Mise au point de biocapteurs pour la détection spécifique in vivo de divers messgers biologiques et substances (glutamate, acétylcholine, D-Serine, glucose, lactacte, etc.)

Les recherches sont focalisées sur l'élaboration de dispositifs micro-enzymatiques permettant la détection in vivo de divers messagers. Le document comprend : une introduction générale ; une revue bibliographique ; un premier chapître décrivant les améliorations apportées à la fabrication du transducteur de base possédant une partie active en fibre de carbone ; un deuxième chapître consacré à l'élaboration des microbiocapteurs permettant la détection de la choline et de l'acétylcholine ; un troisième chapître examinant la possibilité de fabriquer des microbiocapteurs ampérométriques en combinant l'électrométalisation de la fibre de carbone et l'électropolymérisation d'un film de phenylenediamine pour une fixation covalente des enzymes ; un quatrième chapître dévoué à la préparation du microbiocapteur pour la D-serine ; une conclusion générale sur les améliorations apportées à la technologie des microbiocapteursLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Ultramicrobiosensor for the selective detection of glutamate

Carbon fiber microelectrodes, able to detect catecholamine release from single cells, have significantly contributed to our present understanding of the mechanism of secretory neurotransmission. In spite of their obvious advantages, there are only a few amperometric sensors (characterized by appropriate size, sensitivity, and selectivity) able to measure the release of other (not easily oxidizable) neurotransmitters at cellular level. The present work describes the fabrication and characterization of an ultramicrobiosensor for the selective detection of glutamate. ne developed sensor has a size of 2.5 - 15 mu m in diameter, a sensitivity of 0.62 mA mM(-1) cm(-2), and a detection limit of 5 mu M. The excellent selectivity of the sensor (achieved using electrodeposition of Ru, Rh, and poly(m-phenylenediamine)) makes it a promising candidate for monitoring glutamate release at single cell level

Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars

The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four- to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme adhesion on stainless steel electrodes. The developed GOx-SME-GA biosensors were characterized by good reproducibility of biosensor preparation (relative standard deviation (RSD)—18 %), improved signal reproducibility (RSD of glucose determination was 7 %), and good storage stability (29 % loss of activity after 18-day storage). A series of fruit juices and nectars was analyzed using GOx-SME-GA biosensor for determination of glucose concentration. The obtained results showed good correlation with the data of high-performance liquid chromatography (HPLC) (R = 0.99)

Nanobiosensors based on individual olfactory receptors

International audienceThe animal olfactory system represents the gold standard of biosensors, due to its ability to identify and discriminate thousands of odorant compounds with very low thresholds. Using olfactory receptors (ORs) as sensing elements instead of chemical sensors, biosensors would benefit the naturally optimized molecular recognition of odorants to develop a new generation of bioelectronic noses. The purpose of SPOT-NOSED European project was the development of nanobiosensors based on single ORs anchored between nanoelectrodes, to mimic the performances of natural olfactory system. Nanobiosensors arrays could then increase odorant sensitivity or widen the odorant detection spectrum. ORs were expressed in yeasts plasmic membrane, and their functionality tested in whole yeasts. Then, nanosomes bearing the ORs were prepared from S. cerevisiae, and Surface Plasmon Resonance was performed on nanosomes for quantitative evaluation of OR response to odorant stimulation. ORs retain full activity and discrimination power in immobilized nanosomes, thus allowing their use in the fabrication of the nanobiosensors. Nanoelectrodes were fabricated using conventional photolithography and focused ion beam milling, with sizes in adequation with the nanosomes. ORs borne by nanosomes were specifically immobilized onto conducting substrates via mixed Self Assembled Monolayers, neutravidin and specific antibody to the ORs. The process was optimized by microcontact printing, and the anchored nanovesicles visualized by Atomic Force Microscopy. A transimpedance preamplifier suited for low-noise wide-bandwidth measurements was designed to be directly connected to the nanoelectrodes. Electrochemical Impedancemetric Spectroscopy detected significant changes upon electrodes functionalization, grafting of ORs carried by nanosomes, and ORs conformational change induced by odorant binding