JAQUELINE JAMARA SOUZA SOARES

JAQUELINE JAMARA SOUZA SOARES

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Antibacterial activity of graphene oxide/silver nanocomposite synthesized by sustainable process
2018 - 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.
Synthesis and characterization of graphene oxide/nickel nanoparticles using nanoparticle tracking analysis
2018 - JACOVONE, R.M.S.; SOARES, J.J.S.; SAKATA, S.K.
One of the graphene based compounds that has giving attention is graphene oxide (GO). This nanomaterial has oxygenated groups on its surface, which provide hydrophilicity and allow its exfoliation in several polar solvents. Moreover, these reactive sites can be further functionalized, yielding nanocomposites with many applications in electrochemistry and biomaterials fields. The objective of this study is to synthesize nickel / graphene oxide (GO-Ni) nanocomposite using electron beam in water /alcohol solution without stabilizers and to characterize GO and GO-Ni by Nanoparticle Tracking Analysis (NTA). The Nanoparticle Tracking Analysis utilizes the properties of both light scattering and Brownian motion in order to obtain the particle size distribution and to measure the diffusion coefficient. From the Stokes-Einstein equation it was possible to obtain the hydrodynamic diameter of the nanomaterials. The NTA result showed that GO and GO-Ni showed respectively 47 nm and 55nm. Both showed a low polydispersity index, indicating the homogeneity of the size distribution and the formation of a monodisperse system. The results showed that it is possible to obtain nanoparticles of graphene oxide incorporated with nickels smaller than 60 nm and with good distribution without the use of stabilizers.
Synthesis and characterization of magnetic graphene oxide nanocomposites
2018 - TOMINAGA, F.K.; SAKATA, S.K.; SOARES, J.J.S.; JACOVONE, R.M.S.
Graphene oxide (GO) is a unique material that can be described as a single monomolecular layer of graphite containing various oxygen functionalities such as epoxide, carbonyl, carboxyl and hydroxyl groups. Chemical modifications at the surface of the graphene oxide through the incorporation of magnetite can provide magnetic properties to these nanomaterials. This work aims to synthesize and characterize graphene oxide/magnetite (GO/M) nanocomposites, evaluating the different proportions of incorporated magnetite. The synthesis of graphene oxide/magnetite nanocomposites was performed by co-precipitation of iron salts on the graphene oxide (GO) particles in alkaline medium. The characterization of the nanocomposites was performed by thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), X-ray diffraction (XRD), nanoparticle tracking analysis (NTA) and scanning electron microscopy (SEM). The thermogravimetric results showed the incorporation of approximately 20, 50, 70 and 80% of magnetite to the graphene oxide. Regarding the hydrodynamic size, for the magnetite, mode values of 31.3 ± 1.3 nm were determined, whereas for the GO/M, the mode values of size ranged from 72.8 to 194 nm. The results of XRD and FTIR showed the respective characteristic diffraction and absorption peaks only for graphene oxide, magnetite and GO/M(20%). It was not observed characteristic peaks for the other samples of graphene oxide that have higher loads of magnetite incorporated.
The effect of gamma radiation on the stability of aqueous dispersions of graphene oxide and graphene oxide functionalized with amino-peg
2018 - SOARES, J.J.S.; SANTOS, P.S.; ZAIM, M.H.; SAKATA, S.K.
Nanocomposites based on graphene have been prominent in the field of biomedicine due to the biocompatibility with the physiological medium and the possibility of being functionalized by a series of biocompatible polymers, such as chitosan, polyethylene glycol, poly (caprolactone), among others. However, there is a need for sterilization of these nanomaterials in the medical field and gamma irradiation is a promising option. In the present work graphene oxide (GO), produced by the modified Hummers method, was functionalized with amino-PEG (GO-PEG-NH2) through the amidation process. The objective of this study was to evaluate the aqueous dispersions stability of these nanomaterials before and after gamma radiation (Cobalt 60) at a dose of 25 kGy. Dynamics light scattering (DLS) was used to determine the zeta potential. The results showed no significant differences between the zeta potentials of the non-irradiated and irradiated graphene oxide. The dispersion of the functionalized graphene oxide showed to be stable and the irradiated unstable.
Antimicrobial activity of Graphene Oxide/Silver nanocomposite obtained by Electron Beam
2017 - 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.
The effect of GO-PEG-NH2 on the mechanical resistance of bovine pericardium used in cardiovascular device
2017 - SOARES, JAQUELINE J.S.; JACOVONE, RAYNARA M.S.; MATHOR, MONICA B.; ZAIM, MARCIO H.; MAIZATO, MARINA J.S.; CESTARI, IDAGENE A.; JATENE, FABIO B.; SAKATA, SOLANGE K.
Valvular heart disease (VHD) is a clinical condition where one of the four-heart valves is damage or has a defect. It was estimated that approximately 300,000 to 400,000 heart valve replacement surgeries were performed in 2014. There are two types of prostheses, the bioprothesis and the mechanical prosthesis. Even though the first one presents a smaller rejection, its durability is reduced due to calcification followed by deterioration. The objective of this work was to increase the durability of prostheses made from bovine pericardium (BP) by incorporating GO functionalized with amino-PEG (GO-PEG-NH2). Briefly, GO functionalized was firstly sterilized with gamma radiation and then incorporated to BP in two different ways: chemical and physical. Mechanical characterization assays of BP treated with GO-PEG-NH2 and untreated (control) were performed in an INSTRON model 3365 universal test equipment using the BioPlus accessory, which allows the assays to be carried out immersed in a physiological solution of 0,9% NaCl at 36 °C, simulating the environment of material’s application. The static deformation in the uniaxial direction of the test specimens was verified using the ASTM D638-10 standard test method for tensile properties of plastics, 2010 from the American Society for Testing and Materials (ASTM Standards). The results indicated that GO-PEG-NH2 improved the mechanical strength of the biomaterial, increasing the resistance to permanent plastic deformation, maximum supported load, flow limit, maximum traction tension, rupture tenacity and rupture traction tension no matter of GO-PEG-NH2 incorporation methods and it is possible to improve the performance of bioprothesis by coating them with GO-PEG-NH2 and consequently increasing their durability.
