Patent ID: 6218134
Filing Date: 2001-04-17
Classification: G01N,Y10S

Abstract:
A specific binding assay process for measuring the amount of a substance to be assayed in a liquid test sample, comprising the steps of:(a) providing a device comprising:a matrix in which a distribution of a labeled specific binding substance forms,a sample introduction site connected to said matrix,a detection site in contact with substantially the most upstream side or most downstream side of said matrix for detecting a signal which is generated when a signal substance contacts said detection site, andan absorption site in which said liquid test sample flows from said sample introduction site through said matrix;(b) introducing said labeled specific binding substance and said liquid test sample into said matrix through said sample introduction site simultaneously or sequentially, wherein said labeled specific binding substance comprises a specific binding substance and a label, and wherein said labeled specific binding substance specifically competes with said substance to be assayed for a second specific binding substance and generates said signal substance in the presence of at least one substance related to generation of a signal substance, wherein said second specific binding substance preliminarily exists in the matrix or is introduced into the matrix through said sample introduction site with the simultaneous or sequential addition of the test sample,causing said labeled specific binding substance to flow with the liquid test sample through said matrix, andcausing said labeled specific binding substance to compete with said substance to be assayed in the matrix for said second specific binding substance, wherein binding to the second specific binding substance causes a difference in the mobility of said labeled specific binding substance in a bound state from the mobility of said labeled specific binding substance in an unbound state, thereby forming a distribution of bound and unbound labeled specific binding substance, wherein the distribution depends upon the amount of said substance to be assayed in said liquid test sample,causing said label of said labeled specific binding substance to directly or indirectly produce said signal substance with the reaction with at least one substance related to generation of a signal substance, wherein said substance related to generation of a signal substance preliminarily exists in the matrix or the absorption site, or is introduced into the matrix through said sample introduction site with the simultaneous or sequential addition of the test sample, andallowing said signal substance to diffuse independently of the flow direction of said labeled specific binding substance to reach said detection site;(c) measuring the intensity of said signal generated from said signal substance which reaches the detection site, wherein said intensity reflects the distribution of said labeled specific binding substance upon signal generation; and(d) determining the amount of said substance to be assayed by comparing said intensity to reference values;wherein said signal is an electrochemical signal andwherein said labeled specific binding substance is not immobilized in the matrix.