Patent ID: 8639449

Claim:
A method of determining a presence of a detectable substance in a material, comprising: providing a semiconductor nanocrystal composition, comprising: a) a core comprising a first semiconductor material; b) a core-overcoating shell comprising a second semiconductor material, wherein the core and the core-overcoating shell form a core/shell nanocrystal; c) a linking agent; and d) an affinity molecule linked to said core/shell nanocrystal via the linking agent; wherein said semiconductor nanocrystal composition is water-soluble and has a narrow emission wavelength band; contacting a material with the semiconductor nanocrystal composition as an energy transfer reporter for the affinity molecule to selectively bind the detectable substance; irradiating the contacted material with a first wavelength of radiation; and detecting a second wavelength of radiation emitted from the semiconductor nanocrystal composition from the contacted material by the spatial proximal energy transfer of gamma radiation or luminescent radiation.