Magnetic nanosensor compositions and bioanalytical assays therefor

Abstract

Disclosed are magnetic nanosensors or transducers that permit measurement of a physical parameter in an analyte via magnetic reasonance measurements, in particular of non-agglomerative assays. More particularly, in certain embodiments, the invention relates to designs of nanoparticle reagents and responsive polymer coated magnetic nanoparticles. Additionally provided are methods of use of nanoparticle reagents and responsive polymer coated magnetic nanoparticles for the detection of a stimulus or an analyte with NMR detectors.

1 . A system for the detection of an analyte in a liquid sample, the system comprising at least one nanoparticle comprising a polymer matrix layer about a magnetic core, wherein the polymer matrix layer has a specific volume that varies as a function of a presence and/or concentration of the analyte in the liquid sample, and wherein a change in the specific volume of the polymer matrix layer corresponds to a change in an NMR-measured property of protons in the liquid sample in the vicinity of the at least one nanoparticle. 
     
     
         2 . The system of  claim 1 , wherein the NMR-measured property is a T 1  or T 2  relaxivity of protons of (substantially) freely diffusing water molecules in the liquid sample (e.g., wherein the protons are dephased upon RF excitation). 
     
     
         3 . The system of  claim 1 , wherein the polymer matrix layer comprises a hydrophilic mesh comprising binding moieties responsive to the presence and/or concentration of the analyte in the liquid sample. 
     
     
         4 . The system of  claim 1 , wherein the liquid sample is a biological sample;
 wherein the at least one nanoparticle and the liquid sample are in vivo; and/or   wherein the at least one nanoparticle and the liquid sample are ex vivo.   
     
     
         5 . The system of  claim 3 , wherein the binding moieties mediate the extent of cross-linking of the matrix as a function of the presence and/or concentration of the analyte, wherein the specific volume of the matrix is a function of the extent of cross-linking; and/or
 wherein the binding moieties comprise at least one member selected from the group consisting of an amino group, a carboxyl group, a sulfhydryl group, an amine group, an imine group, an epoxy group, a hydroxyl group, a thiol group, an acrylate group, and an isocyano group.   
     
     
         6 . The system of  claim 3 , wherein the analyte comprises at least one member selected from the group consisting of a protein, a peptide, a polypeptide, an amino acid, a nucleic acid, an oligonucleotide, a therapeutic agent, a metabolite of a therapeutic agent, RNA, DNA, an antibody, an organism, a virus, a bacteria, a carbohydrate, a polysaccharide, and glucose. 
     
     
         7 . The system of  claim 1 , wherein the at least one nanoparticle is paramagnetic or superparamagnetic. 
     
     
         8 . The system of  claim 1 , the system comprising a plurality of said nanoparticles arranged in a network. 
     
     
         9 . The system of  claim 8 , wherein said nanoparticles are arranged in said network to allow substantially free diffusion of water molecules in the vicinity of each individual nanoparticle. 
     
     
         10 . The system of  claim 8 , wherein said nanoparticles are at least partially immobilized on a surface (for example, by nonspecific absorption, by specific chemical coupling, or by specific binding); and/or
 wherein a part of each of said nanoparticles is immobilized on said surface, and another part of said each nanoparticle is exposed to said liquid sample; and/or   wherein said nanoparticles each comprise a core that is only partially coated with said polymer matrix layer.   
     
     
         11 . The system of  claim 10 , wherein said nanoparticles comprise a partial polymer coating, wherein said partial polymer coating of each of said nanoparticles is exposed to said liquid sample. 
     
     
         12 . A system for the detection of a property of a liquid sample, the system comprising at least one nanoparticle comprising a polymer matrix layer about a magnetic core, wherein the polymer matrix layer has a specific volume that varies as a function of the liquid sample property to be detected, and wherein a change in the specific volume of the polymer matrix layer corresponds to a change in an NMR-measured property of protons in the liquid sample in the vicinity of the at least one nanoparticle. 
     
