All rights reserved.

de Fatima Cardoso Soares M.,Federal University of Piauí | de Fatima Cardoso Soares M.,Instituto Federal Of Educacao | de Oliveira Farias E.A.,Federal University of Piauí | da Silva D.A.,Federal University of Piauí | And 3 more authors.
Journal of Materials Science | Year: 2016

For the first time, the dye alizarin red S (ARS) was immobilized on indium tin oxide (ITO) electrodes via a layer-by-layer technique (LbL). This was achieved only when ARS was interspersed with the polymers agar (extracted from seaweed Gracilaria birdiae) and PAH [poly(allylamine hydrochloride)]. ARS alone did not show electroactivity when adsorbed onto ITO. Single-walled carbon nanotubes (functionalized with COOH, denoted CNTs) were used to increase the electrochemical signal of the LbL system. Interactions at the molecular level between the CNTs and other materials used in the construction of the films accounted for a threefold increase in the current signal of ARS. The films were developed as trilayer films of agar/PAH/ARS or agar(CNT)/PAH(CNT)/ARS and characterized by differential pulse voltammetry (DPV) and UV–visible spectroscopy and scanning electron microscopy. From the results, it was also possible to calculate the energy diagram for both films. The results showed that the films are promising for applications as electrochemical sensors. Accordingly, the agar(CNT)/PAH(CNT)/ARS film was tested for the reduction of hydrogen peroxide (H2O2). Under a constant potential of −0.5 V versus SCE (saturated calomel electrode), the film exhibited a rapid response for the reduction of peroxide (less than 5 s), and the current stabilized approximately at 30 s. The limit of detection for the amperometric sensor was approximately 0.15 µmol L−1. © 2016 Springer Science+Business Media New York

Oliveira A.M.B.M.,Federal University of Campina Grande | Coelho L.F.O.,Federal University of Campina Grande | Gomes S.S.S.,Federal University of Paraiba | Costa I.F.,Federal University of Paraiba | And 4 more authors.
Water, Air, and Soil Pollution | Year: 2013

Natural palygorskite was used as an adsorbent for the removal of copper, cobalt and nickel from an aqueous solution. All assays were performed under controlled conditions to establish the adsorption capacity of the solid. Initially, the clay was characterized by chemical analysis, XRD, infrared spectroscopy and thermogravimetry. Adsorption experiments for the ions in aqueous solution were carried out by a batch method through which the reaction time, initial concentration of cations, temperature and pH of the aqueous solution were systematically varied. First-order, pseudo-second-order and intraparticle diffusion models were used to describe the kinetic data. The results show that the processes were fitted well by the pseudo-second-order model. Moreover, the equilibrium solid-cation systems followed the Langmuir isotherm model. The results indicate that raw palygorskite could be employed as a low-cost material for the removal of heavy metals from aqueous solution. © 2013 Springer Science+Business Media Dordrecht.

Farias E.A.O.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | Dionisio N.A.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | Quelemes P.V.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | Leal S.H.,Federal University of ABC | And 6 more authors.
Materials Science and Engineering C | Year: 2014

Composites prepared from polyaniline (PANI) and the ceramic technology of titanium dioxide (TiO2) have been proposed, however, the interaction of these materials with greater control of molecular arrangement becomes attractive in order to achieve properties not previously described or yet the optimization of those already reported. Therefore, in this study, thin hybrid films made of polyaniline (PANI), a conductive polymer, and the technological ceramic, titanium dioxide (TiO2), were prepared by the layer-by-layer (LbL) self-assembly technique. The films were characterized by cyclic voltammetry (CV), UV-VIS spectroscopy and atomic force microscopy (AFM). Aiming to improve the dispersion of the ceramic in the polymer matrix, the commercial surfactant, cetyl trimethylammonium bromide (CTAB), was used in the formation of the films. The best condition of deposition was found showing synergic interactions between the conjugated materials. The antibacterial activity of the PANI(TiO2)/CTAB films was studied and the obtained results suggest their use as antimicrobial coatings. © 2013 Elsevier B.V. All rights reserved.

Paiva G.M.S.,Grupo de Inovacoes Tecnologicas e Especialidades Quimicas | Freitas A.R.,Grupo de Inovacoes Tecnologicas e Especialidades Quimicas | Nobre F.X.,Laboratorio Interdisciplinar Of Materiais Avancados | Leite C.M.S.,Grupo de Inovacoes Tecnologicas e Especialidades Quimicas | And 3 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2015

In the present work, the thermal stabilities and decomposition kinetics of the hydrogenated cardanol and its derivative - alkylated hydrogenated cardanol - were investigated using thermogravimetry. The chemical compounds showed results comparable to butylated hydroxytoluene, a commercial product that has antioxidant activity. The kinetic parameters of activation energy (E), Arrhenius pre-exponential factor (A), thermal endurance, and relative thermal index were described. Different heating rates were used, and the standard test methods - ASTM E1131-08, E1641-13, and E1877-13 - were followed. According to the results, the alkylated hydrogenated cardanol showed the highest activation energy 83.02 × 103 J mol-1 and the higher thermal stability, followed by hydrogenated cardanol 40.08 × 103 J mol-1 and butylated hydroxytoluene 33.48 × 103 J mol-1. © 2015 Akadémiai Kiadó, Budapest, Hungary.

De Oliveira Farias E.A.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | Dos Santos M.C.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | De Araujo Dionisio N.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | Quelemes P.V.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | And 5 more authors.
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2015

This paper proposes a new application for natural polysaccharides (agar and carrageenan), both extracted from the cell wall of red seaweeds. Thin films were prepared by the Layer-by-Layer (LbL) self-assembly technique onto ITO (tin-doped indium oxide), where the polysaccharides of interest were deposited in layers alternating with polyaniline (PANI). The films developed were characterized by cyclic voltammetry (CV), ultraviolet-visible spectroscopy (UV-vis) and atomic force microscopy (AFM). Results showed the presence of agar as well as carrageenan, which improves the electrochemical stability of the conducting polymer in an acid medium. The interactions at the molecular level between PANI and the biopolymers affected the most appropriate sequence of deposition as employed in the process of material immobilization and also influenced the resulting morphology. Among the films studied, the most promising system as regards electrochemical measurements was the ITO/agar/PANI system, which was subsequently employed in the electrochemical detection of chromium (VI). ©2015 Published by Elsevier B.V.

Loading Laboratorio Interdisciplinar Of Materiais Avancados collaborators
Loading Laboratorio Interdisciplinar Of Materiais Avancados collaborators