Miniaturized NMR

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Abstract The NMR-based detector includes a microcoil and a magnetic field generator, such as one or more low field permanent magnets or electromagnets, to establish a magnetic field of about 0.5 to about 1.5 T (Tesla) with energization of the microcoil at a frequency that permits detection by NMR of one or more labeled biological objects present in the fluid in the conduit. The NMR-based detector can provide capability of performing routine relaxation time measurements and low-field spectroscopy for the detection of dilute concentrations of magnetic nanoparticle-labeled biological objects in biological fluids such as blood, saliva, and serum as well as aqueous fluids such as drinking water and aqueous industrial waste or effluent streams or spills.   Background: Nuclear magnetic resonance (NMR) spectroscopy is widely used for the real-time identification of chemical compounds in solids, liquids, and gases because it can easily detect and characterize all components of mixtures without requiring separations. Unfortunately, standard high-resolution NMR spectroscopy is not useful for directly detecting dilute biological objects, such as tumor cells, bacteria, bacterial toxins, or viruses, in fluid samples. The weak signals from the analytes in the dilute species are lost against the much stronger background water signal. Even if the dynamic range challenge is met by suppressing the bulk water signal or concentrating the dilute species, the rapid transverse relaxation characteristics of macromolecular, viral, or cellular samples renders their direct detection by NMR difficult. Recent developments involving superparamagnetic iron oxide nanoparticles (SPIONs) have, however, supplied the basis for new applications of NMR with high sensitivity and specificity for the detection and quantitation of dilute biological materials in fluids, such as cancer cells in blood or urine samples, or bacterial contaminants in food products or drinking water.  In recent years, significant advances in the development and fabrication of microcoils (size <1 mm) for NMR have continued. Both planar surface microcoils and solenoidal microcoils have been developed. To enhance sensitivity for tiny samples, much of the work with microcoils has utilized the high fields produced by strong superconducting magnets.   Description: Researchers have developed a NMR-based biological detector and detection method using one or more magnetic nanoparticle-labeled biological objects in a fluid, such as water. The NMR-based detector includes a microcoil and a magnetic field generator, such as one or more low field permanent magnets or electromagnets, to establish a magnetic field of about 0.5 to about 1.5 T (Tesla) with energization of the microcoil at a frequency that permits detection by NMR of one or more labeled biological objects present in the fluid in the conduit. The NMR-based detector can provide capability of performing routine relaxation time measurements and low-field spectroscopy for the detection of dilute concentrations of magnetic nanoparticle-labeled biological objects in biological fluids such as blood, saliva, and serum as well as aqueous fluids such as drinking water and aqueous industrial waste or effluent streams or spills. Such biological objects include, but are not limited to, cancer cells in blood or urine samples, bacterial contaminants in food products or drinking water, and biological warfare agents in aqueous media. The biological objects of the fluid are labeled using specific biological ligands (e.g. antibodies), which are carried on super-paramagnetic or other magnetic nanoparticles detectable by NMR. The nanoparticles can include, but are not limited to, superparamagnetic iron oxide nanoparticles (SPIONs), or nanoparticles made out of cobalt, manganese, nickel, or other small paramagnetic materials.   Advantages: NMR-based biological detector Useful for detecting dilute biological and chemical hazard Relates to a NMR-based biological detector and detection method that involve NMR detection of magnetic nanoparticle-labeled biological objects using a microcoil