Systems and methods for the production of hyperpolarized materials - Patents.com

Abstract

A system and method for increasing the nuclear spin polarization of a target compound are disclosed. According to such a system and method, a first non-thermal equilibrium nuclear spin polarization may be imparted to source atoms of at least one source compound, the source atoms having a nuclear gyromagnetic ratio of at least 12 megahertz per Tesla (MHz / T). A first solution including a source compound and a target compound can be obtained. The at least one source atom can be present in the first solution at a source concentration of at least 0.1 molar (M). A second non-thermal equilibrium nuclear spin polarization of at least 0.01% can be imparted to at least one target atom of the target compound via a Nuclear Overhauser Effect (NOE) transfer of the first non-thermal equilibrium nuclear spin polarization to at least one target atom.

Description

[Technical field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 143,794, filed January 30, 2021. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 147,263, filed February 9, 2021. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 164,675, filed March 23, 2021. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 201,153, filed April 15, 2021. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 260,174, filed August 11, 2021. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 261,152, filed September 14, 2021. Each of these applications is incorporated herein by reference in its entirety.

[0002] The disclosed embodiments relate generally to the production of hyperpolarized materials for use in nuclear magnetic resonance, magnetic resonance imaging, or similar applications. [Background technology]

[0003] Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are techniques with important applications in chemistry, biology, and medical imaging. Despite their success, nuclear magnetic resonance applications require minute nuclear polarization of the analyte (typically 10 -5 It is recognized that there is a limitation due to the small nuclear polarization (on the order of 100 nm). This small nuclear polarization can result in limited sensitivity compared to other analytical techniques such as mass spectrometry.

[0004] Increasing the nuclear spin polarization beyond the thermal equilibrium value can improve magnetic resonance sensitivity. Nuclear spin polarization can be increased using known techniques such as dynamic nuclear polarization. Using such techniques, the nuclear spin polarization of a material can be increased by more than 10,000 times. The enhanced nuclear spin polarization can result in a proportionate increase in NMR / MRI signal. This enhanced polarization decays over time due to the relaxation time of the nuclear spins in the polarized molecules, but for many molecules, the relaxation times can be on the order of seconds to minutes, during which an increase in polarization can result in a dramatic increase in NMR / MRI signal sensitivity. By enabling such a dramatic increase in NMR / MRI signal sensitivity, the increase in nuclear spin polarization can enable new applications such as imaging of in vivo metabolism using metabolites with increased nuclear spin polarization in MRI scanners, accelerating the investigation of single-signal NMR spectroscopy and enabling the visualization of previously invisible molecular dynamics and structures. Summary of the Invention

[0005] According to the present disclosure, the intermolecular nuclear Overhauser effect can be used to transfer polarization from a polarized source compound to a target compound. The polarized target compound can then be used in nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) applications.

[0006] Disclosed embodiments include a method of increasing nuclear spin polarization of a target compound. The method may include an act of imparting a first non-thermal equilibrium nuclear spin polarization of at least 1% to at least one source atom of a source compound, the source atom having a nuclear gyromagnetic ratio of at least 12 megahertz per Tesla (MHz / T). The method may include an act of obtaining a first solution. The first solution may include a source compound and a target compound. The at least one source atom may be present in the first solution at a source concentration of at least 0.1 molar (M). The method may include an act of imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.01% to at least one target atom of the target compound via Nuclear Overhauser Effect (NOE) transfer of the first non-thermal equilibrium nuclear spin polarization to the at least one target atom.

[0007] Disclosed embodiments include a system for increasing nuclear spin polarization of a target compound. The system may include a first solution receiving module configured to receive a first solution. The first solution may include a source compound dissolved therein, the source compound including at least one source atom, and the at least one source non-carbon atom is present in the first solution at a source concentration of at least 0.1 molar (M). The system may include a polarization module coupled to the first solution receiving module, the polarization module configured to impart a first non-thermal equilibrium nuclear spin polarization of at least 1% to the at least one source atom of the source compound. The system may include a second solution receiving module configured to receive a second solution. The second solution may include a target compound dissolved therein. The system can include a mixing module fluidly coupled to the polarization module and the second solution receiving module, the mixing module being configured to mix the first solution and the second solution, thereby allowing a first non-thermal equilibrium nuclear spin polarization to be transferred to at least one target atom of the target compound via Nuclear Overhauser Effect (NOE) transfer, thereby imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.01% to at least one target atom of the target compound.

[0008] Disclosed embodiments may include a system for increasing nuclear spin polarization of a target compound. The system may include a container. The container may include an internal volume configured to accommodate a source compound. The source compound may include at least one PETS portion. The container may include a first magnetic field source at least partially surrounding the internal volume and configured to generate a first magnetic field within the internal volume. The container may include at least one optical window configured to couple to a light source thereby permitting optical polarization of the at least one PETS portion. The container may include at least one container port configured to permit passage of the source compound therethrough. The system may include a solution preparation system. The source preparation system may include a dissolution vessel coupled to the at least one container port and configured to receive the source compound after passage of the source compound through the at least one container port and to receive a first solution including a pressurized gas and a compound dissolved therein. The source preparation system may include a second magnetic field source at least partially surrounding the dissolution vessel and configured to generate a second magnetic field within the dissolution vessel. The source preparation system may include a grinding head positioned within the dissolution vessel and configured to grind the source compound, thereby allowing dissolution of the source compound in the first solution, thereby generating the second solution. The source preparation system may include at least one solution port configured to allow passage of the second solution therethrough.

[0009] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the disclosed embodiments, as claimed.

[0010] The accompanying drawings, which form a part of this specification, illustrate several embodiments and, together with the description, serve to explain principles and features of the disclosed embodiments. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates an exemplary process 100 for the preparation and use of a target compound in an NMR spectroscopy or MRI application, according to disclosed embodiments. [Figure 2A] FIG. 2A illustrates the incorporation of pentacene dopants into naphthalene crystals according to disclosed embodiments. [Figure 2B] FIG. 2B shows naphthalene crystals doped with pentacene according to disclosed embodiments. [Figure 3A] FIG. 3A illustrates spin transfer of an exemplary dynamic nuclear polarization (DNP) method that uses solid effects to achieve spin transfer in accordance with disclosed embodiments. [Figure 3B] FIG. 3B illustrates spin transfer of an exemplary dynamic nuclear polarization (DNP) method that uses solid effects to achieve spin transfer in accordance with disclosed embodiments. [Figure 4] FIG. 4 illustrates an exemplary sequence of light illumination, magnetic field sweeps, and electromagnetic illumination suitable for inducing polarization in a compound according to disclosed embodiments. [Diagram 5] FIG. 5 shows NMR signal readouts from a compound before and after repeating the polarization sequence shown in FIG. 4 in accordance with a disclosed embodiment. [Figure 6] FIG. 6 illustrates an exemplary parahydrogen induced polarization (PHIP) precipitation transfer process according to disclosed embodiments. [Figure 7A] FIG. 7A shows measurement of target thermal T1=1 / ρ relaxation times using a standard non-selective inversion recovery sequence for naphthalene and acetone according to disclosed embodiments. [Figure 7B] FIG. 7B shows the steady-state saturation transfer of naphthalene to acetone according to disclosed embodiments. [Figure 8A] FIG. 8A shows measurement of target thermal T1=1 / ρ relaxation times using a standard non-selective inversion recovery sequence for naphthalene and 1,1,2,2-trichloroethylene (TCE) in accordance with disclosed embodiments. [Figure 8B] FIG. 8B shows the steady-state saturation transfer of naphthalene to TCE according to disclosed embodiments. [Figure 9A] FIG. 9A shows the build-up and decay of polarization of acetone at 1.45 T when a naphthalene source is optically polarized prior to dissolution in a target solution according to disclosed embodiments. [Figure 9B] FIG. 9B shows the frequency shift of the acetone resonance according to disclosed embodiments. [Figure 10A] FIG. 10A shows the build-up and decay of polarization of TCE at 1.45 T when the naphthalene source is optically polarized prior to dissolution in the target solution according to disclosed embodiments. [Figure 10B] FIG. 10B shows the frequency shift of the resonance of TCE according to the disclosed embodiments. [Figure 10C] FIG. 10C illustrates a post-processing method for separating the effects of the sample magnetic field and source compound signals from the remainder of the acquired NMR spectrum according to disclosed embodiments. [Figure 10D] FIG. 10D illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10E] FIG. 10E illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10F] FIG. 10F illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10G] FIG. 10G illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10H] FIG. 10H illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10I] FIG. 10I illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10J] FIG. 10J illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 10K] FIG. 10K illustrates the effect of the method steps of FIG. 10C on an exemplary acquired NMR spectrum, according to disclosed embodiments. [Figure 11] FIG. 11 illustrates an exemplary PHIP precipitation system and process consistent with disclosed embodiments. [Figure 12] FIG. 12 shows an overview of the setup and components of a photoexcited triplet state (PETS) polarizer according to disclosed embodiments. [Figure 13] FIG. 13 illustrates an exemplary transport system consistent with disclosed embodiments. [Figure 14] FIG. 14 illustrates an exemplary system for automatically combining a solid source compound with a target compound, consistent with disclosed embodiments. [Figure 15] FIG. 15 shows a series of NMR spectra acquired after injection of a hyperpolarized solution into a spectrometer according to disclosed embodiments. [Figure 16A] FIG. 16A shows the relationship between the phase of the target resonance and the width of the radiation attenuation signal, according to disclosed embodiments. [Figure 16B] FIG. 16B shows the enhancement curves estimated for each proton site using the preceding procedure, according to the disclosed embodiments. [Figure 17] FIG. 17 shows a spectrum acquired 35 seconds after injection into the spectrometer compared to an average 90 degree flip angle thermal spectrum according to disclosed embodiments. [Figure 18A] FIG. 18A shows an accumulation curve probed at a 1 degree flip angle for propargyl acetate, according to a disclosed embodiment. [Figure 18B] FIG. 18B shows the hyperpolarized spectrum of propargyl acetate compared to the average 90 degree flip angle thermal spectrum in accordance with disclosed embodiments. [Figure 18C] FIG. 18C shows the polarization enhancement over time for a solution containing TCE, dichloromethane (DCM), tetrahydrofuran (THF), and acetone, according to disclosed embodiments. [Figure 18D]FIG. 18D shows the hyperpolarized spectrum of the solution of FIG. 18C compared to the average, 90 degree flip angle thermal spectrum according to disclosed embodiments. [Figure 19] FIG. 19 shows a single-shot hyperpolarized spectrum of propargyl acetate following a 2° flip angle pulse using PHIP-polarized methyl maleate as the source, compared to a single-shot thermal equilibrium spectrum of the same mixture acquired after a 90° flip angle pulse, in accordance with disclosed embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Exemplary embodiments will now be described in detail and discussed with reference to the accompanying drawings. In some instances, the same reference numbers are used throughout the drawings, and the following description refers to the same or similar parts. Unless otherwise defined, technical and / or scientific terms have the meanings commonly understood by those skilled in the art. The disclosed embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosed embodiments. It will be understood that other embodiments may be utilized and changes may be made without departing from the scope of the disclosed embodiments. Accordingly, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0013] NMR spectroscopy can be used for applications ranging from determining chemical structures in synthetic intermediates to determining atomic-level structure and dynamics in proteins and nucleic acids. However, NMR spectroscopy can be limited in sensitivity due to the small size of nuclear magnetic moments combined with the corresponding small polarization at thermal equilibrium. This limited sensitivity may prevent the use of NMR spectroscopy in some applications and can make other applications of NMR spectroscopy impractical in time or material requirements.

[0014] NMR sensitivity can be improved by the use of higher magnetic fields and optimized detection systems. However, an alternative approach is to increase NMR sensitivity by increasing the nuclear spin polarization to levels significantly higher than thermal equilibrium. Such hyperpolarization techniques may enable new NMR spectroscopy applications, such as the observation of low-gamma nuclei or low-concentration analytes.

[0015] Nuclear spin polarization can be increased using a variety of techniques, including dynamic nuclear polarization (DNP), parahydrogen-induced polarization (PHIP), spin-exchange optical pumping (SEOP), optically initialized electronic triplet states (also referred to herein as photoexcited triplet states (PTES)), and other suitable methods. DNP can increase nuclear spin polarization in a wide range of materials, but may require equipment capable of generating cryogenic temperatures and high magnetic fields (e.g., melt dynamic nuclear polarization, etc.) or equipment that provides only limited signal enhancement (e.g., Overhauser DNP, etc.). Parahydrogen-induced polarization (PHIP) and spin-exchange optical pumping (SEOP) can generate high polarization levels, but only in certain suitable materials.

