Electrochemical determination of Saccharomyces cerevisiae sp using glassy carbon electrodes modified with oxidized multi-walled carbon nanotubes dispersed in water -Nafion®.

The electrochemical behavior of Saccharomyces cerevisiae sp was studied using a glassy carbon electrode (GCE) modified with Nafion-dispersed oxidized multi-walled carbon nanotubes (OMWCNT). The morphology was studied using scanning electron microscopy (SEM), showing that the yeast sticks to the carbon nanotube surface instead of the glassy carbon surface. The redox couple Fe(CN)6 4-/Fe(CN)6 3- was used to determine the electroactive area and the heterogeneous transfer constant, which increased 80.5% and 108% respectively by the presence of nanotubes. The studies of the pH effect showed that the anodic potential decreases at alkaline pH and that the highest current intensity occurs at a pH value of 7.00. Studies of the scan rate effect have shown that yeast oxidation is an irreversible mixed control process in which two electrons participate. The relationship between yeast concentration and the anodic current density was studied using different electrochemical techniques obtaining the best analytical parameters through chronoamperometry. The linear range was between 3.36 and 6.52 g L-1, the limit of detection (LOD) and the limit of quantification (LOQ) were 0.98 g L-1 and 3.36 g L-1 respectively, and the sensibility obtained was 0.086 µA L g-1 mm-2. These results show that the multi-walled carbon nanotubes in water and Nafion® allow obtaining an anodic signal corresponding to the yeast, which facilitates its quantification through electrochemical methodologies, favoring the reduction of analysis times and costs compared with other techniques.

Antioxidant capacity of mango fruit (Mangifera indica). An electrochemical study as an approach to the spectrophotometric methods.

The antioxidant capacity in mango (pulp, peel, and seed) was measured using spectrophotometric and electrochemical methods in order to make traditional methods comparable with electrochemical ones, using reference standards Gallic Acid and Trolox. ABTS, DPPH, Total polyphenols, and electrochemical index were evaluated. In order to present the electrochemical results in a more comparable way, the voltammetric charge (using Differential pulse voltammetry) was used. Spectrophotometric methods allowed to determine the difference in contents of metabolites with antioxidant capacity, except in peel and seed, while the electrochemical method separated the three extracts and is not affected by interferences. Spectrophotometric methods present a good correlation with electrochemical methods, using the same reference standards, therefore, a better comparison between methods is possible.

Electrochemical methods as a tool for determining the antioxidant capacity of food and beverages: A review.

The growing interest in functional foods had led to the use of analytical techniques to quantify some properties, among which is the antioxidant capacity (AC). In order to identify and quantify this capacity, some techniques are used, based on synthetic radicals capture; and they are monitored by UV-vis spectrophotometry. Electrochemical techniques are emerging as alternatives, given some of the disadvantages faced by spectrophotometric methods such as the use of expensive reagent not environmentally friendly, undefined reaction time, long sample pretreatment, and low precision and sensitivity. This review focuses on the four most commonly used electrochemical techniques (cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and chronoamperometry). Some of the applications to determine AC in foods and beverages are presented, as well as the correlation between both spectrophotometric and electrochemical techniques that have been reported.

Algunos aspectos hereditarios y ambientales en casos de fibrosis quística en la ciudad de Cartagena (Colombia) / Some hereditary and environmental aspects in cystic fibrosis cases from Cartagena (Colombia)

Objetivos: Describir las características de la transmisión hereditaria de la enfermedad en familias de la ciudad de Cartagena (Colombia) y analizar algunos factores medioambientales del núcleo familiar de los pacientes que pudieran influir en la evolución y/o severidad de la patología. Materiales y métodos: Se estudiaron 22 pacientes, distribuidos en 16 familias, del “Programa de atención integral a pacientes con fibrosis quística” de la Universidad de Cartagena. Se recopiló información acerca de las condiciones de vivienda del grupo familiar y se evaluaron aspectos fenotípicos hereditarios, y se construyeron genealogías para esta enfermedad. Resultados: El análisis de pedigríes reveló lo siguiente: en ocho familias (67%), los individuos afectados presentan rasgos caucásicos; en cinco familias (42%) se reconoce existencia de ancestros europeos; en dos familias (17%) existe consaguinidad. En relación con el aspecto ambiental, se encontró que 33% de las familias estudiadas habitan viviendas en malas condiciones. Conclusiones: Entre las familias de los pacientes con fibrosis quística de la ciudad de Cartagena detectados en este estudio se verifica la transmisión hereditaria autosómica recesiva, se confirma el mestizaje de nuestras poblaciones. La reincidencia de enfermos y la consanguinidad en varias familias denota la falta de asesoramiento genético y el desconocimiento de la evolución de la enfermedad por su grupo familiar. Estos resultados pueden ser el punto de partida de estudios más amplios que sirvan de fundamento para la implementación de políticas tendientes a reducir la frecuencia y severidad de la enfermedad a nivel local y nacional...

Objective: Describe characteristics of hereditary transmissión diseases in families in Cartagena (Colombia) also analysing some environmental factors that might affect the evolution and or severity of this diseases. Materials and methods: Twenty-two patients distributed into 16 families attending to the Universidad de Cartagena's Integral attention program for CF families were studied. Information about family house conditions was collected; some inherited phenotype aspects were evaluated, and genealogy trees were constructed for this disease. Results: Our pedigree analysis reveals the next issues: first, caucasian traits in affected individuals are present in eight families (67%); second, european ancestors are reported in five families (42%); third, inbreeding was detected in two families (17%). Thirty three percent of these families are living in bad housing conditions. Conclusions: Between relatives of cystic fibrosis patients from Cartagena it is verified the autosomal recessive hereditary transmission, it is confirmed the crossbreeding inside our population. The relapse of patients and the blood relationship in several families reveal the lack of genetic counseling and inadequate knowledge about the evolution of the disease between the members of the families. These results could be the starting point of larger studies that serve as a foundation of politics tending to reduce the frequency and severity of the disease in a local and national level...