CARACTERIZAÇÃO TECNOLÓGICA EM AMOSTRAS MINERALIZADAS A ESTANHO DO ESTADO DE RONDÔNIA

A crescente demanda por estanho no cenário mundial vem promovendo maior interesse no estudo de mineralizações primárias e mais complexas. Nesse contexto, estudos de caracterização tecnológica foram efetuados em duas amostras (sulfetada e oxidada), provenientes do norte do Brasil, Estado de Rondônia, com o objetivo de verificar as características da cassiterita e dos sulfetos presentes e suas associações com a ganga. Os estudos envolveram análises granulométricas, separações minerais e estudos de mineralogia quantitativa por microscopia eletrônica de varredura (MEV/EDS) utilizando análise de imagens automatizada (Mineral Liberation Analyser - MLA), possibilitando a obtenção da composição mineral, as características de associação e de liberação dos minerais de interesse e a partição dos elementos químicos nos minerais portadores. Os resultados indicam que as amostras têm teores semelhantes de estanho e de zinco e a mesma assembleia mineralógica, variando apenas a proporção relativa entre os minerais presentes. O grau de liberação da cassiterita para o material cominuído abaixo de 3,36 mm é da ordem de 40 a 50%. Os estudos sugerem que o processamento da cassiterita poderia ser efetuado em duas etapas de cominuição conjugados com concentração gravítica; os mistos e rejeitos, a depender dos teores de Sn e Zn, poderiam ser remoídos para a recuperação da esfalerita por flotação, obtendo-se ainda um eventual concentrado acabado de estanho

Regenerative and Anti-Inflammatory Potential of Regularly Fed, Starved Cells and Extracellular Vesicles In Vivo

Background: Mesenchymal stem/stromal cells (MSC) have been employed successfully in immunotherapy and regenerative medicine, but their therapeutic potential is reduced considerably by the ischemic environment that exists after transplantation. The assumption that preconditioning MSC to promote quiescence may result in increased survival and regenerative potential upon transplantation is gaining popularity. Methods: The purpose of this work was to evaluate the anti-inflammatory and regenerative effects of human bone marrow MSC (hBM-MSC) and their extracellular vesicles (EVs) grown and isolated in a serum-free medium, as compared to starved hBM-MSC (preconditioned) in streptozotocin-induced diabetic fractured male C57BL/6J mice. Results: Blood samples taken four hours and five days after injection revealed that cells, whether starved or not, generated similar plasma levels of inflammatory-related cytokines but lower levels than animals treated with EVs. Nonetheless, starved cells prompted the highest production of IL-17, IL-6, IL-13, eotaxin and keratinocyte-derived chemokines and induced an earlier soft callus formation and mineralization of the fracture site compared to EVs and regularly fed cells five days after administration. Conclusions: Preconditioning may be crucial for refining and defining new criteria for future MSC therapies. Additionally, the elucidation of mechanisms underpinning an MSC's survival/adaptive processes may result in increased cell survival and enhanced therapeutic efficacy following transplantation

Sulfadiazine-based drug delivery systems prepared by an effective sol-gel process

In the present contribution a versatile and sustainable strategy for the formulation of a Drug Delivery System (DDS) for the controlled release of antibiotics for topical administration was developed. Silver sulfadiazine (AgSD), an antimicrobial agent for preventing infections on burn wounds, was selected as model drug. The DDS was formulated by an effective one-pot sol-gel approach by using chitosan and silica alkoxides as organic and inorganic precursor, respectively, in order to obtain a hybrid material. Different silica alkoxides, characterized by different functionalities of the organic chain, and a series of synthetic parameters (water/precursor ratio, excipients, drug amount) were evaluated. The composition of the hybrid gel was selected to achieve the optimal synergy between the physico-chemical features and the gel texture taking into great account the final application, i.e., a topical administration. Drug delivery tests were performed in vitro with a Franz vertical diffusion cell. The new DDS reaches the therapeutic concentration in the same time of a commercial sample and allows the complete release of even 2.5wt% AgSD. The drug delivery is totally controlled and gradual over 48 hours and the formulated is stable in time. Such innovative organic-inorganic hybrid material is therefore an efficient DDS for acute skin infections treatment by controlled delivery.In the present contribution a versatile and sustainable strategy for the formulation of a drug delivery system for the controlled release of antibiotics for topical administration was developed. Silver sulfadiazine (AgSD), an antimicrobial agent for preventing infections on burn wounds, was selected as model drug. The drug delivery system was formulated by an effective one-pot sol-gel approach by using chitosan and silica alkoxides as organic and inorganic precursor, respectively, in order to obtain a hybrid material. Different silica alkoxides, characterized by different functionalities of the organic chain, and a series of synthetic parameters (water/precursor ratio, excipients, and drug amount) were evaluated. The composition of the hybrid gel was selected to achieve the optimal synergy between the physico-chemical features and the gel texture taking into great account the final application, i.e., a topical administration. Drug delivery tests were performed in vitro with a Franz vertical diffusion cell. The new drug delivery system reaches the therapeutic concentration in the same time of a commercial sample and allows the complete release of even 2.5 wt% AgSD. The drug delivery is totally controlled and gradual over 48 h and the formulated is stable in time. Such innovative organic-inorganic hybrid material is therefore an efficient drug delivery system for acute skin infections treatment by controlled delivery.[GRAPHICS