Characterization by atomic force microscope (AFM) of graphene oxide and graphene oxide-PEG-NH2 incorporated in bovine pericardium
2017 - SOARES, JAQUELINE J.S.; COSTA, CARLOS A.R.; JACOVONE, RAYNARA M.S.; ZAIM, MARCIO H.; SAKATA, SOLANGE K.
Atomic force microscopy (AFM) is a technique that allows images from the surface topography with high spatial resolution at Nano metric scales. AFM has being used in several fields in science such as Biology, Medicine, Chemistry and Pharmaceuticals. In this study, the tecnhique was used to characterize graphene oxide and graphene oxide functionalized with amino-PEG (GO-PEG-NH2) in the bovine pericardium (BP) surface. The treatment of BP with GO and (GO-PEG-NH2) improved the mechanical properties of the biomaterial that will be used in the manufacture of cardiovascular device that is used to replace heart valves. For the BP coating, two different pathways were tested: 1) chemical pathway using solution containing 1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and GO; and 2) in physical adsorption the incorporation were performed by ultrassom. The same procedure was performed to incorporate GO-PEG-NH2. The images of the BP with its modified surface were obtained by AFM and proof the efficiency in the two incorporation processes. The study also demonstrated the applicability of AFM to characterize incorporated nanomaterial in the biological samples.
Sustainable synthesis of transition metals/graphene oxide nanocomposites by electron beam irradiation
2017 - SAKATA, S.K.; SOBRINHO, L.F.; JACOVONE, R.M.S.; SOARES, J.J.S.; TOMINAGA, F.K.; ANGNES, L.; GARCIA, R.H.L.
Graphene is nanomaterial with unique physical and chemical properties that makes it a precursor for the synthesis of new materials, such as conductive nanocomposites. Graphene can be obtained by the reduction of graphene oxide, but when it is incomplete, reduced graphene oxide (rGO) is produced with both graphene and graphene oxide properties: it is electrical and thermal conductor, it can be exfoliated in several polar solvents and moreover, the oxygen groups can later be functionalized, affording nanocomposites for electrochemical applications and also in biomaterials. A method of increasing the electrical conductivity of graphene-based compounds is by the incorporation of metallic nanoparticles. When these nanomaterials are joined together the surface area increases for the passage of electric current and the electrical conductivity. The chemical reduction method for the incorporation of metallic nanoparticle on GO involves toxic reagents or it is a time-consuming and it also requires high costs for the removal of excess reagents and by-products. The general synthesis of transition Metal/graphene-based nanocomposites by the electron beam in a sustainable process will be presented. The experiments were performed in a 1.5 MeV electron accelerator at room temperature and no hazardous wastes were generated. The nanocomposites were characterized by FT-IR, DRX and TEM/EDS as metallic nanoparticle at the average size of 5-20 nm incorporated into reduced graphene oxide layers. The electrochemical behavior of these nanocomposites was evaluated by cyclic voltammetry.
Gamma radiation assisted reduction of graphene oxide in unoxidized environment
2017 - MOURA, TIAGO S.; GOTO, PAULA T.; GARCIA, RAFAEL H.L.; SALVADOR, PABLO A.V.; SANTOS, PAULO S.; SOARES, JAQUELINE J.S.; NODA, LUCIA; SAKATA, SOLANGE K.
Graphene is a honeycomb like structure of carbon atoms of sp2 hybridization, with remarkable physical and chemical properties. Perhaps, the most desirable properties of a such material is the quasi-ballistic electronic transport and its excellent thermal conductivity that make graphene an excellent alternative to build electronic devices related to silicon, for instance. However, the lack of organic functions and the strong bonds between carbons in graphene nano-sheets make them unable to undergo functionalization reactions, that is important for many applications such as gas and biochemical sensors or nanoparticles decoration. So, in order to allow the functionalization of graphene nano-sheets and make possible a variety of new applications it was developed a nanomaterial based on the oxidation and exfoliation of graphite: the graphene oxide. This new material has epoxide and hydroxyl groups in the basal planes, with carboxyl groups in the borders, improving the hydrophilic properties and potential for chemical functionalization. Graphene oxide also serves as a starting material to graphene production by reduction routes. Partial reduction of graphene oxide leads to reduced graphene, a nanomaterial that combines both proprieties of graphene and graphene oxide: an excellent electrical and thermal conductivity, high superficial area and remaining oxygen groups that allow its functionalization. In the literature is described different ways to produce reduced oxide graphene from graphene oxide, such as chemical reduction using hydrazine hydrate or NaBH4, thermal reduction using high temperatures and plasma hydrogenation. Here in it is described a sustainable process to reduce graphene oxide in sodium bisulfite solution using gamma radiation. Exfoliated Graphene oxide (1-100mg/L) with NaHSO3 under inert medium was submitted to gamma radiation. The radiation dose ranged from 50 to 500 kGy and the product was centrifuged and analyzed by X-ray diffraction (XRD), Raman and infra-red (FT-IR) spectroscopies. It was observed that depending on the dose total or partial reduction was achieved. This methodology does not produce any toxic residue.
Synthesis of reduced graphene oxide/nickel (rGO/NiO) nanocomposite via electron beam
2017 - 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.