Patent ID: 7332344

Claim:
A method of detecting or quantifying an analyte by means of luminescence assay based on detection of transfer of energy between an energy donor species and an energy acceptor species as an acceptor of said energy, in which (i) the energy donor species is an upconversion medium that affects a transition to an excited state by absorption of electromagnetic radiation having an energy less than that of said transition and is provided as a solid phase having a surface or is immobilized in a solid phase having a surface or is immobilized on a surface of a solid phase and (ii) said acceptor species when bound to the surface of said solid phase in proximity to the energy donor species being excited by energy transfer from the said excited state of the donor species, the method comprising the steps of (a) combining a sample potentially containing the analyte with the energy donor species and the acceptor species or a precursor thereof that is converted by the analyte to the acceptor species, (b) irradiating said donor species with said electromagnetic radiation to excite the donor species to its said excited state for said energy transfer between the excited donor species and acceptor species bound to the surface, said analyte being one which if present either causes the acceptor species to bind to the surface in said proximity to the donor species or causes displacement of said bound acceptor species from said proximity thereby resulting in change in the excitation condition of at least one of the donor species and acceptor, species; and (c) detecting luminescence in at least one spectral region of the emission of said donor species or of said acceptor if said acceptor is luminescent, provided that the excitation of such a luminescent acceptor to a luminescent state emitting in said spectral region of the emission of the acceptor does not occur by absorption of a single quantum of the radiation used to excite the donor species.