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Perpignan, France

The University of Perpignan is a French university, located in Perpignan. Wikipedia.

Aptamer-based bioreceptors that can easily adopt their surroundings have captured the attention of scientists from a wide spectrum of domains in designing highly sensitive, selective and structure switchable sensing assays. Through elaborate design and chemical functionalization, numerous aptamer-based assays have been developed that can switch their conformation upon incubation with target analyte, resulting in an enhanced output signal. To further lower the detection limits to picomolar levels, nanomaterials have attracted great interest in the design of aptamer-based sensing platforms. Associated to their unique properties, nanomaterials offer great promise for numerous aptasensing applications. This review will discuss current research activities in the aptasensing with typical example of detection of ochratoxin A (OTA). OTA, a secondary fungal metabolite, contaminates a variety of food commodities, and has several toxicological effects such as nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic activities. The review will introduce advances made in the methods of integrating nanomaterials in aptasensing, and will discuss current conformational switchable design strategies in aptasensor fabrication methodologies. Source

Grain-size distributions in lower beach and nearshore sands of a segment of the coast of the Golfe du Lion (France) were analyzed by a parametric method and by modal analysis. The results have been considered both in a spatial framework delineating geographically distinct sedimentary compartments and cells, and in a morphodynamic framework separating the dynamic components of the shoreline (berm, collision zone, inner bar, outer bar, lower shoreface). Modal statistics indicate that a mixture of three dominant components (end members) contributes to the grain-size distribution (GSD) of the sediments: fine sand (Sedimentary Type I: Modal value: 0.195 mm; σI (φ): 0.35), medium and coarse sand (ST II: Modal value: 0.680 mm; σI (φ): 0.8) and very coarse sand and gravel (ST III I: Modal value: 2.3 mm; σI (φ): 1.5). Quasi log-normal one-component GSDs form a minority group and mixtures produce various apparently unimodal sands and bimodal sediments. A large variation of grain-size indices results from mixing. A simulation of mixing of log-normal populations close to the end members shows the great sensitivity of parameters (sorting, skewness, and kurtosis) to small changes in the compositional formula of the mixture. The procedure followed supplies a good preliminary tool enabling rapid identification and localization of the main sand sources on a regional scale. These components derive from potential sources available in the region, well known from previous studies. ST I originates from the River Rhône and provides the textural base for most of the sediments. ST II and III form a local component originating either from fluvial input (Aude, Orb, and Hérault rivers) or from the nearshore reworking of ancient Quaternary sediments and late Holocene beachrocks. Each ST takes on local aspects in relation to the morphological environment, but the regional scale of the study was too large to precisely reflect the local morphodynamic regime. A significant change in the ST I sorting of bar sands is, however, observed, probably due to the net offshore migration reported for the bar system. Copyright © 2011, SEPM (Society for Sedimentary Geology). Source

Sassolas A.,CNRS Institute of Molecular and Supramolecular Chemistry and Biochemistry | Sassolas A.,University of Perpignan | Blum L.J.,CNRS Institute of Molecular and Supramolecular Chemistry and Biochemistry | Leca-Bouvier B.D.,CNRS Institute of Molecular and Supramolecular Chemistry and Biochemistry
Biotechnology Advances | Year: 2012

Immobilization of enzymes on the transducer surface is a necessary and critical step in the design of biosensors. An overview of the different immobilization techniques reported in the literature is given, dealing with classical adsorption, covalent bonds, entrapment, cross-linking or affinity as well as combination of them and focusing on new original methods as well as the recent introduction of promising nanomaterials such as conducting polymer nanowires, carbon nanotubes or nanoparticles. As indicated in this review, various immobilization methods have been used to develop optical, electrochemical or gravimetric enzymatic biosensors. The choice of the immobilization method is shown to represent an important parameter that affects biosensor performances, mainly in terms of sensitivity, selectivity and stability, by influencing enzyme orientation, loading, mobility, stability, structure and biological activity. © 2011 Elsevier Inc. Source

Santi C.,University of Perpignan | Bogusz D.,IRD Montpellier | Franche C.,IRD Montpellier
Annals of Botany | Year: 2013

BackgroundNitrogen is an essential nutrient in plant growth. The ability of a plant to supply all or part of its requirements from biological nitrogen fixation (BNF) thanks to interactions with endosymbiotic, associative and endophytic symbionts, confers a great competitive advantage over non-nitrogen-fixing plants.ScopeBecause BNF in legumes is well documented, this review focuses on BNF in non-legume plants. Despite the phylogenic and ecological diversity among diazotrophic bacteria and their hosts, tightly regulated communication is always necessary between the microorganisms and the host plant to achieve a successful interaction. Ongoing research efforts to improve knowledge of the molecular mechanisms underlying these original relationships and some common strategies leading to a successful relationship between the nitrogen-fixing microorganisms and their hosts are presented.ConclusionsUnderstanding the molecular mechanism of BNF outside the legume-rhizobium symbiosis could have important agronomic implications and enable the use of N-fertilizers to be reduced or even avoided. Indeed, in the short term, improved understanding could lead to more sustainable exploitation of the biodiversity of nitrogen-fixing organisms and, in the longer term, to the transfer of endosymbiotic nitrogen-fixation capacities to major non-legume crops. © 2013 The Author. Source

Paniel N.,University of Perpignan
Sensors (Basel, Switzerland) | Year: 2010

We have developed an electrochemical immunosensor for the detection of ultratrace amounts of aflatoxin M(1) (AFM(1)) in food products. The sensor was based on a competitive immunoassay using horseradish peroxidase (HRP) as a tag. Magnetic nanoparticles coated with antibody (anti-AFM(1)) were used to separate the bound and unbound fractions. The samples containing AFM(1) were incubated with a fixed amount of antibody and tracer [AFM(1) linked to HRP (conjugate)] until the system reached equilibrium. Competition occurs between the antigen (AFM(1)) and the conjugate for the antibody. Then, the mixture was deposited on the surface of screen-printed carbon electrodes, and the mediator [5-methylphenazinium methyl sulphate (MPMS)] was added. The enzymatic response was measured amperometrically. A standard range (0, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.3, 0.4 and 0.5 ppb) of AFM(1)-contaminated milk from the ELISA kit was used to obtain a standard curve for AFM(1). To test the detection sensitivity of our sensor, samples of commercial milk were supplemented at 0.01, 0.025, 0.05 or 0.1 ppb with AFM(1). Our immunosensor has a low detection limit (0.01 ppb), which is under the recommended level of AFM(1) [0.05 μg L-1 (ppb)], and has good reproducibility. Source

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