LUIZ GUSTAVO HIROKI KOMATSU

LUIZ GUSTAVO HIROKI KOMATSU

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 54

Effects of silver addition in zinc oxide nanoparticles on films of HMSPP/SEBS against Staphylococcus aureus and Escherichia coli contamination
2022 - KOMATSU, LUIZ G.H.; CAJADO, GIUSEPPE M.; PARRA, DUCLERC F.
In this research we decided to analyze the addition of silver (Ag°) on zinc oxide (ZnO) utilizing two nanoparticles: the synthesized zinc oxide-doped-silver nanoparticles (ZnO/Ag_Lab) utilizing the zinc nitrate as metal precursor for ZnO and silver nitrate as metal precursor for Ag°; and the commercial nanoparticle ZnO/Ag. For the study of application of the nanoparticles, they were processed in the form of films and the polymer utilized was the blend of HMSPP (high melt strength polypropylene) and styrene-ethylene/butadiene-styrene. For the study of nanoparticles, they were submitted to biocide tests against Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC8739) and XRD (X-Ray Diffraction). The XRD analysis results indicated, in both of nanoparticles, with the presence of wurtzite phase of ZnO, being that on the commercial nanoparticles the intensity of peak was higher than that of synthesized one, on other hand, the peaks attributed to Ag°, were more intense in the synthesized nanoparticle.
Film of the blend of HMSPP/SEBS with TiO2@Ag for biocide activity against Candida albicans and Aspergillus niger for medical applications
2022 - KOMATSU, LUIZ G.H.; COSTA, FERNANDA A.T. da; FERREIRA, BARBARA V.; CAJADO, GIUSEPPE M.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
One of the most promising ways to overcome the biocide infections on medical materials is the use of metal oxides. The nanoparticle of Titanium Dioxide doped with Silver (TiO2@Ag) is one of the most promising materials due to the biocide properties against the Candida albicansand Aspergillus niger. With these observations, in the present work, the nanoparticles of TiO2@Ag were synthesized by adapting the method of Turkevich [1] and in the sequence, they were incorporated in the polymeric blend of High Melt Strength Polypropylene (HMSPP)[1]/Styrene-Ethylene/Butadiene-Styrene (SEBS). Following that incorporation, it was obtained thin films of 0,3 and 1 %wt concentrations (based in previous results[1]) for characterization tests. The films were evaluated by Biocide tests following the JIS 2801-10 norm with Candidaalbicans ATCC 10231 and Aspergillus niger ATCC 6275, X-ray Diffraction (DRX), Raman Spectroscopy. On biocide tests were observed biocide activity of the film with 0,3wt% of TiO2@Ag showed, in the logarithmic reduction of the bacteria, count upward the standard normalized by the norm (≥2), value of 3,24 of logarithmic reduction. In the Raman Spectroscopy and DRX were confirmed the presence of the Ag on the TiO2: DRX the peak of θ = 23,81 ° was attributed to TiO2@Ag on the film and on Raman Spectroscopy the peak of 1048 cm-1refered to the NO3 -residual of the the silver nitrate, other peaks at 1334 and 1459 cm-1of the silver indicating the presence in the film [2].
The effect of ZnO nanoparticles as Ag‑carrier in PBAT for antimicrobial films
2022 - SOUZA, ALANA G. de; KOMATSU, LUIZ G.H.; BARBOSA, RENNAN F.S.; PARRA, DUCLERC F.; ROSA, DERVAL S.
