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...

This review illustrates the state of air, water and soil pollution with heavy metals resulting from mining activities in the cross-border area of Romania and the Republic of Serbia. It also emphasizes the possible human health effects that certain heavy metals can cause. The heavy metals that were identified as polluting the air, water, and/or soil in the area of interest are: As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, and Zn. Acute or chronic exposure to these heavy metals may cause numerous human health effects as they affect numerous organs and tissues (gastrointestinal tract, liver, lungs, kidneys, bladder, central nervous system, reproductive system, etc.). The review shows that the pollution produced by both abandoned and active mines cannot be neglected and underlines the necessity of changes in the current mining practices so that mining operations will assure better protection for the environment and human health.

Mesoporous silica particles were prepared by the sol-gel method from different alkoxysilane precursors and used as a host matrix for encapsulation of glucoamylase, an enzyme widely used in fermentative industry. The aim was to investigate the physico-chemical properties of the different silica powders and their effect on the enzyme kinetics. The encapsulated enzymes followed Michaelis-Menten kinetics. The Michaelis constant (KM) and the maximum rate of starch hydrolysis reaction (Vmax) were calculated according to the Michaelis-Menten and Lineweaver-Burke plots. The values of the Michaelis constant (KM) of the encapsulated enzymes were higher than those of the free enzyme. The temperature and pH influence on the activity of free and immobilized glucoamylase were also compared. The results of this study show that the enzymes immobilized in organic/inorganic hybrid silica matrixes (obtained by the sol-gel method), allowing the entrapped glucoamylase to retain its biological activity, are suitable for many different applications, (medicinal, clinical, analytical).

This work is focused on a novel class of hybrid materials exhibiting enhanced optical properties and high surface areas that combine the morphology offered by the vinyl substituted silica host, and the excellent absorption and emission properties of 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin-Zn(II) tetrachloride as a water soluble guest molecule. In order to optimize the synthesis procedure and the performance of the immobilized porphyrin, silica precursor mixtures of different compositions were used. To achieve the requirements regarding the hydrophobicity and the porous structure of the gels for the successful incorporation of porphyrin, the content of vinyltriacetoxysilane was systematically changed and thoroughly investigated. Substitution of the silica gels with organic groups is a viable way to provide new properties to the support. An exhaustive characterization of the synthesized silica samples was realised by complementary physicochemical methods, such as infrared spectroscopy (FT-IR), absorption spectroscopy (UV-Vis) and photoluminescence, nuclear magnetic resonance spectroscopy (29Si-MAS-NMR) transmission and scanning electron microscopy (TEM and SEM), nitrogen absorption (BET), contact angle (CA), small angle X ray and neutron scattering (SAXS and SANS). All hybrids showed an increase in emission intensity in the wide region from 575 to 725 nm (Q bands) in comparison with bare porphyrin. By simply tuning the vinyltriacetoxysilane content, the hydrophilic/hydrophobic profile of the hybrid materials was changed, while maintaining a high surface area. Good control of hydrophobicity is important to enhance properties such as dispersion, stability behaviour, and resistance to water, in order to achieve highly dispersible systems in water for biomedical applications.

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Amyloglucosidase (AMG) from Aspergillus niger was encapsulated in various matrices derived from tetraethoxysilane, methyltriethoxysilane, phenyltriethoxysilane and vinyltriacetoxysilane by different methods of immobilization. The immobilized enzyme was prepared by entrapment in two steps, in one-step and entrapment/deposition, respectively. The activities of the immobilized AMG were assayed and compared with that of the native enzyme. The effects of the organosilaneprecursors and their molar ratios, the immobilization method, the inorganic support (white ceramic, red ceramic, purolite, alumina, TiO2, celite, zeolite) and enzyme loading upon the immobilized enzyme activity were tested. The efficiency of the sol-gel biocomposites can be improved through combination of the fundamental immobilization techniques and selection of the precursors

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