Detection of analytes using nanoparticles as light scattering enhancers

A method for detecting presence of an analyte in a solution comprising:

• providing at least a first probe and a second probe different from each other, each probe comprising a nanoparticle conjugated with a receptor specific to the analyte, the first probe and the second probe having spectral optical responses separated from each other, wherein the spectral optical response of each probe is defined as a function of wavelength by a ratio between light scattered by the probe in a given solid angle of detection at the wavelength and an amount of light incident on the probe, wherein the nanoparticle of the second probe is different from the nanoparticle of the first probe;
• contacting the solution with the first probe and the second probe to form a sample solution, wherein the sample solution comprises aggregates comprising the analyte combined with the first probe and the second probe;
• illuminating the sample solution with a light source having at least a first exciting wavelength and a second exciting wavelength different from each other wherein the first exciting wavelength and the second exciting wavelength are chosen to get distinct optical responses from the first probe and the second probe respectively when illuminated;
• detecting as a function of time light scattered by the first probe at a first detection wavelength and light scattered by the second probe at a second detection wavelength different from the first detection wavelength to get a first signal and a second signal respectively;
• detecting temporal coincidences between the first signal and the second signal;
• and
• detecting the presence of the analyte based on the detection of temporal coincidences.