Navegando por Autor "Vieira, Lucia"

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    Anatase film on orotracheal tubes to mitigate Staphylococcus aureus
    (American Scientific Publishers) Manfroi, Lucas Augusto; Silva, Michely Glenda Pereira da; Vieira, Angela Aparecida; Macário, Paulo Fabrício; Silva, Newton Soares da; Marques, Francisco Chagas; Vieira, Lucia
    Bacterial contamination in hospital environments is a significant concern for patient admissions. Aiming to reduce contamination, titanium dioxide film (TiO2) in the anatase phase has been prepared on the surface of polyvinyl chloride (PVC) tubes. The PVC tube material was used to study the film’s effectiveness in inhibit- ing bacterial growth and cell viability. The morphology and composition of deposited films were investigated using a Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) map. In addition, Fourier-Transform Infrared Spectroscopy (FTIR) and XRD diffractogram were used to analyze film composition and phase, respectively. The adhesion of TiO2 film on PVC substrate was determined using ScotchTM tape-test according to ASTM: D3359-09, 2010, and the film surface morphology was analyzed by the MEV-FEG tech- nique and EDS map. The bacterial viability was performed with Staphylococcus aureus, and cell viability was performed using L929 strain mouse fibroblasts. The results of TiO2 in the anatase phase deposited by ALD on the PVC surface demonstrate good adherence and the film’s effectiveness in inhibiting bacterial growth and cell viability.
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    Bioactivity of Ti6Al4V alloy with bioglass and corrosion protection by silane coating
    (CDRR Editor) Marcolin, Patricia; Frozza, Caroline Olivieri da Silva; Henriques, João Antonio Pêgas; Kunst, Sandra Raquel; Crovace, Murilo Camuri; Ely, Mariana Roesch; Vieira, Lucia; Farias, María Cristina Moré; Brandalise, Rosmary Nichele
    The Ti6Al4V alloy is usually employed as a biomaterial, however, when in use, exhibits a few drawbacks such as corrosion, caused by the release of aluminum and vanadium ions besides the bioinert behavior. Bioactive coatings offer a barrier effect and bioactivity, promoting biocompatibility and osseointegration processes. The present work aims to study the biocompatibility behavior of a bioglass-containing silane film deposited on a titanium alloy (Ti6Al4V) substrate. The effect of the surface roughness of the metallic substrate was also evaluated. Film/substrate systems were characterized as their morphological, chemical, physical, electrochemical behavior, and cell cytotoxicity and cell viability. The main results pointed out that silane films augment corrosion resistance of titanium alloy substrates. The biological results indicated a growth of osteoblast cells (MG-63), for all the test conditions. The bioglass film deposited on the ground substrate exhibits the highest cell density.
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    Effect of water and alkali on purification bacterial cellulose membrane from Kombucha
    (CDRR Editors) Sousa, Letícia Pereira dos Santos Barbosa de; Leite, Priscila Maria Sarmeiro Correa Marciano; Vieira, Angela Aparecida; Faria, Anderson Carlos; Vieira, Lucia
    Bacterial cellulose membrane (BCM) is a biomaterial synthesized by bacteria of the genus Gluconocetobacter hansenii with a higher degree of purity than plant cellulose. The commonly used raw material for manipulating bacterial cellulose is kombucha, a beverage consumed by a vast population around the world that promises health benefits. The beverage is composed of tea species Camellia sinenses and a carbon source, refined sucrose, and a starter culture of bacteria and yeast with 10% fermented tea (starter tea) to activate the fermentative process. The Kombucha’s bacterial cellulose membranes (KBCM) are formed over 7 to 10 days on the surface of the fermented product and have the appearance of a gelatinous membrane, this being the by-product of interest. In this work, the objective was to obtain the membrane composed of cellulose via Kombucha and purify it to obtain crystalline cellulose. The purification was performed with distilled water and 0.5M NaOH sodium hydroxide solution to remove residues from the fermentation, successfully removing sugars and bacteria. At the end of the experiments, a lighter film was obtained with coloration close to white, and comparative analyses were performed to verify the structural chemical composition, crystallinity, and morphology of the samples by techniques FTIR, DRX, and SEM, respectively. Then, once the biomaterial was purified, the range of applications expanded to several products to meet the biomedical area, sustainable packaging, and even the fashion industry.
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    High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates
    (MDPI) Ferreira, Eder Henrique Coelho; Vieira, Angela Aparecida; Vieira, Lucia; Fechine, Guilhermino José Macêdo
    Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE- UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a signifi- cant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomogra- phy, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction co- efficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.
