SOLANGE KAZUMI SAKATA

SOLANGE KAZUMI SAKATA

(Fonte: Lattes)

Resumo

Possui graduação em Química bacharelado e licenciatura pela Universidade de São Paulo. Doutorado na área de Química Orgânica, com ênfase em Eletrossintese Orgânica pelo Instituto de Química da Universidade de São Paulo. Pós - doutorados em Biotecnologia no Scripps Institution of Oceanography na University of California - San Diego -USA) e no Instituto de Química da Universidade de São Paulo. Foi pesquisadora visitante no Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB-Stuttgart - Alemanha no estudo do metagenoma na produção de enzimas para fins catalíticos e no Centro Tecnológico da Marinha de São Paulo (CTM-SP) no desenvolvimento e caracterização de polímeros. Atualmente é pesquisadora do Instituto de Pesquisas Energéticas e Nucleares (IPEN- SP / CNEN) no Centro de Tecnologia das Radiações e estuda o efeitos das radiações em nano materiais de carbono. (Texto extraído do Currículo Lattes em 27 dez. 2021).

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Study of obtaining ZnO film for application in dye-sensitized solar cells using the doctor blade method
2024 - GALEGO, E.; SAKATA, S.K.; SERNA, M.M.; FARIA, R.N.
The conversion of solar energy into electricity is considered one of the best sustainable technologies for the future replacement of traditional methods of generating electrical energy, such as thermoelectric and nuclear plants. Photovoltaic conversion is the generation system with the greatest potential for growth to meet growing demand, which includes dye-sensitized solar cells (DSSC). DSSC is notorious for mimicking photosynthesis, which mainly focuses on generating electricity under any light intensity. The DSSC is composed by: a semiconductor oxide layer (SO), that functions as a support for the adsorption of a dye; this set is encapsulated between two translucent electrodes and; the space between them is filled with a specific electrolyte. The DSSC, being translucent, acquires the color of the adsorbed dye, which gives it a colorful appearance, a desirable characteristic for applications such as: decorative and architectural objects, among others. The dye is the active element in DSSC and, to have the best possible performance, the dye must be exposed to lighting over the largest area possible. To achieve this, the OS film must have a nanometric porous structure that will guarantee a greater apparent exposure area. This structure is obtained using a mixture of semiconductor oxide with organic products which, after heat treatment, are eliminated. This work aimed to study the influence of organic compounds: polyethylene glycol, ethyl cellulose and glycerin, on the paste viscosity for application by the doctor blade (DB) technique and on the efficiency of DSSC. The pastes were prepared using nanoparticulate ZnO (< 100 nm) in the following compositions: (a) ZnO + ethyl cellulose + terpineol (0.2 g + 0.1 g + 0.5 mL); (b) ZnO + PEG 400 G (0.3 g + 0.3 m?) and; (c) ZnO + liquid glycerin (0.3 g + 0.3 mL). All mixtures were homogenized in an agate mortar and rested for 24 h. Afterwards, they were applied to a glass electrode (FTO) by DB, with a defined area of 8 x 8 mm and subjected to heat treatment: from room temperature to 450 °C with a heating rate of 5 °C min-1 maintained for 1h. Then, the samples were sensitized in the dye N719 for 16h. Next, sealed DSSCs were assembled using an FTO+Pt counter-electrode and filled with electrolyte (I-/I3-). The electrical parameters were obtained from the IV curve obtained under lighting of 100 mW cm-2, air mass: 1.5 G. From the point of view, the applicability by DB, paste (a) presented best result evaluated by ease of application and homogeneity in green. However, electrical parameters revealed that using paste (c) presented the highest short-circuit current value (Isc) however, lowest conversion efficiency n= 0.49%; pastes (a) and (b) showed similar efficiency: n = 0.58% and n = 0.56%. The paste (a) was chosen for future application and studies.
