Development of derivative spectrophotometric method for simultaneous determination of pyrazinamide and rifampicin in cubosome formulation

The ultraviolet spectrophotometry analysis for quantitative assay of drugs is a method accurate, sensitive, selective and reproductive with the advantage of being a simple and less expensive method. In this study, a derivative ultraviolet spectrophotometric method was developed for simultaneous determination of pyrazinamide (PYZ) and rifampicin (RIF). The spectrophotometric method was evaluated according to validation guidelines for specificity, linearity, limits of detection and quantification, precision, accuracy and robustness. The first-derivative spectra were obtained and by the zerocrossing point, the wavelength 247 nm and 365 nm were selected for PYZ and RIF quantification, respectively. No interference from cubosome excipients was detected in the proposed method. The results demonstrated linearity in a range of 4.0 – 12.0 µg/mL with an adequate correlation coefficient for both drugs. The intra and inter-day precision results (RSD < 5%) indicated the reproducibility of the method. The accuracy data showed satisfactory results (RSD < 5%) from recovery test. In addition, the robustness results showed that the PYZ and RIF content were unaffected by the solvent alteration of methanol to methanol:water (99:1, v/v). The derivative ultraviolet spectrophotometric method proved to be an excellent strategy for simultaneous determination of PYZ and RIF

Gelatinized and nongelatinized starch/pp blends : effect of starch source and carboxylic and incorporation

Due to the environmental impact caused by incorrect disposal and the non-biodegradability of synthetic polymers, the packaging sector seeks renewable raw materials. An alternative is the utilization of natural renewable polymer, such as thermoplastic starch (TPS), mixed with synthetics. However, the chemical incompatibility between these two materials leads to the use of a compatibilizer agent. Even though the compatibilizer effect of carboxylic acid on TPS blends have been studied, the correlation between the carboxylic acid and the starch source has not been investigated yet. Thus, this study focuses on the effects of added carboxylic acids (myristic (C14) and stearic (C18) acid) and the starch sources (corn, cassava, and potato) on the properties and microstructure of blends with TPS/PP (70/30). The results suggested that the compatibilizer effect of acids depends on the starch source and the length of the acid chain, where cassava blends with C14 showed better results. Acid insertion increased tensile strength and deformation at break, but reduced the elastic modulus, indicating a plasticizer effect. This behavior was related to the formation of amylose and lipid complexes (endogenous or added) during heating. Torque reduction and Tg displacement were also observed for acid blends. The SEM images showed two different morphological dispersions and a non-gelatinization effect due to the acid insertion. Results suggested that acids act differently according to the starch source

Influência da adição de resíduo de pneu em matriz de SEBS para aplicação em pisos industriais

O descarte inadequado de pneus representa um grave problema ambiental, pois seu elevado tempo de decomposição, aliado ao seu descarte incorreto, o torna uma grande ameaça aos recursos naturais, causando contaminação de solos e rios, além de enfermidades provocadas pelo acúmulo de resíduos e água em seu interior, proliferando vírus e bactérias. Dentre as alternativas possíveis de reutilização deste resíduo é possível optar por sua incorporação em outros materiais, o que além de torná-lo um resíduo economicamente atrativo, possibilita que sejam desenvolvidas novas composições de materiais com propriedades diferenciadas. A proposta deste trabalho consiste na adição de resíduo de pneu em matriz de elastômero termoplástico SEBS (copolímero de estireno - etileno/butileno - estireno). Em um primeiro momento avaliou-se a influência do tamanho de grão do resíduo. Foram utilizados grãos de tamanhos de 12, 24 e 35 mesh. Após a realização de ensaios físicos, térmicos e mecânicos, que permitiram a escolha da melhor granulometria, variou-se a concentração de resíduo em 10, 20 e 30% em massa de SEBS. Os resultados mostraram que o composto desenvolvido com granulometria de 12 mesh, em concentração de 10% em massa de SEBS, mostrou-se a composição com melhores propriedades mecânicas, o que sugere sua vantagem em aplicação em pisos industriais.The inadequate disposal of tires represents a serious environmental problem, since its high decomposition time, together with its incorrect disposal, makes it a great threat to natural resources, causing contamination of soils and rivers, as well as diseases caused by to the accumulation of waste and water inside and the proliferating viruses and bacteria. Among the possible alternatives of reuse of this residue is its incorporation in other materials, which in addition to making it an economically attractive residue and allows the development of new compositions of materials with different properties. The purpose of this work is the addition of tires residue in SEBS thermoplastic elastomer matrix (styrene - ethylene / butylene - styrene block copolymer). In first step, the influence of the grain size of the residue was evaluated. Tires particles of 12, 24 and 35 mesh sizes were used. After physical, thermal and mechanical analysis, which allowed the choice of the best granulometry, the residue concentration was varied in 10, 20 and 30% by mass in SEBS matrix. The results showed that the compound developed with 12 mesh granulometry at a concentration of 10% by mass SEBS matrix showed the composition with better mechanical properties, which suggests its advantage in application on industrial floors

