http://repositorio.ufc.br/handle/riufc/306 2026-05-25T12:07:07Z http://repositorio.ufc.br/handle/riufc/86248 Título: Desenvolvimento e validação de métodos para análise de clorato em água de processo e suco de acerola por cromatografia de íons Autor(es): Menezes, Josália Liberato Rebouças Abstract: Brazil, as a major producer and exporter of fruits, including acerola, must meet international standards to remain competitive in the global market. These food products are often contaminated by chlorinated substances (DBPs) present in treated water, associated with the use of chlorine-based sanitisers. In fruits and vegetables, among the chlorinated inorganic contaminants, chlorate (ClO3⁻) stands out, which has aroused increasing concern among health and food safety authorities such as WHO, EFSA, and EPA. Considering that exposure to this substance occurs predominantly through the ingestion of contaminated water and food, international regulatory bodies have established maximum chlorate limits for the marketing of these products. Thus, the identification and quantification of this anion are essential to ensure food safety and public health. Since export specifications for fruit and its products allow for very low chlorate concentrations (MRL of 0.05 mg/kg for citrus), sensitive and selective analytical methods become indispensable for monitoring in the agro-industry. Ion chromatography (IC) stands out as a regulated technique for the determination of ClO3⁻, offering high selectivity, rapid result acquisition, the ability to detect multiple ionic species, and low cost compared to LC-MS. In 2024, fifty years after the first survey on DBPs, chlorate was reaffirmed as a target analyte in several methods published by the USEPA. Aiming to contribute to advances in chlorate determination, this work reports the development of two methods for chlorate quantification, one in process water and the other in acerola juice. For water analysis, a more sensitive method than direct injection was developed, using solid-phase extraction coupled with ion chromatography in conductimetric detection (SPE-IC-DC), through factorial design to optimize the extraction conditions. The method showed selectivity, absence of matrix effect, and detection and quantification limits of 0.2 and 0.6 µg/L, respectively. A method based on liquid-liquid extraction combined with solid-phase extraction and ion chromatography (LLE-SPE-IC) was also developed for the analysis of concentrated acerola juice, obtaining a quantification limit three times lower (18 µg/Kg) than the European limit. Thus, the SPE-IC-DC and LLE-SPE-IC methods proved to be viable and efficient for quality control in juice processing industries. Tipo: Tese 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85983 Título: Hidrogel de colágeno e Ca10(PO4)6(OH)2 provenientes de tilápia do nilo e associados a Fe3O4@bPEI para aplicação em enxerto ósseo xenógeno Autor(es): Câmara, Gabriela Ibiapina Figueiredo Abstract: The development of new products with high added value based on raw materials derived from fish processing residues opens possibilities for the sustainable advancement of the sector. In this work, the skins of Nile tilapia (Oreochromis niloticus) were used as raw material to obtain collagen, enabling the development of a collagenous matrix hydrogel associated with hydroxyapatite and incorporated with functionalized magnetic nanoparticles (Fe3O4, magnetite). Collagen was enzymatically extracted (pepsin) from pre-treated skins. The hydroxyapatite (HAp) used in this work was obtained from Nile tilapia scales. Magnetite was synthesized in a single step from solutions of Fe2+ and Fe3+ ions and functionalized with branched polyethyleneimine (bPEI). The hydrogels were prepared by UV-Riboflavin crosslinking, considering a collagen and HAp ratio of 4:1 (w/w), with 0.5%, 1.0%, 1.5% and 3.0% (w/v) of functionalized magnetite (Fe3O4@bPEI), totaling four samples: Col+HA+Fe3O4@bPEI_0.5%, Col+HA+Fe3O4@bPEI_1.0%, Col+HA+Fe3O4@bPEI_1.5%, and Col+ HA+Fe3O4@bPEI_3.0%. Collagen, functionalized magnetite, and hydrogels were characterized to determine their chemical, physical, and biological properties. The integrity of the triple helix of collagen was preserved after extraction, presenting, microscopically, a microfibrillar morphology suitable for its use as a matrix to produce hydrogels. The superparamagnetic behavior of Fe3O4@bPEI particles was satisfactory for biomedical applications, without hysteresis and with temperature increase (hyperthermia), when subjected to an external magnetic field. The collagenous matrix presented a porous structure, with the HA covering the surface of the collagen microfibrils. The Fe3O4@bPEI particles were successfully associated with the collagen and HAp matrix, obtaining hydrogels with a solid and consistent structure. Cell viability assays of the hydrogels did not show cytotoxic effects on fibroblasts (L929 cell line), with cell viability above 70%. For osteoblasts (MC3T3 cell line), cell viability above 70% was observed only for samples with a lower concentration of Fe3O4@bPEI. Among the proposed samples, the