Assay method and kit for assay employing sensor chip for fluorescent measuring apparatus utilizing surface plasmon-field enhanced fluorescence spectrometry

1. An assay method with use of a sensor chip which includes a flow passage having a metal member on a support, a self-assembled monolayer (SAM) on another surface of the metal member which is not in contact with the support, a hydrophilic high molecule layer on the SAM, and first ligands immobilized at least one of in the hydrophilic high molecule layer and on the surface of the hydrophilic high molecular layer, and which is configured to be used for a fluorescence measuring apparatus with utilization of a surface plasmon-field enhanced Fluorescence Spectrometry,

the assay method comprising the steps of:

(a) bringing an analyte liquid in contact with the first ligands of the sensor chip;

(b) making the sensor chip acquired through the process (a) to react with a conjugate material of fluorescent dyes and second ligands which may be the same with or different from first ligands contained in this sensor chip;

(c) irradiating laser light via a prism to another surface, on which the above metal member is not formed, of the support of the sensor chip acquired through the process (b) and measuring an amount of fluorescence emitted from the fluorescent dye excited with the irradiated laser light;

(d) calculating an amount of analyte contained in the analyte liquid from the measurement results obtained by the process (c);

wherein

the assay method further comprises the step of

feeding and circulating a moisturizer to the flow passage to coexist with the hydrophilic high molecule layer at the time of start of the step (b), and

wherein the moisturizer is at least one kind of material selected from the group consisting of urea, ethylene glycol, glycerin, ammonium lactate, pyrrolidone carboxylate, diol, lactic acid, hyaluronic acid, and chondroitin sulfate.

2. The assay method described in claim 1 , wherein the hydrophilic high molecule layer contains high molecules in an amount of 0.001 ng/mm 2 or more and 30 ng/mm 2 or less.

3. The assay method described in claim 1 , wherein the hydrophilic high molecule layer contains high molecules in an amount of 0.2 ng/mm 2 or more and 6 ng/mm 2 or less.

4. The assay method described in claim 1 , wherein the hydrophilic high molecule layer contains at least one kind of high molecules selected from a group consisting of polysaccharide, polyethylene glycol, polyacrylic acid, and polymethacrylic acid.

5. The assay method described in claim 4 , wherein the polysaccharide is dextran or dextran derivative.

6. The assay method described in claim 5 , wherein the polysaccharide is carboxy methyl dextran.

7. The assay method described in claim 1 , wherein the moisturizer is at least one kind of material selected from a group consisting of urea, ethylene glycol, glycerin, and ammonium lactate.

8. The assay method described in claim 1 , wherein the hydrophilic high molecule layer has an average layer thickness of 3 nm or more and 130 nm or less.

9. The assay method described in claim 1 , wherein the hydrophilic high molecule layer has an average layer thickness of 50 nm or more and 100 nm or less.

10. The assay method described in claim 1 , wherein the moisturizer has a rehydration sample moisture content of 40 to 200% by Riviere method.

11. The assay method described in claim 1 , wherein the first ligands are immobilized in the hydrophilic high molecule layer, and the immobilized first ligands are 10 femto-mol/cm 2 or more and 100 pico-mol/cm 2 or less.

12. The assay method described in claim 1 , wherein the moisturizer is added preliminarily into a liquid containing analytes, and the liquid containing the analytes and the moisturizer are fed and circulated to the flow passage so that the moisturizer coexists with the hydrophilic high molecule layer.

13. The assay method described in claim 12 , wherein the moisturizer has a concentration of 5 to 30% in the liquid containing the analytes and the moisturizer.

14. The assay method described in claim 1 , wherein the moisturizer is added preliminarily into a cleaning liquid to clean an inside of the sensor chip before a liquid containing analyte is brought in contact with the ligands, and the cleaning liquid containing the moisturizer are fed and circulated to the flow passage with the hydrophilic high molecule layer so that the moisturizer coexists with the hydrophilic high molecule layer.

15. The assay method described in claim 14 , wherein the moisturizer has a concentration of 5 to 30% in the cleaning liquid containing the moisturizer.

16. The assay method described in claim 1 , wherein the support is a transparent support.

17. A kit for an assay for use in the assay method described in claim 1 , comprising:

a sensor chip which includes a flow passage having a metal member on a support, a self-assembled monolayer (SAM) on another surface of the metal member which is not in contact with the support, a hydrophilic high molecule layer on the SAM, and first ligands immobilized at least one of in the hydrophilic high molecule layer and on the surface of the hydrophilic high molecule layer, and which is configured to be used for a fluorescence measuring apparatus; and

a moisturizer,

wherein the moisturizer is at least one kind of material selected from the group consisting of urea, ethylene glycol, glycerin, ammonium lactate, pyrrolidone carboxylate, diol, lactic acid, hyaluronic acid, and chondroitin sulfate.

18. The kit for an assay, described in claim 17 , wherein the hydrophilic high molecule layer has a dried film thickness of 1 nm or more and 50 nm or less.