[0016] Polarization via optically initialized electronic triplet states (e.g., in organic molecular crystals, or in nitrogen vacancies (NVs) or other defect centers) can produce high polarization levels in certain suitable materials. Such optical polarization methods also benefit from reduced equipment requirements and can produce polarized materials with long relaxation times. Optical polarization methods can produce nuclear spin polarization at room temperature and low magnetic fields (<1 T) to more than a few tens of percent. The polarization rate can be controlled by the optical pump speed. The relaxation time of the nuclear spins after polarization can be very long, since paramagnetic electrons can only exist under laser irradiation. For example, in naphthalene crystals doped with pentacene 1 H nuclei are polarized up to 80% polarization and have a lifetime of about 50 hours at liquid nitrogen temperatures, long enough to be transported to remote facilities.

[0017] A convenient method of polarization transfer can allow for the separation of the originally polarized material (e.g., source compound) from the material used in NMR spectroscopy (e.g., target compound). Although referred to herein as a source compound, the originally polarized material may include a source molecule or source material. Although referred to herein as a target compound, the material used in NMR spectroscopy may include a target molecule or target material. The source compound can then be selected based on the polarization method (e.g., DNP, PHIP, SEOP, optical polarization, etc.), relaxation time, ease of preparation, ease of separation from the target compound, ease of transportation, or other technical concerns. The target compound can be selected based on the NMR spectroscopy application of interest. Thus, separating the technical requirements of polarization from the technical requirements of NMR spectroscopy can address the technical problem of obtaining high nuclear spin polarization in a suitable target compound.

[0018] The disclosed embodiments transfer polarization using the intermolecular Nuclear Overhauser Effect (NOE). The disclosed embodiments can provide NMR signal enhancement for a variety of source and target compounds. The disclosed polarization transfer from source to target compounds can occur on time scales of minutes or less, and in some embodiments may not require cryogenic temperatures. Furthermore, because of the absence of paramagnetic contaminants, target compounds polarized using the disclosed embodiments can be used to generate high-resolution NMR spectra. Unlike conventional polarization transfer systems, the disclosed embodiments can be automated, can operate at room temperature, and can be used with existing equipment.

[0019] As described herein, the disclosed embodiments can be used to polarize molecules and molecular mixtures. Signal enhancements of over 200 times and up to 1730 times or more (corresponding to 0.86% polarization or more) can be achieved at a field strength of 1.45 T for the benchmark molecule propargyl acetate.

[0020] "Polarization" may include imbalance in electronic or nuclear spin orientation. In some embodiments, polarization may be the normalized, approximate difference between the number of spins in a first direction minus the number of spins in the opposite direction. As a non-limiting example, 200,000 1 Assuming a nuclear spin of H, a polarization of 2% can correspond to 102,000 spins in a first direction and 98,000 spins in the opposite direction. In some embodiments, "hyperpolarization" can include the polarization of a species (e.g., nuclear, selective, or the like) that exceeds the typical polarization level of that species observed at thermal equilibrium upon exposure to a particular magnetic field. As a non-limiting example, 1 A sample in a magnetic field of 1 T at thermal equilibrium where the H nuclear spin polarization exceeds 0.000341% is substantially higher (e.g., at least one or more orders of magnitude higher) than the 0.000341% thermal equilibrium polarization. 1 As a further non-limiting example, the ion beam may be hyperpolarized to have a H nuclear spin polarization of greater than 0.000257%. 13 A sample in a magnetic field of 3 T at thermal equilibrium with a spin polarization of C can be hyperpolarized. 15 A sample in a magnetic field of 3 T at thermal equilibrium with a spin polarization of N can be hyperpolarized.

[0021] PETS (photoexcited triplet state) materials may include polarized molecules having electron spins of greater than 0.1% polarization, 1% polarization, 2% polarization, 3% polarization, 4% polarization, 5% polarization, 6% polarization, 7% polarization, 8% polarization, 9% polarization, 10% polarization, 20% polarization, 30% polarization, 40% polarization, 50% polarization, 60% polarization, 70% polarization, 80% polarization, or more when exposed to appropriate optical radiation. In some embodiments, the polarizable material may have triplet spin states. In some embodiments, appropriate optical irradiation may induce electronic polarization through an initial selection population of triplet spin states. In various embodiments, appropriate optical radiation may induce electronic polarization through differential decay rates in triplet spin states. In some embodiments, suitable light exposure can induce electron polarization through a combination of a reversal pulse and differential decay rates between triplet states after light exposure.

[0022] In some embodiments, the nuclear spins of the PETS material may be suitable for polarization using the spin-polarized electronic triplet states of the PETS material. For example, in some embodiments, the spin order associated with the spin-polarized electronic triplet states of the PETS material may be transferred to the nuclei within the PETS material. The spin-polarized photoexcited electronic triplet states can provide on-demand electronic polarization over a wide range of magnetic fields and temperatures, even in combinations where the thermal electronic polarization is orders of magnitude less than unity. Furthermore, the photoexcitable triplet states can have a singlet ground level to which they decay. Thus, whenever an electron is not excited to an excited state, it is not a paramagnetic center and does not cause relaxation. Thus, the PETS material may have a nuclear relaxation time at or above liquid nitrogen temperatures of more than 1 hour, more than 2 hours, more than 5 hours, more than 10 hours, more than 20 hours, more than 50 hours, or more, in the absence of photoirradiation. In some embodiments, the PETS material may include a combination of a polarizable material and a host material. The host material may be, for example, naphthalene.

[0023] A "porous" material can be a material that contains voids. In some embodiments, the ratio between the surface area of ​​the voids in the volume of porous material and the surface area of ​​the volume of porous material can be 1, 10, 100, 1000, 10000, or greater than 10000. Accessible voids are voids that are accessible from the envelope surface of the volume of porous material (e.g., open cells as opposed to closed cells).

[0024] A "microparticle" may be a particle smaller than 1000 micrometers (μm), 500 μm, 200 μm, 100 μm, 50 μm, 20 μm, 10 μm, 5 μm, 2 μm, or 1 μm in at least one dimension (e.g., less than 200 μm in two or three dimensions). In some embodiments, the microparticle may be spherical. In various embodiments, the microparticle may have a single dimension that is significantly larger than other dimensions. For example, in some embodiments, the microparticle may be rod-shaped or fiber-shaped. In such embodiments, the length of a rod- or fiber-like microparticle may be smaller than 1000 μm, 500 μm, 200 μm, 100 μm, 50 μm, 20 μm, 10 μm, 5 μm, 2 μm, or 1 μm. Similarly, a "nanoparticle" can be a particle smaller than 1000 nanometers (nm), 500 nm, 200 nm, 100 nm, 50 nm, 20 nm, 10 nm, 5 nm, 2 nm, or 1 nm in at least one dimension (e.g., smaller than 200 nm in two or three dimensions). In some embodiments, the nanoparticle can be spherical. In various embodiments, the nanoparticle can have a single dimension that is significantly larger than the other dimensions. For example, in some embodiments, the nanoparticle can be rod-shaped or fiber-shaped. In such embodiments, the length of the rod- or fiber-like nanoparticle can be smaller than 1000 nm, 500 nm, 200 nm, 100 nm, 50 nm, 20 nm, 10 nm, 5 nm, 2 nm, or 1 nm. In some embodiments, the microparticles or nanoparticles can be densely packed, thereby producing a semi-polycrystalline structure. As used herein, unless otherwise specified, a "particle" can be a nanoparticle or a microparticle. The semi-polycrystalline structure can be porous and have accessible voids.

[0025] overview

[0026] FIG. 1 illustrates an exemplary process 100 for preparation and use of target compounds in NMR spectroscopy and MRI applications according to disclosed embodiments. Process 100 separates the initial polarization of the source compound from the polarization of the target compound used in the NMR spectroscopy or MRI application. Instead, the source compound is polarized and then the polarization is transferred to the target compound. Process 100 may optionally include transporting the polarized source compound and separating the polarized target compound from the source compound prior to using the target compound in the spectroscopy or imaging application. Process 100 may allow for greater flexibility in the selection of polarization method, source material, target material, and polarization position. Process 100 may thus improve NMR spectroscopy or MRI by enabling the production of more highly polarized target materials and increasing NMR or MRI sensitivity.

[0027] At step 110 of process 100, a polarized source compound can be obtained. In some implementations, obtaining a source compound can include generating a source compound. Consistent with disclosed embodiments, obtaining a polarized source compound can include placing the source compound in a solution. In some embodiments, the source compound can be present in the solution at a source compound concentration of at least 0.01 molar (M), 0.02M, 0.05M, at least 0.1M, at least 0.2M, at least 0.5M, 1M, at least 2M, at least 5M, or at least 10M. The concentration of the source compound can be selected to allow for substantial polarization of the source compound. In some embodiments, the source compound can include at least one source atom. In some embodiments, the source atom can be present in the solution at a source atom concentration of at least 0.01M, 0.02M, 0.05M, 0.1M, at least 0.2M, at least 0.5M, at least 1M, at least 2M, at least 5M, or at least 10M. In step 110, polarizing the source compound can include polarizing at least one source atom. In some embodiments, the ability to transfer polarization between source and target atoms by NOE can depend on the gyromagnetic ratio of the source atom, with a high gyromagnetic ratio enhancing polarization transfer. In such embodiments, the source atom can have a gyromagnetic ratio of at least 12 megahertz per Tesla (MHz / T), at least 14 MHz / T, at least 16 MHz / T, at least 18 MHz / T, at least 20 MHz / T, at least 22 MHz / T, at least 24 MHz / T, at least 26 MHz / T, at least 28 MHz / T, at least 30 MHz / T, at least 32 MHz / T, at least 34 MHz / T, at least 36 MHz / T, at least 38 MHz / T, at least 40 MHz / T, at least 42 MHz / T, or at least 44 MHz / T.For example, the source atoms can be hydrogen atoms (e.g., a gyromagnetic ratio of 42.58 MHz / T), tritium atoms (e.g., a gyromagnetic ratio of 45.42 MHz / T), fluorine-19 atoms (e.g., a gyromagnetic ratio of 40.08 MHz / T), phosphorus-31 atoms (e.g., a gyromagnetic ratio of 17.25 MHz / T), or the like.

[0028] In some embodiments, the source compound may be a molecule and the source atom may be part of that molecule. For example, if the source compound is naphthalene, the source atom may be 1 As an additional example, when the source compound is fluorostyrene, the source atom can be 19 As a further example, if the source compound is triphenylphosphine, the source atom can be 31 In various embodiments, the source compound may be a combination of molecules and the source atom may be part of one of these molecules. For example, the source compound may be a crystalline host that may include a dopant molecule. The source atom may be part of a dopant molecule. In some embodiments, the crystalline host may be or include naphthalene, p-terphenyl, or benzoic acid. In various embodiments, the dopant may be or include pentacene.

[0029] In some embodiments, the solution can be an organic solution. In some embodiments, the organic solution is a common organic solution used in NMR spectroscopy, such as acetone, chloroform, DMSO, toluene, ethyl acetate, benzene, methanol, ethanol, other short alcohols, or deuterated versions thereof. In some embodiments, the solution is an aqueous solution. In some embodiments, the solution can be selected such that the source compound is at least partially soluble in the solution. For example, if the source compound is naphthalene, the solution can be deuterated acetone, DMSO, methanol, or chloroform.

[0030] Consistent with disclosed embodiments, obtaining a polarized source compound can include polarizing the source compound. The disclosed embodiments are not limited to a particular method of polarizing the source compound. In some embodiments, the source compound can be polarized using dynamic nuclear polarization (DNP), optical polarization, parahydrogen induced polarization (PHIP), or parahydrogen induced polarization by side-arm hydrogenation (PHIP-SAH), signal amplification by reversible exchange (SABRE), or another suitable method.

[0031] Consistent with the disclosed embodiments, the source compound can be polarized using DNP at low temperature and high magnetic field. In some implementations, the free electron spins in the radicals or paramagnetic defects of the source compound can be highly polarized at thermodynamic equilibrium at temperatures below 4K and magnetic fields above 1T. Using the DNP protocol, this high thermal polarization of electrons can be transferred to the nuclear spins in the source compound. In some embodiments, after polarization, the compound can be dissolved in a solution where dissolution DNP is performed.