Sodium alginate and nanocellulose hydrogel as scaffold to in vitro 3D prostate cancer irradiated model
2023 - SILVA, G.D.; SAKATA, S.K.; ASSIS, J.V.A.; VIEIRA, D.P.
Introdução: Recently, traditional cell culture systems structured in 2 dimensions using monolayers of cells in culture media are being replaced by 3D structures, in which cells can be organized in spheroids. To obtain these structures, hydrogels can be used as permeable to gas and nutrients scaffolds, also providing physical support to cells. This work aimed to produce a double network hydrogel containing sodium alginate (SA) and nanocellulose (NC), obtained by irradiation of microcrystalline cellulose, and its ability to maintain in culture of human prostate adenocarcinoma. Objetivos: To analyze whether SA+NC gels can keep viable 3D LNCap (prostatic carcinoma) in vitro, with and without exposure to radiation (0 and 2Gy gamma). Métodos: 0.75g of microcrystalline cellulose (Sigma-Aldrich, 435236) dispersed in water were irradiated (300 kGy) (25 mm column height) in an electron beam source (Dynamitron® Job 188 ,RDI- Radiation Dynamics Inc.). The precipitated powder was washed in water by centrifugation. Nanocellulose pellet was added to a sodium alginate (2.5%) dissolved in PBS. LNCaP cells were maintained in RPMI 1640 medium in monolayers in culture flasks and controlled atmosphere (37º, 5% CO2). 24-well plates were used, pre-treated with Pluronic® F-127 solution (0.5g/mL in 2-propanol). The hydrophobic portions of Pluronic molecules were directed towards the center of the well, thus preventing cell adhesion to the culture plastic. In each well 1x105 cells were added, forming clusters of cells after 3 days. Clusters were removed and added to the hydrogel seeded in 96-well plates. Crosslinking was achieved using 100 μL of 2mM CaCl2 solution on top of the gels. After gelation, the saline solution was removed and the wells received 100μL of culture medium and were submitted to gamma irradiation with doses of 0 and 2 Gy (GammaCell, Canada), and further kept in incubator for 24h. Medium was replaced by fresh medium with Hoescht 33342 (10mg/mL) and SYTOX? Green (5mM) and kept in an incubator for 30 minutes. Plates were imaged in an INCell Analyzer 2500HS and images were obtained to determine the dead cell count. Resultados: Visual evidence of spheroids enclosed in gels showed increased cell viability in SA+NC comparing to SA gels only. No visual differences were observed in irradiated (2Gy) spheroids. Conclusão: SA+NC gels can sustain cell viability and cause no changes in cell radioresistance, being a suitable model to in vitro studies.
Production of a double-network hydrogel using sodium alginate and nano-structured cellulose to 3D cell cultures
2023 - SILVA, GIOVANA D. da; SAKATA, SOLANGE K.; ASSIS, JOAO V.A. de; SANTOS, ESTHER C. dos; PRUDENTE, SULEYNA R.; RODRIGUES, ALEX A.; FALCAO, PATRICIA L.; VIEIRA, DANIEL P.
