Patent ID: 8614099

Claim:
A FRET detection method of detecting FRET (Fluorescence Resonance Energy Transfer) in which energy of a donor molecule is transferred to an acceptor molecule, the method comprising the steps of: a) measuring fluorescence emitted from each of samples by two or more detection sensors having different light-receiving wavelength bands, each of the samples being labeled with a donor molecule and an acceptor molecule and being irradiated with laser light whose intensity is modulated at a predetermined frequency, to acquire detection values including fluorescence intensity information and phase information on the fluorescence emitted from each of the samples; b) reading calibration information previously stored in a memory means, which includes at least a first intensity ratio that is a ratio between fluorescence intensities at the light-receiving wavelength bands of a donor molecule fluorescence component emitted from the donor molecule included in the fluorescence emitted from each of the samples, phase information on the donor molecule fluorescence component relative to the modulated laser light, a second intensity ratio that is a ratio between fluorescence intensities at the light-receiving wavelength bands of an acceptor molecule fluorescence component emitted from the acceptor molecule included in the fluorescence, phase information on the acceptor molecule fluorescence component relative to the laser light, and a non-FRET fluorescence lifetime of the donor molecule fluorescence component when the FRET does not occur, which is a lifetime defined by assuming that fluorescence emitted from the donor molecule excited by laser light is a relaxation response of a first-order lag system; c) calculating fluorescence intensity information and phase information on the fluorescence at each of the light-receiving wavelength bands, based on the detection values, and determining a FRET fluorescence lifetime of the donor molecule fluorescence component, which is defined by assuming that fluorescence emitted from the donor molecule excited by laser light is a relaxation response of a first-order lag system, using the calculated fluorescence intensity information, the calculated phase information, the first intensity ratio, the phase information on the donor molecule fluorescence component, the second intensity ratio, the phase information on the acceptor molecule fluorescence component; and d) determining information on FRET occurrence using a ratio between the FRET fluorescence lifetime of the donor molecule fluorescence component and the non-FRET fluorescence lifetime of the donor molecule fluorescence component.