Abstract Clay minerals are still widely used in pharmaceutical products for human health and cosmetic purposes. Pre-formulation studies were conducted to identify solid-state properties of pink clay, a sample from Diamantina, Brazil. Among the solid properties to be analyzed, we have selected type identification, iron phases, crystallinity, powder flow characteristics, thermal behavior, and non-isothermal phase transition kinetics. The pink clay is composed of (1:1) clay type and kaolinite as the main component. The Mössbauer spectrum of pink clay shows Fe3+(α-Fe2O3) hematite, Fe2+, and Fe3+ with large Δ/2ξq of about 2.80 and 2.69 mm.s-1 respectively, related to iron silicates, most likely pyroxene, and a superparamagnetic Fe3+. Pink clay exhibits poor flow properties. The thermal behavior indicates a phase-transition between 400 - 600 ºC associated with the dehydroxylation of the pink clay system requiring ~300 kJ mol-1, being constant until the process reaches a conversion of ~50% when the energy is enhanced to ~530 kJ mol-1, concluding the whole dehydroxylation process (α=80%). Solid-state properties and characteristics found for the pink clay must be considered for the proper design of formulations. This type of clay shows unique pharmaceutical properties that can be favorably exploited by the cosmetic industry.

Abstract Chagas disease is a neglected parasitic disease caused by Trypanosoma cruzi, whose treatment has remained unsatisfactory for over 50 years, given that it is limited to two drugs. Benznidazole (BZN) is an efficient antichagasic drug used as the first choice, although its poor water-solubility, irregular oral absorption, low efficacy in the chronic phase, and various associated adverse effects are limiting factors for treatment. Incorporating drugs with such characteristics into nanostructured lipid carriers (NLC) is a promising alternative to overcome these limiting obstacles, enhancing drug efficacy and bioavailability while reducing toxicity. Therefore, this study proposed NLC-BZN formulations in different compositions prepared by hot-melt homogenization followed by ultrasound, and the optimized formulation was characterized by FTIR, DRX, DSC, and thermogravimetry. Biological activities included in vitro membrane toxicity (red blood cells), fibroblast cell cytotoxicity, and trypanocidal activity against epimastigotes of the Colombian strain of T. cruzi. The optimized NLC-BZN had a small size (110 nm), negative zeta potential (-18.0 mV), and high encapsulation (1.64% of drug loading), as shown by infrared spectroscopy, X-ray diffraction, and thermal analysis. The NLC-BZN also promoted lower in vitro membrane toxicity (<3% hemolysis), and 50% cytotoxic concentration (CC50) for NLC-BZN in L929 fibroblast cells (110.7 µg/mL) was twice the value as the free BZN (51.3 µg/mL). Our findings showed that the NLC-BZN had higher trypanocidal activity than free BZN against the epimastigotes of the resistant Colombian strain, and this novel NLC-BZN formulation proved to be a promising tool in treating Chagas disease and considered suitable for oral and parenteral administration.

Abstract In the hospital environment, postoperative pain is a common occurrence that impairs patient recovery and rehabilitation and lengthens hospitalization time. Racemic bupivacaine hydrochloride (CBV) and Novabupi® (NBV) (S (-) 75% R (+) 25% bupivacaine hydrochloride) are two examples of local anesthetics used in pain management, the latter being an alternative with less deleterious effects. In the present study, biodegradable implants were developed using Poly(L-lactide-co-glycolide) through a hot molding technique, evaluating their physicochemical properties and their in vitro drug release. Different proportions of drugs and polymer were tested, and the proportion of 25%:75% was the most stable for molding the implants. Thermal and spectrometric analyses were performed, and they revealed no unwanted chemical interactions between drugs and polymer. They also confirmed that heating and freeze-drying used for manufacturing did not interfere with stability. The in vitro release results revealed drugs sustained release, reaching 64% for NBV-PLGA and 52% for CBV-PLGA up to 30 days. The drug release mechanism was confirmed by microscopy, which involved pores formation and polymeric erosion, visualized in the first 72 h of the in vitro release test. These findings suggest that the developed implants are interesting alternatives to control postoperative pain efficiently.

