Biosensor para el diagnóstico y seguimiento de inmunodeficiencias

La infección por el Virus de Inmunodeficiencia Humano (VIH) y el Síndrome de Inmunodeficiencia adquirida (SIDA) afecta a millones de personas en todo el mundo, y constituye una amenaza a la salud y la vida de muchas otras más, sobre todo en países en vías de desarrollo. Existe un gran interés en el desarrollo de nuevas metodologías analíticas para el diagnóstico de dicha enfermedad de forma rápida, económica y fuera del ámbito del laboratorio por personal no especializado. Los biosensores son dispositivos ideales para cubrir esta demanda analítica facilitando la toma de decisiones y permitiendo un uso racional de técnicas analíticas confirmatorias más costosas. Se plantea el diseño de una estrategia magneto-ELISA con detección óptica así como un dispositivo magneto biosensor electroquímico para el diagnóstico de SIDA a través del recuento de células marcadoras de la enfermedad presentes en la sangre. Ambas estrategias se basan en la captura inmunomagnética de linfocitos T CD4+ con partículas magnéticas modificadas con anticuerpos monoclonales específicos (anti-CD3). La detección de las células capturadas se realiza con un anticuerpo primario anti-CD4 marcado con biotina (antiCD4-biotina) y con un conjugado de estreptavidina y de la enzima HRP (peroxidasa de rábano picante). La unión de esta enzima al anticuerpo primario se realiza a través del complejo biotina/estreptavidina. Se proponen dos tipos de sistemas de detección: óptico y electroquímico. Esto se logra mediante la elección adecuada del sustrato para cada sistema planteado. El dispositivo biosensor basados en un transductor electroquímico renovable y magnético acoplado a partículas magnéticas específicas para las células marcadoras de la enfermedad, consigue la simplificación metodológica y facilita la transferencia de la tecnología hacia la fabricación de un biokit diagnóstico en el ámbito clínico. La potencial aplicación de los dispositivos analíticos propuestos en este trabajo tienen un interés social elevado por su idoneidad para realizar análisis, rápidos, económicos y en el ámbito de la propia consulta médica.

Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode

Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of Fe2+ (AO-BDD-Fe2+) and under UVA irradiation (AO-BDD-Fe2+-UVA), along with electro-Fenton (EF-BDD), was tested. The oxidation of both acids and their iron complexes on BDD was clarified by cyclic voltammetry. AO-BDD allowed the overall mineralization of oxalic acid, but oxamic acid was removed much more slowly. Each acid underwent a similar decay in AO-BDD-Fe2+ and EFBDD, as expected if its iron complexes were not attacked by hydroxyl radicals in the bulk. The faster and total mineralization of both acids was achieved in AO-BDD-Fe2+-UVA due to the high photoactivity of their Fe(III) complexes that were continuously regenerated by oxidation of their Fe(II) complexes. Oxamic acid always released a larger proportion of NH4 + than NO3- ion, as well as volatile NOx species. Both acids were independently oxidized at the anode in AO-BDD, but in AO-BDD-Fe2+-UVA oxamic acid was more slowlydegraded as its content decreased, without significant effect on oxalic acid decay. The increase in current density enhanced the oxidation power of the latter method, with loss of efficiency. High Fe2+ contents inhibited the oxidation of Fe(II) complexes by the competitive oxidation of Fe2+ to Fe3+. Low current densities and Fe2+ contents are preferable to remove more efficiently these acids by the most potent AO-BDD-Fe2+-UVA method.

Electrochemical synthesis of mesoporous CoPt nanowires for methanol oxidation

A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W) microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane"s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter) dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

Electrochemical synthesis of mesoporous CoPt nanowires for methanol oxidation

A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W) microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane"s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter) dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.