THAINA SILVA E SOUSA
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Artigo IPEN-doc 26718 Antibacterial activity of silver/reduced graphene oxide nanocomposite synthesized by sustainable process2019 - JACOVONE, RAYNARA M.S.; SOARES, JAQUELINE J.S.; SOUSA, THAINA S.; SILVA, FLAVIA R.O.; GARCIA, RAFAEL H.L.; NGUYEN, HANG N.; RODRIGUES, DEBORA F.; SAKATA, SOLANGE K.Traditional methods to incorporate metals into graphene oxide (GO) usually require toxic reagents or high temperatures. This study proposes an innovative and sustainable method to incorporate silver (Ag) into graphene oxide using electron beam and evaluate its antibacterial activities. The method is based on green synthesis, without toxic reagents or hazardous wastes, and can be carried out at room temperature, in short reaction times. To synthesize the Ag/rGO nanocomposite, a water/isopropanol solution with dispersed graphene oxide and silver nitrate was submitted to a dose range from 150 to 400 kGy. The product was characterized by thermogravimetry analysis, X-ray diffraction and transmission electron microscopy. The antibacterial activity of Ag/rGO was observed against Gram-negative Escherichia coli by plate count method and atomic force microscopy. The results showed that concentrations as low as 100 lg/mL of produced Ag/rGO were enough to inactivate the cells.Resumo IPEN-doc 25918 Antibacterial activity of graphene oxide/silver nanocomposite synthesized by sustainable process2018 - JACOVONE, R.M.S.; SOARES, J.J.S.; SOUSA, T.S.; RODRIGUES, D.F.; SILVA, F.R.O.; GARCIA, R.H.L.; VICENTE, E.J.; SAKATA, S.K.Graphene oxide/silver nanocomposite has excellent antimicrobial properties [1]. The traditional methods of incorporation of metal in graphene oxide usually require toxic reagents or with long periods of reaction and in high temperature [2]. The objective of this study is to develop an innovative and sustainable method of incorporating silver into graphene oxide by electron beam. This methodology does not involve toxic reagents or residues and it is carried out in a short reaction time at room temperature. Dispersed graphene oxide was mixed with silver in the complex form in water- isopropanol solution. The mix was submitted to a dose of radiation varying between 150 and 400 KGy. The nanocomposite GO/Ag characterization was performed by thermogravimetry analysis (TGA), X-ray diffraction (XDR), scanning transmission electron microscope coupled to the energy dispersive X-ray spectrometry (TEM/EDS). The antibacterial activity of GO/Ag was observed against Gram negative, Escherichia coli by plate count method. The viable cells of GO and GO-Ag was determined by plating the inoculum after 4h of exposure to different concentrations of the nanomaterials (10, 50, 100, 200 and 500 μg/mL). The results showed that for 500 μg/mL of GO, inactivation cells were ca of 5,4 %, while for GOAg, the concentration to inactivate all cell were 5 times lower (100 μg/mL). The silver nanoparticles size range from 20 to 50 nm. This work showed that GO/Ag nanocomposites that were widely studied by their antibacterial properties can be produce by ionizing radiation. This is a sustainable method that does not require toxic reagents and does not generate hazardous wastes. The short reaction time of some minutes and the ambient temperature also make the process attractive.Resumo IPEN-doc 24852 Antimicrobial activity of Graphene Oxide/Silver nanocomposite obtained by Electron Beam2017 - SOUSA, THAINA S.; JACOVONE, RAYNARA M.S.; SOARES, JAQUELINE J.S.; RODRIGUES, DEBORA F.; SILVA, FLAVIA R. de O.; GARCIA, RAFAEL H.L.; ZAIM, MARCIO H.; SAKATA, SOLANGE K.Graphene oxide is a carbon-based nano material that has a high specific surface area, high chemical stability, excellent electrical and thermal conductivities, high mechanical resistance, the oxygen groups facilitate dispersion in polar solvents and its functionalization. In the literature, is described several methods of metal