Sclareol (SC) is arousing great interest due to its cytostatic and cytotoxic activities in several cancer cell lines. However, its hydrophobicity is a limiting factor for its in vivo administration. One way to solve this problem is through nanoencapsulation. Therefore, solid lipid nanoparticles (SLN-SC) and nanostructured lipid carriers (NLC-SC) loaded with SC were produced and compared regarding their physicochemical properties. NLC-SC showed better SC encapsulation than SLN-SC and was chosen to be compared with free SC in human cancer cell lines (MDA-MB-231 and HCT-116). Free SC had slightly higher cytotoxicity than NLC-SC and produced subdiploid DNA content in both cell lines. On the other hand, NLC-SC led to subdiploid content in MDA-MB-231 cells and G2/M checkpoint arrest in HCT-116 cells. These findings suggest that SC encapsulation in NLC is a way to allow the in vivo administration of SC and might alter its biological properties

Abstract This work describes the synthesis of composites steatite/flexible polyurethane by replacing 4.5 wt. % of polyol with steatite rock powder. We evaluated two mechanical properties of composites (comfort factor and support factor) for various formulations based on a fractional factorial design. The new synthesized composites showed higher support factor, greater comfort factor, and lower cost, compared to conventional flexible polyurethane foams. There is not a significant change in the chemical composition of the foams, due to substitution of 4.5 wt. % polyol by steatite. However, there was a decrease in cell size and greater interaction between the hard segments of the composite.

Kinetic models of solid thermal decomposition are traditionally used for individual fit of isothermal experimental data. However, this methodology presents unacceptable errors in some regions of the data. To solve this problem, a neural network was adopted in this work. The implemented algorithm uses the rate constants as predetermined weights between the input and intermediate layer and kinetic models as activation functions of neurons in the hidden layer. The contribution of each model in the overall fit of experimental data is calculated as the weights between the intermediate and output layer. In this way, the phenomenon is better described as a sum of kinetic processes. Two rigid polyurethane foam samples: loaded with Al2O3 and no inorganic filler were used in this work. The R3 and D2 models described the thermal decomposition kinetic process for all temperatures for both foams with smaller residual error. However, the network, combining the kinetic models, presented residual errors on average 102 times lower compared to these individual models. The determined activation energy is 12.44 kJ mol-1 higher for the loaded foam. This result corroborates the use of this material as flame retardant, even with the presence of a small amount of charge in its structure.

Apesar da grande importância ambiental do mercúrio (Hg), dada a sua elevada toxicidade e capacidade de contaminar extensas áreas via deposição atmosférica, pouco se conhece sobre seu comportamento em solos, especialmente nos tropicais, comparando-se com outros metais pesados. Certamente, essa escassez de informações ocorre porque os métodos de determinação de Hg são caros e laboriosos. Em relação à especiação do Hg em solos, a situação é mais precária, uma vez que os métodos de extração sequencial também são ineficientes para esse metal. Objetivou-se com este trabalho apresentar a técnica de termodessorção associada à espectrometria de absorção atômica, TDAAS, como ferramenta eficiente para a determinação quantitativa de Hg em amostras de solos. O método consiste na liberação de Hg, por aquecimento, seguido da quantificação desse por espectrometria de absorção atômica, e foi desenvolvido construindo-se curvas de calibração em diferentes matrizes de solo, a partir de soluções-padrão de Hg2+. Os parâmetros de desempenho, exatidão, precisão, limites de detecção e quantificação foram avaliados. Não houve interferência da matriz no resultado. As amostras de referência certificadas e a comparação com a determinação direta de Hg, DMA, outra técnica consagrada, foram utilizadas na validação do método, que se evidenciou exato e preciso.

