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Biofonctionnalisation, caractérisation et mise en oeuvre de particules magnétiques sur biocapteurs : application au génotypage plaquettaire

Marie Trévisan 1
1 INL - C&N - INL - Chimie et Nanobiotechnologies
INL - Institut des Nanotechnologies de Lyon
Abstract : Manipulation and utilization of magnetic nano/microparticles have raised some interest in the field of biology, biodetection and diagnostics during the last few years. This work explores the uses of magnetic properties of particles in two different axes.In a first part, we used magnetic particles in a bio-barcode assay for the capture and biological target concentration steps. The detection was done using a new evanescent wave biosensor. The aim was to perform a platelet genotyping without polymerase chain reaction (PCR) with the collaboration of the French national blood service (EFS). We used the biallelic system HPA-1 as proof-of-concept, using synthetic oligonucleotides as target in order to validate our protocols. The assay allows to specifically detect single nucleotide polymorphism for HPA-1 gene with a detection of 2 fmol/l of label-free target synthetic oligonucleotides. Our bio-barcode assay allows to lower the inferior limit of detection of our biosensor by a factor of 125 000. We can detect 6.105 copies of synthetic target without using a PCR amplification step. The next step will be to adapt our assay to analyze real biological samples.In a second part, we explored the assemblage of magnetic particles with a magnetic field to create permanent filaments anchored on a surface and that can be actuated. The filaments could be grafted on homogeneous glass or gold supports and also on mixed glass/gold supports with orthogonal functionalization. Filaments could be localized on precise support zones using either metallic tips concentrating locally the magnetic field (500 µm spots) or selective functionalization on mixed supports (1 mm gold squares). Assembling 200 nm diameter particles allowed to typically obtain filaments 5 µm long and 200 - 400 nm wide. The filament formation conditions could still be improved.Permanent magnetic filaments were used for two applications. Firstly, we used magnetic filaments which can be actuated to validate a polarimetric surface resonance imaging biosensor (P-SPRI) developed by the LCFIO (Palaiseau). First measurements tend to show that the anisotropy can be detected by the P-SPRI biosensor. It is necessary to continue this work to better validate the results already obtained. Secondly, we used magnetic filaments biofunctionalized by oligonucleotide probes to type platelets. In non-optimized measurement conditions, the hybridization of fluorescent target oligonucleotides on filaments anchored on a surface allows to multiply by 3 the fluorescence signal compared to hybridization on plane surface by increasing the support specific surface.
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  • HAL Id : tel-00713534, version 1

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Marie Trévisan. Biofonctionnalisation, caractérisation et mise en oeuvre de particules magnétiques sur biocapteurs : application au génotypage plaquettaire. Autre. Ecole Centrale de Lyon, 2011. Français. ⟨NNT : 2011ECDL0008⟩. ⟨tel-00713534⟩

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