Surface assay utilizing fluorescence signal manipulation on different nanoparticles. Antibody against analyte of interest is immobilized on “gold only” particles, and analyte-fluorophore conjugate is bound on this surface (fluorophore fluorescence is quenched). Then after adding of the sample with analyte of interest (black rhombs), this analyte will replace the conjugate, and conjugate will detach from the gold particles and fluorescence will be restored (proportionally to the sample analyte concentration). By transferring the supernatant solution onto a surface coated with silver-shelled gold, containing immobilized anti-fluorophore antibodies, we further enhance the conjugate fluorescence due to it’s binding to the silver-coated “enhancing” particles.