     
         13 . The system of  claim 12 , wherein the detected property of the liquid sample is a member selected from the group consisting of static pH, dynamic pH, and ionic strength; and/or
 wherein the detected property of the liquid sample is a concentration of one or more of the following in the liquid sample: a lipid, a gas (e.g., oxygen, carbon dioxide), an electrolyte (e.g., sodium, potassium, chloride, bicarbonate, BUN, creatinine, glucose, magnesium, phosphate, calcium, ammonia, lactate), a lipoprotein, cholesterol, a fatty acid, a glycoprotein, a proteoglycan, and/or a lipopolysaccharide.   
     
     
         14 . A method for detecting an analyte in a liquid sample, the method comprising the steps of:
 (a) exposing at least one magnetic nanoparticle to a liquid sample, wherein the at least one nanoparticle comprises a polymer matrix layer about a magnetic core, the polymer matrix layer having a specific volume that varies as a function of the presence and/or concentration of the analyte; and/or   (b) applying an external magnetic field to the at least one magnetic nanoparticle;   (c) applying an RF excitation to detect protons of freely diffusing water molecules in the liquid sample in the vicinity of the at least one magnetic nanoparticle;   (d) measuring a T 1  and/or T 2  relaxivity following application of the RF excitation; and   (e) determining the presence and/or concentration of the analyte in the liquid sample using the T 1  and/or T 2  relaxivity.   
     
     
         15 . The method of  claim 14 , further comprising the step of determining one or more calibration curves relating the T 1  and/or T 2  relaxivity to the presence and/or concentration of the analyte in solution. 
     
     
         16 . A method for detecting a property of a liquid sample, the method comprising the steps of:
 (a) exposing at least one magnetic nanoparticle to a liquid sample, wherein the at least one nanoparticle comprises a polymer matrix layer about a magnetic core, the polymer matrix layer having a specific volume that varies as a function of the liquid sample property to be detected;   (b) applying an external magnetic field to the at least one magnetic nanoparticle;   (c) applying an RF excitation to detect protons of freely diffusing water molecules in the liquid sample in the vicinity of the at least one magnetic nanoparticle;   (d) measuring a T 1  and/or T 2  relaxivity following application of the RF excitation;   (e) determining the liquid sample property using the T 1  and/or T 2  relaxivity.   
     
     
         17 . An apparatus for the detection of an analyte in a liquid sample, the apparatus comprising:
 a substrate;   at least one nanoparticle at least partially immobilized on the substrate, wherein the at least one nanoparticle comprises a polymer matrix layer about a magnetic core, wherein the polymer matrix layer has a specific volume that varies as a function of a presence and/or concentration of the analyte in the liquid sample, and wherein a change in the specific volume of the polymer matrix layer corresponds to a change in an NMR-measured property of protons in the liquid sample in the vicinity of the at least one nanoparticle.   
     
     
         18 . The apparatus of  claim 17 , wherein the substrate comprises a membrane;
 wherein the apparatus is implantable; and/or   further comprising a controlled release unit in communication with a sensing unit, wherein the sensing unit comprises the substrate and the at least one nanoparticle, and wherein the controlled release unit dispenses a substance into a body in accordance with instructions, the instructions at least partially determined according to one or more signals from said sensing unit, said one or more signals indicative of a presence, absence, or concentration of an analyte in the body.   
     
     
         19 . A smart device for delivery or release of a moiety into a body, the smart device comprising: a sensing element comprising at least one nanoparticle, said nanoparticle comprising a polymer matrix layer about a magnetic core, said polymer matrix layer responsive to a condition of a volume of fluid (e.g., fluid of a body) in contact with said nanoparticle;
 an RF antenna configured to detect an echo RF signal from said volume of fluid following RF excitation of said volume;   a processor configured to determine a measurement of said condition based at least in part on said detected echo RF signal;   a stimulus emitter configured to emit a stimulus in response to said measurement of said condition; and   a control release element configured to release or deliver a moiety out of said polymer matrix layer (e.g., and into said body) upon receiving said stimulus.   
     
     
         20 . The smart device of  claim 19 , wherein at least part of said smart device (e.g., said sensing element, said RF antenna, said processor, said stimulus emitter, and/or said control release element) is implantable within said body;
 wherein said volume of fluid is in vivo or wherein said volume of fluid is ex vivo;   wherein said moiety delivered out of said polymer matrix layer comprises one or more of the following: an atom, an ion, a molecule, a compound, a catalyst, an enzyme, an electroactive mediator, an electron-pair donor, an electron-pair acceptor, a lanthanide, an amino acid, a nucleic acid, an oligonucleotide, a therapeutic agent, a biological molecule, a metabolite of a therapeutic agent, a peptide, a polypeptide, a protein, a carbohydrate, a polysaccharide and/or insulin;   wherein said condition is a concentration of an analyte in said body (e.g., glucose); and/or   wherein said smart device is configured to operate in an open loop.   
     
