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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ZnO-DSSC
2024 - SERNA, M.M.; GALEGO, E.; FARIA, R.N.; SAKATA, S.K.
In the search for clean energy generation, solar energy has so far occupied the leading role; among the various factors that favor it are the possibility of generating energy on the surface of the planet and in outer space, in addition to the small environmental impact of generation plants and the possibilities of generation in urban environments. Within the different types of solar cells, dye-sensitized solar cells (DSSC) promise to revolutionize energy generation through their application as the external coating of large buildings. In the manufacture of this type of cell, non-toxic and low-cost materials are used; however the maximum conversion efficiency is still low when compared to silicon cells. One of the factors that contribute to the decrease in efficiency is the process of recombination of the photogenerated electron with the electrolyte. In the most common type of DSSC that uses a glass substrate coated with SnO2:F (FTO) to manufacture the photoanode, this surface acts as a recombination site. The objective of this work was to study the addition of a graphene layer between the FTO and the semiconductor oxide film in order to minimize recombination processes through the insertion of a new energy level. The deposition of reduced graphene oxide (rGO) was carried out by dip coating with different numbers of deposition cycles (0, 2, 5, 10 cycles). A ZnO paste was deposited on this film using the doctor blade technique with a green thickness of 50 µm. The assembly was heat treated at 450 °C for 1 h, aiming to reduce rGO to graphene and aggregate ZnO into a porous structure. The set was sensitized with the dye N719 and the solar cells were assembled with an FTO/Pt counter electrode and an electrolyte with the iodide/triodide redox couple. The electrical parameters were obtained from the survey of IV curves in a solar simulator with a power of 100 mW cm-2 and air mass 1.5. The morphology of the photoanode was studied by scanning electron microscopy (SEM). The micrographs obtained by SEM show that a porous ZnO film was formed with an average thickness of 25 µm. The cell efficiency increased with the increase in the number of dip coating cycles from 0.39% without rGO to 0.72% with 10 cycles of rGO deposition. The variation in the fill factor was less than 10%. The series resistance values are of the same order of magnitude, indicating that the rGO did not act to increase the conductivity at the rGO/FTO interface, whereas the series resistance values will increase with the increase in the number of cycles, which allows us to conclude that the rGO acts as a blocking layer preventing the regeneration of the electrolyte with the photogenerated electron.
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.
Sustainable synthesis of cobalt nanoparticles for supercapacitors application
2024 - DUARTE, M.; FOO, CHOO T.; OLIVEIRA, K.; SILVA, D.V. da; FARIA JUNIOR, R.N.; SAKATA, S.K.
Characterization and antibacterial activity of a nickel nanocomposite based on graphene
2024 - DUARTE, M.; GONCALVES, K.O.; SAKATA, S.K.
The effect of different radiation sources on graphene oxide reduction and scale-up
2024 - ALVES, A.; DUARTE, M.; SAKATA, S.K.
Effects of gamma radiation on biopolymer processed by 3D printing
2024 - GONCALVES, KARINA de O.; ALMEIDA JUNIOR, JOSE N. de; DIAS, DJALMA B.; JUNIOR, ORLANDO R.; SAKATA, SOLANGE K.
The stability in different solvents of rGO/magnetite obtained via ionizing radiation
2024 - DUARTE, M.; JACOVONE, R.M.S.; LIMA, M.M.P.; SILVA, C.L.; BRANDAO, O.A.B.; SAKATA, S.K.
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.
Aptasensing of beta-amyloid (Aβ(1− 42)) by a 3D-printed platform integrated with leaf-shaped gold nanodendrites
2023 - NEGAHDARY, MASOUD; VELOSO, WILLIAM B.; BACIL, RAPHAEL P.; BUORO, RAFAEL M.; GUTZ, IVANO G.R.; PAIXAO, THIAGO R.L.C.; LAGO, CLAUDIMIR L. do; SAKATA, SOLANGE K.; MELONI, GABRIEL N.; FRANCA, MESAQUE C.; OLIVEIRA, THAWAN G. de; AMEKU, WILSON A.; DURAZZO, MICHELANGELO; ANGNES, LUCIO
In this study, beta-amyloid (Aβ(1− 42)), an essential biomarker for diagnosing Alzheimer’s disease (AD), was detected via an electrochemical aptasensing platform. Here, an innovative signal transducer was developed using a CO2 laser-ablated 3D-printed electrode modified with leaf-shaped gold nanodendrites (LSG NDs, mean diameter: ~ 92 nm), which could provide an efficient interface for immobilizing aptamer strands. The modified electrode with LSG NDs exhibited an enhancement in its electrochemically active surface area about 7 times, compared with the bare electrode. This modification showed that the size, morphology, and distributions of LSG NDs in amplifying electrochemical signals might effectively provide a highly sensitive infrastructure for analyte detection. The strands of a thiol-functionalized aptamer sequence interacted with the gold surface, which created an optimized biointerface to detect Aβ(1− 42) in a linear range from 0.1 pg mL− 1 to 10 ng mL− 1 (limit of detection (LOD): 84 fg mL− 1 , (S/N = 3)). The developed aptasensor confirmed satisfactory stability, desired reproducibility and regeneration, and minimal impact of interfering agents. In addition, the application of this aptasensor was monitored via an assay of spiked analyte concentrations in 20 samples, including cerebrospinal fluid (CSF) and human serum.