Sensor impedimétrico para la detección de bacterias patogénicas mediante péptidos antimicrobianos

Áccesit Congreso SIBB 2015La peri-implantitis, una inflamación causada por la formación del biofilm, es una de las causas más importantes de la fallida de los implantes en odontología. Por esto, la detección de bacterias patogénicas al inicio del proceso de formación de biofilms, representa una estrategia muy potente para la prevención de las infecciones en los implantes. Entre los diferentes métodos para la detección de bacterias patogénicas, los biosensores electroquímicos, especialmente los sistemas basados en impedancia (EIS), presentan una serie de ventajas como la miniaturización, la mejora en sensibilidad y el bajo coste. En este sentido, los péptidos antimicrobianos (AMPs), conocidos como componentes del sistema inmune y con actividad hacia las bacterias, pueden ser usados para desarrollar elementos de bioreconocimiento altamente efectivos. Por lo tanto, el objetivo de este estudio es la combinación del uso de EIS y la habilidad de los AMPs para obtener biosensores con alta sensibilidad, especificidad y límites de detección muy bajos para la detección de bacterias patogénicas.Peer ReviewedAward-winnin

Copper and bezafibrate cooperate to rescue cytochrome c oxidase deficiency in cells of patients with sco2 mutations.

BACKGROUND: Mutations in SCO2 cause cytochrome c oxidase deficiency (COX) and a fatal infantile cardioencephalomyopathy. SCO2 encodes a protein involved in COX copper metabolism; supplementation with copper salts rescues the defect in patients' cells. Bezafibrate (BZF), an approved hypolipidemic agent, ameliorates the COX deficiency in mice with mutations in COX10, another COX-assembly gene. METHODS: We have investigated the effect of BZF and copper in cells with SCO2 mutations using spectrophotometric methods to analyse respiratory chain activities and a luciferase assay to measure ATP production.. RESULTS: Individual mitochondrial enzymes displayed different responses to BZF. COX activity increased by about 40% above basal levels (both in controls and patients), with SCO2 cells reaching 75-80% COX activity compared to untreated controls. The increase in COX was paralleled by an increase in ATP production. The effect was dose-dependent: it was negligible with 100 uM BZF, and peaked at 400 uM BZF. Higher BZF concentrations were associated with a relative decline of COX activity, indicating that the therapeutic range of this drug is very narrow. Combined treatment with 100 uM CuCl2 and 200 uM BZF (which are only marginally effective when administered individually) achieved complete rescue of COX activity in SCO2 cells. CONCLUSIONS: These data are crucial to design therapeutic trials for this otherwise fatal disorder. The additive effect of copper and BZF will allow to employ lower doses of each drug and to reduce their potential toxic effects. The exact mechanism of action of BZF remains to be determined

3D impedimetric sensors as a tool for monitoring bacterial response to antibiotics

The presence of antimicrobial contaminants like antibiotics in the environment is a major concern because they promote the emergence and the spread of multidrug resistant bacteria. Since the conventional systems for the determination of bacterial susceptibility to antibiotics rely on culturing methods that require long processing times, the implementation of novel strategies is highly required for fast and point-of-care applications. Here the development and characterization of a novel label-free biosensing platform based on a microbial biosensor approach to perform antibiotic detection bioassays in diluted solution is presented. The microbial biosensor is based on a three-dimensional interdigitated electrode array (3D-IDEA) impedimetric transducer with immobilized E. coli bacteria. In 3D-IDEA to increase the sensitivity to superficial impedance changes the electrode digits are separated by insulating barriers. A novel strategy is employed to selectively immobilize bacteria in the spaces over the electrode digits between the barriers, referred to here as trenches, in order to concentrate bacteria, improve the reproducibility of the E. coli immobilization and increase the sensitivity for monitoring bacterial response. For effective attachment of bacteria within the trenches an initial anchoring layer of a highly charged polycation, polyethyleneimine (PEI), was used. To facilitate immobilization of bacteria within the trenches and prevent their deposition on top of the barriers an important novelty is the use of poly(N-isopropylmethacrylamide) p(NIPMAM) microgels working as antifouling agents, deposited on top of the barriers by microcontact printing. The reported microbial biosensor approach allows the bacterial response to ampicillin, a bacteriolytic antibiotic, to be registered by means of impedance variations in a rapid and label-free operation that enables new possibilities in bioassays for toxicity testing