Despite the considerable environmental importance of mercury (Hg), given its high toxicity and ability to contaminate large areas via atmospheric deposition, little is known about its activity in soils, especially tropical soils, in comparison with other heavy metals. This lack of information about Hg arises because analytical methods for determination of Hg are more laborious and expensive compared to methods for other heavy metals. The situation is even more precarious regarding speciation of Hg in soils since sequential extraction methods are also inefficient for this metal. The aim of this paper is to present a technique of thermal desorption associated with atomic absorption spectrometry, TDAAS, as an efficient tool for quantitative determination of Hg in soils. The method consists of the release of Hg by heating, followed by its quantification by atomic absorption spectrometry. It was developed by constructing calibration curves in different soil samples based on increasing volumes of standard Hg2+ solutions. Performance, accuracy, precision, and quantification and detection limit parameters were evaluated. No matrix interference was detected. Certified reference samples and comparison with a Direct Mercury Analyzer, DMA (another highly recognized technique), were used in validation of the method, which proved to be accurate and precise.

A correlação entre as características físicas e químicas do solo e o teor de mercúrio natural é importante para identificar aquelas que mais influenciam na retenção desse elemento nesses solos e sua distribuição nos diversos compartimentos ambientais. Esse estudo teve por objetivos determinar o teor de Hg de solos sem influência antropogênica e correlacionar esse teor com as características físicas e químicas dos solos. A relevância deste trabalho se deve ao fato que a maioria das pesquisas é focada em solos contaminados e, em caso de solos tropicais, as pesquisas são ainda mais escassas. As características físicas e químicas de diferentes solos de mata natural do Estado de Minas Gerias e de um solo do Estado do Rio de Janeiro foram correlacionadas com os teores naturais de Hg dos solos. O teor de Hg foi determinado empregando-se o analisador direto de Hg DMA-80. A faixa de concentração de Hg encontrada foi de 0 a 215 µg kg-1 com média de 81 µg kg-1. O teor de Hg dos solos correlacionou-se principalmente com o teor de argila e o pH do solo. Não houve correlação entre o teor de Hg e o de C. Para solos com teores mais altos de Hg e mesma textura, a capacidade de troca catiônica passa a ser uma variável importante.

Correlation between physical and chemical characteristics of soils and their natural mercury content is important for identifying the parameters that most influence Hg retention in these soils and its distribution in different environmental compartments. The aim of this study was to quantify the Hg content of tropical soils without anthropogenic influence and correlate it with physical and chemical soil characteristics. The present study is relevant because most research focuses on contaminated soils and, in the case of tropical soils, research is even more limited. Therefore, different soils from natural forests of southeastern Brazil were characterized and the results of chemical and physical characterization were correlated with soil Hg content. Mercury content was determined through the direct Hg analyzer DMA-80. Mercury concentrations in soils were between 0 and 215 μg kg-1 and the average was 81 µg kg-1. Soil Hg content correlated mainly with the clay content and soil pH. There was no correlation between Hg content and C content. For soils with higher levels of Hg and the same texture, cation exchange capacity becomes an important variable.

Cyclosporine-A-loaded PLGA implants were developed intended for ocular route. Implants were prepared using solvent extraction/evaporation technique followed by casting of the cake into rods in a heated surface. XRD patterns showed that cyclosporine-A was completely incorporated into PLGA. FTIR and DSC results indicated alterations on drug molecular conformation aiming to reach the most stable thermodynamic conformation at polymer/drug interface. Implants provided controlled/sustained in vitro release of the drug. During the first 7 weeks, the drug release was controlled by the diffusion of the cyclosporine-A; and between 7-23 week period, the drug diffusion and degradation of PLGA controlled the drug release.

In this study, an analytical method was developed and validated for quantitation of the drug bevacizumab (Avastin®) by high performance liquid chromatography (HPLC). The HPLC column was a BioSuite 250® HR SEC, 300 x 7.8 mm x 5 µm (Waters, USA). The mobile phase consisted of phosphate buffered saline (PBS). The results revealed that the method was specific, precise, accurate, robust and linear (r² = 0.998) from 5 to 75 µg mL-1. Therefore, this method can be used in drug release studies or in quality control ampoules of the drug.

In this study we prepared an inclusion complex between an iodide analogue of metronidazole (MTZ-I) and cyclodextrin (CD) to develop a safer and more effective method of treating Trypanosoma cruzi infections. According to our results, MTZ-I and MTZ-I:β-CD were 10 times more active than MTZ, demonstrating that the presence of an iodine atom on the side chain increased the trypanocidal activity while maintaining its cytotoxicity. The selective index shows that MTZ-I was 10 times more active against T. cruzi than it was against mammalian cells. The modification of MTZ side chains provides a promising avenue for the development of new drugs.

