Cromatografia de afinidade por íons metálicos imobilizados (IMAC) de biomoléculas: aspectos fundamentais e aplicações tecnológicas

Immobilized Metal Ion Affinity Cromatography - IMAC - is a group-specific based adsorption applied to the purification and structure-function studies of proteins and nucleic acids. The adsorption is based on coordination between a metal ion chelated on the surface of a solid matrix and electron donor groups at the surface of the biomolecule. IMAC is a highly selective, low cost, and easily scaled-up technique being used in research and commercial operations. A separation process can be designed for a specific molecule by just selecting an appropriate metal ion, chelating agent, and operational conditions such as pH, ionic strength, and buffer type.

Adsorción física sobre sólidos: aspectos termodinámicos

A thermodynamic formalism based on the Gibbs Dividing Surface (GDS) for the description of a solid-fluid interface is presented, so that the adsorption layer is understand as a phase and the adsorption process as the transference of components between a 3-dimensional phase and a 2-dimensional one. Using a state equation derived from the Henry's Law, we shall show how the Langmuir isotherm is deduced from de Gibbs isotherm. The GDS is useful also for understanding the release of heat by a system as the adsorption occurs.

Nanotecnologia: aspectos gerais e potencial de aplicação em catálise

In recent years nanomaterials, such as metallic nanoparticles, nanowires, nanotapes, nanotubes and nanocomposites, have attracted increasing interest for several technological applications. In catalysis, the great potential of nanomaterials is related to the high catalytic activity exhibited by these materials as a function of the high surface/volume ratio when the particles acquire diameter below 5 nm. In this work, a review about concepts and background of nanoscience and nanotechnology is presented with emphasis in catalysis. Special attention is given to gold nanoparticles and carbon nanotubes, focusing the properties and characteristics of these materials in several catalytic reactions.

Aspectos coloidais da adesão de micro-organismos

The ability of bacteria to attach to surface and develop into a biofilm has been of considerable interest to food industry. Electrostatic, Lifhistz-van der Waals and Lewis acid-base forces are usually considered responsible for the interactions at the interface of the bacterial adhesion. The study of microbial adhesion thermodynamic is important because it represents the reflection of microbial surface and food processing surface physicochemical characteristics. This review examines the most important aspects involved in bacterial attachment to a surface with emphases in thermodynamics of adhesion process.

Aspectos históricos dos cursos de licenciatura em química no Brasil nas décadas de 1930 a 1980

This article describes some historical moments in the establishment and development of chemistry teacher's training courses since 1930, with the creation of universities in Brazil, until 1980. Correlations between educational and political questions that influenced the directions taken for the formation of chemistry teachers in Brazil are discussed. From a review of the bibliographical sources available, we revisited stances of discussions on public policies related to science teacher's formation in general and in chemistry, particularly, in order to provoke a reflection on what challenges and prospects exist in the current scenario of undergraduate chemistry education in Brazilian universities and colleges.

Aspectos químicos e farmacológicos de Byrsonima (Malpighiaceae)

Species of the Byrsonima genus are widely distributed around the neotropical zone, being frequently used in folk medicine to treat gastrointestinal, respiratory and skin diseases. This article briefly reviews the ethnopharmacology, pharmacology and phytochemistry of the Byrsonima genus. Eighty three compounds isolated from different species are reported, most of them being flavonoids or triperpenes. The pharmacological studies carried out with the extracts from these plants emphasize on the antimicrobial activity, however other activities have also been investigated leading to promising results. The data presented in this work strongly supports the view that plants of Byrsonima genus have potential therapeutic action.

A reação "click" na síntese de 1,2,3-triazóis: aspectos químicos e aplicações

The Copper-catalyzed azide-alkyne cycloaddition (CuAAC), often referred to as "click" reaction, has become a very popular reaction in the last years. It affords exclusively 1,4-disubstituted 1,2,3-triazoles and has been widely used to connect readily accessible building blocks containing various functional groups. The great success of this reaction is based on the fact that it is general, virtually quantitative and very robuste. The scope of this copper-catalyzed synthesis is extraordinary and the reaction has found numerous applications in many research fields, including biological chemistry and materials science. In this review, the main chemical aspects and applications of the "click" reaction in the synthesis of 1,2,3-triazoles are presented.

