Um método estável, confiável, eficiente com relação a tempo e custo para detecção de açúcares redutores, baseado no método colorimétrico do ácido dinitrossalicílico (DNS), adaptado para placas de microtitulação em um banho de água modificado com tratamento de microondas é proposto. Além da influência benéfica sobre o meio ambiente devido à redução do volume dos reagentes utilizados, o método modificado é rápido e permite a análise de um número relativamente alto de amostras. Pode ser aplicado em diversos tipos de laboratórios, de processamento de alimentos à indústrias farmacêuticas. O método adaptado foi parcialmente validado (intervalo de linearidade entre 7 µg e 5 mg per poço; limite de detecção 3 µg per poço, desvio padrão em torno de 5% para curvas de calibração com glucose, e recuperação superior a 90%) e aplicado à séries de produtos contendo açúcares redutores, como amostras de mel e vinho e medicamentos que contêm lactose como excipiente. O método proposto é bem adaptado como uma técnica de alto rendimento para determinação de açúcares redutores, pois todas amostras analisadas deram resultados esperados de acordo com as suas notas técnicas.A sound, reliable, time-and cost-efficient method for detection of reducing sugars, based on the well known dinitrosalicylic acid (DNS) colorimetric method, adapted for microtiter plates, in a modified water bath with microwave treatment is proposed. Besides the benefic influence on the environment due to the reduction of the volume of the reagents, the modified method is rapid and allows the analysis of a relatively high number of samples. It can be applied in many types of laboratories from food processing to pharmaceutical industries. The adapted method was partially validated (linearity range between 7 µg and 5 mg per well; limit of detection 3 µg per well, standard deviation around 5% for calibration curves with glucose, and a recovery higher than 90%) and applied to a series of products containing reducing sugars, such as honey, wine samples and drugs containing lactose as an excipient. The proposed method is well-suited as a high-throughput technique for determination of reducing sugars as all the analyzed samples gave the expected results according with their technical notes.Keywords: dinitrosalicylic acid (DNS), microtiter plate assay, microwave supported reaction, reducing sugars IntroductionMonosaccharides, most of oligosaccharides, glucose polymers, such as starch and cellulose, and copolymers, like chitin, contain reducing ends. The measurements of the concentration of reducing ends can give valuable information about the analyzed sample. 1 Especially due to their presence in many natural products, reducing sugars (RS) have received considerable attention, which lead to a growing number of methods for their assay. The ability to measure the concentration of RS bears much significance for understanding the amount of sugar in foodstuffs, in beverages and even, although indirectly, the activities of some enzymes which are responsible for the hydrolysis of po...

In this paper, the electrochemical behaviour of several parabens preservatives, i.e. esters of p-hydroxybenzoic acid, methyl-, ethyl- and propyl-4-hydroxybenzoates as methyl-, ethyl- and propyl-parabens (MB, EB, and PB), has been investigated at a commercial boron-doped diamond electrode (BDDE), especially in the anodic potential range, in both hydro-alcoholic and aqueous media. The cyclic voltammetric and chronoamperometric measurements yielded calibration plots with very good linearity (R2 between 0.990 and 0.998) and high sensitivity, useful for detection and analytical applications. The determination of the characteristics of individual compounds, of an “overall paraben index”, the assessment of the stability and the saturation solubility in water, and the amperometric sensing and determination in double distilled, tap and river water matrix of the relatively slightly soluble investigated parabens have been carried out using electrochemical alternative. Estimated water solubility was correlated with the octanol-water partition coefficient. Several ideas regarding stability and persistence of the presumptive eco-toxic investigated preservatives in the environment or water systems have been adjacently discussed.

Chitosan is a polymer that is extensively used to prepare nanoparticles (NPs) with tailored properties for applications in many fields of human activities. Among them, targeted drug delivery, especially when cancer therapy is the main interest, is a major application of chitosan-based NPs. Due to its positive charges, chitosan is used to produce the core of the NPs or to cover NPs made from other types of polymers, both strategies aiming to protect the carried drug until NPs reach the target sites and to facilitate the uptake and drug delivery into these cells. A major challenge in the design of these chitosan-based NPs is the formation of a protein corona (PC) upon contact with biological fluids. The composition of the PC can, to some extent, be modulated depending on the size, shape, electrical charge and hydrophobic / hydrophilic characteristics of the NPs. According to the composition of the biological fluids that have to be crossed during the journey of the drug-loaded NPs towards the target cells, the surface of these particles can be changed by covering their core with various types of polymers or with functionalized polymers carrying some special molecules, that will preferentially adsorb some proteins in their PC. The PC’s composition may change by continuous processes of adsorption and desorption, depending on the affinity of these proteins for the chemical structure of the surface of NPs. Beside these, in designing the targeted drug delivery NPs one can take into account their toxicity, initiation of an immune response, participation (enhancement or inhibition) in certain metabolic pathways or chemical processes like reactive oxygen species, type of endocytosis of target cells, and many others. There are cases in which these processes seem to require antagonistic properties of nanoparticles. Products that show good behavior in cell cultures may lead to poor in vivo results, when the composition of the formed PC is totally different. This paper reviews the physico-chemical properties, cellular uptake and drug delivery applications of chitosan-based nanoparticles, specifying the factors that contribute to the success of the targeted drug delivery. Furthermore, we highlight the role of the protein corona formed around the NP in its intercellular fate.

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A new method for the determination of methylparaben by ultra-performance liquid chromatography (UPLC) was developed. Methylparaben is often used as preservative, alone or in combination with other parabens, being added to cosmetic products, pharmaceutical products and foods to avoid microbial contamination. Due to its widespread use and potential risk to human health, assessing human exposure to this compound is of interest. A good determination and quantification of methylparaben was developed with a gradient elution using a mixture of methanol and water (60:40, v/v) within 1.455 min. Under optimized conditions, the linear working range extends over two orders of magnitude with relative standard deviations of intra- and inter-day precision below 2.3 %, and a detection limit of 0.02 ng ?L-1 for methylparaben. The proposed method was successfully applied to the assay of methylparaben in cosmetic products with minimal sample preparation.