Magnetic capture of a target from a fluid

Abstract

Disclosed herein is an improved method for magnetic capture of target molecules (e.g., microbes) in a fluid. Kits and solid substrates for carrying the method described herein are also provided. In some embodiments, the methods, kits, and solid substrates described herein are optimized for separation and/or detection of microbes and microbe-associated molecular pattern (MAMP) (including, e.g., but not limited to, a cell component of microbes, lipopolysaccharides (LPS), and/or endotoxin).

What is claimed is: 
     
         1 . A method of capturing at least one target from a fluid comprising: introducing a fluid and target-binding magnetic particles to a magnetic separation chamber of a device in the presence of a magnetic field gradient (a gradient of a magnetic field), wherein the target-binding magnetic particles are magnetic particles adapted to bind a target, wherein the device comprises a magnetic separation chamber, wherein at least a portion of a fluid-contact surface of the magnetic separation chamber comprises magnetic field gradient concentrating particles distributed thereon, wherein magnetic field gradient concentrating particles are substantially aligned along magnetic flux lines of the magnetic field in presence of a magnetic field gradient, and wherein the magnetic field gradient concentrating particles act as local magnetic field gradient concentrators in presence of the magnetic field gradient. 
     
     
         2 . The method of  claim 1 , wherein the target is selected from the group consisting of cells, proteins, nucleic acids, microbes, small molecules, chemicals, toxins, drugs, and combinations thereof. 
     
     
         3 . The method of  claim 1 , wherein the target-binding magnetic particles are microbe-binding magnetic particles and comprise on their surface microbe-binding molecules. 
     
     
         4 . The method of  claim 3 , wherein the microbe-binding molecule is selected from the group consisting of proteins, peptides, peptidomimetics, nucleic acids, carbohydrates, lipids, steroids, hormones, lipid-binding molecules, cofactors, nucleosides, nucleotides, nucleic acids, peptidoglycan, small molecules, and any combination thereof. 
     
     
         5 . The method of  claim 3 , wherein the microbe-binding molecule is selected from the group consisting of carbohydrate-binding proteins, lipopolysaccharide-binding proteins, and any combination thereof. 
     
     
         6 . The method of  claim 3 , wherein the microbe-binding molecule is selected from the group consisting of opsonins, lectins, and any combination thereof. 
     
     
         7 . The method of  claim 3 , wherein the microbe-binding molecule comprises at least a microbial-binding portion of C-type lectins, collectins, ficolins, receptor-based lectins, lectins from the shrimp Marsupenaeus japonicas, non-C-type lectins, lipopolysaccharide (LPS)-binding proteins, endotoxin-binding proteins, peptidoglycan-binding proteins, or any combinations thereof. 
     
     
         8 . The method of  claim 3 , wherein the microbe-binding molecule is selected from the group consisting of mannose-binding lectin (MBL), surfactant protein A, surfactant protein D, collectin 11, L-ficolin, ficolin A, DC-SIGN, DC-SIGNR, SIGNR1, macrophage mannose receptor 1, dectin-1, dectin-2, lectin A, lectin B, lectin C, wheat germ agglutinin, CD14, MD2, lipopolysaccharide-binding protein (LBP), limulus anti-LPS factor (LAL-F), mammalian peptidoglycan recognition protein-1 (PGRP-1), PGRP-2, PGRP-3, PGRP-4, C-reactive protein (CRP), or any combinations thereof. 
     
     
         9 . The method of  claim 3 , wherein the microbe-binding molecule is selected from the group consisting of MBL (mannose binding lectin), FcMBL (IgG Fc fused to mannose binding lectin), AKT-FcMBL (IgG Fc-fused to mannose binding lectin with the N-terminal amino acid tripeptide of sequence AKT (alanine, lysine, threonine)), and any combination thereof. 
     
     
         10 . The method of  claim 3 , wherein the microbe-binding molecule comprises an amino acid sequence selected from SEQ ID NO. 1, SEQ ID NO. 2, SEQ ID NO. 3, SEQ ID NO. 4, SEQ ID NO. 5, SEQ ID NO. 6, SEQ ID NO. 7, SEQ ID NO. 8, and any combination thereof. 
     
     
         11 . The method of  claim 1 , wherein the fluid is a biological fluid obtained or derived from a subject, a fluid or specimen obtained from an environmental source, a fluid from a cell culture, a microbe colony, or any combinations thereof. 
     
     
         12 . The method of  claim 1 , wherein the fluid comprises the target-binding magnetic particles. 
     
     
         13 . The method of  claim 1 , wherein the magnetic field gradient concentrating particles form magnetic micro- or nano-structures on said at least a portion of the fluid-contact surface of the magnetic separation chamber. 
     
     
         14 . The method of  claim 1 , wherein the magnetic separation chamber comprises a channel, a microfluidic channel, a sample well, a microtiter plate, a slide, a flask, a tube, a nanotube, a fiber, a filter, a membrane, a scaffold, an extracorporeal device, a mixer, a hollow fiber, or any combinations thereof. 
     
     
         15 . The method of  claim 1 , wherein the magnetic field gradient concentrating particles are a mixture of different sized magnetic field gradient concentrating particles. 
     
     
         16 . The method of  claim 1 , wherein the target-binding magnetic particles are paramagnetic particles. 
     
     
         17 . The method of  claim 1 , wherein the magnetic separation chamber comprises a source fluid channel and a collection fluid channel connected to each other by a plurality of transfer channels. 
     
     
         18 . The method of  claim 17 , wherein the plurality of transfer channels is oriented substantially perpendicular to the source channel and the collection channel. 
     
     
         19 . The method of  claim 17 , wherein the device further comprises a first magnetic source positioned in close proximity to the collection channel. 
     
     
         20 . The method of  claim 18 , wherein the device further comprises a second magnetic source positioned in close proximity to the source channel.