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    Molhabilidade de não tecido eletrofiado contendo nanopartículas de prata para uso em filtro
    (Faculdade Senai Roberto Mange) Shimada, Yoshio Manoel Nunes; Silva, Daniele Cristina; Bustamante, Gabriel Costa; Vieira, Angela Aparecida; Gonçalves, Érika Peterson; Vieira, Lucia
    Sabe-se que hospitais podem ser ambientes endêmicos onde a coinfecção por vírus e bactérias pode ocorrer. O uso de novos materiais e métodos de processamento para fabricar filtros ou máscaras ocorrem devido à sua ampla aplicação. Para este estudo, um sistema de eletrofiação foi usado para fabricar não tecidos baseados em fibras de poliacrilonitrila (PAN), com e sem a adição de nanopartículas de prata (Ag). Após a produção, as amostras receberam um tratamento térmico em atmosfera de nitrogênio, a fim de reduzir o efeito eletrostático. Os materiais foram avaliados em termos de molhabilidade pela medição de ângulo de contato. Para a análise da morfologia das fibras, foram usadas microscopia eletrônica de varredura e transmissão. Os testes de molhabilidade mostraram que o PAN+Ag possuí características hidrofóbicas, de acordo com as recomendações para filtros de proteção pessoal sendo capaz de reter gotículas e aerossóis.
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    Non-thermal plasma applied to treating diabetic foot
    (CDRR Editors) Arisawa, Emilia Angela Lo Schiavo; Cardoso, Juliana Cunha; Vieira, Lucia; Oliveira, Rauirys Alencarde de
    Objective: Evaluate the effects of non-thermal plasma therapy (NTP) for the treatment of diabetic foot injuries in two patients, considering the evolution of the steps of the healing process, pain sensitivity, and quality of life. Methodology: Lesions in the lower limbs of two patients with Diabetes mellitus (DM) with similar anatomical location and dimensions were treated, one patient with controlled DM and the other classified as uncontrolled DM. The application of NTP was performed for 10 minutes, 3 times a week in direct contact with the lesions. The same protocol was applied in both clinical cases to allow a reliable evaluation of the healing process. Results and Discussion: The lesions presented progressive regression until their complete regeneration (100%), without the development of infections during treatment. Conclusion: The results obtained in the two clinical cases allow us to attest that the NTP application in the treatment of diabetic foot injuries resulting from DM constituted an important therapeutic tool for the evolution of the healing process of these injuries, with a significant reduction in the lesion area in a short period of time. The definition of the ideal treatment protocol depends on the expansion of the number of studies and the increase of the studied population.
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    Processo para obtenção de lipídeos pra uso em biocombustíveis utilizando a fração orgânica do lixo urbano
    (2024) Pradella, José Geraldo da Cruz; Vieira, Lucia; Costa, Maricilia Silva
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    SERS-active substrates using DVD-R coated in silver thin films: A preliminary study for detection of commercial glyphosate
    (Elsevier) Murcia-Correa, Luz Stefany; Usuriaga, Omar; Vieira, Lucia; Raniero, Leandro José
    Glyphosate (GLP) is the herbicide with the highest level of global commercialization and historical use. Even though numerous studies have found this substance to be harmless, current research demonstrates that GLP might affect human health. For this reason, researcher efforts are concentrating on alternatives for analytical quantification, such as Surface Enhanced Raman Spectroscopy (SERS). In this work, a DVD-R@AgNPs SERS substrate was produced by the Cathodic Cage Plasma Deposition (CCPD) technique, which allowed a thin film layer deposition of silver nanoparticles (AgNPs) on the PC grating structure from Digital Video/Versatile Disc Recordable (DVD-R). Scanning Electron Microscopy with energy-dispersive X-ray spectroscopy was used to characterize the substrate and chemical changes on the surface after AgNPs deposition. The DVD-R@AgNPs substrate was used to detect standard crystal violet (CV), GLP, and RoundupTM GLP (GLP-RU) using Raman Spectroscopy. The CV was used as a control sample for SERS measurement, allowing the calculation of the substrate enhancement factor, which was in the order of ∼ 105. To evaluate the efficiency of the SERS substrate, the limit of detection was calculated and showed values of ∼ 10-10 mol/L for CV, 10-7 and 10-8 mol/L for GLP, and 10-6 mol/L for GLP-RU. Thus, the DVD-R@AgNPs SERS sensor is a low-cost substrate that analyzes traces of pesticides such as commercial GLP, demonstrating high SERS sensitivities and many applications.
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    Síntese e Caracterização de Nanossondas Bifuncionais com Clorina E6 e Cetuximabe para Aplicação em Terapia Fotodinâmica
    (2025-02-28) Raniero, Leandro José; Simioni, Andreza Ribeiro; Vieira, Lucia; Liu, Andrea Santos; Marmo, Vitor Luca Moura; São José dos Campos
    O receptor do fator de crescimento epidérmico superexpresso (EGFR) em cânceres de pulmão, mama, colo do útero e colorretal está associado a um risco aumentado de mortalidade, destacando a importância de abordagens terapêuticas direcionadas. Portanto, a terapia fotodinâmica (TFD) utilizando nanossondas bifuncionais (NB) pode aumentar a seletividade e induzir a morte celular em tumores. Isto se deve à afinidade do anticorpo monoclonal IgG cetuximabe (CX) e à capacidade do fotossensibilizador clorina e6 (ce6) de produzir espécies reativas de oxigênio (ROS) que induzem células tumorais à morte. Este trabalho teve como objetivo sintetizar NB que consistem em um sistema de nanopartículas de ouro (AuNPs) funcionalizadas com CX e ce6. Para sintetizar este sistema foi necessário modificar a estrutura do CX e ce6 utilizando carbodiimida, permitindo a funcionalização com as AuNPs. As caracterizações das NB foram realizadas utilizando as técnicas de espectroscopia UV-visível, espectroscopia no infravermelho com transformada de Fourier (FTIR), espalhamento dinâmico de luz (DLS), espalhamento eletroforético da luz (ELS) e espectroscopia de fluorescência. A absorção UV-visível revelou a permanência da banda de Soret e da banda Q em 390 nm e 667 nm, respectivamente, no NB. Os espectros de FTIR mostraram vibrações referentes à estrutura da ce6 e CX que não foram alteradas durante a reação da carbodiimida e o aparecimento da banda amida formada entre os compostos. Obtendo resultados promissores em testes in vitro na linhagem celular MDA-MB-468. Assim, os resultados indicam que as NB sintetizadas possuem potencial para aplicação na TFD direcionada contra tumores com superexpressão de EGFR.