[0032] Consistent with the disclosed embodiments, the source compound can be optically polarized. In some embodiments, the optical polarization can use optical defects such as color centers. In such methods, optically active defects in semiconductors such as diamond and silicon carbide can be used to polarize the surrounding nuclear spins. In various embodiments, the optical polarization can hyperpolarize the nuclear spins in the PETS compound by polarization transfer from optically polarizable electron spins to the nuclear spins in the PETS polarized molecules. Figures 2-5 show the generation of polarized source compounds using optically initialized electronic triplet states.

[0033] Consistent with the disclosed embodiments, the source compound may be polarized using PHIP, PHIP-SAH, or SABRE. Parahydrogen, orthodeuteurium, or paratritium may be used to induce an electronic spin order in the source compound, which may be converted to nuclear spin polarization (e.g., via application of an appropriate RF pulse sequence, etc.). In SABRE embodiments, a catalyst may bind the source compound and parahydrogen, orthodeuteurium, or paratritium. The source compound may be polarized while bound to the catalyst. In PIP or PHIP-SAH embodiments, the precursor compound may be hydrogenated (e.g., using parahydrogen, orthodeuteurium, or paratritium) to form a parahydrogenated, orthodeuterated, or paratritized precursor, respectively. In PHIP embodiments, the hydrogenated precursor may be polarized to form the source compound, while in PHIP-SAH embodiments, the hydrogenated precursor may be polarized and a side arm may be cleaved to form the source compound. In some embodiments, the hydrogenation catalyst and / or reaction by-products can be separated from the source compound. In some embodiments, the source compound can be precipitated or solidified. Figure 6 shows the generation of polarized source compounds using PHIP.

[0034] In some embodiments, polarizing the source compound can include hyperpolarizing at least one source atom of the source compound. As described herein, such hyperpolarization can include increasing the level of polarization of the at least one source atom above that observed at thermal equilibrium. In some embodiments, the non-thermal equilibrium polarization imparted to the at least one source atom can be greater than at least 1%. In various embodiments, the non-thermal equilibrium polarization imparted to the at least one source atom can be greater than at least 2%, 5%, 10%, 20%, or 50%.

[0035] In optional step 120, if the source compound is polarized in solution (e.g., if the source compound is polarized using PHIP, PHIP-SAH, or SABRE), the source compound can be extracted from the solution or undesired solutes can be removed from the solution. Such undesired solutes can include hydrogenation catalysts and reaction by-products. The disclosed embodiments are not limited to any particular method of separating the source compound. In some embodiments, the concentration of the compound increases during separation. In some embodiments, the separation is performed by liquid-liquid separation. In various embodiments, the source compound (or undesired solutes) can be extracted from the solution by precipitation or solidification. Such precipitation or solidification can be induced to reduce the solubility of the source compound in the solution. In some embodiments, the solution can be modified (e.g., by changing the pH of the solution, temperature, adding other solvents or solvents, or the like). In various embodiments, the precursor molecule to the source compound may be modified. For example, a side arm of the precursor molecule may be cleaved to form the source compound. The source compound may become less soluble in the solution than the precursor, causing the source compound to precipitate. In some embodiments, after precipitation, the precipitated source compound may be separated from the solution (e.g., using a filter, a centrifuge, or another suitable method).

[0036] In an optional step 130 of the process 100, the polarized source compound can be transported. In some embodiments, the polarized source compound can be made in a facility separate from the facility where the NMR spectroscopy is previously performed. For example, the polarized source compound can be produced in a facility dedicated to the production of the polarized source compound, while the NMR spectroscopy is performed in one of many facilities that require the polarized target compound. In this manner, efficiencies of scale can be realized in the production of the source compound. In some embodiments, the polarized source compound can be transported for a period of time greater than 30 minutes, or 1 hour, or 2 hours, or 5 hours, or 10 hours, or more. The polarized source compound can be transported in a cryogenic container. The polarized source compound can be subjected to a predetermined magnetic field during transport. In some embodiments, the predetermined magnetic field can be greater than the magnetic field of the Earth. FIG. 9 shows an exemplary container for transporting the polarized source compound.

[0037] In step 130 of step 100, polarization may be transferred to a target compound. In preparation for polarization transfer, the target compound and the source compound may be combined. In some embodiments, the source compounds may be combined in solid form. The solid source compound may be combined with the solid target compound. The combined compounds may then be mixed into a solution. The solid source compound may be redissolved in the solution. This solution may contain the target compound, or the target compound may be added later.

[0038] As can be appreciated, precipitating and redissolving the source compound allows for separate preparation of a solution in which the source compound is polarized (first solution) and a solution in which polarization transfer occurs (second solution). The properties of the first solution (e.g., biocompatibility, concentration, volume, temperature, pH, polarity, or other relevant properties) may be different from those of the second solution. For example, the concentrations of the source compound may be different in the original and subsequent solutions. A lower concentration of the source compound in the original solution of step 110 allows for greater polarization of the source compound. A higher concentration of the source compound in the subsequent solution of step 140 allows for greater polarization transfer from the source compound to the target compound.

[0039] In some embodiments, the source compound or target compound can remain solid, semi-solid, or suspended in solution.For example, the source compound or target compound can be incorporated into a surface, solid, film, nanoparticle, or microparticle.In such embodiments, the polarization of the target atom can then occur by cross relaxation at the liquid-solid interface.

[0040] In some embodiments, the source compounds can be combined in solution. In such embodiments, optional step 120 may not be performed. The source compounds can remain in solution in step 110. The target compounds can be dissolved in the source compound solution, or a solution containing the target compounds can be added to the source compound solution.

[0041] In some embodiments, the target compound can be or include a small molecule (e.g., a molecule having a molecular weight less than 1000 Daltons, 900 Daltons, 800 Daltons, 700 Daltons, 600 Daltons, 500 Daltons, 400 Daltons, 300 Daltons, 200 Daltons, or 100 Daltons), a peptide, a polypeptide, a protein, a nucleic acid, a ribonucleic acid, a deoxyribonucleic acid, a carbohydrate, a polymer, or other suitable target compound. In some embodiments, the target compound can be a particle suspended in a solution or impregnated with a solution. In some embodiments, the target compound can be a surface of a solid or thin material in contact with the solution. In some embodiments, the target compound can be a non-crystalline structure in contact with the solution, such as a gel, a membrane, a polymer, or a porous material. Transferring the polarization to the target compound can include transferring the polarization from at least one source atom of the source compound to the nuclear spin polarization of at least one target atom of the target compound. The target atom can be selected based on the intended NMR spectroscopy application. In some embodiments, the target atom can be hydrogen, tritium, carbon-13, nitrogen-15, fluorine-19, silicon-29, phosphorus-31, iron-57, selenium-77, yttrium-89, rhodium-103, silver-107, silver-109, cadmium-111, cadmium-113, tin-117, tin-119, tellurium-123, tellurium-125, thulium-169, ytterbium-171, tungsten-183, osmium-187, platinum-195, mercury-199, thallium-203, thallium-205, lead-207, polonium-209, or plutonium-239. In some embodiments, the target atom can have a nuclear spin of 1 / 2. In other embodiments, the target atom can have one or more nuclear spins.

[0042] In some embodiments, the ability to transfer polarization from the source atom to the nuclear spin polarization of the target atom may depend on the electron cloud size of the target atom (e.g., a lower electron cloud size improves the ability to transfer polarization by decreasing the minimum distance to other molecules) and the gyromagnetic ratio of the target atom (e.g., increasing the gyromagnetic ratio improves the ability to transfer polarization). In some embodiments, the target atom has a gyromagnetic ratio of at least 2 MHz / T, at least 4 MHz / T, at least 6 MHz / T, at least 8 MHz / T, at least 10 MHz / T, at least 12 MHz / T, at least 14 MHz / T, at least 16 MHz / T, at least 18 MHz / T, at least 20 MHz / T, at least 22 MHz / T, at least 24 MHz / T, at least 26 MHz / T, at least 28 MHz / T, at least 30 MHz / T, at least 32 MHz / T, at least 34 MHz / T, at least 36 MHz / T, at least 38 MHz / T, at least 40 MHz / T, at least 42 MHz / T, or at least In some embodiments, the gyromagnetic ratio may be greater than 44 MHz / T, up to 44 MHz / T, up to 42 MHz / T, up to 40 MHz / T, up to 38 MHz / T, up to 36 MHz / T, up to 34 MHz / T, up to 32 MHz / T, up to 30 MHz / T, up to 28 MHz / T, up to 26 MHz / T, up to 24 MHz / T, up to 22 MHz / T, up to 20 MHz / T, up to 18 MHz / T, up to 16 MHz / T, up to 14 MHz / T, up to 12 MHz / T, up to 10 MHz / T, up to 8 MHz / T, up to 6 MHz / T, up to 4 MHz / T, up to 2 MHz / T, or within a range defined by any two of the preceding values.

[0043] In some embodiments, the target compound may be a molecule and the target atom may be a part of that molecule. For example, if the target compound is a metabolite, the target atom may be 1 H, 13 C. 15 As an additional example, if the target compound is a silicate, the target atom can be 29In various embodiments, the target compound may be a combination of molecules and the target atom may be part of one of these molecules.

[0044] Consistent with the disclosed embodiments, polarization can be transferred using SPINOE. Nuclear spins on the target atoms can be polarized by cross relaxation from polarized source atoms. In some embodiments, the source compound containing the source atoms can be in a solution with the target compound containing the target atoms. In some embodiments, the concentration of the target compound in the solution can be less than 1,000 millimolar (mM), 500 mM, 200 mM, 100 mM, 50 mM, 20 mM, 10 mM, 5 mM, 2 mM, 1 mM, 500 micromolar (μM), 200 μM, 100 μM, 50 μM, 20 μM, 10 μM, 5 μM, 2 μM, 1 μM, 500 nanomolar (nM), 200 nM, 100 nM, 50 nM, 20 nM, 10 nM, 5 nM, 2 nM, 1 nM, or less in the first solution.

[0045] In some embodiments, at least one target atom may be hyperpolarized via polarization transfer. As described herein, such hyperpolarization may include increasing the polarization level of the at least one target atom above the thermal equilibrium polarization level observed at thermal equilibrium. In some embodiments, a non-thermal equilibrium polarization of at least 0.01% may be imparted to the at least one target atom via polarization transfer. In various embodiments, the non-thermal equilibrium polarization imparted to the at least one target atom may be at least 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, or more than 10%.

[0046] In an optional step 140 of process 100, the target compound can be separated from the source compound. The disclosed embodiments are not limited to any particular method of separating the target compound from the source compound. In some embodiments, the target compound can be separated from the source compound using liquid-liquid separation. The target compound and the source compound can be selected such that the polarity of the target compound is different from the polarity of the source compound (e.g., a polar target compound and a non-polar source compound). In some embodiments, a solution of the source compound, the target compound, and a first solvent can be combined with a second solvent. For example, when the target compound and the source compound are mixed in the cavity, the second solvent can be introduced into the cavity. The source compound can be more soluble in the first solvent, while the target compound can be more soluble in the second solvent. In some embodiments, the first solvent and the second solvent can be immiscible. The first solvent can be separated from the second solvent to separate the target compound from the source compound. For example, the source compound can be selected to be preferentially soluble in an organic solvent and the target compound can be selected to be preferentially soluble in an aqueous solvent (or vice versa). Separation of the target compound from the source compound can then be carried out by separating the aqueous solution from the organic solution.

[0047] In various embodiments, the target compound may be crystallized or precipitated from the solution. The disclosed embodiments are not limited to any particular method of inducing such precipitation. For example, such precipitation may be induced via a change in temperature or pH, application of an electromagnetic stimulus (e.g., optical radiation such as ultraviolet radiation or optical radiation at another suitable wavelength or wavelengths), a mechanical stimulus (e.g., ultrasound, agitation, or another suitable mechanical stimulus), addition of another solute or solvent to the solution, or another suitable method, or any combination thereof. In some embodiments, after precipitation, the target compound may be separated from the solution (e.g., using a filter, or another suitable method). In some embodiments, the target compound may then be combined with another solution or redissolved. This second solution may have desirable properties (e.g., biocompatibility, concentration, volume, temperature, pH, polarity, or other relevant properties, or any combination thereof) for the intended imaging application.

