Nanomaterial-based photothermal immunosensing for quantitative detection of disease biomarkers

An immunoassay for detecting or measuring an analyte contained in a sample, comprising:

• reacting the analyte with a binding reagent, the binding reagent capable of specifically binding the analyte and forming a binding reagent/analyte complex;
• contacting the binding reagent/analyte complex with a detection reagent comprising-an iron oxide nanoparticle reagent that specifically binds the binding reagent/analyte complex;
• contacting the iron oxide nanoparticle reagent with a detection solution comprising a photothermal agent precursor under conditions forming a photothermal agent, wherein the photothermal agent is oxidized TMB;
• irradiating the photothermal agent produced by a reaction catalyzed by the iron oxide nanoparticle with light having a wavelength that is absorbed by the photothermal agent and is converted to heat;
• and
• measuring temperature change associated with the light irradiation, wherein a temperature increase is proportional to the amount of iron oxide nanoparticle bound to the analyte;
• or
• measuring the analyte concentration through a colorimetric method.