BLANC - Blanc

Nouveau microsystème dédié à l'immunodiagnostic en phase liquide à base de nanoparticules magnétiques fonctionnalisées – SOLUDIAG

Submission summary

Micro total analytical systems (micro-TAS) meet many needs in separation sciences, among them in diagnosis. These miniaturized systems offer the possibility to provide high throughput analysis, with a low sample and reagent consumption (such as enzymes, receptors, antibodies), allowing the setup of specific interactions while maintaining relatively low analysis costs. Nevertheless, up to now, no miniaturized analytical system was built up for an immunodiagnostics allowing both a quantitative analysis of the patient antibodies, and the measurement of the antibody-antigen interactions (through their binding constant). Furthermore, most of the current systems use antigens which are immobilized on a large-dimension solid phase (as ELISA on plates), which does not allow to mimic the reactions in solution, occurring in vivo. In this context, our proposal consists in developing an original, miniaturized and fully automated immunodiagnostics, which aims to mimic in vivo interactions, by using magnetic nanoparticles, functionalized with one of the partners of the immunological reaction, and a separation system such as lab on chips. Detection being performed thanks to a second labeled antibody, separation and quantitation of the free and bound forms of this antibody can be performed by applying electric and/or magnetic fields and/or pressure. Thus, in complement to the diagnosis itself, this immunodiagnostics will allow to access to affinity constant of antibodies to their specific antigens (avidity constant or mean affinity of the naturally human polyclonal antibodies for a purified antigen), which is a crucial information in the diagnosis domain, so as to estimate the gravity of the disease. The innovative character of this project essentially lies in the integrated liquid phase format of the immunodiagnostics and the complementary separation modes, allowing the quantification of immunological interaction. This project proposes the integration in a single format of the antibody/antigen interaction, free and bound forms separation, detection and quantification steps. Furthermore, contrary to existing systems already employing nanoparticles (usually latex, of 200 nm to a few micrometers diameter), the functionalized particles of this project are magnetic nanoparticles forming a colloidal suspension in an aqueous medium of composition close to physiological ones (high ionic strength). This provides two main advantages: (1) antibody/antigen recognition in this colloidal suspension is more relevant to mimic in vivo interactions occurring in blood, than existing immunodiagnostics, for which one partner of the interaction is bound to a solid phase ; (2) the confinement under a magnetic field of magnetic nanoparticles of adequate diameter (15 to 50 nm) can be exploited for the separation of free and bound forms of labeled antibodies. By integrating all the steps of the immunodiagnostics on a chip (immunological interaction, separation, detection), the small reaction volumes employed will allow to reduce diffusion distances and thus reaction and global analysis times. The case of an immunodiagnostics dedicated to allergy will be studied. Indeed, the frequency of allergies has doubled over the last fifteen years and 15 to 30% of the population of developed countries is affected, according to the employed diagnosis. Among potential reasons for such an increase, air pollution effects on aero-allergens stimulation and emergence of new foods can be outlined. About 400 allergen sources can be tested in vitro. In our case, the immunoassay specificity will be provided by the use of specific available antibodies and sensitivity should reach 0.1 ng of immunoglobulin E per milliliter of allergic patient serum, thanks to electrokinetic preconcentration studies. In conclusion, this project participates to the development of a new analytical methodology for diagnosis. The main objectives of this project lie in (1) the liquid phase format of this immunodiagnostics which allows to mimic in vivo interactions occurring in blood, (2) the use of alternative separation modes (under magnetic, electric fields, pressure) to access to both antibody titration and antibody/antigen interaction characterization and (3) the development of a microdevice dedicated to integrate all the immunodiagnostics steps. This analytical tool, tested in the case of allergy, can then be extended to other domains requiring immunodiagnostics, such as health, foodstuff and environment.

Project coordination

Marie Claire HENNION (Organisme de recherche)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR EST
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR PARIS A

Help of the ANR 500,000 euros
Beginning and duration of the scientific project: - 36 Months

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