Structural changes of polyethylene in blown films with different pro-oxidants

The accumulation of polymeric residues has been one of the most impacting environmental problems in recent human history, coming, above all, from disposable artefacts, such as plastic bags. Processing polyolefins with pro-oxidant additives is an alternative to favour the abiotic degradation process of macromolecules, including thermooxidation, so that the oxygenated fragments produced can be assimilated by microorganisms. The objective of this work was to evaluate the process of thermomechanical oxidative degradation of polyethylene (PE) during tubular extrusion of HDPE/LDPE films, without and with 1% of two different pro-oxidants, d2wTM and benzoin. The results of viscosimetric and MFI analyses indicated smaller chain sizes in the additivated films. The FTIR spectra and contact angles indicate a higher presence of polar functional groups in the samples with pro-oxidants. The surface morphological analysis by SEM indicated difference of PE homogeneity in the films. Benzoin, however, proved to be a better pro-oxidant than d2wTM

Influence of the nature of pro-oxidants on the photooxidation of polyethylene blown films

In an attempt to reduce the accumulation of polymeric waste in the environment, such as plastic bags, the use of pro-oxidants has been adopted in polyolefins, including polyethylene (PE), which is one of the most used polymers in film production. The incorporation of this additive to PE film aims to accelerate its oxidation in the process of abiotic degradation, generating oxygenated groups that can facilitate the biotic degradation. Commercial pro-oxidants are commonly organic salts of transition metals. However, their use can lead to a secondary problem, the inappropriate accumulation of transition metals at the site where the polymeric waste was deposited and, for this reason, it has been sought pro-oxidants metals free and that can also be biodegraded. In this context, this work aimed to evaluate the photodegradation of PE blown films obtained by extrusion using a commercial pro-oxidant, d2w™, an alternative organic pro-oxidant, benzoin, and also a standard film, without pro-oxidant. After undergoing 96 and 144 h of UV light exposure, the blown films were evaluated by dilute solution viscometry, FTIR and SEM analysis. The results showed that the pro-oxidants lead to the formation of more macromolecular fragments containing carbonyl groups than in the standard PE film. The film extruded with benzoin showed greater fragmentation, which may be associated with a greater reduction in the average viscosimetric molar mass, therefore, this additive being a promising organic substance in the induction of photooxidation, as demonstrated by the other results obtained by FTIR and SEM

Nanopartículas de dióxido de titânio promovem efeitos histopatológicos e genotóxicos em Danio rerio após exposição aguda e crônica

Titanium dioxide nanoparticles (TiO2-NPs) are among the most used nanomaterials worldwide, but studies evaluating its genotoxicity and histopathological effects are scarce, dealing with short exposure times and low concentrations for human use. The aim was to evaluate TiO2-NPs genotoxicity and histological alterations in the intestine and liver of zebrafish after exposure to human consumption compatible concentrations. Fishes were acutely (96 hours) and chronically (30 days) exposed to 5.0, 20 and 40 mg L-1 of TiO2-NPs and later euthanized for organ and blood analysis through histological procedures and the micronucleus test, respectively. An increase in the thickness of intestinal villi was observed after acute and chronic exposure in the higher concentrations. The liver showed an increase in vacuolated hepatocytes after both exposures, besides an increase in hepatocytes with peripheral nucleus. Genotoxicity was only observed after chronic exposure, demonstrated by the increase in micronucleus and cell buddings. These findings indicate that TiO2-NPs cause histopathological damage even in acute exposures, as the intestine serves as a barrier for NPs and the liver is an organ that accumulates Ti. Genotoxicity was possibly mediated by reactive oxygen species through chronic inflammation, leading to tissue damage and carcinogenesis in longer exposures that represents human exposure time.Nanopartículas de dióxido de titânio (Nano-TiO2) estão entre os nanomateriais mais usados em todo o mundo, mas os estudos avaliando sua genotoxicidade e efeitos histopatológicos são escassos, tratando-se de curtos tempos de exposição e baixas concentrações para uso humano. O objetivo foi avaliar a genotoxicidade de Nano-TiO2 e as alterações histológicas no intestino e no fígado de peixes-zebra após exposição a concentrações compatíveis com o consumo humano. Os peixes foram expostos agudamente (96 horas) e cronicamente (30 dias) a 5, 20 e 40 mg L-1 de Nano-TiO2 e posteriormente eutanasiados para análise de órgãos e sangue por meio de procedimentos histológicos e teste de micronúcleo, respectivamente. Um aumento na espessura das vilosidades intestinais foi observado após exposição aguda e crônica nas concentrações mais altas. O fígado apresentou aumento de hepatócitos vacuolizados após ambas as exposições, além de aumento de hepatócitos com núcleo periférico. A genotoxicidade só foi observada após exposição crônica, demonstrada pelo aumento de micronúcleos e brotamentos celulares. Esses achados indicam que as Nano-TiO2 causam danos histopatológicos mesmo em exposições agudas, pois o intestino serve como uma barreira para as NPs e o fígado é um órgão que acumula Ti. A genotoxicidade foi possivelmente mediada por espécies reativas de oxigênio por meio de inflamação crônica, levando a danos nos tecidos e carcinogênese em exposições mais longas que representam o tempo de exposição humana

