Methods and compositions for improving detection and/or capture of a target entity

Abstract

Methods, compositions, kits and systems for detecting and/or capturing a target entity in a sample. In particular, the methods, compositions and kits described herein can be used for pre-treatment of target-binding agents with a blocking agent to reduce non-target binding in a complex matrix (e.g., blood). Methods and compositions for detecting and/or capturing a microbe in a test sample, including bodily fluids such as blood and tissues of a subject, food, water, and environmental surfaces are also disclosed.

What is claimed is: 
     
         1 . A composition comprising a) a target-binding agent and b) a blocking agent that is bound to the target-binding agent and is displaceable by a target entity to be captured from a sample;
 wherein the effective binding affinity of the blocking agent for the target-binding agent is lower than the effective binding affinity of the target entity; and   wherein the effective binding affinity of the blocking agent for the target-binding agent is higher than the effective binding affinity of at least one interfering agent present in the sample.   
     
     
         2 . The composition of  claim 1 , further comprising the target entity bound to the target-binding agent. 
     
     
         3 . The composition of  claim 1 , wherein the target-binding agent and the blocking agent are present in a buffered solution. 
     
     
         4 . The composition of  claim 1 , further comprising a solid substrate affixed with the target-binding agent. 
     
     
         5 . The composition of  claim 4 , wherein the solid substrate is selected from the group consisting of:
 a nucleic acid scaffold; a protein scaffold; a lipid scaffold; a dendrimer; microparticle or a microbead; a nanotube; a microtiter plate; a medical apparatus or implant; a microchip; a filtration device; a membrane; a diagnostic strip; a dipstick; an extracorporeal device; a mixing element; a spiral mixer; a microscopic slide; a hollow-fiber reactor; and any combinations thereof.   
     
     
         6 . The composition of  claim 1 , wherein said at least one interfering agent is a second target molecule to be captured or detected. 
     
     
         7 . The composition of  claim 1 , wherein said at least one interfering agent is a non-specific binding molecule, or a specific but lower affinity binding molecule. 
     
     
         8 . The composition of  claim 1 , wherein the target-binding agent, the blocking agent, and said at least one interfering agent are each independently selected from the group consisting of:
 peptides; polypeptides; proteins; peptidomimetics; antibodies; antibody fragments; antigen binding fragments of antibodies; carbohydrate-binding protein; a lectin; glycoproteins; glycoprotein-binding molecules; amino acids; carbohydrates (including mono-; di-; tri- and poly-saccharides); lipids; steroids; hormones; lipid-binding molecules; cofactors; nucleosides; nucleotides; nucleic acids; DNA; RNA; analogues and derivatives of nucleic acids; nucleic acid aptamers; peptide aptamers; peptidoglycan; lipopolysaccharide; small molecules; endotoxins; bacterial lipopolysaccharide; cells; and any combinations thereof.   
     
     
         9 . The composition of  claim 1 , wherein the target-binding agent comprises an antibody. 
     
     
         10 . The composition of  claim 1 , wherein the target-binding agent comprises a microbe-binding agent. 
     
     
         11 . The composition of  claim 10 , wherein the microbe-binding agent comprises a carbohydrate recognition domain derived from at least one carbohydrate-binding protein selected from the group consisting of: lectin; collectin; ficolin; mannose-binding lectin (MBL); maltose-binding protein; arabinose-binding protein; glucose-binding protein; Galanthus nivalis agglutinin; peanut lectin; lentil lectin; DC-SIGN; C-reactive protein; and any combinations thereof. 
     
     
         12 . The composition of  claim 10 , wherein the microbe-binding agent comprises a lectin. 
     
     
         13 . The composition of  claim 10 , wherein the microbe-binding agent comprises a FcMBL molecule. 
     
     
         14 . The composition of  claim 10 , wherein the microbe-binding agent comprises an amino acid sequence selected from SEQ ID NO: 1-SEQ ID NO: 8. 
     
     
         15 . The composition of  claim 1 , wherein the blocking agent is a monomer, the monomer having no free binding site after binding to the target-binding agent. 
     
     
         16 . The composition of  claim 1 , wherein the blocking agent is a multimer, the multimer having at least one free-binding site after binding to the target-binding agent. 
     
     
         17 . The composition of  claim 1 , wherein the blocking agent comprises glucose, maltose, N-acetyl-muramic acid, or any combinations thereof. 
     
     
         18 . The composition of  claim 1 , wherein the blocking agent comprises glucose. 
     
     
         19 . The composition of  claim 18 , wherein the glucose is present at a concentration of from 5 mM to 200 mM. 
     
     
         20 . The composition of  claim 1 , wherein the blocking agent comprises a detectable label.