Concentrating immunochemical test device and method

A method for determining the presence of an analyte in a sample suspected of containing said analyte, which comprises:

• (a) contacting, with a test solution containing said sample and antibodies to said analyte, the end portion of a strip of bibulous material capable of being traversed by said test solution by capillary migration,
• said strip containing particles non-diffusively bound to a small situs on said strip separate from said end portion,
• the surface area of said situs being substantially less than that of said strip,
• said particles having a member of a specific binding pair ("sbp member") non-diffusively bound thereto, which sbp member is capable of binding to said antibodies to said analyte,
• with the proviso that, where said sbp member is able to bind said antibodies to said analyte when said antibodies are not bound to said analyte, an analog of said analyte capable of binding said antibodies to said analyte is non-diffusively bound to said strip between said small situs and said end portion,
• (b) allowing the test solution to traverse at least a portion of said strip by capillary migration,
• (c) contacting said strip (1) with a developer solution containing members of a signal producing system to provide contact of said developer solution with said situs following contact of said test solution with said situs and (2) with any remaining members of said signal producing system, said signal producing system being capable of producing a detectible signal at said situs in relation to the amount of analyte in the test solution, and
• (d) comparing said detectible signal at said situs with the signal detectible at a portion of the strip other than said situs to determine the presence of the analyte in the sample.

A device for determining the presence of an analyte is a test solution comprised of a first member of a specific binding pair (sbp member) complementary to said analyte and a sample suspected of containing the analyte, which comprises:

• a bibulous strip capable of traversal by said test solution by capillary migration, said strip having an end portion for contacting said test solution and
• a second sbp member different than said analyte non-diffusively bound to a small situs on said strip separated from said end portion,
• the surface area of said situs being substantially less than that of said strip,
• said second sbp member having the characteristic of binding said first sbp member when said first sbp member is bound to said analyte,
• with the proviso that, where said second sbp member is able to bind said first sbp member when said first sbp member is not bound to said analyte, an analog of said analyte capable of binding said first sbp member is non-diffusively bound to said strip at least between said small situs and said end portion.

A device for determining the presence of an antigen in a test solution comprised of an antibody for the antigen and a sample suspected of containing said antigen, which comprises:

• a strip of bibulous material capable of being traversed by said test solution of capillary migration, said strip having an end portion for contacting in said test solution and
• particles non-diffusively bound to said strip at a small situs separate from said end portion,
• said situs having a surface area substantially less than that of said strip, through which situs said test solution passes as it traverses said strip,
• said particles having non-diffusively bound thereto a member of a specific binding pair ("sbp member") different from said antigen and capable of binding to a complex of said antigen with said antibody,
• with the proviso that, where said sbp member can bind to said antibody when said antibody is not complexed with said antigen, an antigen analog is non-diffusively bound to said strip at least between said small situs and said end portion.

A method for determining the presence of an analyte in a sample suspected of containing said analyte, which analyte is a member of a specific binding pair ("sbp member") consisting of ligand and its complementary receptor, which method comprises

• (a) contacting, with a test solution containing said sample and a first sbp member capable of binding to said analyte, a portion of bibulous material capable of being traversed by said test solution by capillary migration,
• said bibulous material containing a second sbp member non-diffusively bound to a small situs on said bibulous material separated from said end portion, the surface area of said situs being substantially less than that of said bibulous material,
• said second sbp member having the characteristic of binding said first sbp member when said first sbp member is bound to said analyte,
• with the proviso that, where said second sbp member is able to bind said first sbp member when said first sbp member is not bound to said analyte, an analyte analog capable of binding said first sbp member is non-diffusively bound to said bibulous material at least between said small situs and said portion,
• (b) allowing the test solution to traverse at least a portion of said bibulous material by means of capillary migration,
• (c) contacting said bibulous material (1) with a developer solution containing members of a signal producing system to provide contact of said developer solution with said situs following contact of said test solution with said situs and (2) with any remaining members of said signal producing system, said signal producing system being capable of producing a detectible signal at said situs in relation to the amount of analyte in said sample, and
• (d) comparing said detectible signal at said situs with the signal detectible at a portion of the bibulous material other than at said situs to determine the presence of analyte in said sample.

A device for determining the presence of an analyte in a test solution comprised of a first member of a specific binding pair (sbp member) complementary to said analyte and a sample suspected of containing the analyte, which comprises:

• bibulous material capable of traversal by said test solution by capillary migration, said bibulous material having portion for contacting said test solution and
• a second sbp member different than said analyte non-diffusively bound to a small situs on said bibulous material separated from said portion for contacting,
• the surface area of said situs being substantially less than that of said bibulous material,
• said second sbp member having the characteristic of binding said first sbp member when said first sbp member is bound to said analyte,
• with the proviso that, where said second sbp member is able to bind said first sbp member is when said first sbp member not bound to said analyte, an analog of said analyte capable of binding said first sbp member is non-diffusively bound to said bibulous material at least between said small situs and said portion for contacting.