incorporation on graphene oxide surface using toxic reagents or with long periods of reaction. The objective of this work is to develop an innovative and sustainable method of incorporating silver into graphene oxide that does not involve toxic reagents or generated residues. in a short reaction time at room temperature beyond the use of the as an alternative process to the chemical processes traditional.A silver solution in the complex form was added to a dispersed graphene oxide in water/isopropanol solution. The mixture wassubmitted to a dose of radiation ranged from 150 to 400 KGy using a electron beam acelerator. The nanocomposite GO/Ag characterization was performed by thermogravimetry analysis (TGA), X-ray diffraction (XDR), scanning transmission electron microscope coupled to the energy dispersive X-ray spectrometry (TEM/EDS). The antimicrobial activity of GO/Ag was observed by Escherichia coli, a Gram negative bacterium and Bacillus subtilis a Gram positive bacterium in solid culture medium. The minimum inhibitory concentration of GO/Ag was 50 mg/L. .It is noteworthy that the incorporation of silver occurred at the same time the reduction of graphene oxide without the generation of toxic chemical residues.Resumo IPEN-doc 23240 Synthesis of reduced graphene oxide/nickel (rGO/NiO) nanocomposite via electron beam2017 - SOUSA, THAINA S.; JACOVONE, RAYNARA M.S.; SOARES, JAQUELINE J.S.; RODRIGUES, DEBORA F.; SILVA, FLAVIA R. de O.; GARCIA, RAFAEL H.L.; FELIX, FABIANA S.; ANGNES, LUCIO; SAKATA, SOLANGE K.Introduction Electron Beam is a flow of electrons with energy that has been used mainly for sterilization and to cross-link polymers. However, little is known about graphene based /metal nanocomposites generated by electron beam metal nanoparticles on graphene-based surfaces produces new materials with wide application in optics, electronics and catalysis 1. The aims of this work are to syntheze and characterize reduced graphene oxide/nickel oxide (rGO/NiO) via electron beam to generate conductive materials. Method, Results and discussion Dispersed graphene oxide was mixed with nickel in the complex form in water-isopropanol (1:1) solution. The mix was submitted to a dose of radiation varying between 150 and 400 KGy. The nanocomposite rGO/NiO characterization was performed by thermogravimetry analysis (TGA), X-ray diffraction (XDR), cyclic voltammetry (CV) and scanning transmission electron microscope coupled to the energy dispersive X-ray spectrometry (TEM/EDS). The TGA curve showed that the incorporation amount of Ni was 20% (w/w) and the presence of Ni was confirmed by TEM/EDS and nanoparticle size was 20 nm. The nanocomposite crystalline structure was confirmed by XRD as well as the number of layers of rGO, which are four. From the XDR pattern of the rGO/NiO, a peak corresponding to the rGO at 2θ=9.10°. These results indicate the incorporation of Ni nanoparticles to the rGO. The electrochemical characterization of rGO/NiO was performed by CV. From the voltammetric profile, current peaks were observed at 0,45 V (vs.Ag/AgCl) and correspond to 0,75 A/mol/cm2 in ascorbic acid media and pH = 5.0. According to the data obtained, it was possible to observe that the rGO/NiO showed a higher current density compared to graphene oxide at the same conditions. Conclusions The analysis demonstrated that it is possible to apply electron beam in the synthesis of rGO/NiO and as confirmed by the characterization results. It is noteworthy that the incorporation of NiO occurred at the same time the reduction of graphene oxide. The voltammetric results showed that the presence of rGO/NiO facilitated the transfer of charge during the electrooxidation of ascorbic acid. This study allowed the generation of a conductive nanocomposite that can be widely used in the electrochemical area.Resumo IPEN-doc 22964 Síntese do nanocompósito oxido de grafeno com níquel (OG – Ni) via feixe de elétrons2016 - SILVA e SOUSA, THAINA; SAKATA, SOLANGE K.