Zinc oxide (ZnO) and ZnO-silver (ZnO-Ag) nanoparticles (NPs) are widely used in different fields, such as biomedicine and food packaging, due to their recognized antibacterial activity and safety for human health. In this paper, ZnO and ZnO-Ag NPs were incorporated into poly(butylene adipate-co-terephthalate) (PBAT), in two contents (0.5 and 1 wt%), to prepare antibacterial films. The NPs were characterized by TEM and FT-Raman, and the films were analyzed by FT-Raman and FTIR, mechanical properties, SEM–EDS, TGA, DSC, XRD, and antibacterial properties against Escherichia coli. The results indicate that both NPs were physically retained in the polymer structure, with a strong electrostatic interaction between the mixture components, reflecting excellent mechanical behavior. The films showed good thermal stability, without significant changes, and the nanocomposites enhanced PBAT crystallinity from 18 to 23% and 27% for PBAT-ZnO and PBAT-ZnO-Ag films, respectively. The mechanical, thermal, and crystallinity results indicated the excellent potential of NPs in biodegradable films to improve properties and expand applicability. The antimicrobial activity is higher for PBAT-ZnO-Ag films than the pristine PBAT due to the synergic effect between the NPs and the oxidation–reduction potential of each nanoparticle, where the ZnO protect and stabilized the Ag-NPs, acting as an Ag-carrier, enhancing its antimicrobial effects after the film’s preparation and allowing its applicability in biomedical products or food packaging.
Study of the incorporation of TiO2/Ag nanoparticles in polyamide by casting method aiming for biocide application
2021 - VECCHIA, MARIA E.K.D.; ZAINE, MARIANA A.; KOMATSU, LUIZ G.H.; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS; PARRA, DUCLERC F.
This study consists in the characterization of polyamide (PA6) films charged with different concentrations of silver nanoparticles deposited in titanium dioxide (TiO2) carrier. The silver nanoparticles were synthesized according to the method adapted from Turkevich using a titanium dioxide carrier and inserted, by suspension, in a polyamide solution. The preparation of PA: AgNp films was performed by the casting method by the dissolution of PA pellets in formic acid. The analysis and characterization of the films by the XRD, DSC, TGA and Raman confocal techniques indicated incorporation of nanoparticles into the polymers, a second thermogravimetric decomposition event as the concentration of AgNp-TiO2 increased and there was no significant change in crystallinity.
Preparation of irradiated silver nanoparticles for polypropylene nanocomposites with pineapple fiber
2021 - ZAINE, M.A.; DALLA VECCHIA, M.E.K.; KOMATSU, L.G.H.; OLIANI, W.L.; PARRA, D.F.
Síntese e aplicação de Óxido de Zinco e do Dióxido de Titânio como carregadores de Prata na blenda de HMSPP/SEBS visando atividade biocida
2021 - KOMATSU, LUIZ G.H.
O foco deste estudo foi realizar a síntese e dopagem do Óxido de Zinco (ZnO) e do Dióxido de Titânio (TiO2) com a Prata (Ag), visando a ação biocida de sua inserção na blenda de Polipropileno com Alta Resistência do Fundido (HMSPP) obtido por meio do processo de irradiação gama (γ) e o elastômero termoplástico Estireno-Butadieno/Etileno-Estireno (SEBS). As concentrações escolhidas para estudo foram de 0,3% e 1% de cada partícula na blenda HMSPP/SEBS. Para a realização dos testes foram obtidos filmes finos (aprox. 0,07 mm de espessura) utilizando-se o processamento no estado fundido no equipamento extrusora mono-rosca com acessório de filme. As amostras foram caracterizadas por: Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (MET), Espalhamento de Luz Dinâmico (DLS) e testes biocidas com as bactérias Escherichia coli ATCC 8739 e Staphylococcus aureus ATCC 6538 e com os fungos Candida albicans ATCC 10231 e Aspergillus niger ATCC6275, seguindo a norma JIZ 2801 e a norma INCQS 65.3210.006. Na micrografia de TEM constatou-se a presença de nanopartículas menores que 30 nm. Na superfície do filme também foi constatado a presença de aglomerados. Estes aglomerados são formados pelas nanopartículas com tamanho médio de 150 nm. Nos resultados de DRX constatou-se que os filmes de PP/SEBS/ nanopartículas retiveram as nanopartículas em função de sua concentração e corroboraram com os resultados de EDS. As nanopartículas atuaram como agente nucleante modificando a cristalinidade dos filmes conforme evidenciado por DSC. As micrografias de MEV demonstraram que as partículas de TiO2 e TiO2/Ag; ZnO e ZnO/Ag estão localizadas próximas à superfície, melhorando assim a sua possível interação com o meio microbiano. A atividade biocida avaliada nos filmes apresentou um resultado positivo , portanto satisfatório, principalmente dos filmes que possuem partículas dopadas com prata ZnO/Ag e TiO2/Ag. Identificou-se um aumento da atividade biocida dentre as concentrações estudadas, após o processo de esterilização realizado por irradiação gama. Isso pode explicar-se em razão da formação de grupos hidroxila na superfície dos filmes, a ocorrência de radiólise devido a umidade do óleo e do polímero, alteração da band-gap dos óxidos metálicos devido a incorporação da prata.