Aspectos históricos da visita de Marie Sklodowska Curie a Belo Horizonte

In the year 2011 it is celebrated the Marie Sklodowska Curie Nobel Prize centenary and the International Year of Chemistry. However, it is not generally known that Marie Sklodowska Curie, one of the greatest scientists of all time, visited Belo Horizonte, state of Minas Gerais, Brazil. She arrived by train at Belo Horizonte city on 16 August 1926, coming from Rio de Janeiro and accompanied by her daughter Irène Joliot-Curie. The scientists visited the Institute of Radium of Belo Horizonte. The approach in this work emphasizes the presence of Marie Sklodowska Curie in Belo Horizonte, exploring the admiration and respect that people had for her.

Designer drugs: aspectos analíticos e biológicos

In the recent years, analytical toxicologists have been facing difficulties in detecting designer drugs due to the chemical modifications on the existing structures and the speed in which they are released into the market, requiring the development and improvement of specific and appropriate analytical methods. This work is a review of the literature which summarizes the characteristics of the drugs and the analytical validated methods using conventional and unconventional matrices currently used for correct identification and quantification of the following classes of emerging drugs of abuse: derivatives of opiates, amphetamines, tryptamines, piperazines and cannabinoids.

Aspectos analíticos da resposta do detector de ionização em chama para ésteres de ácidos graxos em biodiesel e alimentos

The analysis of fatty acid (FA) esters by gas chromatography and flame ionization detector (FID) normally uses the normalization method. However, if one FA is wrongly estimated, the results could be greatly affected. In this study, methodologies using internal standards and correction factors for the FID response are described. The results show that by using theoretical correction factors associated to the internal standardization, the quantitative analyses of the FAs are expressed in mass, increasing the accuracy and facilitating the interpretation and comparison of the results for foods and biodiesels.

Aspectos estruturais de algumas neolignanas hidrobenzofurânicas

The neolignans are defined as dimers of allylphenol and propenylphenol between itself or crossed, whose bond does not occur by the 8-8' carbons like lignans. This review centered on stereochemical aspects of the hydrobenzofuran type, a widespread skeleton among neolignans. The chemical structures established based on spectrometric data are registered in the literature. The absolute configurations reported previously were determined by chiroptical techniques. Some chemical transformations with neolignans, performed in previous studies, afforded products which are accumulated in other vegetal species and contributed to assign the unknown stereochemistry of these natural compounds. Possible biosynthetic pathways are also proposed.

Ocorrência de biflavonoides em Clusiaceae: aspectos químicos e farmacológicos

This work describes the biflavonoids found in species of Clusiaceae, particularly the genera Garcinia and Calophyllum, emphasizing the importance of these metabolites as chemical markers of this family, their contribution to the pharmacological potential of these species, besides the promising potential of these compounds in the search for new drugs.

Aspectos analíticos e regulatórios na determinação de resíduos de macrolídeos em alimentos de origem animal por cromatografia líquida associada à espectrometria de massas

This is an overview of LC-MS techniques applied for macrolide determination in food, including sample preparation and method validation, as well as the policies adopted by international agencies regarding their presence in food. Techniques for the analysis of macrolides in food normally include solid phase or liquid-liquid extraction followed by HPLC. UHPLC presents advantages in running time, detectability and solvent consumption. Triple-quadrupoles are the most common analyzers in instruments used for the determination of contaminants in food, but time-of-flight and ion-trap spectrometers have been successfully applied for analyses focusing on the investigation of structural formula or the presence of degradation products.

Nanotecnologia em medicina: aspectos fundamentais e principais preocupações

The recent advances in the development of nanomaterials have opened new and exciting opportunities for their applications in medicine. These applications include molecular imaging, drug-delivery, and photothermal therapy. Despite the progress in medicinal applications of nanomaterials, several key problems remain unaddressed. Recent advances in this area include the enhancement of sensitivity in early diagnosis and therapy, in addition to investigations into the possible toxicity of nanomaterials. However, since little is known about the toxicity of nanomaterials, the regulation of these materials is a slow and complex process. This paper reviews the current scenario in the applications of nanomaterials in medicine as well as the main concerns and regulatory questions.

Produção de hidrogênio via fermentação anaeróbia - aspectos gerais e possibilidade de utilização de resíduos agroindustriais brasileiros

Biological production of hydrogen through anaerobic fermentation has received increasing attention and offers a great potential as an alternative process for clean fuel production in the future. Considering biological systems for H2 production, anaerobic fermentation stands out, primarily due to its higher production of H2 compared with other biological processes. In addition the possibility of using different agro-industrial wastes as substrates opens up infinite possibilities. The development and implementation of sustainable processes for converting renewable materials into different value-added products is essential for the full exploitation of Brazilian agro-industrial wastes.