[0048] In step 150 of process 100, the target compound can be used for imaging or spectroscopy applications. In some embodiments, at least a portion of the target compound can be injected into a subject or patient. In various embodiments, at least a portion of the target compound can be used in NMR spectroscopy. During step 150, at least one NMR or MRI pulse sequence can be applied to the target compound. In some embodiments, the signal from the source molecule is reduced by at least 50%, 60%, 70%, 80%, 90%, 95%, or 99% in spectroscopy applications. In some embodiments, the source polarization is reduced prior to the detection scheme. In some embodiments, a pulse sequence is utilized that reduces the transverse vibration signal of the source molecule compared to the target molecule. In some embodiments, a signal post-processing scheme is applied to the signal to reduce the effects of the highly polarized source molecule, including removal of the signal from the source molecule, improving the phase and frequency of the target molecule, and improving the phase and frequency of the target molecule to best match its phase and frequency without the effects of the highly polarized source molecule. In some embodiments, the at least one NMR or MRI pulse sequence may include at least one radiation attenuation procedure configured to reduce radiation attenuation of the target compound by at least 50%, 60%, 70%, 80%, 90%, 95%, or 99% compared to a pulse sequence without the at least one radiation attenuation procedure. Such radiation attenuation procedure may include at least one Q-switching procedure or at least one detuning procedure. The at least one Q-switching procedure or at least one detuning procedure may be applied to an induction coil configured to receive NMR or MRI signals from the target compound. In some embodiments, the at least one Q-switching procedure or at least one detuning procedure includes changing a quality (Q) factor of the induction coil from (i) a first value of at least 100, at least 50, at least 20, or at least 10 during application of a hard excitation pulse to the molecule, to (ii) a second value of at most 1, at most 0.5, at most 0.2, or at most 0.1 during application of a frequency-selective pulse to the molecule.

[0049] In some embodiments (not shown in FIG. 1 ), the target compound and the source compound can be combined in solution prior to polarization of the source compound in step 110. In some such embodiments, the combination of the target compound and the polarized source compound can be transported as described in optional step 130. The combination can be transported in solution, as a precipitate, or in some other suitable form. In some embodiments, the steps of polarizing the source compound (e.g., using SABRE), transferring the polarization to the target compound, and detecting the target compound signal can be repeated. In such embodiments, the source compound repeatedly increases the polarization of the target compound, and multiple hyperpolarized signals can be obtained from the target molecule. Such repeated polarization transfers can be used for signal averaging or to perform spectroscopy in more than one dimension. In some embodiments, the target compound can be separated in step 150 (e.g., via liquid-liquid separation or precipitation). The separated target compound can be used in NMR spectroscopy or imaging applications in step 160.

[0050] Preparation and polarization of PETS source compounds

[0051] As described above with respect to step 110 of step 100, the source compound can be a PETS material. As described herein, many organic molecules exhibit a phenomenon in which, when excited with certain wavelengths of light or ultraviolet (UV) spectrum, electrons in the molecule's low-level singlet state S0 are excited to a higher-level singlet electronic state S1. From this state, radiative decay back to the singlet state or intersystem crossing (ISC) to a triplet state can occur. These triplet states exhibit two main characteristics: first, they are long-lived (e.g., on the order of microseconds to seconds) and therefore can be addressed on reasonable time scales. Second, the triplet state population between the three spin levels is inhomogeneous for many molecules, thereby generating polarized states.

[0052] Some polarized molecules suitable for inclusion in PETs materials (e.g., acridine, pentacene, benzophenone, etc.) may have one of more than 90% of the spin states loaded. Such polarized molecules may have nearly uniform polarization in temperatures and magnetic fields where the thermodynamic polarization of the electron spins is otherwise orders of magnitude smaller. Additionally, these polarized molecules may have different triplet spin states that exhibit different decay times to the singlet state, thereby creating another process by which the population of differences between the spin states, and hence the polarization, can be obtained.

[0053] An important aspect of these optically excited triplet states is that the electrons decay from the triplet state to the singlet ground state. The free electrons can be the primary source of nuclear relaxation at lower temperatures. Thus, when the electrons in the molecule decay back to the singlet state (and thus have no free electron spin), the molecule no longer contains paramagnetic impurities with free electron spins that can relax the surrounding nuclear spins. Thus, the nuclear spin polarization can reach higher levels and the material can have significantly longer relaxation times after the polarization sequence. Thus, the optically excited triplet state can serve as a long-term source of polarized target compounds via SPINOE.

[0054] Polarized molecules can be incorporated into the PETS material to form a source compound in a number of different ways. In some embodiments, the source compound can be a crystal grown from a melt. The disclosed embodiments are not limited to any particular method of growing a crystal from a melt. In some embodiments, the crystal can be grown using rapid temperature reduction, the Bridgman growth method, the Czochralski method, the cell method, another suitable crystal growth method, or any combination thereof. The polarized molecules may be included in a melt-in concentration selected to produce a suitable source compound (e.g., a source compound having desired polarization characteristics).

[0055] In some embodiments, the source compound may be a crystal grown using another suitable method, such as from a solution, gel, or vapor. Exemplary suitable crystal growth methods are disclosed in "Growth of Bulk Single Crystals of Organic Materials for Nonlinear Optical Devices: An Overview" by Penn, Benjamin G et al., which is incorporated herein by reference in its entirety for all purposes. Relevant portions of this specification describe methods of molecular crystal growth and purification, including growth by physical vapor transport, growth from the melt by the Bridgman-Stockbarger method, Czochralski Growth or Kyropoulos method, growth from solution including slow cooling processes, solvent evaporation processes, and temperature difference processes.

[0056] In some embodiments, the source compound can be a Shpolsky matrix incorporating an appropriate polarized molecule. For example, pentacene can be incorporated into n-heptane, n-nonane, n-decane, n-dodecane, n-tetradecane, and n-hexadecane Shpolsky matrices. Methods for such incorporation are disclosed by Banasiewicz, M., I. Deperasiska, and B. Kozankiewicz in "Spectroscopic Properties of Pentacene in Shpol'skii Matrices," incorporated herein by reference in its entirety for all purposes. As described in this paper, liquid samples can be bubbled with argon to remove oxygen and gently heated to increase the solubility of the host. The liquid sample can then be quickly frozen in liquid nitrogen and then inserted into the polarizer cryostat.

[0057] In some embodiments, the source compound can be a pentacene:naphthalene crystal. As shown in FIG. 2A, the pentacene dopant can be incorporated into the crystal lattice of the naphthalene crystal in two possible orientations. The existence of such defined orientations can enable hyperpolarization in relatively high amounts, up to about 10 -4Pentacene can be doped into naphthalene crystals at mol / mol, and an example of such a pentacene:naphthalene crystal is shown in Figure 2B.

[0058] In some embodiments, pentacene:naphthalene crystals can be grown using the self-seeded vertical Bridgman method. A variation of Bridgman growth uses a double-walled ampoule with the inner wall having a capillary opening into the space between the walls. The ampoule can be filled with naphthalene and pentacene and then moved through a steep temperature gradient, including the melting temperature of naphthalene. This temperature gradient can be achieved by a bath with two liquid phases heated to different temperatures. As the ampoule is lowered into the upper and warmer part of the bath, the pentacene-naphthalene mixture dissolves into a homogenous liquid. When the bottom of the ampoule reaches the phase separation of the heated bath, crystallization begins in the space between the ampoule walls. Here, solidification occurs at multiple nuclei, leading to a polycrystalline region in the space between the walls. By moving the ampoule slowly in that region, the number of nucleation events can be kept to a minimum, resulting in polycrystals with relatively large grains. As the ampoule is lowered further, the capillaries of the inner wall come into contact with the polycrystals. Ideally, only one single grain crystal orientation forms within the capillary. This self-seeding process favors the emergence of a single crystal within the inner wall of the ampoule.

[0059] Consistent with disclosed embodiments, DNP can be used in step 110 of process 100 to transfer polarization from electron spins to nuclear spins of source atoms of a source compound. DNP can use electromagnetic irradiation (e.g., microwave or radio frequency irradiation) or magnetic field tuning to transfer the electron spins to nuclear spins. In some embodiments, polarization transfer can be achieved via level avoidance crossing (LAC), or other suitable phenomenon. DNP protocols can take advantage of at least one of the interactions between the electron spins or the underlying physical mechanisms (e.g., satisfying a resonance condition, such as a Hartmann-Hahn state, or excitation of a selective transition, such as irradiation at a frequency matching the energy gap between two quantum states). DNP protocols can differ in the configurations used to achieve these conditions. DNP protocols can also differ in the use of microwave pulses or continuous microwave radiation.

[0060] In some embodiments, DNP can be used in conjunction with a PETS material in step 110 of process 100 to obtain a polarized source compound. In some implementations, high nuclear polarization can be obtained in a PETS material using DNP (e.g., >10%, >20%, >30%, >40%, >50%, >60%, >70%, or >80%). However, the disclosed embodiments are not limited to using DNP in conjunction with a PETS compound. DNP can be used with other compounds and the PETS material can be polarized using other methods.

[0061] Consistent with the disclosed embodiments, suitable DNP protocols are described in "Hyperpolarization of Nuclear Spins in Bulk at Room Temperature" by Kenichiro Tateishi et al. (e.g., for pentacene: p-terphenyl), "High Proton Spin Polarization by DNP Using the Triplet State of Pentacene-d14" by Eichhorn, TR et al. (e.g., for pentacene: naphthalene), and "Photopolarization in Polycrystalline Samples" by Kazuyuki Takeda, K. Takekoshi, Takehiko Terao et al. (e.g., for polycrystalline samples of pentacene: naphthalene with random crystal orientation). "Dynamic Nuclear Polarization with Excited Triplet Electron Spins", discussed in "Dynamic Nuclear Polarization in High Magnetic Fields", by Maly, Thorsten, et al., Section II. In addition, sophisticated DNP sequences such as those disclosed in "Robust Optical Polarization of Nuclear Spin Baths Using Hamiltonian Engineering of Nitrogen-Vacancy Center Quantum Dynamics" by Schwartz, Ilai, et al., can enable fast polarization transfer. Suitable DNP methods disclosed in "Dynamic Nuclear Polarization with Multicolor Control of Color Centers in Diamond", by Yang, Pengcheng, Martin B Plenio, and Jianming Cai, and "Enhanced Dynamic Nuclear Polarization via Swept Microwave Frequency Comb" by Ajoy, A, et al., can enable nuclear polarization transfer in nanocrystals, polycrystalline source materials, and bulk samples (e.g., using color centers in nanodiamonds). The DNP protocols and preparation techniques disclosed in these references are incorporated herein in their entirety by reference for all purposes.

[0062] Consistent with the disclosed embodiments, the DNP protocol may include a polarization sequence. Such a polarization sequence may include a polarization step followed by a translation step. In the polarization step, the source compound may be exposed to an intense light pulse. The duration of the light pulse may be at least about 10 nanoseconds (ns), 20 ns, 50 ns, 100 ns, 200 ns, 500 ns, 1 microsecond (μs), 2 μs, 5 μs, 10 μs, 20 μs, 50 μs, 100 μs, or more. The duration of the light pulse may be up to about 100 μs, 50 μs, 20 μs, 10 μs, 5 μs, 2 μs, 1 μs, 500 ns, 200 ns, 100 ns, 50 ns, 20 ns, 10 ns, or less. The duration of the light pulse may be within a range defined by any two of the preceding values, such as 100 ns to 10 μs. The energy of the light pulse can be at least about 0.1 millijoules (mJ), 0.2 mJ, 0.5 mJ, 1 mJ, 2 mJ, 5 mJ, 10 mJ, or more. The energy of the light pulse can be up to about 10 mJ, 5 mJ, 2 mJ, 1 mJ, 0.5 mJ, 0.2 mJ, 0.1 mJ, or less. The energy of the light pulse can be within a range defined by any two of the preceding values, such as between 0.1 mJ and 10 mJ, or more. The energy and duration of the light pulse can be selected to populate triplet states of polarized molecules in the source compound in a polarized manner.