     
         21 . A smart device for delivery or release of a moiety into a body, the smart device comprising:
 a sensing element implantable within a body, said sensing element comprising at least one nanoparticle, said nanoparticle comprising a polymer matrix layer about a magnetic core, said polymer matrix layer responsive to a condition of a volume of fluid in contact with said nanoparticle;   a miniaturized NMR detector functioning in conjunction with said sensing element to detect an echo RF signal from said volume of fluid following RF excitation of said volume;   a processor configured to determine a measurement of said condition based at least in part on said detected echo RF signal;   a stimulus emitter configured to emit a stimulus in response to said measurement of said condition;   a control release element configured to release or deliver a moiety out of said polymer matrix layer (e.g., and into a body) upon receiving said stimulus; and   a power source for powering operation of said smart device.   
     
     
         22 . The smart device of  claim 21 , wherein said smart device is configured to operate in a closed loop. 
     
     
         23 . A method for detection of an analyte in a sample, the method comprising:
 (a) providing nanosensors, wherein the nanosensors comprise magnetic nanoparticles linked to an analyte or analog thereof, and one or more binding moieties linked thereto, the binding moieties responsive to said analyte or analog thereof;   (b) providing a fluid sample and placing the sample and the nanosensors in a container under conditions and for a sufficient period of time to allow analyte in the sample to bind to and compete off the binding moiety from the nanosensor;   (c) placing the container in proximity to an NMR detector;   (d) measuring one or more relaxivity parameters of the sample in the container; and   (e) determining one or more attributes relative to the sample;   wherein the nanoparticle, binding moiety and analyte or analog thereof linked to the nanoparticle are size optimized to confer optimal relaxation measurements.   
     
     
         24 . A method for detection of an analyte in a sample, the method comprising:
 (a) providing a fluid sample and one or more binding moieties, the binding moieties responsive to a target analyte or analog thereof and placing the sample and binding moieties under conditions and for a sufficient period of time to allow analyte in the sample to bind to binding moiety;   (b) providing nanosensors comprising magnetic nanoparticles linked to analyte or an analog thereof;   (c) placing the pre-incubated sample and binding moiety and the nanosensors in a container under conditions and for a sufficient period of time to allow analyte linked to nanosensors to bind to and compete off the binding moiety from the analyte in the sample;   (d) placing the container in proximity to an NMR detector;   (e) measuring one or more relaxivity parameters of the sample in the container; and   (f) determining one or more attributes relative to the sample;   wherein the nanoparticle, binding moiety and analyte or analog thereof linked to the nanoparticle are size optimized to confer optimal relaxation measurements.   
     
     
         25 . The method of  claim 23  or  claim 24 , wherein the attribute is selected from the group consisting of presence of the analyte, amount of the analyte and concentration of the analyte. 
     
     
         26 . The method of  claim 23  or  claim 24 , wherein the analyte comprises at least one member selected from the group consisting of a protein, a peptide, a polypeptide, an amino acid, a nucleic acid, an oligonucleotide, a therapeutic agent, a metabolite of a therapeutic agent, RNA, DNA, an antibody, an organism, a virus, a bacteria, a carbohydrate, and a polysaccharide. 
     
     
         27 . The method of  claim 23  or  claim 24 , wherein the binding moiety comprises an antibody or a conjugated antibody. 
     
     
         28 . The method of  claim 27 , wherein the antibody is a monoclonal antibody. 
     
     
         29 . The method of  claim 23  or  claim 24 , wherein the fluid sample is water, saline, buffered saline, or a biological fluid. 
     
     
         30 . The method of  claim 29 , wherein the biological fluid is blood, a cell homogenate, a tissue homogenate, a cell extract, a tissue extract, a cell suspension, a tissue suspension, milk, urine, saliva, semen, or spinal fluid.