Microporous substrate for use in a disposable bioassay cartridge

Abstract

A microporous substrate for detection of surface bound target analyte molecules includes a microporous substrate material having opposed surfaces and tapered micropores extending through the substrate with the micropores having wider openings on one side of the substrate compared to the other side. The micropores have bound therein analyte specific receptors complementary to the target molecules. When a liquid sample containing the target analyte molecules with optical probes attached to the target molecules is flowed through the substrate, they bind to their complementary analyte specific receptors and emit light. This substrate structure gives an increase in the collection efficiency of light emitted from optical probes when the light is detected by a light detector spaced from the side of the substrate facing the larger micropores openings compared to a light collection efficiency of light emitted from the optical probes when the micropores are straight and not tapered.

Therefore what is claimed is: 
     
         1 . A microporous substrate for use in a flow through system for detection of target analyte molecules present in a liquid sample, the target analyte molecules having optical probes bound thereto, comprising:
 a microporous substrate material having opposed surfaces and tapered micropores extending completely through a thickness of said microporous substrate, and wherein ends of the tapered micropores have larger micropore openings on one surface of the microporous substrate compared to smaller pore openings on the opposed surface;   analyte-specific receptors complementary to the target analyte molecules being bound to walls of the tapered micropores such that upon flowing the liquid sample through the microporous substrate the target analyte molecules bind to the analyte-specific receptors and the optical probes emit light when the target analyte molecules in the liquid sample bind to the analyte specific receptors;   the microporous substrate being characterized such that when said microporous substrate is spaced from said light detector with said light detector facing the surface of said microporous substrate having the larger micropore openings a collection efficiency of light emitted from analyte-specific receptors in said tapered micropores detected by the light detector is increased compared to a light collection efficiency of light emitted from the analyte-specific receptors when the micropores are straight and not tapered.   
     
     
         2 . The microporous substrate according to  claim 1  in which the pores are progressively wider near one surface of the microporous substrate. 
     
     
         3 . The microporous substrate according to  claim 1 , wherein the micropores have any one of a rectangular cross section, a square cross section and a circular cross section. 
     
     
         4 . The microporous substrate according to  claim 1 , wherein tapering of the micropores is conical, spherical, or parabolic. 
     
     
         5 . The microporous substrate according to  claim 1 , which the micropores are of uniform dimensions and morphology. 
     
     
         6 . The microporous substrate according to  claim 1 , further comprising reinforcement ribs to provide structural stability. 
     
     
         7 . The microporous substrate according to  claim 6  in which the reinforcement ribs are an integral part of the microporous substrate. 
     
     
         8 . The microporous substrate according to  claim 6 , wherein the reinforcement ribs are separate from the substrate and made in a form of a rigid supporting mesh. 
     
     
         9 . The microporous substrate according to  claim 11  with the said microporous substrate is attached to a supporting mesh placed on the surface of the said substrate opposite to the surface with the larger micropore openings. 
     
     
         10 . The microporous substrate according to  claim 1  having a thickness of between about 0.15 to about 0.75 mm. 
     
     
         11 . The microporous substrate according to  claim 1  made of silicon. 
     
     
         12 . A microporous substrate for detection of surface bound target analyte molecules, comprising:
 a microporous substrate material having opposed surfaces and micropores, the micropores having bound therein analyte specific receptors complementary to the target analyte molecules, the pores having tapered walls extending through a thickness of said microporous substrate in which the pores are wider near one surface of the substrate compared to a width of the micropores on the opposed surface to increase the collection efficiency of light emitted from optical probes bound to target analyte molecules when the target analyte molecules are captured by the analyte specific receptors which is detected by a light detector spaced from the side of the microporous substrate facing the larger micropores openings compared to a light collection efficiency of light emitted from the optical probes when the micropores are straight and not tapered.   
     
     
         13 . A method for detection of target analyte molecules, comprising:
 mixing a liquid sample with a solution containing optical probes known to bind to the target analyte molecules to form a sample solution;   flowing the sample solution through a microporous substrate having opposed surfaces and pores, the pores having bound therein analyte specific receptors complementary to the target analyte molecules being tested for, wherein upon binding of the target analyte molecules to the analyte specific receptors the optical probes emit light; and   the pores having tapered walls extending through a thickness of said substrate in which the pores are wider near one surface of the substrate compared to a width of the pores on the opposed surface to increase the collection efficiency of light emitted from optical probes which is detected by a light detector spaced from the side of the substrate facing the larger pore openings compared to a light collection efficiency of light emitted from the optical probes when the pores are straight and not tapered.   
     
     
         14 . The method according to  claim 13 , wherein the optical probes are selected to emit any one of colorimetric light, fluorescent light, chemiluminescent light or bioluminescent light.