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    SiOx Top Layer on DLC Films for Atomic Oxygen and Ozone Corrosion Protection in Aerospace Applications
    (Universidade Federal de São Carlos) Ferreira, Leandro Lameirão; Radi, Polyana Alves; Silva Sobrinho, Argemiro Soares da; Vieira, Lucia; Leite, Douglas Marcel Gonçalves; Recco, Abel Andre Candido; Reis, Danieli Aparecida Pereira; Massi, Marcos
    Every year, billions of dollars are invested in research and development for space applications, including new systems, new technologies, and new materials. DLC (Diamond-Like Carbon) is a promising material for use in these applications, but its use faces a technological barrier, since it is severely etched by atomic oxygen and ozone. In this study, SiOx-DLC thin films were deposited as a top layer of diamond-like carbon (DLC) films on Ti-6Al-4V substrates to increase resistance against corrosion by atomic oxygen and ozone as well as meet the requirements for use in Low Earth Orbit (LEO) satellites. The corrosion resistance of the films was evaluated using oxygen plasma, and the tribological and mechanical properties were investigated. The SiOx-DLC top layer reduced the corrosion rate two orders of magnitude and increased the critical load from 16.2 ± 1.5 N to 18.4 ± 0.4 N.
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    Study of (12Co–4Cr WC) and (Cr3C2–25NiCr) coatings sprayed by the HVOF process and subsequently laser remelted
    (UFSCar) Oliveira, Ana Claudia Costa; Carvalho, Edinelson; Dyer, Paulo; Silva, Maria Margareth da; Vieira, Lucia; Silveira, Carolina Hahn da; Vasconcelos, Getúlio de
    The laser remelting technique on tungsten carbide (12Co–4Cr WC) and chromium carbide (Cr3 C2 –25NiCr) coatings deposited by HVOF provides improvements in surface properties, such as increased hardness and resistance to abrasive wear. This process uses a laser beam to selectively melt the coating, promoting a uniform and adherent layer. In the present work, tungsten carbide and chromium carbide alloy coatings were deposited on properly prepared SAE 1020 substrates using the high-speed oxy-fuel (HVOF) technique. After deposition, the coatings were remelted with a laser beam, varying the scanning speed and the laser beam power of the ytterbium fiber to obtain a pore- and crack-free coating and better metallurgical anchorage to the substrate. The samples were characterized by scanning electron microscopy (SEM), X-ray diffractogram, ASTM G132 Standard Test Method for Pin Abrasion Testing wear and microhardness. The results show that it was possible to obtain coatings with greater hardness after the laser remelting process, reducing pores or imperfections and metallurgically bonding to the substrate.
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    Tribocorrosion Susceptibility and Osseointegration Studies of Silicon–Carbon–Titanium Oxide Coatings Produced on SS316L by Laser Cladding
    (Springer Nature Link) Vieira, Angela Aparecida; Manfroi, Lucas Augusto; Lobo, Larissa Zamboni; Santos, Thaisa Baesso; Silva, Silvelene Alessandra da; Vasconcelos, Getúlio; Radi, Polyana Alves; Silva, Newton Soares da; Vieira, Lucia
    Metallic implants are frequently exposed simultaneously to cyclic micromovements and a corrosive medium at the interface between implant and bone, constituting a tribocorrosive environment. Ions from natural body fluids can increase the release of debris in the wear zone. This debris can penetrate soft or hard tissue, leading to implant failure and metallic contamination of the tissues around the prosthesis. Surface modification of implants has been studied to improve the lifespan of metallic implants in the body. In this work, a CO2 laser was used to irradiate silicon carbide with and without anatase titanium oxide (TiO2), in order to produce protective coatings for improving the tribocorrosion and osseointegration performance of stainless steel (SS316L). Tribocorrosion resistance and osseointegration tests were performed using simulated body fluid (SBF), in order to understand the behavior in this environment. Chemical composition and hardness analyses showed that the coatings were effective in improving passivation of the surface, when compared to bare SS316L. Osteoblasts were well dispersed on these surfaces, displaying improved proliferation and viability, compared to the SS316L sample. A statistically significant increase of cell viability was observed when the surface was covered with a low silicon content coating.