Analytical element for immunoassay and method for its preparation

Abstract

A dry-type analytical element for immunoassay utilizing antigen-antibody reaction in which the antigenic component is isolated from the antibody component by incorporating both components in separate layers or separately in a layer using different solvents. The analytical element is excellent in sensitivity and accuracy, and the analytical operation is simple.

We claim: 
     
       1. A dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least two integrated water-permeable layers, the water-permeable layers containing components participating in the antigen-antibody reaction, one of said components being an antigen, the other of said components being a labeled antibody, wherein at least one of the water-permeable layers is a porous layer, said porous layer containing one of the components but not containing the other component, and a water-permeable layer located distal from the liquid-receiving face of the analytical element as compared to the porous layer, and which contains the other of the components but does not contain the component contained in such porous layer. 
     
     
       2. The analytical element of claim 1 wherein the labeled antibody is contained in the porous layer and the antigen is contained in the distal water-permeable layer. 
     
     
       3. The analytical element of claim 1 wherein the antigen is contained in the porous layer and the labeled antibody is contained in the distal water-permeable layer. 
     
     
       4. The analytical element of claim 1 wherein the protein is albumin. 
     
     
       5. A dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least integrated two water-permeable layers, the water-permeable layers containing components participating in the antigen-antibody reaction, one of said components being a labeled antigen, another of said components being an antibody to said labeled antigen and to an unlabeled antigen, wherein at least one of the water-permeable layers is a porous layer, said porous layer containing the labeled antigen but not containing the labeled antigen but not containing the antibody, and a water-permeable layer located distal from the liquid-receiving face of the analytical element as compared to the porous layer and which contains the antibody but not the labeled antigen. 
     
     
       6. The analytical element of claim 5 wherein said porous layer is a liquid-spreading layer of the element. 
     
     
       7. A method of preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least two integrated water-permeable layers, the water-permeable layers containing an antigen and a labeled antibody at least one of the water-permeable layers being a porous layer, which comprises providing the porous layers on the water-permeable layer containing the antigen, and thereafter applying to the porous layer a composition containing said labeled antibody and not dissolving nor solubilizing said antigen. 
     
     
       8. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least integrated two water-permeable layers, the water-permeable layers containing an antigen and a labeled antibody and at least one of the water-permeable layers being a porous layer, which comprises providing the porous layer to which a composition containing said labeled antibody is previously applied on the water-permeable layer which contains said antigen or its fragment. 
     
     
       9. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least two integrated water-permeable layers, the water-permeable layers containing an antigen and a labeled antibody, and at least one of the water-permeable layers being a porous layer, which comprises providing the porous layer on the water-permeable layer containing the labeled antibody, and thereafter applying to the porous layer a composition which contains said antigen and not dissolving nor solubilizing said labeled antibody. 
     
     
       10. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least two integrated water-permeable layers, the water-permeable layers containing an antigen and a labeled antibody, and at least one of the water-permeable layers being a porous layer, which comprises providing the porous layer, to which a composition which contains said antigen is previously applied, on the water-permeable layer containing said labeled antibody. 
     
     
       11. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least integrated two water-permeable layers, the water-permeable layers containing a labeled antigen and an antibody to the labeled antigen and to an unlabeled antigen as the components participating in the antigen-antibody reaction, and at least on of the water-permeable layers being a porous layer, which comprises providing the porous layer on the water-permeable layer containing the antibody so that the water-permeable layer is located distal from the liquid-receiving face of the analytical element as compared to the porous layer, and thereafter applying to the porous layer a composition containing said labeled antigen and not dissolving nor solubilizing said antibody in the water-permeable layer. 
     
     
       12. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction and comprising at least integrated two water-permeable layers, the water-permeable layers containing a labeled antigen and an antibody to the labeled antigen and to an unlabeled antigen as the components participating in the antigen-antibody reaction, and at least one of the water-permeable layers being a porous layer, which comprises providing the porous layer, to which a composition containing said labeled antigen is previously applied, on the water-permeable layer containing the antibody, so that the water-permeable layer is located distal from the liquid-receiving face of the analytical element as compared to the porous layer, and which contains the other of the components but does not contain the component contained in such porous layer. 
     
     
       13. A method for preparing a dry analytical element for immunoassay using an antigen-antibody reaction, said element comprising at least one water-permeable porous layer and containing an antigen and a labeled antibody as components participating in the antigen-antibody reaction in said porous layer, which comprises separately applying to the porous layer a composition containing said antigen and a composition containing said labeled antibody. 
     
     
       14. The method of claim 13, wherein the composition containing the antigen contains water as a solvent. 
     
     
       15. The method of claim 13, wherein the composition containing the labeled antibody contains a solvent from the group consisting of alcohols, ketones and ethers. 
     
     
       16. The method of claim 13, wherein the composition containing the labelled antibody contains a solvent from the group consisting of ethanol, methanol, acetone or ethyl cellosolve. 
     
     
       17. The method of claim 13 wherein, after the composition containing said antigen is applied to the porous layer, a composition containing said labeled antibody and a solvent not swelling a hydrophilic polymer is applied to the porous layer. 
     
     
       18. The method of claim 13 wherein, after the composition containing said labeled antibody is applied to the porous layer, a composition containing said antigen and a solvent not swelling a hydrophilic polymer is applied to the porous layer. 
     
     
       19. The method of claim 17 or 18 wherein solvent does not dissolve the antigen or antibody present in the porous layer. 
     
     
       20. A method of claim 13, 7, 8, 9, or 10 wherein the protein is albumin.