Col+HA+Fe3O4@bPEI_1.0% hydrogel showed more adequate cytocompatibility results, with potential application to act as a xenogeneic bone graft, which will both help in the bone regeneration process and in local hyperthermia to stop the growth or destroy cancer cells. Tipo: Tese 2022-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85964 Título: Eletrodeposição de Snx-In(1−x) e NixMo(1−x) a partir de cloreto de colina e etilenoglicol Autor(es): Sousa, Natalia Gomes Abstract: The objective of this work was to electrodeposit, under potentiostatic control, SnIn and NiMo coatings in a eutectic solvent medium consisting of choline chloride (ChCl) and ethylene glycol (EG) in a 1:2 ratio (1ChCl:2EG). For SnIn coatings, solutions containing 0.025 mol L−1 SnCl2 and/or 0.025 mol L−1 InCl3 were used; for NiMo coatings, 0.4 mol L−1 NiCl2 and 0.025 mol L−1 Na2MoO4.H2O were used. The characterization of the coatings was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The morphologies of the SnIn coatings at 298 K varied from cubic crystallites to a denser arrangement with interconnected forms from −1.0 V to −1.4 V. At 343 K, irregular layers were observed at −1.4 V. The Sn content was always higher than that of In, increasing slightly with increasing deposition potential, but the temperature did not affect this trend. For the NiMo coatings, the morphology obtained at 298 K resulted in a thin film for both Ni and NiMo, evidenced by the presence of grooves from the surface treatment. At 343 K, nodules formed for Ni, and for NiMo, the morphology was similar to a cauliflower and compact. The temperature facilitated Mo deposition, as indicated by EDS results, which showed a threefold increase in Mo at 343 K, resulting in 4% Mo. Computational simulations were performed for both coatings using density functional theory (DFT). For SnIn, the behavior of the Sn2+ and In3+ ions was evaluated. The results indicated that both cations interacted more strongly with the Cl− ion than with EG and showed no interaction with ChCl. For the NiMo coatings, their application for the hydrogen evolution reaction (HER) was studied. It was observed that the best performance and stability were achieved with the Ni96Mo4 coating, as it exhibited the lowest overpotential and highest exchange current values. Computational simulations were performed for the Ni100 and Ni96Mo4 surfaces, yielding Gibbs energy values of −4.15 and −2.31 kcal mol−1, respectively. These Gibbs energy values agreed with the experimental results, and Ni96Mo4 was found to be the best coating for HER. Tipo: Tese 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85484 Título: Estudo computacional da interação de fármacos anti-Parkinson com nanoestruturas de carbono Autor(es): Mendonça, Glaydson Leandro Farias Abstract: One of the consequences of increased life expectancy is the higher incidence of cases of neurodegenerative diseases, more common in older people. The most present in this category are: Alzheimer's disease and Parkinson's disease. The treatment of patients with Parkinsonism is often extremely exhausting, full of adverse effects; in certlin cares, the use of anti-Parkinson's drugs must cease so that individuals do not die or have permanent sequelae. Non-toxic nanostructured carbon particles interact with drugs, forming supramolecules capable of crossing the blood-brain barrier more easily, this show characteristics of good drug delivers. The present work aims to computationally study the interaction of the anti-Parkinson drugs Levodopa (LDP), Carbidopa (CDP), Entacapone (ECP) and Benserazide (BZD) with carbon nanostructures: Fullerane (C60), Single-walled carbon nanotube (NTCPS) and Fullerol (C60OH24) with the purpose of evaluating the application of these nanoparticles in a Drug delivery system. Molecular properties were obtained using DFT-level calculations, aiming to correlate them with pharmacological activity, as well as estimating the preferential adsorpition sites. The drug-nanostructure interactions were made using Monte Carlo and Molecular Dynamics Methods, obtaining the interaction energies and preferred orientations. It was observed that the interaction of drugs with C60 and NTCPS resulted in physical adsorption, where ECP binds more strongly to nanostructures, followed by LDP, BZD and CDP respectively, results attributed to molecular properties, such as LUMO and the electron density distribution in drugs. In the interaction of the molecules with C60OH24, chemisorption was observed, a consequence of the interaction of the heteroatoms of the drugs with the hydroxyl groups of the nanostructure, the interaction force undergoes a change and is shown as: ECP > BZD > CDP > LDP. As a final consideration, we have a potential suggestion for the treatment of Parkinson's disease would be the administration of LDP and CDP together with the carbon nanotube, making the drugs adhere to the carbon structure, facilitating the passage of drugs through the blood-brain barrier and potentially be released in the brain region, thus ensuring better use of the pharmacological effects of the drugs. Tipo: Tese 2017-01-01T00:00:00Z