[0063] In some embodiments, the electron spins can be transferred to hydrogen nuclear spins in the source compound in a transfer step using integrated solid effect (ISE). By changing the parameters of the transfer step, other types of nuclear spins can be affected. In some embodiments, for example, the electron spins can be transferred to hydrogen nuclear spins in the compound by using a different B1 microwave (MW) field. 13C nuclear spins. In some embodiments, the B1 microwave field is applied transversely to the magnetization field B0 in which the compound is located. In various embodiments, the electron spins can be transferred to the nuclear spins in a transfer step using alternatives to the ISE. For example, spin transfer can be performed using solid effects, cross effects, or low-field thermal mixing (for very high concentrations of PETS molecules). As additional examples, spin transfer can be performed using pulsed DNP methods such as the Nuclear Spin Orientation via Electron Spin Locking (NOVEL) sequence or the Dressed State Solid Effect.

[0064] 3A and 3B show the spin transfer that occurs during an exemplary DNP protocol using solid state effects to achieve spin transfer. This exemplary method transfers polarization from electron spins to nuclear spins, increasing the nuclear polarization while decreasing the electron polarization. 3A and 3B show the different electron / nuclear spin states in the source atoms of the source compound as four levels, with the black bars representing the population in the source compound at each level. Before the onset of spin transfer, as shown in FIG. 3A, the source compound exhibits a larger electron spin polarization than the nuclear spin polarization. Thus, the two lower levels are shown with a larger population than the two upper levels. Using microwave or rf irradiation, the states

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[0065] In some embodiments, the polarization of the electron spins can be transferred to the nuclear spins using interactions involving at least two electron and nuclear spins (e.g., using cross effects and low-field thermal mixing DNP protocols). Such interactions can rely on several allowed transitions of the electron and nuclear spins, including homogeneously or inhomogeneously broadened electron paramagnetic resonance (EPR) lines. Simultaneous flipping of two or more electron and nuclear spins can conserve energy in the broadening of the EPR lines.

[0066] In various embodiments, electron spins can be transferred to nuclear spins using a variation of the Integrated Solid Effect (ISE), in which a multi-frequency microwave "comb" sweeps several microwave frequencies in parallel. Such techniques can be particularly suitable for transferring polarization in nanocrystals, polycrystalline source materials, or bulk samples.

[0067] In some embodiments, the triplet lifetime can be extended and the polarization of the compound can be increased by preparing the triplet state prior to the DNP protocol. This can be done via collective transfer between excited state sublevels (e.g., by 180-degree pulse resonance with the transition frequency) to a different spin state with a longer relaxation time. Further details of preparing the triplet state prior to the DNP protocol are provided in "Dynamic Nuclear Polarization with Paramagnetic Centers Generated by Photoexcitation" by Eichhorn, Tim Rolf, which is incorporated herein by reference in its entirety for all purposes.

[0068] In some embodiments, polarization transfer from electron spins to nuclear spins can be achieved without the use of microwaves by aligning an external magnetic field with the level avoidance crossing (LAC) of the electron spins. Further details of polarization transfer are provided in Eichhorn, Tim Rolf, "Dynamic Nuclear Polarization with Paramagnetic Centers Generated by Photoexcitation," incorporated herein by reference in its entirety for all purposes.

[0069] In some embodiments, the external magnetic field can be selected according to the desired application. For example, for polarization of target compounds for hyperpolarized MRI applications, or NMR spectroscopy in an external spectrometer, the magnetic field can be less than 5 Tesla (T). In some embodiments, an external magnetic field with a low magnetic flux density (e.g., less than 2 T, less than 1 T, less than 0.5 T, less than 0.2 T, less than 0.1 T, less than 0.05 T, less than 0.02 T, less than 0.01 T, or less) can be used. Advantageously, such magnetic flux density can be achieved using permanent magnets or electromagnets without the need to use cryogenic superconducting materials. Furthermore, such magnetic fields can be measured using conventional methods (e.g., using a Gaussmeter). Thus, the equipment requirements (and therefore costs) for such methods can be reduced compared to other methods of polarizing source compounds.

[0070] Consistent with the disclosed embodiments, induced relaxation of nuclear spins in a source compound can be reduced by actively isolating the nuclear spins from possible electron spins on the surface of the source compound (e.g., electron spins arising from contaminants on the surface of the source compound). Such isolation can be achieved by using microwave or radio frequency irradiation to drive the electron spins at their Larmor frequency or energy transition frequency (e.g., in the presence of strong hyperfine splitting or spin-1 electron spins), or at electron-nuclear zero-quantum or double-quantum resonance conditions.

[0071] In some embodiments (e.g., for NMR spectroscopy applications), it may be advantageous to perform the polarization transfer from optically polarizable electron spins to nuclear spins in situ (e.g., in an NMR instrument). In such embodiments, steps 110, 130, and 150 of process 100 can be performed in situ. Thus, the same magnet can be used to obtain the source compound (e.g., through the transfer of polarization to the nuclear spins of the source compound) and to perform NMR spectroscopy. For compounds that include polycrystalline, monocrystalline, or monocrystalline in micro- or nanoparticle form, a low magnetic field (e.g., less than 1000 millitesla (mT), 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or another suitable field) can allow for addressing many of the orientations of the PETS electron spins.

[0072] FIG. 4 shows an exemplary sequence of optical and magnetic interactions (e.g., polarization sequences) suitable for inducing polarization in a source compound. In this example, the source compound is a sample of pentacene-d14:naphthalene-h8 crystals. The sample is 100-300 mm 3In some embodiments, the sample can be cooled to below 100 Kelvin (K) while being placed in a magnetic field of at least 1 kilogauss (kG), 2 kG, 5 kG, 10 kG, 20 kG, 50 kG, or 100 kG oriented along the long axis of the pentacene molecule. The sequence can include multiple repetitions of the light pulse followed by a magnetic field sweep. In each repetition, one or more light pulses (e.g., laser pulses) can excite the pentacene molecule to a short-lived triplet state. This can be achieved by injecting light pulses (e.g., light pulses 410) into a higher singlet state, each light pulse having a light pulse amplitude 411 and a light pulse duration 413, where a slower intersystem crossing from the singlet to triplet state is performed. In some embodiments, the light pulse amplitude has a pulse energy of at least about 1 mJ, 2 mJ, 5 mJ, 10 mJ, 20 mJ, 50 mJ, 100 mJ, 200 mJ, 500 mJ, 1000 mJ, or more, up to about 1000 mJ, 500 mJ, 200 mJ, 100 mJ, 50 mJ, 20 mJ, 10 mJ, 5 mJ, 2 mJ, 1 mJ, or less, or a pulse energy within a range defined by any two of the preceding values. In some embodiments, the pulse duration is at least about 10 ns, 20 ns, 50 ns, 100 ns, 200 ns, 500 ns, 1 μs, 2 μs, 5 μs, 10 μs, 20 μs, 50 μs, 100 μs, or more, up to about 100 μs, 50 μs, 20 μs, 10 μs, 5 μs, 2 μs, 1 μs, 500 ns, 200 ns, 100 ns, 50 ns, 20 ns, 10 ns, or less, or within a range defined by any two of the preceding values. After the delay 415, the previously ramped up magnetic field 420 is irradiated with a microwave pulse 430 having a microwave pulse duration 431 to facilitate Hartmann-Hahn matching of all spin packets in the line while sweeping the electron spin resonance linewidth (e.g., magnetic field sweep amplitude 421) of several G's of all triplets.In some embodiments, the delay is at least about 10ns, 20ns, 50ns, 100ns, 200ns, 500ns, 1000ns, or more, up to about 1000ns, 500ns, 200ns, 100ns, 50ns, 20ns, 10ns, or less, or within a range defined by any two of the preceding values. After repeating this sequence N times, the proton signal can be read out via the free induction decay 441 of a resonant radio frequency pulse 443 with a non-destructive small tip angle amplitude. As shown in FIG. 5, this sequence of optical and magnetic interactions can increase the polarization in the sample by more than 50%.

[0073] FIG. 5 shows the NMR signal read from the compound before and after repeating the polarization sequence shown in FIG. 4. In FIG. 5, the x-axis is the frequency of the NMR signal and the illustrated y-axis is the signal intensity. The first trace shows the NMR signal from the compound at thermal equilibrium (multiplied by 16,000). The second trace shows the NMR signal read from the compound with 4% polarization (multiplied by 4). The third trace shows the NMR signal read from the compound with 50% polarization. The increase in polarization is a result of repeating the polarization sequence shown in FIG. 4.

[0074] Generation and polarization of source compounds using spin order

[0075] Consistent with disclosed embodiments, electron spin order can be transferred to the nuclear spins of source atoms of a source compound to polarize the source compound in step 110 of process 100. Such methods (e.g., PHIP, PHIP-SAH, SABRE, etc.) are described herein with respect to parahydrogen for the purposes of this disclosure, but are equally applicable to orthodeterium and paratritium.

[0076] 6 illustrates a process 600 for producing and isolating a polarized source compound using PHIP, PHIP-SAH, or SABRE polarization. In some embodiments, such production and isolation can be performed as part of step 110 of process 100. In various embodiments, the polarized source compound can optionally be separated from the hydrogenation catalyst or reaction by-products (e.g., as in step 120 of process 100) and / or transported from where it was produced to another location for use (e.g., as in step 130 of process 100). The polarized source compound can be combined with a target compound (e.g., as in step 140 of process 100).

[0077] In step 610 of process 600, parahydrogen can be generated and optionally transported. Parahydrogen is a form of molecular hydrogen. In this form of molecular hydrogen, the two proton spins are in a singlet state. In some embodiments, parahydrogen can be formed in gaseous or liquid form. For example, in some embodiments, parahydrogen can be generated in gaseous form by flowing hydrogen gas through a chamber with a catalyst. In some embodiments, the hydrogen gas can be subjected to a low temperature, such as a temperature of up to about 100K, 90K, 80K, 70K, 60K, 50K, 40K, 30K, 20K, 10K, 9K, 8K, 7K, 6K, 5K, 4K, 3K, or lower. In some embodiments, the catalyst can be iron oxide. In some embodiments, the hydrogen gas contains both parahydrogen and orthohydrogen, and the low temperature brings the hydrogen gas to thermodynamic equilibrium in the chamber during which a population of parahydrogen grows.

[0078] In some embodiments, the gas may be generated at a first location and then transported to a second location for use. In some embodiments, the first location may be a chamber that may be part of a container, bottle, holder, or other area that may hold a gas or liquid. Such a chamber may be maintained at an appropriate pressure, temperature, or combination thereof. In some embodiments, the first location may refer to a physical location such as a room, a laboratory, a specific warehouse, a hospital, or other place where parahydrogen may be generated.

[0079] In some embodiments, the generated parahydrogen may be transported in a chamber different from the chamber in which the parahydrogen was generated. The chamber transporting the parahydrogen gas may be maintained at an appropriate pressure or temperature, which may be transported by vehicle or person. In some embodiments, transporting the parahydrogen may involve moving the parahydrogen from one container to a different container. In some embodiments, transporting the parahydrogen may involve moving the parahydrogen within the same location, such as from one part of a room to another part of a room. In some embodiments, transporting the parahydrogen may involve moving the parahydrogen from one room of a building to another room of the same building or a nearby building. In some embodiments, transporting the parahydrogen may involve moving the parahydrogen to another part of the same city, or to another location in a different city. For example, transporting the parahydrogen may bring the parahydrogen near a polariscope or an NMR / MRI machine. In another example, in some embodiments, transporting the parahydrogen includes packaging or shipping the parahydrogen in a suitable container, as shown in FIG. 10.

[0080] In step 620 of process 600, a source compound can be generated using parahydrogen. In some embodiments, a solution can be formed by combining a precursor molecule (or source compound in SABRE embodiments), a solvent, and a catalyst for hydrogenation (e.g., a hydrogenation catalyst). The solution can be formed in a mixing mechanism, which can be configured to introduce, hold, or facilitate a blend, mixture, or solution of two or more materials. In some embodiments, the mixing mechanism can be disposed within the chamber, and mixing can occur within the chamber. In some embodiments, the solution can be mixed at a location remote from the chamber. In some embodiments, the solution can be at least 10 microliters (μL), 20 μL, 50 μL, 100 μL, 200 μL, 500 μL, 1000 μL, or more in volume. The concentration of the precursor molecule can be at least 10 millimolar (mM), 20 mM, 50 mM, 100 mM, 200 mM, 500 mM, 1 M, 2 M, 5 M, or more. In some embodiments, the mixing mechanism can be a gas-liquid exchange mechanism. For example, the gas-liquid exchange mechanism can be a bubbler or a diffusion system. In some embodiments, the mixing mechanism can include a membrane adapted to allow diffusion of molecular hydrogen. In some embodiments, the mixture can be formed when parahydrogen gas is bubbled into the mixture.

