Method for the detection of lateral flow assay and strip and laser-induced epifluorescence and compact scanner therefor

A lateral flow quantitative assay strip, comprising:

• a backing;
• a sample pad adhered to one end of the backing and to which a liquid sample is applied;
• a conjugate releasing pad adhered to the backing in such a way that one end of the sample pad, close to an opposite end of the backing, overlaps with an end of the conjugate releasing pad to which a labeled detector is releasably attached to react with an analyte in the liquid sample to form a conjugate;
• a chromatography medium adhered to the backing in such a way that one end of the medium overlaps with an end of the conjugate releasing pad, close to an opposite end of the backing, and on which a captor is immobilized, which is identical to or different from the labeled detector and reacts with and captures a conjugate released from the conjugate releasing pad as the sample develops to form a sandwich type conjugate;
• and
• an absorption pad to absorb the sample developing along the chromatography medium and to absorb and remove unreacted labeled substances,
• wherein the strip is characterized in that:
• the labeled detector releasably attached to the conjugate releasing pad is labeled with a fluorescent material;
• a reference detector that is labeled with a fluorescent material identical to that used in labeling the labeled detector and reacts with a reference material in the liquid sample is further releasably attached to the conjugate releasing pad;
• the captor is dispensed and immobilized in lines within a viewing window on the chromatography medium, and
• an unlabeled reference captor that is different from the detector and the captor is dispensed and immobilized in double reference lines in front of the viewing window on the chromatography medium, to form a conjugate of fluorescently-labeled detector-analyte-unlabeled captor and a reference conjugate of fluorescently-labeled reference detector/reference material-unlabeled reference captor as the liquid sample passes through the chromatography medium;
• and
• an amount of the analyte is determined by passing a laser presented from a laser beam shape control lens through an exciter filter, irradiating the filtered light to the epifluorescence medium containing the triple analyte conjugate and the reference conjugate, passing light reflected from the epifluorescence medium through a collection lens to form parallel light, passing the parallel light through a fluorescent filter to remove scattered incident light and presenting only a pure fluorescence component to a condenser lens to focus the pure fluorescence component to a center of a pinhole, removing light except for the parallel light at the pinhole, presenting the parallel light to an optical detector, transmitting the incident parallel light to a CPU via an analog digital converter (ADC), and comparing a fluorescence intensity of the triple analyte conjugate with a reference fluorescence intensity of the reference conjugate to quantify the analyte.

A small scanner for quantitative analysis of an analyte, which is integrated with a laser-induced epifluorescence detection device into a single body,

• wherein the laser-induced epifluorescence detection device comprises:
• (i) a strip, comprising:
• a backing;
• a sample pad adhered to one end of the backing and to which a liquid sample is applied;
• a conjugate releasing pad adhered to the backing in such a way that one end of the sample pad, close to an opposite end of the backing, overlaps with an end of the conjugate releasing pad to which a labeled detector is releasably attached to react with an analyte in the liquid sample to form a conjugate;
• a chromatography medium adhered to the backing in such a way that one end of the medium overlaps with an end of the conjugate releasing pad, close to an opposite end of the backing, and on which a captor is immobilized, which is identical to or different from the detector and reacts with and captures a conjugate released from the conjugate releasing pad as the sample develops to form a sandwich type conjugate;
• and
• an absorption pad to absorb the sample developing along the chromatography medium and to absorb and remove unreacted labeled substances,
• wherein the strip is characterized in that:
• the detector releasably attached to the conjugate releasing pad is labeled with a fluorescent material;
• a reference detector that is labeled with a fluorescent material identical to that used in labeling the detector and reacts with a reference material in the liquid sample is further releasably attached to the conjugate releasing pad;
• the captor is dispensed and immobilized in lines within a viewing window on the chromatography medium;
• and
• an unlabeled reference captor that is different from the detector and the captor is dispensed and immobilized in double reference lines in front of the viewing window on the chromatography medium;
• (ii) a cartridge to install therein the strip, the cartridge including a sample loading inlet and a window having a sloped wall surface, which are formed on a top plate of a cartridge housing;
• and
• (iii) a laser, a shape control lens for laser beam, an exciter filter, a collection lens, a fluorescent filter, a condenser lens, a spatial filter, an optical detector, an analog digital converter (ADC) and a CPU,
• wherein the components of the detection device are arranged in a structure such that a laser presented from a lens for control of shape of a laser beam of the laser is passed through an exciter filter, the filtered light is irradiated to an epifluorescence medium containing a conjugate of fluorescently-labeled detector-analyte-unlabeled captor and formed in the viewing window and a reference conjugate of fluorescently-labeled reference detector-reference material-unlabeled reference captor formed in the reference line as the liquid sample passes through the chromatography medium of the strip, light reflected from the epifluorescence medium is passed through a collection lens to form parallel light, the parallel light is passed through a fluorescent filter to remove scattered incident light, only a pure fluorescence component is presented to a condenser lens to focus the pure fluorescence component to a center of a pinhole, light except for the parallel light is removed at the pinhole, the parallel light is presented to an optical detector, and the incident parallel light is transmitted to CPU via an analog digital converter (ADC),
• wherein the small scanner allows the detection device to determine an amount of the analyte in the sample by comparing a fluorescence intensity of the triple analyte conjugate with a reference fluorescence intensity of the reference conjugate.