Several matters of the pharmaceutical demonstrate the great importance of thermal analysis application, especially TG and DSC for the pharmaceutical industry future, namely: characterization of the drugs with the thermal events definition, in studies of drug purity, in the polymorphs identification, in compatibility studies of solid dosage pharmaceutical formulations, in drugs and pharmaceutical formulations thermal stability, and in determination of shelf life for isothermal degradation kinetics by extrapolation using the Arrhenius equation. Thus, the test results obtained from thermal analysis are directly related to the quality of a pharmaceutical product, whether the stability or bioavailability of the pharmaceutical product.

This paper deals with the post fire behavior of hybrid nanocomposites under dynamic loadings. A series of tests were performed to investigate how nanoparticles (i.e. nanoclay and graphene nanosheets) affect the post-fire overall composite behavior. Carbon fiber/epoxy-nanoclay and carbon fiber/epoxy-graphene nanosheets were manufactured. The nanoparticles employed were Cloisite 30B nanoclay, and surface modified graphene nanosheets. The epoxy system used was RemLam M/HY956. The nanocomposites were made using ultrasonic mixer for nanoparticle dispersion in acetone followed by a shear mixing of acetone/nanoparticle/hardener. The following steps involved degassing, the addition of resin to the mixture and, the hand lay-up with vacuum assisted cure. Thermo gravimetric analysis (TGA) indicates an average decrease on peak mass loss around 41% with the addition of small amount of nanoparticles. The sample plates were exposed to a heat flux of 800 kW.m-2 for a period up to 120 seconds. The post-fire low velocity impact tests indicated the impact resistance degraded as a function of heat exposure. However, the addition of nanoclay leads to an increase on impact peak force of 11.69%. The carbon oxidation could be the main cause of the increase on impact peak load is lower than expected, only 6.72%. The model predictions are overestimated by approximately 8%. Even though, it can be a good tool for composites design.

Thermogravimetry (TG) and differential scanning calorimetry (DSC) are used in pharmaceutical studies for drugs characterization, purity, formulations compatibility, polymorphism identification, stability evaluation, and thermal decomposition of drugs and pharmaceutical formulations. Simvastatin showed fusion at 138.5 ºC and thermal stability up to 248 ºC. Simvastatin was incompatible with preservative excipient butylhydroxyanisole (BHA) performing a process of crystal amorphization. The drug showed morphological polymorphism, where it has the same unit cell but with different crystal habits according to the recrystallization solvent.

O objetivo desse trabalho é a adsorção de cianocomplexos de ouro, cobre e ferro de efluentes que são gerados no processo de beneficiamento do minério de ouro. Para a adsorção foram testadas duas alternativas: resina de troca aniônica com base fraca e o carvão ativado quimicamente modificado. A resina utilizada foi a LEWATIT MP 62 da Bayer S.A. O processo de modificação química do carvão ocorreu em duas etapas: nitração do carvão ativado comercial, seguida de redução do grupo nitro (NO2) para grupo amino (NH2). Os testes de adsorção revelaram que o carvão ativado modificado apresentou pior eficiência na recuperação de complexos de Au, em relação ao carvão ativado sem tratamento, e que ambos não adsorveram complexos de Cu e Fe. A resina foi a que apresentou melhor recuperação dos complexos de ouro (100%), cobre (99%) e ferro (100%).

Herein, the adsorption of gold, copper, and iron cyano complexes fromeffluents of t gold ore processing is presented. . For recovery, two alternatives were tested: weak-base ion - exchange resin and chemically modified activated carbon. The resin used was LEWATIT MP 62 from Bayer S.A. Chemical modification was carried out in two steps: nitration of commercial activated carbon followed by the reduction of the nitro group (NO2) to amino group (NH2). Adsorption testes revealed that activated carbon presented poorer efficiency in the recovery of Au complexes in relation to untreated activated carbon, and that they did not adsorb either Cu or Fe complexes. Resin recovered Cu (99%) and Fe(100%) and Au (100%) complexes was the best.