[0081] In some embodiments, the hydrogenation catalyst can be any molecule, complex, or particulate system that catalyzes a hydrogenation reaction (for the PHIP or PHIP-SAH process) or catalyzes polarization transfer from parahydrogen (for the SABRE process). In some embodiments, homogeneous metal catalysts such as rhodium or ruthenium complexes can be used to prepare and activate the precursor molecules and parahydrogen. In embodiments utilizing SABRE, iridium complexes can be used as homogeneous catalysts. In some embodiments, heterogeneous metal catalysts connected to nanoparticles can be used to prepare and activate the precursor molecules and parahydrogen.

[0082] In some embodiments, the precursor molecule may have an unsaturated bond that can be hydrogenated by parahydrogen gas. In PHIP embodiments, the hydrogenated precursor molecule may be a source compound. In PHIP-SAH embodiments, the hydrogenated precursor molecule may be a parahydrogenated precursor of the source compound. Preferably, after bubbling parahydrogen gas, more than 50%, more than 80%, or nearly all of the molecule may be hydrogenated. In some embodiments, the hydrogenation may generate a lower energy state between |↑>|↓>, |↓>|↑>, or a singlet spin order of Iz1Iz2 on the two hydrogen spins of the hydrogenated molecule. In such embodiments, the hydrogenated precursor molecule may act as a source compound for the process 100.

[0083] In some embodiments, polarization occurs via non-hydrogenated PHIP, also referred to as signal amplification by reversible exchange (SABRE). In such embodiments, the hydrogenation and polarization transfer steps described can occur by polarization transfer from parahydrogen to a source compound, while both are bound to the catalyst. The source compound, e.g., pyridine, can be reversibly bound to the catalyst. Bubbling parahydrogen gas may also be reversibly bound to the catalyst, allowing spin order or polarization transfer to the source compound. Preferably, at the end of the process, the average polarization (or spin order) of the source atoms of the source compound is at least 1%, 2%, 5%, 10%, 20%, 50%, or more.

[0084] Consistent with disclosed embodiments, generating the source compound in step 620 can include polarization transfer from electron spins to nuclear spins. Such polarization transfer can be performed in a magnetic field and can use electromagnetic radiation. In some embodiments, polarization transfer can include application of at least one RF waveform to the para-hydrogenated precursor molecules.

[0085] In some embodiments, the at least one RF waveform may be generated by a waveform generator, which may further include one or more computing units, processors, controllers, associated memory, PCs, computer servers, or any device capable of carrying out computational processing using an input and generating an output.

[0086] At least one RF waveform can be applied to the source compound using an RF coil. The RF coil can be positioned around the chamber in which parahydrogenation was performed or around a separate polarization transfer chamber. The RF coil can have one or more channels. Such channels can be paths for applying an RF signal to the source compound. At least one channel can be provided for each different type of nuclear spin species. In some embodiments, a channel can be provided for each different nuclear spin species (e.g., 3 H, 13 C. 19 F, 31 P, or other suitable species) 1 H) channel and at least one other channel (e.g., an additional channel). 1 The RF waveforms applied to the H channel and each of the additional channels may be different. In some embodiments, at least one proton channel is 1 In some embodiments, the ion exchange coupling is used to selectively address one of the H spins. 1 H channel and additional channels (e.g. 13 The RF waveform on the C channel) is configured to apply a polarization transfer sequence such as PH-INEPT, Goldman's sequence, S2M, S2hM or ESOTERIC.

[0087] In some embodiments, the polarization transfer is at least 1 microtesla (μT), 2 μT, 5 μT, 10 μT, 20 μT, 50 μT, 100 μT, 200 μT, 500 μT, 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 10 The measurement may be performed using a magnetic field having a strength of 00mT, 500mT, 200mT, 100mT, 50mT, 20mT, 10mT, 5mT, 2mT, 1mT, 500μT, 200μT, 100μT, 50μT, 20μT, 10μT, 5μT, 2μT, 1μT, or less, or a magnetic field strength within a range defined by any two of the preceding values, such as 10μT to 2000mT. The magnetic field may be generated by an electromagnet or a permanent magnet. The magnetic field may be applied to the sample in pulses or continuously. The magnetic field may be static or time varying. The applied magnetic field may be non-uniform. The non-uniformity of the magnetic field may be characterized in parts per million (ppm) across the diameter of the spherical volume. In some embodiments, the applied magnetic field can have a non-uniformity of at least about 1 ppm, 2 ppm, 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, or more, up to about 100 ppm, 50 ppm, 20 ppm, 10 ppm, 5 ppm, 2 ppm, 1 ppm, or less, or within a range defined by any two of the preceding values.

[0088] In such a magnetic field, at least one RF waveform can be applied to the source compound to transfer the polarization between the parahydrogen and the nuclear spins of the source compound (e.g., the nuclear spins of the source atoms). The at least one RF waveform can include a sequence of elements. An element in the sequence of elements can be an RF pulse. For example, an element in the sequence of elements can be an excitation pulse. An excitation pulse can be an RF pulse that changes the energy level or spin phase of the material (e.g., to increase the detectable polarization signal in the source compound), such as a 90 degree (or approximately 90 degree pulse). An element in the sequence of elements can be a separation sequence. In some embodiments, the separation sequence can include one or more pulses, or a group of one or more RF pulses (e.g., described herein as a block of RF pulses or a pulse block).

[0089] In other embodiments, the polarization transfer can be performed using a magnetic field of less than 0.1 G. In such a magnetic field, the polarization is induced by the proton spins and 13 C. 15 N, 19 F, or 31 It can be moved by utilizing level avoidance crossing (LAC) between other spin species of interest, including P. The magnetic field can be tuned to the exact field of the LAC or varied in time, for example, to sweep through the LAC states.

[0090] In various embodiments utilizing SABRE, spin order transfer can occur in a magnetic field that allows for spontaneous transfer between parahydrogen and the selected molecule, for example, using signal amplification by reversible exchange in a shield to allow alignment transfer to the heteronucleus (SABRE-SHEATH). The spin order of the parahydrogen can be transferred to the polarization on the molecule, or to the spin order on the molecule.

[0091] In various embodiments, SABRE, PHIP, or PHIP-SAH were used. 1The polarization of the H molecule can be transferred by chemical exchange to other molecules, for example using the SABRE-RELAY method. Such other molecules can form the source compounds described herein with respect to FIG.

[0092] In various embodiments, the spin order on the proton spins is not transferred to other spin species, but instead converted to polarization on the proton spins. This can be done, for example, by a singlet to magnetization conversion pulse, e.g., S2M, or using spin-lock induced crossover (iSLIC), similar to the method used in singlet NMR. In another embodiment, the spin order is converted to polarization by a PHIP-echo sequence in a high magnetic field.

[0093] In some embodiments, the spin order on the protons can be converted to polarized light through the application of a pulse sequence. In some embodiments, the spin order on the protons of a molecule with a chemical shift difference between the hydrogenation spins can be converted to polarized light by first hydrogenating the molecule at a low magnetic field and then moving the molecule to a high magnetic field, i.e., using adiabatic longitudinal transport after dissociation produces a net alignment (ALTADENA) sequence. The spin order of the two protons by hydrogenation can then be transferred to the ALTADENA order, i.e., most of the spins adiabatically go from the singlet state to the |↑>|↓> state (or alternatively, most of the spins go to the |↓>|↑> state). To transfer this spin order to polarized light, selective pulses can be applied to invert only one of the two spins, since the spins are separated by a chemical shift. In another specific embodiment, molecules with hydrogenated protons with the same chemical shift are hydrogenated at high or low magnetic fields, and the singlet orders are converted to magnetization using pulse sequences (e.g., S2M, PulsePol) or RF irradiation (e.g., iSLIC).

[0094] In some embodiments, using high concentrations of source compounds and high electron or nuclear spin polarization of the source compounds, application of a selective pulse or pulse sequence can induce substantial radiation attenuation. In some embodiments, the radiation attenuation effect during the transfer of spin order to polarization is due to the application of a selective pulse or pulse sequence. 1 This can be mitigated by reducing the effective quality factor Q of the polarizer (e.g., NMR spectrometer) at the H resonance to less than 20, 10, 5, 1, 0.5, 0.2, or 0.1. In some embodiments, this can be achieved by reducing the effective quality factor Q of the polarizer (e.g., NMR spectrometer) at the H resonance to less than 20, 10, 5, 1, 0.5, 0.2, or 0.1. 1 This is done by a controllable readjustment of the resonance from the H resonance to a demodulated value, whereby 1 Decrease the gain of the polarizer RF coil (e.g., the NMR coil of an NMR spectrometer) at the H resonance. In some embodiments, the quality factor Q of the probe circuit can be reduced by nulling the voltage in the receiver coil induced by the strong NMR signal via an electronic feedback circuit.

[0095] In some embodiments, the transfer of spin order to the magnetization can be achieved using radiation damping. 1 In an ALTADENA experiment with H spins, for example, if the splitting due to the chemical shift is large enough, the application of an excitation pulse (even one with a small flip angle) induces radiative decay and both 1 H spins. In some embodiments, the radiation damping can be induced without an excitation pulse (e.g., by statistical fluctuations).

[0096] The disclosed embodiments further include a method for preparing a fluorinated ... 1 The present invention is not limited to the embodiment in which the nuclear spins on the H source atom are converted to H. In some embodiments, the source compound may be combined with a target compound, and then the spin order is 1H can be converted to the nuclear spin polarization of the H source atom, which can then be transferred to the target atom using NOE, as described herein.

[0097] Source Compound Precipitation

[0098] As described above with respect to step 120 of process 100, the polarized source compound may be at least partially isolated according to disclosed embodiments. In some embodiments, the polarized source compound may be induced to solidify and precipitate, thereby producing polarized or spin-order-containing crystals. As used herein, spin order generally refers to an excess population of some electronic or nuclear states (e.g., certain spin eigenstates of spin-1 / 2 electrons or nuclei, or singlet or triplet states of spin-1 systems such as PETS systems). In some embodiments, such precipitation may be induced by reducing the solubility of the polarized or spin-order-containing source compound. The solubility of the source compound in solution may be reduced by modifying the solvent (or mixture or solvent) in which the source compound is dissolved. The solidification and precipitation of the polarized source compound may allow for efficient mechanical separation of the source compound.

[0099] Solid hyperpolarized source compound particles can be used in several applications. Hyperpolarized source compound microparticles configured to be insoluble in aqueous solutions can be used as NMR / MRI tracers. Hyperpolarized source compound precipitates can also provide a source for transferring polarization to a target compound, as described herein.

[0100] As a non-limiting example, fumaric acid polarized by PHIP can precipitate in aqueous solution. Disodium fumarate and fumaric acid exhibit a large solubility difference in aqueous solution (e.g., 1.42M vs. 60mM, respectively). Disodium fumarate was polarized and dissolved in water at a concentration of 1.2M. Upon addition of acid (HCl), the resulting fumaric acid precipitated quickly to form microcrystals.

[0101] Consistent with disclosed embodiments, an organic solvent can be used for precipitation of the polarized source compound. In some embodiments, para-hydrogen induced polarization occurs in an organic solvent. Para-hydrogen is typically more soluble in organic solvents than in aqueous solvents, and therefore hydrogenation can occur more efficiently in organic solvents.

[0102] In various embodiments, hydrogenation and, optionally, polarization transfer can be carried out in an aqueous solution. The aqueous solution can be mixed with a miscible organic solvent to induce precipitation. In organic solvents, carboxylic acids are typically sufficiently soluble for the PHIP concentration. For example, fumaric acid is soluble at about 220 mM in acetone at room temperature. However, salts of these acids are usually very insoluble (e.g., less than 1 mM, 0.1 mM, 0.01 mM, or less). Thus, precipitation in organic solvents can be used at source compound concentrations suitable for achieving high polarization using PHIP or SABRE.

[0103] Consistent with disclosed embodiments, solidification or precipitation can separate the polarized source compound (or polarized molecule) from the hydrogenation catalyst used to hydrogenate the precursor molecule (or in a SABRE implementation, facilitate polarization transfer). As described herein, the polarized source compound (or polarized molecule) can be solidified or precipitated into a crystal, an amorphous solid particle, or a polycrystalline material. After solidification or precipitation, the source compound (or polarized molecule) can be separated from the solution containing the hydrogenation catalyst (e.g., through filtration of the precipitate and a washing step with a solvent that does not dissolve the source compound). In some embodiments, a majority of the hydrogenation catalyst can be separated from the polarized molecule in the sample by solidification. For example, more than 99% by weight of the hydrogenation catalyst (or 99.99%, 99.999%, or more) can be separated from the source compound (or polarized molecule).