Introduction and objective 2D cell cultures have limitations regarding on tissue representativity. 3D cell cultures can use hydrogels of alginate with cellulose with adequate viscoelasticity properties for cell growth, being from plant sources, abundant and low cost. This work consisted of producing a biocompatible gel from plant sources for threedimensional cultures, promoting polymeric matrices for cells, helping in cell interactions and nutrient transport, providing mechanical support, self-assembly capacity, biodegradation, ability to reticulation, stability control and mechanical resistance. Methodology Transformation of microcrystalline cellulose into nanofibers was achieved freezing aqueous suspensions on presence of 4M NaOH to proper dissociation of fibers. To obtain suitable dispersion, sodium citrate was added to prevent aggregation. Suspensions were analyzed by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Zeta Potential. For cell viability analysis, murine fibroblastic cell lines (NIH/3T3) were plated (2.5 x 105 cells per well) 24-well plate embedded in gel (100µL). Results and discussion The analysis of cellulose suspensions through SEM, showed a significant change in the size and shape of the structures after hydrolysis, indicating the obtention of structures on a nanometric scale. For the analysis of cellulose aggregation, the zeta potential values indicated that after the addition of sodium citrate, greater dispersion was obtained between the cellulose structures, enabling resistance to the structure in a uniform way. FTIR analysis showed changes in the covalent bonds of the products. Cell viability assay showed structures containing fibroblast cells, alginate and cellulose with 1 cycle of freezing with citrate showed an intact gel structure, with cell aggregates indicating possible cell growth, while the one with only alginate showed dead cells and showed that the hydrogel did not induce cellular toxicity. These results suggest that the hydrolysis of microcrystalline cellulose can lead to obtaining cellulose nanofibers with potential for applications in tissue engineering. Conclusions Hydrogels, they have potential for applications in tissue engineering, since they have mechanical resistance and cell viability. In addition, hydrogels from exclusively vegetable sources, since these are in large quantity, low cost and environmental impact, given that the alginate comes from brown algae found in several coastal regions and the cellulose can be extracted from renewable sources or various vegetable waste from agroindustry.
Reduced graphene oxide obtained by gamma radiation to produce screen printed glucose biosensor
2022 - SAKATA, SOLANGE; JACOVONE, RAYNARA M.S.; DUARTE, MIGUEL; GARCIA, RAFAEL; ANGNES, LUCIO
Screen printed biosensor has attracted attention as point care device due to its fast and accurate response in a compact portable platform. Due the high electrical carrier mobility, reduced graphene oxide (rGO) has been used to modify the working electrode surface and increase the biosensor sensibility. However, there are some disadvantages during the reduction of graphene oxide that include the use of chemical reductants that need to be removed after the reaction and the toxic residues. The purification usually requires tedious steps and a lot of efforts to recover the nanomaterial. In this work screen printed carbon electrode (SPCE) was modified using rGO produced by gamma radiation. Graphene oxide (GO) was prepared by modified Hummers and the reduction was performed in a water/isopropanol solution and inert medium. Sample was irradiated in the Multipurpose Gamma Irradiation Facility at Radiation Technology Center from Nuclear and Energy Research Institute (IPEN/CNEN-SP), a category IV gamma irradiator by the IAEA classification under the radiation dose at 80,0 kGy. rGO characterization was performed by X-Ray Diffraction (XRD). From the XRD patterns: the 2θ the peak located at 11o shift to 23o, demonstrating the reduction of GO to rGO. The decrease of the distance between layers was attributed on partial remove of the oxygen groups from GO. For the glucose biosensor preparation, first of all, the SPCE (Metrohm, model 6. 1208. 110) was modified by drop-coating rGO solution and dried at room temperature for 24h. Then, for Glucose Oxidase (GOx) immobilization, the carboxylic groups from rGO were activated using N-hydroxysuccinimide (NHS) and 1-Ethyl-3-(3-dimethyalaminopropyl) carbodiimide (EDC) for 30 min at room temperature, followed by adding GOx 10KU from A. niger Type II (5mg/mL). The solution was incubated at 4oC overnight. SEM images showed GOx onto SPCE surface and the electrocatalysis of GOx toward glucose was measured to confirm the enzymatic activity. For electrochemical studies, cyclic voltammetry was carried out in a Portable Potentiostat model 910 PSTAT mini, Metrohm and PSTAT software. The fabricated amperiometric biosensor detects glucose ranged from 1mM to 5mM with LOD of 0.9 mM at 0.70V. Moreover, the biosensor exhibited repeatability, reproducibility and practicability. This study showed that rGO synthesized by gamma radiation without any further purification is a simple and sustainable approach to fabricate electrode for biosensors.
