http://bdtd.uftm.edu.br/handle/tede/993 Antigo Programa de Pós-Graduação Interdisciplinar de Biociências Aplicadas 2026-04-05T22:19:20Z http://bdtd.uftm.edu.br/handle/123456789/2071 Título: Estudo do encapsulamento e da liberação de quercetina em sistemas lipídicos: efeitos de carga e rigidez Abstract: Quercetin is a bioactive that has a wide range of applications, but its use for pharmacological purposes presents difficulties related to its low bioavailability and solubility in aqueous media, high propensity to degradation by light, heat and oxygen, as well as its reduced biological activity. in the gastrointestinal tract. A powerful strategy to enhance its biological activity is to encapsulate it in nanoparticulate and microparticulate systems. MLVs (multilamellar vesicles) represent a suitable low cost alternative to encapsulate hydrophobic bioactive molecules being successfully used in several areas. Due to the versatility in the preparation of MLVs and considering the variety of lipids and sterols found in nature, we investigated the effect of different lipid compositions in the manufacture of MLVs for encapsulation and controlled release of quercetin. In order to do so, the effects of load and stiffness on the average size of the formulation, size distribution, load properties and the encapsulation efficiency and release of this polyphenol were considered. Our results demonstrated that the rigidity imposed by Colesterol increased both the homogeneity of the size distribution and the encapsulation efficiency enabling a significant rate of quercetin release at the system with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoColine/Colesterol (80:20). The charge modulated both the average size and size distribution as well as resulted in high encapsulation and release efficiencies in the formulation composed of (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoColine/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (80:20). To the best of our knowledge, this is the first study concerning charge and rigidity effects on the encapsulation of quercetin in multilamellar vesicles, with great potential for technological application. Furthermore, the news presented in this work is a starting point on the use of lipid composition as a modulating agent of important parameters in the development of nano and micro systems. Tipo: Dissertação 2022-06-02T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/2059 Título: Desenvolvimento e caracterização de filmes biodegradáveis de fécula de mandioca modificados com ácido malônico e hipofosfito de sódio Abstract: This study aimed to synthesize and characterize biodegradable films based on cassava starch modified with malonic acid and sodium hypophosphite, in order to understand the structural, physicochemical, and barrier changes promoted by chemical modification. The films were prepared using the casting technique and subjected to different analyses, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), moisture content determination, water vapor permeability (WVP), and solubility tests in organic and aqueous solvents. FTIR spectra evidenced the incorporation of the modifying agents into the polymer matrix, confirmed by the appearance and intensification of carbonyl (C=O) bands. SEM micrographs revealed homogeneous surfaces with uniform texture and low porosity, especially in samples with higher concentrations of malonic acid. The WVP test demonstrated that the modified films exhibited better water vapor barrier performance compared to the control, while the moisture content analysis indicated that the chemical modification increased the water retention capacity of the polymer matrix. The solubility test revealed high resistance of the films to organic solvents and a characteristic swelling behavior in highly polar solvents, such as DMSO and water, confirming the hydrophilic nature of the material. The results indicate that modification with malonic acid and sodium hypophosphite promoted significant structural changes, enhancing barrier properties and influencing water– polymer interactions without compromising the integrity of the starch matrix. Tipo: Dissertação 2025-07-31T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/2058 Título: Areno complexos de rutênio contendo ligantes derivados de hidrazidas: síntese, caracterização e estudo da estabilidade Abstract: A large number of coordination compounds have been studied in the last decades with the aim of developing more effective drugs for the treatment of various diseases. Among these, ruthenium (II) compounds are of great interest due to their ability to participate in redox reactions capable of promoting the generation of reactive oxygen species (ROS) in biological media, which are harmful to pathogenic biological agents. However, the stability of the complexes is a fundamental point for their use as a possible drug. In this sense, the present work aimed to develop new organometallic ruthenium complexes with potential medicinal use based on ruthenium arene-complexes containing hydrazide-derived ligands and to study their stability. Initially, a series of three complexes were synthesized, using as precursor the complex [{RuCl2(η6-p-cym)}2] and the thiosemicarbazide ligands HLR (R = allyl, phenyl and fluorophenyl), forming complexes of composition [RuCl(η6-p-cym)(HLR)]PF6. The obtained complexes were characterized by electronic spectroscopy, infrared spectroscopy, elemental analysis, mass spectrometry, 1H NMR and had their molecular structure optimized by computational calculations (DFT). However, the UV-Vis and 1H NMR measurements indicated the instability of the complexes in solution, concluding that there was a need to prepare new precursors to obtain more stable complexes. Thus, the precursors [RuCl(η6-p-cym)(bipy)]PF6 and [RuCl(η6-p-cym)(o-phen)]PF6 were used to prepare two new series of complexes with composition [Ru(η6-p-cym)(bipy)(HLR)]PF6 and [Ru(η6-p-cym)(o-phen)(HLR)]PF6. The characterizations performed were used for the two new series of complexes, however, it was found that even containing the N-heterocyclic ligand, the thiosemicarbazide derivatives did not present stability in solution. Finally, a new complex was prepared using 2-(di(pyridin-2-yl)methylene)-N-phenylhydrazinecarboxamide (HDPKPhS) as ligand, a compound from the semicarbazone class. In fact, the characterizations indicated that the ligand acts in N,N-bidentate coordination mode, which led to the stability of the complex in solution. Thus, it is possible to conclude that ruthenium arene complexes with similar ligands to HDPKPhS are promising compounds to be evaluated in biological studies. Tipo: Dissertação 2025-02-06T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/2057 Título: Síntese de cristais de HgI2 por evaporação isotérmica de solvente através da análise dos diagramas de Ostwald-Miers Abstract: In this research, crystals of mercury iodide (HgI2), with millimetric dimensions, were obtained through the technique of Isothermal Solvent Evaporation (ISE), making use of acetone and ethyl ether as solvents, at controlled temperatures. In addition, crystals were also grown, using these same solvents, together with N,N-dimethylformamide (DMF). There is a great interest in semiconductor materials with high atomic number and wide-bandgap, for applications such as ionizing radiation detectors at room temperature, using the direct detection method. Materials such as HgI2, PbI2, TlBr and CdTe are photoconductors and are examples of devices that present these conditions. HgI2has a band gap of 2.13 eV, a mass density of 6.36 g/cm3 and a high atomic number (ZHg=80, ZI=53). Along with the isothermal solvent evaporation technique, experiments were carried out to determine the metastable region of the Ostwald-Miers diagram during the crystallization process from seven different HgI2 solutions. The samples were separated into groups, where parameters such as temperature, concentration, volume, and solvent nature were changed for a better understanding of them. The growth of HgI2 crystals was associated with Ostwald-Miers diagrams for each solvent used. The final regular crystal had a length of roughly 4.0 mm and was obtained using both solvents, ethyl ether and acetone. Crystal growth mechanisms will be discussed, along with electrical transport measurements. Tipo: Dissertação 2021-12-16T00:00:00Z