Dry chemistry, lateral flow-reconstituted chromatographic enzyme-driven assays

Abstract

A lateral flow chromatographic assay format for the performance of rapid enzyme-driven assays is described. A combination of components necessary to elicit a specific enzyme reaction, which are either absent from the intended sample or insufficiently present therein to permit completion of the desired reaction, are predeposited as substrate in dry form together with ingredients necessary to produce a desired color upon occurrence of the desired reaction. The strip is equipped with a sample pad placed ahead of the substrate deposit in the flowstream, to which liquid sample is applied. The sample flows from the sample pad into the substrate zone where it immediately reconstitutes the dried ingredients while also intimately mixing with them and reacting with them at the fluid front. The fluid front moves rapidly into the final “read zone” wherein the color developed is read against predetermined color standards for the desired reaction. Pretreatment pads for the sample, as needed, are placed in front of the sample pad in the flow path as appropriate. The assay in the format of the invention is faster and easier to perform than analogous wet chemistry assays.

1 - 19 . (canceled) 
     
     
         20 . An assay device comprising at least two pads in fluid communication and positioned on an adhesive backing, wherein
 (1) the first pad is a sample receiving pad adapted to receive a sample which flows through the sample receiving pad, and   (2) the second pad is a substrate pad on which has been deposited a mobilizable dry mixture of components including a substrate for an enzyme, which components, when reconstituted by forward flow of the sample, perform an assay on the sample.   
     
     
         21 . The assay device of  claim 20 , wherein a result of the assay performed on the sample is determined by a color indicative of the presence or concentration of the enzyme in the sample. 
     
     
         22 . The assay device of  claim 20 , wherein a region of the first pad has been treated to remove or reduce the concentration of a substance in the sample as the sample moves through the first pad, which substance is known to interfere with, obscure the result of or otherwise hinder the performance of the assay. 
     
     
         23 . The assay device of  claim 20 , wherein a region of the first pad has been treated to concentrate the sample as it flows through the first pad. 
     
     
         24 . The assay device of  claim 20 , wherein the first pad comprises a lysing agent. 
     
     
         25 . The assay device of  claim 20 , wherein the sample comprises blood, serum, plasma, saliva, urine, nasal wash, or a bacterial culture. 
     
     
         26 . The assay device of  claim 20 , wherein an intermediate pad is interposed between the first pad and the second pad, and said intermediate pad has been treated with an immovable deposit of at least one substance that removes and binds at least one sample component that would otherwise interfere with or obscure the result of the assay. 
     
     
         27 . The assay device of  claim 20 , wherein the sample is obtained from a patient. 
     
     
         28 . The assay device of  claim 21 , wherein the color is formed at a forward flow front of the assay device. 
     
     
         29 . The assay device of  claim 20 , wherein the enzyme is selected from the group consisting of glucose-6-phosphate deydrogenase (G6PD), alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, beta-lactamase, creatine kinase and peroxidase.