The influence of gamma radiation doses on rGO/Ni for energy storage applications
2022 - GARCIA, RAFAEL H.L.; CARNEIRO, FELIPE W.; JACOVONE, RAYNARA M.S.; SAKATA, SOLANGE K.; ANGNES, LUCIO
Metallic nanoparticles (MN) have been the subject of intense research in the last decades because of their high catalytic activity, associated with its large surface-to-volume ratio. However, it is difficult to obtain pure active metal nanoparticles surfaces, since its contamination and aggregation frequently result in deactivation and loss of catalytic activities. MN immobilization can minimize these effects. Thermal, mechanical, and electrical properties of reduced graphene oxide (rGO) make this material an excellent candidate for MN support for batteries and supercapacitors. The production of metallic nanoparticles on rGO surface based on gamma radiation allows less formation of residual impurities, absence of reducing agents, uniform mass production, no aggregation and low costs. Herein, we demonstrated a green and efficient one-step, gamma radiation-based method for Ni/rGO production. Graphene oxide (GO) was prepared by modified Hummers method. Ni+2 and graphene oxide reduction were performed in water/isopropanol solution (1:1) under inert medium. Samples were irradiated in the Multipurpose Gamma Irradiation Facility at CETER/IPEN/CNEN-SP, a category IV gamma irradiator by the IAEA classification, in radiations doses of 20, 40, and 80 kGy, at 10 kGy/h. From X-ray diffraction, the correlation between radiation doses and crystallite size was evaluated. For supercapacitor studies, cyclic voltammetry was carried out in a screen printed carbon electrode (SPCE) in K₄[Fe(CN)₆]. The working electrode was modified with produced rGO-Ni 80 kGy, Pt wire was used as counter and Ag/AgCl as reference electrode. Experiments were performed in KOH 1.0 M. Results showed that produced Ni/rGO has good potential to be used in electrochemical devices such as supercapacitors or batteries.
Characteristics of electric double layer capacitors prepared with electrolytes based on deep eutectic solvents
2022 - GALDINO, G.S.; RODRIGUES, W.C.; CRUZ, P.D.; CASINI, J.S.; SAKATA, S.K.; FARIA, R.N.
The storage capacity of electric double layer capacitors or electrochemical supercapacitors with electrolytes based on deep eutectic solvents (DES) composed of L-lactic acid with several hydrogen bond acceptors (nicotinamide, L-alanine, ammonium acetate, sodium acetate, choline chloride, amino acetic acid) with a molar ratio of 7:1 have been investigated. A DES based on urea and choline chloride with at a molar ration of 2:1 has also been included for comparison. The electrochemical supercapacitors were prepared using commercial activated carbon electrodes after removing the volatile organic electrolyte with a vacuum pump. The characteristics of the electrochemical supercapacitors were determined by cyclic voltammetry at temperature room temperature and also after heating at 353 K using scan rates that varied from 2 to 25 mVs-1. Lowest scan rate led to higher specific capacitance of 150±8 Fg-1 with a maximum applied potential of 1.7 V for the urea and choline chloride DES with a molar ration of 2:1. The lactic acid with all the hydrogen bond acceptors with a molar ratio 7:1 it has been necessary to increase the temperature above room temperature to improve the specific capacitance.
Characteristics of electric double layer capacitors produced with electrolytes based on deep eutectic solvents
2022 - GALDINO, G.S.; RODRIGUES, W.C.; CRUZ, P.D.; CASINI, J.S.; SAKATA, S.K.; FARIA, R.N.