Caracterização mecânica e morfológica de solados produzidos com resíduos de laminados de PVC da indústria calçadista

 A indústria de calçados emprega em seus produtos diversas matérias primas derivadas do setor de plásticos. Um dos mais utilizados é o laminado sintético de PVC, utilizado na construção de cabedais devido à grande versatilidade de cores, estampas e espessuras. O laminado é composto de PVC e de fibra têxtil, normalmente na proporção mássica de 60/40. O corte das peças gera uma grande quantidade de aparas que normalmente são descartadas ou depositadas em aterros sanitários ou ARIPs (Aterros de Resíduos industriais Perigosos). O presente trabalho avalia a viabilidade de incorporação destes resíduos em forma de pó em matriz de PVC virgem para uso em solados nas proporções de 0, 5, 15, 25, 35 pcr (partes por cento de resina), bem como seu desempenho mecânico. Foram avaliadas propriedades físico-mecânicas com tração, dureza shore A e cola-gem, microscopia eletrônica de varredura (MEV) e espectroscopia no infravermelho (FTIR). Os resultados dos ensaios de dureza e tração demonstraram um decréscimo no desempenho na medida em que a concentra-ção de resíduo no compósito aumentou. A força de colagem também apresentou queda na resistência final obtida pelo efeito pull out, confirmado pelas micrografias da superfície de fratura. Pode-se dizer que as mis-turas com resíduos de laminados em pó apresentam características aceitáveis, segundo as normas indicadas e os padrões especificados para a utilização como material para solado. Além disso, a incorporação deste resí-duo diminui a quantidade de material descartado reduzindo o impacto ambiental.Palavras-chave: PVC, compósitos, resíduos de laminado sintético, reciclage

Development of a clioquinol nanocarrier as a new, promising option for the treatment of dermatomycosis

Dermatomycosis is a common fungal infection, and its treatment is limited by few antifungal agents. Clioquinol (CQ) is an antiparasitic agent that has been studied for new uses, such as antifungal and antiviral applications. CQ was incorporated into a lipid-based nanocarrier as a new, promising option for dermatomycosis. This study aimed to develop a CQ-loaded lipid-based nanocarrier for cutaneous application and to evaluate its antifungal activity. CQ-loaded nanoformulation (LBN-CQ) was developed using the ultrasonication method, and the particle size, polydispersity index (PDI), pH, zeta potential, and drug content were monitored for 45 days. To evaluate antifungal activity, broth microdilution and a time-kill assay were performed. LBN-CQ presented a particle size of 91 3 nm and PDI of 0.102 0.009. The zeta potential and pH values were 9.7 2.0 mV and 6.0 0.1, respectively. The drug content was 96.4 2.3%, and the encapsulation efficiency was 98.4%. LBN-CQ was able to reduce the minimum inhibitory concentration (MIC) in a 2-fold or 4-fold manner in most of the tested strains. Additionally, LBN-CQ presented stable fungistatic action that was not concentration- or time-dependent. In conclusion, the developed CQ-loaded nanocarrier is a promising treatment for skin fungal infections and a promising candidate for future randomized clinical trials