Low frequency modulation sensors using nanosecond fluorophores
First Claim
1. A method of measuring a concentration of an analyte in a sample, wherein said method comprises:
- a) irradiating said sample with modulated incident light wherein said sample comprises a first fluorophore which absorbs a portion of said incident light and then emits emitted light, wherein the portion of said incident light absorbed by said first fluorophore is sensitive to the concentration of the analyte in the sample;
b) allowing said emitted light to irradiate a second fluorophore;
c) measuring light emitted from said sample;
d) determining the phase angle or modulation of said light emitted from said sample; and
e) correlating said phase angle or modulation to said concentration of said analyte, wherein in said first fluorophore has a decay time on a nanosecond timescale, wherein said second fluorophore has a decay time on a microsecond timescale.
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Abstract
Described is a new approach to fluorescence sensing based on a mixture of fluorophores, one of which is sensitive to the desired analyte. If a long lifetime analyte-insensitive fluorophore is mixed with a short lifetime analyte-sensitive fluorophore, the modulation of the emission at conveniently low frequencies becomes equal to the fractional fluorescence intensity of the sensing fluorophore. Under these conditions the modulation can be used to determine the analyte concentration. This can be used with any fluorophore which changes intensity in response to analyte, and does not require the sensing fluorophore to display a change in lifetime. The feasibility of modulation-based sensing was demonstrated using mixtures of 6-carboxyfluorescein and [Ru2,2′(bipyridyl)3]2+ as a pH sensor and of the calcium probe Fluo-3 and [Ru2,2′(bipyridyl)3]2+ as a calcium sensor.
42 Citations
38 Claims
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1. A method of measuring a concentration of an analyte in a sample, wherein said method comprises:
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a) irradiating said sample with modulated incident light wherein said sample comprises a first fluorophore which absorbs a portion of said incident light and then emits emitted light, wherein the portion of said incident light absorbed by said first fluorophore is sensitive to the concentration of the analyte in the sample;
b) allowing said emitted light to irradiate a second fluorophore;
c) measuring light emitted from said sample;
d) determining the phase angle or modulation of said light emitted from said sample; and
e) correlating said phase angle or modulation to said concentration of said analyte, wherein in said first fluorophore has a decay time on a nanosecond timescale, wherein said second fluorophore has a decay time on a microsecond timescale. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification