Ultra-sensitive detection method using photoluminescent particles

A process for the ultrasensitive in vitro detection and/or quantification of a target substance of biological or chemical interest by detecting luminescence emission by photoluminescent inorganic nanoparticles, comprising at least the following steps:

• providing a sample having the target substance in an amount below 10 pM;
• immobilizing the target substance to a functionalized surface;
• providing photoluminescent particles to the immobilized target substance on the functionalized support to associate with the target substance, the photoluminescent particles consisting, in whole or in part, of a photoluminescent inorganic nanoparticle consisting of a crystalline matrix having at least 103 rare-earth ions, and coupled to at least one targeting agent for the target substance to be analyzed, under conditions conducive to their association with the target substance to be analyzed of the sample, said nanoparticles having an average size greater than or equal to 20 nm and strictly less than 1 μm, and being capable of emitting luminescence after absorption of a photon;
• wherein the nanoparticle is of the following formula (I):
• (A1-xLnx)a(MpOq) (I)
• wherein:
• M represents one or more elements capable of associating with oxygen (O) to form a crystalline compound;
• Ln corresponds to one or more luminescent lanthanide ion(s);
• A corresponds to one or more constituent ion(s) of the crystalline matrix whose electronic levels are not involved in the luminescence process;
• 0<x<1;
• and
• the values of p, q and a are such that the electroneutrality of (A1-xLnx)a(MpOq) is respected;
• illuminating of the rare-earth ions of the photoluminescent particles associated with the target substance, by an illumination device, with a power of at least 50 mW, and an excitation intensity of at least 1 W/cm2;
• detecting luminescence emitted by the photoluminescent particles after single-photon absorption, and
• determining of the presence and/or concentration of the substance by interpretation of said luminescence measurement, where appropriate by reference to a standard or calibration, wherein the target substance is determined to be present in the sample in an amount below 10 pM;
• said process providing detection and/or quantification of a substance of interest present in a sample in a content strictly below 10 pM;
• and
• the process using a light intensity 2D detection device comprising a single detector allowing simultaneous measurement of the emission signal of nanoparticles from different areas corresponding to different target substances to be analyzed on the surface of the functionalized support and does not require any movement of the support or the excitation beam.