Nanocomposites foams of polypropilene modified by ionizing radiation containing CaCo3/ag° nanoparticles of bio-calcium carbonate-study of bactericidal effect
2019 - PARRA, DUCLERC F.; SILVA, ORELIO L. da; KOMATSU, LUIZ G.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
This paper presents a study of high melting strengh polypropylene (HMSPP) foams by gamma irradiation with insertion of silver nanoparticles (AgNPs) adsorbed in carrier of CaCO3 (natural source) aiming bactericidal effect. The use of silver (Ag°) gives important antibacterial property since silver is highly toxic against bacterae. The HMSPP matrix was processed in a twin screw extruder under CO2 atmosphere and polypropylene nanocomposites (HMSPP-AgNC) were obtained in different concentrations of silver. The material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction spectroscopy (XRD), cytotoxicity assay and reduction colony-forming-unit (CFU). The analyzed foams showed spherical clusters and homogeneous regions with good distribution of the silver nanoparticles. Furthermore, the HMSPP@AgNCs foams exhibited a antibacterial efficiency against E. coli and S. aureus due to the presence of the biocidal silver nanoparticles.
Films of polyethylene-AgNPs
2019 - OLIANI, WASHINGTON L.; KOMATSU, LUIZ G.H.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
In recent years, antimicrobial packaging has attracted much attention from the food industry because of the increase in consumer demand for minimally processed, preservative-free-products. Different grades of polyethylene, LLDPE and LDPE play a major role in the film blowing industry and are widely used for packing applications. In our study, blown films of LLDPE / LDPE, and their blends were produced using a twin screw extruder. The combination of PEs as matrix, and silver nanoparticles with oleic acid solution, improved the AgNPs dispersion in the films. The films were evaluated by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), and Ecotoxicity. Further, the antibacterial properties of the films were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria.
Aplicação de ZnO como carregador de prata em uma blenda de HMSPP/SEBS visando ação biocida
2019 - KOMATSU, LUIZ G.H.; OLIANI, WASHINGTON L.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
Este estudo consiste em utilizar o óxido de zinco (ZnO) como carregador de nanoprata metálica (Ag°). Foi testado um método para síntese das partículas com a prata, o método de Turkevich. A confecção dos filmes poliméricos em matriz de HMSPP/SEBS foi realizada via processamento no estado fundido em extrusora. Os materiais obtidos foram caracterizados pelas técnicas de DLS, MEV e ensaios biocidas. As partículas apresentaram-se em tamanhos variando entre 100 à 200 nm, juntamente a isso, elas também apresentaram resultados de morte celular nos ensaios biocidas com as bactérias E.coli e S.aureus de acordo com a norma JIZ 2801.
AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect
2021 - PARRA, DUCLERC F.; MARCHINI, LEONARDO G.; KOMATSU, LUIZ G.H.; OLIVEIRA, CAMILA B. de; OLIANI, WASHINGTON L.; RANGARI, VIJAYA K.
This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO2 NPs (silver/Zinc oxide/SiO2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique (SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus, are reported and these results showed potential application in health care products.