The storage capacity of electric double layer capacitors or supercapacitors with electrolytes based on deep eutectic solvents (DES) has been investigated in this study. DES composed of L-lactic acid with nicotinamide, L-alanine, ammonium acetate, sodium acetate and choline chloride have all been prepared at a molar ratio of 7:1. Furthermore, urea with choline chloride at a molar ratio of 2:1 has also been used as electrolyte for the electrochemical supercapacitors. The DES supercapacitors were prepared using commercial activated carbon electrodes after removing the volatile organic electrolyte with back-pumping vacuum. The electric characteristics of these supercapacitors with DES electrolytes were determined by cyclic voltammetry at room temperature and above up to 80°C. The cyclic voltammetry scan rates were varied from 2 to 25 mVs-1. The lowest scan rate led to a high specific capacitance of 150±8 Fg-1 for urea with choline chloride at a molar ratio of 2:1 and using a maximum applied potential of 1.7 V. For higher molar ratio (7:1) of Llactic acid with the others hydrogen bond acceptors (HBA) it was necessary to increase the temperature above room temperature to improve the specific capacitance. The best results have been obtained with two solids (urea and choline chloride) as starting compounds for preparing the DES. Equivalent series resistances (ESR) have also been determined in this work employing galvanostatic cycling tests with current densities between 2 and 20 mAg-1.
Uso do Kahoot! como ferramenta avaliativa em um ambiente interdisciplinar e remoto
2021 - JACOVONE, RAYNARA M.S.; JESUS, JULIANA M.S. de; SAKATA, SOLANGE K.; RICARDO, ELIO C.
O presente estudo visa apresentar as primeiras impressões observadas após o uso da plataforma on-line Kahoot! como ferramenta avaliativa do processo de aprendizagem ativa da disciplina IPN 0034 – Fundamentos dos Nanomateriais, integrante do conjunto de disciplinas optativas da graduação disponibilizadas no Instituto de Pesquisas Energéticas e Nucleares (IPEN). O curso baseia-se na fundamentação de conceitos aplicados ao estudo de nanomateriais, tais como síntese, caracterização e aplicação dessa tecnologia no âmbito científico e industrial. No ano atual, a disciplina, que ainda está em curso, é ministrada por quatro professores e quatro monitores do Programa de Aperfeiçoamento de Ensino (PAE), com 48 alunos dos seguintes cursos: Bacharelado em Biotecnologia (19%), Engenharia Química (19%), Química (17%), bacharelado em Física Médica (4%), além de alunos de outras Engenharias, Odontologia e Ciências Contábeis. Neste contexto, foram previamente selecionadas, dentro do plano da disciplina, a inserção de ferramentas e estratégias educacionais que buscam promover um aprendizado ativo. A heterogeneidade do público-alvo atribui ao curso um caráter multidisciplinar, além de motivar a atual necessidade de aprimorar a interação professor-aluno em um ambiente remoto. A título de exemplo, a disciplina em estudo propõem o uso de ferramentas como Kahoot! Mentimeter , uso de mapas conceituais e apresentações de posters na plataforma on-line Wonder . Entre as vantagens da plataforma Kahoot!, destaca-se a obtenção do desempenho imediato dos alunos. O questionário foi desenvolvido com questões de múltipla escolha, sendo apenas uma das alternativas correta, sendo aplicado ao término de cada aula, pelos monitores da disciplina. A hipótese que está sendo avaliada, após a execução de cinco aulas, refere-se à observação de que, ao disponibilizar material para consulta/estudo, antes da aula, os alunos tiveram um maior/melhor desempenho no Kahoot! As evidências obtidas até o momento indicam que em aulas que foram apresentadas questões referentes ao conteúdo pré-aula, cerca de 74% a 96% das questões foram respondidas corretamente. Porém, nas aulas sem material prévio, o máximo de acertos foi de 48%. Esses dados consideram a participação de 48 a 44 alunos, sem considerar o tempo para resposta das questões, mas apenas o que foi pontuado como certo e errado. Essa distinção de desempenho aponta para a importância do aluno estudar ou ter um contato prévio com o conteúdo que será dado em sala. Destaca-se que a investigação da efetividade de uma ferramenta no decorrer do curso permite ao professor aprimorar ou, até mesmo, rever suas escolhas didáticas propostas no plano de aula, o qual não deve ser engessado, mas sim dinâmico, em resposta ao grupo de alunos e suas particularidades. Portanto, é possível identificar que a aplicação de material pré-sala e o uso do Kahoot! está permitindo avaliar de forma efetiva o desempenho dos alunos, oferecendo indicadores para avaliar também as práticas do professor na disciplina em questão.
