title: Optical protein detection based on magnetic clusters rotation.
abstract: In this paper we present a simple method to quantify aggregates of 200nm magnetic particles. This method relies on the optical and magnetic anisotropy of particle aggregates, whereas dispersed particles are optically isotropic. We orientate aggregates by applying short pulses of a magnetic field, and we measure optical density variation directly linked to this reorientation. By computing the scattering efficiency of doublets and singlets, we demonstrate the absolute quantification of a few % of doublets in a well dispersed suspension. More generally, these optical variations are related to the aggregation state of the sample. This method can be easily applied to an agglutination assay, where target proteins induce aggregation of colloidal particles. By observing only aligned clusters, we increase sensitivity and we reduce the background noise as compared to a classical agglutination assay: we obtain a detection limit on the C-reactive protein of less than 3pM for a total assay time of 10min.
authors: Laboratoire Colloïdes et Matériaux Divisés, from the Institute of Chemistry, Biology and Innovation (CBI)-ESPCI ParisTech, CNRS-UMR8231, PSL* Research University, 10 rue Vauquelin, 75005 Paris, France.
authors: Donatien
authors: D
authors: Ramiandrisoa
authors: Bertin Systèmes, Bertin Technologies, 10 Avenue Ampère, 78180 Montigny-le-Bretonneux, France.
authors: Elodie
authors: E
authors: Brient-Litzler
authors: Laboratoire Colloïdes et Matériaux Divisés, from the Institute of Chemistry, Biology and Innovation (CBI)-ESPCI ParisTech, CNRS-UMR8231, PSL* Research University, 10 rue Vauquelin, 75005 Paris, France; Horiba Medical, Parc Euromédecine, Rue du Caducée, 34000 Montpellier Cedex 4, France.
authors: Aurélien
authors: A
authors: Daynes
authors: Bertin Systèmes, Bertin Technologies, 10 Avenue Ampère, 78180 Montigny-le-Bretonneux, France.
authors: Eric
authors: E
authors: Compain
authors: Laboratoire Colloïdes et Matériaux Divisés, from the Institute of Chemistry, Biology and Innovation (CBI)-ESPCI ParisTech, CNRS-UMR8231, PSL* Research University, 10 rue Vauquelin, 75005 Paris, France.
authors: Jérôme
authors: J
authors: Bibette
authors: Laboratoire Colloïdes et Matériaux Divisés, from the Institute of Chemistry, Biology and Innovation (CBI)-ESPCI ParisTech, CNRS-UMR8231, PSL* Research University, 10 rue Vauquelin, 75005 Paris, France. Electronic address: jean.baudry@espci.fr.
authors: Jean
authors: J
authors: Baudry
mesh_terms: D002097:C-Reactive Protein / Q000032:analysis; D003102:Colloids; D057230:Limit of Detection; D008280:Magnetics; D055095:Optics and Photonics
chemical_list: D003102:Colloids; D002097:C-Reactive Protein