[0104] In some embodiments, forming the polarized source compound may include cleaving a side arm of the polarized molecule (e.g., as in PHIP-SAH). The side arm of the polarized molecule may be cleaved by hydrolysis. In some embodiments, the cleavage of the side arm may be performed in a solvent in which the polarized molecule is more soluble than the polarized source compound (e.g., the polarized molecule without the side arm). Thus, the cleavage of the side arm may cause precipitation of the polarized source compound. In some embodiments, the solvent may be an organic solvent and the cleavage may be performed under basic conditions. After cleavage, the less soluble polarized source compound may undergo rapid solidification while maintaining its polarization. In various embodiments, the hydrogenation, polarization transfer, and side arm cleavage may be performed in the same solvent. In some embodiments, the hydrogenation and polarization transfer may be performed in a first solution, and then a second solution may be added to the first solution prior to cleavage of the side arm. For example, a basic solution (e.g., an aqueous solution of sodium hydroxide, etc.) may be added to cleave the side arm.

[0105] In some such embodiments, precipitation of the polarized precursor molecule can occur prior to cleavage, such that the polarized precursor molecule retains the side arms (e.g., still in ester form) while solidifying. Such embodiments can be used, for example, when the polarized precursor molecule (e.g., with side arms) is more stable than the polarized source compound (e.g., without side arms). Such precipitation can be performed by altering the pH of the solvent such that the solubility of the polarized molecule is reduced, or by mixing in a solution or other compound that reduces the solubility of the polarized molecule, or any combination thereof. In such embodiments, cleavage can be performed after redissolution of the polarized molecule or the polarized source compound in another solvent (e.g., a more biocompatible solvent).

[0106] In some embodiments, precipitation may occur after cleavage of a side arm from the polarized molecule (thereby forming the polarized source compound). Such precipitation may be accomplished by altering the pH of the solvent such that the solubility of the polarized source compound is reduced, or by mixing in a solution or other compound that reduces the solubility of the polarized source compound, or any combination thereof.

[0107] In some embodiments, the conversion of spin order to polarization can occur before the polarized molecule or polarized source compound is solidified and precipitated, in other embodiments, this conversion occurs after redissolution of the solidified source compound with the target compound.

[0108] Source compound transport

[0109] As described herein with respect to FIG. 1, a polarized compound (e.g., a source compound or a target compound) can be transported (e.g., in step 130 of process 100) from an origin location to a destination location. Consistent with disclosed embodiments, the compound can have a long nuclear relaxation time. Thus, the polarized compound can be stored and transported without undergoing an unacceptable degree of depolarization (e.g., greater than 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% depolarization). Because polarization of the source compound or the target compound can be performed separately from any further processing of the source compound or the target compound, polarization and further processing can be performed by separate equipment, each optimized for a different purpose. Additionally, production of polarized compounds for sufficient multiple end users can be performed at a central facility, allowing for greater efficiency and economies of scale.

[0110] In some embodiments, the polarized source compound may be transported to a destination location and then processed into microparticles or nanoparticles prior to transferring polarization from the polarized source compound to the target compound. In some embodiments, the polarized source compound may be processed into microparticles or nanoparticles prior to transport to the destination location. In various embodiments, the polarized target compound may be transported to a destination location and then dissolved in a solvent suitable for use in the intended NMR spectroscopy or MRI application.

[0111] The transport device may be configured to transport the polarized source compound or the polarized target compound. The transport device may be arranged and configured to simultaneously transport one or more samples of the polarized source compound or the polarized target compound (or a plurality of polarized source compounds or target compounds). The transport device may be configured to maintain the one or more samples in a magnetic field of at least 1 Gauss (G), 2G, 5G, 10G, 20G, 50G, 100G, 200G, 500G, or 1000G.

[0112] A permanent magnet or electromagnet included in the transport device can provide the magnetic field. Additionally, in some embodiments, the permanent magnet or electromagnet can be shielded to reduce the strength of the magnetic field outside the transport device. The transport device can also include a cooling system. The cooling system can be configured to maintain the sample at a predetermined temperature or within a predetermined temperature range during transport. For example, the cooling system can be configured to maintain the sample below 270K, below 80K, or below 4K. In some embodiments, the transport device can be configured to maintain the sample at approximately the temperature of dry ice, liquid nitrogen, or liquid helium. The transport device can include insulation between the cooling system and the exterior of the transport device to minimize heat exchange with the external environment. In some embodiments, the cooling system can be configured to maintain the temperature of the sample using a cold gas flow. In various embodiments, the cooling system can be configured to maintain the temperature of the sample using a solid or liquid coolant, such as dry ice, liquid nitrogen, or liquid helium. In various embodiments, the transport device can include a dewar that provides cooling for the sample. To distribute the polarized samples over large distances, the containers can preferably be transported by standard transport vehicles, such as planes, trains, trucks, automobiles, and ships.

[0113] Combining source and target compounds

[0114] As described herein with respect to FIG. 1, the polarized source compound can be combined with the target compound (e.g., as described in step 140 of process 100). Such combination is not limited to any particular method of polarizing the source compound. In various embodiments, the source compound is polarized using DNP (e.g., dissolution DNP as described herein) using PHIP, PHIP-SAH, or SABRE, or a source compound is polarized using DNP (e.g., dissolution DNP as described herein). 1 H, 19 F, or 31 P atoms), using PETS, or using another suitable method.

[0115] Consistent with disclosed embodiments, the polarized source compound can be combined with the target compound in a solution. In some embodiments, the solution can be generated by dissolving the polarized source compound in a solution. The solution can already contain the target compound. Alternatively, the target compound can be added to the solution (e.g., in solid form, dissolved in another solution, etc.). In some embodiments, the source compound (or target compound) can first be processed (e.g., crushed, ground, chopped, etc.) into microparticles prior to dissolution to enhance the rate of dissolution. In some embodiments, the source compound can be polarized in a first solution, and the target compound can be added to the first solution (e.g., in solid form, dissolved in another solution, etc.).

[0116] Consistent with the disclosed embodiments, the source compound may be soluble in a solvent and may be selected to retain polarization after dissolution. For example, a source compound such as disodium fumarate has a long relaxation time when dissolved at room temperature or other temperatures ranging from -150 degrees (°C) to -200°C, allowing dissolution while maintaining the polarization of the source atoms. Potential solvents may depend on the source compound selected. As a non-limiting example, if the polarized source compound is disodium fumarate or pyridinium sodium crystals, potential solvents may include aqueous solutions, glycerol, dimethyl sulfoxide (DMSO), and alcohols. As another non-limiting example, if the polarized source compound is pentacene:naphthalene, pentacene:p-terphenyl, or 3-phenylpropanoate crystals, potential solvents may include organic solvents such as toluene, ether, ethanol, carboxylic acids, chloroform, hexane, acetic acid, butyric acid, DMSO, and mixtures or derivatives thereof. In some embodiments, the solvent is at least 50%, 60%, 70%, 80%, 90% or more deuterated.

[0117] In some embodiments, dissolution and mixing of source and target compounds is performed in an automated system. In some embodiments, the automated polarization transfer system includes a transport magnet to maintain the polarization of the source compound. The source compound is then loaded into a vessel for grinding and dissolution. The transfer system includes a mechanism for mechanically breaking down the source compound into smaller particles for faster dissolution, for example, by a grinding head, pestle, or ultrasonic probe. In the dissolution vessel, a solution that may contain the target compound is mixed with the ground source compound for rapid dissolution. A separator such as a frit is used to separate the solution of dissolved source compound and solid particles, and the solution is pumped into the NMR spectrometer.

[0118] In some embodiments, the concentration of the source compound in the solution can be selected for efficient polarization transfer to the target compound. This concentration can be at least 100 mM, 200 mM, 500 mM, 1 M, 1.5 M, 2 M, 3 M, 4 M, 5 M, 6 M, or more. Such high concentrations can allow efficient polarization transfer from at least one source atom of the source compound to at least one target atom of the target compound. As can be appreciated, the concentration of the source compound in the solution during polarization transfer to the target compound (e.g., step 140 of process 100) can be different from the concentration of the source compound during the initial polarization of the source compound (e.g., step 110 of process 100). In some embodiments, the source compound concentration during polarization transfer may be much greater than the source compound concentration during initial polarization (e.g., 250 mM or less, 200 mM or less, 150 mM or less, 100 mM or less, 50 mM or less, 20 mM or less, or 10 mM or less), because high source compound concentrations can inhibit the initial polarization.

[0119] In some embodiments, the concentration of the source compound can be equal to or greater than the concentration of the target compound. For example, the concentration ratio of at least one source atom to at least one target atom can be at least 1:1, 2:1, 5:1, 10:1, 20:1, 50:1, 100:1, 200:1, 500:1, 1000:1, or more, up to 1000:1, 500:1, 200:1, 100:1, 50:1, 20:1, 10:1, 5:1, 2:1, 1:1, or less, or within a range defined by any two of the preceding values. When a source compound is polarized using the PHIP or SABRE process, the concentration of any hydrogenation catalyst (or reaction by-products such as cleaved side arms) in the solutions of source and target compounds may be less than 1 μM, 500 nM, 200 nM, 100 nM, 50 nM, 20 nM, 10 nM, 5 nM, 2 nM, 1 nM, or less, greater than 1 nM, 2 nM, 5 nM, 10 nM, 20 nM, 50 nM, 100 nM, 200 nM, 500 nM, 1 μM, or more, or within a range defined by any two of the preceding values. Such reduced concentrations may be achieved by separating (e.g., using a filter, liquid-liquid separation, or other suitable method) the polarized source compound from the hydrogenation catalyst (or reaction by-products).

[0120] Nuclear polarization transfer

[0121] 1, the nuclear spin polarization can be transferred from polarized source atoms of a source compound to target atoms of a target compound (e.g., as described with respect to step 140 of process 100). Consistent with disclosed embodiments, the nuclear spin polarization can be transferred by cross-relaxation (e.g., the spin-polarization induced nuclear Overhauser effect, or SPINOE).

[0122] Consistent with the disclosed embodiments, the source compound may be selected to improve polarization transfer. In some embodiments, the polarized source atoms may be selected to have a high gyromagnetic ratio, thereby inducing a high cross-relaxation rate on the target atoms. In some embodiments, the ratio of the cross-relaxation of at least one nuclear spin of the target compound induced by the source molecule to the total relaxation of the same nuclear spin is at least 0.001, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.3, 0.5, or more. In some embodiments, the polarization of at least one nuclear spin on the target compound after cross-relaxation is at least 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, or more.

[0123] In some embodiments, the source compound can be purified by, for example, selective deuteration of a portion of the source compound or by slow deuteration. 1 By choosing a molecule with H spin, it can be chosen to have a small intramolecular relaxation relative to the polarized source atom.

[0124] In some embodiments, the source compound can be selected such that the polarized source atoms protrude from the source compound and are therefore fully exposed to the surrounding environment. For example, the polarized source atoms can be located on a portion of the source molecule that is fully exposed to the surrounding environment, such as at or near the end of a side chain or arm of the source molecule. Such a configuration can increase cross-relaxation with the target atoms.

[0125] In some embodiments, the cross-relaxation rate can be increased by selection of the solvent in which the source and target compounds are combined, the temperature of the solvent, the magnetic field at which the NOE is generated, and / or the viscosity of the solvent.

[0126] In some embodiments, the source compound may be selected to have a long relaxation time compared to the time required to transfer the intended amount of polarization to the target compound (e.g., to achieve the polarization of the target compound described herein). The transfer time may depend on factors including the diffusion rate, the concentration of the source molecule, the concentration of the target molecule, and the cross-relaxation rate. In some embodiments, the relaxation time of the source compound may be at least 10 seconds, 20 seconds, 30 seconds, 50 seconds, 100 seconds, or more.

[0127] In some embodiments, RF irradiation (such as a rotating frame Overhauser enhanced spectroscopy (ROESY) NMR pulse sequence) may be provided to effect polarization transfer.