Screen printed electrode modified with reduced graphene oxide obtained by ɤ radiation for levonorgestrel detection
2021 - JACOVONE, RAYNARA M.S.; JESUS, JULIANA M.S. de; TEIXEIRA, ANTONIO C.S.C.; SAKATA, SOLANGE K.
INTRODUCTION Screen printed electrodes (SPE) have attracted attention due to their fast and accurate response, high sensibility, specificity, and portable platforms. To increase their electrical carrier mobility and sensibility, the working electrode surface has been modified using reduced graphene oxide (rGO) [1]. In the present work, gamma radiation reduced Graphene Oxide (GO) to produce rGO in a sustainable method that avoids toxic reagents and the production of hazardous chemical residues [2]. Levonorgestrel (LNG) is a synthetic contraceptive hormone of worldwide concern, being harmful to aquatic organisms, even at low concentrations, e.g., 0.024 nmmol L-1 [3]. METHODOLOGY Reduced graphene oxide was obtained using GO (10 mg mL-1) dispersed in a water/isopropanol. The sample was irradiated in the Multipurpose Gamma Irradiation Facility at CETER/IPEN/CNEN-SP, at a dose rate of 10 kGy h-1 and 80.0 kGy in inert conditions. The SPE was modified by drop casting 10 μL of the rGO solution and dried at room temperature. The rGO-SPE was characterized by Raman spectroscopy and the electrochemical behavior of LNG was investigated using cyclic voltammetry (CV) in phosphate buffered saline (PBS) medium (pH 7.0) within the oxidation window 0.0-1.0 V and 25 mV s-1 (Fig. 1). RESULTS The Raman spectrum showed D (1.347 cm-1) e G (1.594 cm-1) bands for both rGO-SPE and SPE. The ID/IG ratio was 0.85 and 1.40 for SPE and rGO-SPE, respectively. For rGO-SPE, cyclic voltammograms showed a reversible behavior in K4Fe(CN)6 [2 mmol L-1] and in the presence of LNG [6410-9 mol L-1], anode inflection was observed at 0.6 V, associated with the non-reversible oxidation reaction of LNG. CONCLUSIONS The surface of the rGO-SPE was uniform, being the ID/IG ratio for the covered electrode higher than that exhibited by the uncovered one. This electrode presented electrochemical response to LNG, even at low concentrations, thus proving its application as an electrochemical sensor for the LNG hormone.
The synthesis of palladium nanoparticles by electron beam into graphene oxide and its electrochemical behavior
2020 - CARNEIRO, F.W.; KAWABATA, V.J.; JACOVONE, R.M.; ANGNES, L.; GARCIA, R.H.; SAKATA, S.K.
In this work, graphene oxide (GO) was synthesized by the modified Hummers method and was used as support for palladium nanoparticles to study its electrochemical behavior. The main objective was the incorporation of Pd on the graphene oxide by the electron beam irradiation at 40kGy and 80kGy doses. The GO-Pd nanocomposite was characterized by thermogravimetry analysis (TGA), X-ray diffraction (XRD), electron transmission microscopy (TEM), zeta potential analysis and cyclic voltammetry (CV). The results were satisfactory, indicating success in incorporating the metal in the GO surface. CV studies were conducted using screen printed electrode modified with nanocomposite, SPE/GO-Pd, at a scan rate of 50 mVs-1, potentials range from -0.5 V until 1.0 V in KCl medium (0.05 mol.L-1) adding aliquots of 4 mmol L ?1 ferricyanide solution and its results showed a linear increase in the current. It can therefore be inferred that palladium /graphene oxide nanocomposites have a potential for sensors.