[0128] In some embodiments, a first magnetic field may be applied during polarization transfer and a second, different magnetic field may be applied during NMR spectroscopy. In some embodiments, the first magnetic field may be selected to achieve high NOE polarization between the source and target compounds. The different magnetic fields may be implemented using magnetic field cycling or physical transport of the solution from the first magnetic field to the second magnetic field.

[0129] Intermolecular NOE in liquids can be understood as the transfer of magnetization between nuclear spins on nearby molecules induced by the stochastic modulation of dipole-dipole coupling via their relative motion. Intramolecular NOE enhancements are typically measured in NMR analysis, while smaller intermolecular enhancements are sensitive to the average molecular distance and find application in the study of intermolecular interactions. 129 Similar transfer mechanisms for hyperpolarized systems have been observed in solutions with Xe, polarized via dissolved DNP, and with PHIP. 129 Previous attempts at polarization transfer via SPINOE from Xe, from sources polarized via dissolved DNP, and from sources polarized via PHIP have typically resulted in only small target compound signal enhancements.

[0130] The magnetization transfer from the source spin S to the target spin I is expressed by the autorelaxation rate

number

number

number

number

[0131]

number

[0132] Note that the magnetization transfer curve follows an initial linear accumulation in the opposite direction of the magnetization of the hyperpolarized source. Fitting only to equation (1) does not allow for independent determination of the cross-relaxation rate and source polarization, but standard (thermally polarized) measurements of NOE can be used to resolve both parameters. In such experiments, the source spins can be saturated by continuous RF irradiation, resulting in a steady-state enhancement of the target spins given by equation (2):

[0133]

number

[0134] A separate measurement T1 can then unambiguously determine σ.

[0135] Consistent with the disclosed embodiments, NOE can be demonstrated in solutions containing high concentrations (e.g., 10% v / v, 20% v / v, 50% v / v, or similar) of naphthalene-h8 as a source compound in CDCl3. Such solutions can further contain low concentrations of acetone, 1,1,2,2-tetrachloroethane (TCE), tetrahydrofuran (THF), toluene, and / or acetone as target compounds for spin polarization transfer. Both naphthalene and the target compounds have T1 relaxation times greater than 10 seconds, so the polarization buildup time is long enough to be easily monitored by small flip angle experiments. Acetone and TCE can be selected as target compounds because the T1 relaxation time of acetone, 13.5 seconds, is shorter than the relaxation time of the source, while the T1 relaxation time of TCE, 35.6 seconds, is longer.

[0136] For thermally poled samples, the cross relaxation rate σ is given by ρ and

number

number

number

[0137] Figure 9A (pentacene:naphthalene and acetone) and Figure 10A (pentacene:naphthalene and TCE) show the polarization build-up and decay at 1.45 T when the pentacene:naphthalene source compound was optically polarized before dissolving in a target solution containing 20% ​​v / v pentacene:naphthalene and either 25 mM acetone or 100 mM TCE in CDCl3. The acetone concentration differs between the thermal and hyperpolarized experiments, but this is unlikely to affect the estimated cross-relaxation rate because the pentacene:naphthalene concentration is much higher than either target compound concentration, and thus the source concentration effectively determines the average intermolecular separation in solution. The polarization transfer curves generally match the characteristic profile expected from equation (1), although there are some deviations in the short term. To obtain a better fit, the fitting function was modified to include an offset time t0 and a stretching factor β in equation (1), thereby obtaining equation (3).

[0138]

number

[0139] The polarization of the source compound in solution at the onset of NOE accumulation is as described herein and shown in Figures 9B and 10B.

number

[0140] In a separate experiment, 38 milligrams (mg) of pentacene:naphthalene crystals were polarized in an optical polarizer at approximately 25% 1 The crystals were polarized to H polarization. After polarization, the crystals were transferred to a transport system and placed in a mixing and dissolution chamber. In the chamber, the crystals were dissolved and mixed for 8 seconds in DMSO-d6 (99.96%) solvent containing 100 mM caffeine and a similar amount of acetone. The mixture was then transferred to a 60 megahertz (MHz) Spinsolve spectrometer for measurement. A selective Gaussian pulse centered at 3.2 ppm was used to significantly reduce the signal from the naphthalene nuclear spins. Hyperpolarized peaks from acetone, caffeine, and residual DMSO protons were observed. NMR spectra were measured approximately every 10 seconds. The first spectrum was measured approximately 12 seconds after the end of mixing. The enhancement of acetone and caffeine was 120-170.

[0141] Optimized detection and NMR spectra

[0142] As described herein with respect to FIG. 1, combinations of source and target compounds can be used in NMR spectroscopy or MRI applications. In some embodiments, the source compound NMR signal can be selectively reduced to allow for improved detection of the target compound signal. This selective reduction can prevent the NMR signal produced by the highly concentrated and polarized source compound from masking the NMR signal produced by the target compound. In the absence of such selective reduction, target compounds having NMR spectral features (e.g., peaks) that overlap with NMR spectral features of the source compound can be difficult to identify or characterize.

[0143] Consistent with disclosed embodiments, selective reduction of source compound NMR signals can be achieved through reduction of the polarization of the source compound, which may be achieved by selection of the source compound, selection of a particular pulse sequence for acquiring the NMR spectrum, or post-processing of the acquired NMR spectrum.

[0144] In some embodiments, the source compound may be selected to contain at least one fast relaxing atom (e.g., deuterium, which has a short relaxation time in both low and high magnetic fields). The solution containing the source compound may be placed in an ultra-low magnetic field (e.g., less than 1 uT, less than 100 nT, or less) where the Larmor frequency difference between the source atomic spins and the fast relaxing atomic spins is sufficiently small (e.g., less than 10 Hz, or less than 1 Hz). The coupling between the source atomic spins and the fast relaxing atomic spins may then cause selective relaxation of the source atoms. In some embodiments, the solution containing the source compound may be non-adiabatically moved to an ultra-low electric field, thereby inducing relaxation of the source atoms.

[0145] In some embodiments, relaxation of the source atomic spins via coupling with fast relaxing atomic spins can be enhanced using RF irradiation. For example, such RF irradiation can establish a Hartmann-Hahn resonance in a rotating frame between the source atomic spins and the fast relaxing atomic spins. As an additional example, an INEPT pulse sequence can transfer the polarization between the source atomic spins and the fast relaxing atomic spins. For example, the source compound may be at least partially deuterated and the target compound is not deuterated. Enhancement of relaxation through interaction with deuterium spins allows selectively affecting at least partially deuterated source compounds and reducing the masking effect of the source molecules on the NMR spectrum.

[0146] In some embodiments, the pulse sequence may be selected to reduce the polarization or signal of the source compound according to any suitable NMR solvent suppression technique. In some embodiments, the selected pulse sequence may depend on the particular J-coupling of the polarized spins of the source compound. For example, if the source compound is a polarized spin-polarized NMR signal having the same chemical shift, the pulse sequence may be selected to reduce the polarization or signal of the source compound according to any suitable NMR solvent suppression technique. 1 If it contains H nuclear spins (e.g., when the source compound was polarized using PHIP or SABRE), apply an S2M or iSLIC pulse, 1 H nuclear spin is converted to electron spin, thereby 1 The use of such pulse sequences can reduce the polarization of the source compound and, therefore, the detected source compound signal. In some embodiments, sequences utilizing selective pulses are used.

[0147] In some embodiments, NMR spectra can be post-processed to correct for the magnetic field produced by the high magnetization of the source compound. This magnetic field can produce significant drift in the resonance of the target and source atoms, and therefore the frequency of the detected peaks. For a long cylinder magnetized transversely to its axis of symmetry, the magnetic field in a small spherical cavity inside the cylinder is B M =μ0M / 2-2μ0M / 3=-μ0M6, nuclear magnetization

number

number

number

[0148] NMR spectra can also be post-processed to correct for effects of the source compound signal. Such effects can include a large broad peak centered at the source compound frequency. This broadening may be due to the reverse action of the detection circuit on the source compound spins, creating a negative feedback, referred to in NMR as "radiation damping." In some implementations, positive feedback may be possible when the source is reverse polarized, such as the so-called "laser" (radio amplification by stimulated emission of radiation) effect.

[0149] The source compound signal may be strong enough to affect other spin species. Relatively short-lived magnetic fields induced by process spin and radiation decay may couple to other spins. Such magnetic fields may act similarly to weak RF pulses and induce frequency-dependent phase shifts on other resonances. These magnetic fields may be related to the radiation decay signal measured by the spectrometer. Thus, the phase of the target compound resonance was approximately linearly dependent on the magnitude of the naphthalene signal at the target resonance frequency. In some embodiments, the fit of the source compound signal may be multiplied by a constant to define a frequency-dependent phase correction of other spin species (e.g., spin species associated with the target compound).

[0150] The width of the radiation attenuation signal may be related to the magnitude of magnetization of the source compound and the strength of the radiation attenuation itself, and therefore the phase of the target resonance and the width of the radiation attenuation signal may be related.

[0151] FIG. 10C illustrates a post-processing method 1000 for separating the effects of the sample magnetic field and the source compound signal from the remainder of the acquired NMR spectrum according to the disclosed embodiment. In this manner, the performance of the method 1100 can improve the detection of the 1D NMR spectrum of the target compound. The method 1100 can be performed using multiple NMR spectra acquired repeatedly or periodically by an NMR spectrometer. As will be appreciated, the NMR spectrum generated by the method 1000 can be analyzed in the same manner as a conventional NMR spectrum. In some embodiments, the order of operations of the method 1000 can be changed. For example, the phase shift due to the magnetization of the source compound can be determined before subtracting the signal of the source compound (e.g., step 1030 can be performed before one or more of steps 1010 and 1020).

[0152] In step 1010, the source compound signals may be removed from each acquired NMR spectrum, consistent with disclosed embodiments. In some implementations, the source compound signals may be fitted to a complex Lorentzian (or sum of Lorentzian) lineshape. Such a Lorentzian may have the following formula:

[0153]

number

[0154] Figure 10D shows an example spectrum with mask data used for the fit, where peaks from the target molecule are excluded from the fit calculation. Figure 10E shows a complex Lorentzian fit. The lineshape of the source compound can be subtracted from the NMR spectrum to yield the spectrum shown in Figure 10F. Any residual distortion of the NMR spectrum baseline can be corrected using moving averages or other standard techniques.

[0155] In step 1020, a nonlinear phase correction is applied based on the fit of the source compound signal, followed by the standard zero-order and first-order phases. In addition to the standard zero-order and first-order phase adjustments, a second-order correction can be estimated by multiplying the normalized Lorentzian of the source background (A=1) by a constant ψ. The phase, background-subtracted spectrum, is given by ψS(v), where S(v) is the background-subtracted spectrum and ψ is the phase correction including zero-order, first-order, and second-order terms.

[0156]

number

[0157] Applying zero-order, first-order, and second-order phase corrections gives the result in FIG. 10G, where the baseline is nearly flat and only narrow features of the naphthalene source signal remain.

[0158] In step 1030, the NMR spectra may be aligned, consistent with disclosed embodiments. In some implementations, a complex Lorentzian (or sum of Lorentzians) lineshape may be fitted to the target compound signal for each NMR spectrum. In the example shown in FIG. 10H, a complex Lorentzian is fitted to the higher frequency peak of THF. An example of this fit is shown for 32.9 seconds, 49.3 seconds, 65.7 seconds, and 82.2 seconds. The real and imaginary components are labeled in each plot. The center frequency of each target compound lineshape may be extracted. These center frequencies may then be fitted to a decay exponential, as shown in FIG. 10I, to determine the exponential decay of the phase shift due to the decaying naphthalene source compound magnetization over time. Alternatively, the center frequency of the source compound lineshape from step 1010 may be extracted. In either implementation, the decay exponent may define the frequency shift required to align the NMR spectra. If the source compound lineshape is used to determine the frequency shift, some additional manual alignment adjustments may be performed. Once the phase shift of each spectrum is determined, each spectrum can be shifted by the determined amount to align the spectra and correct the chemical shift axis of each spectrum. Figure 10J shows the spectrum before correcting the chemical shift axis, while Figure 10K shows the spectrum after correction of the chemical shift axis.

[0159] In some embodiments, radiation decay can be utilized to allow several polarization transfer and detection iterations. Due to the very high magnetization of the source compound, after the excitation pulse, radiation decay rapidly rotates the source magnetization / polarization back to the z-axis, preferably in less than 100 ms, 50 ms, 30 ms, 10 ms, 5 ms. This rate is related to the rate of decoherence of the source compound (T2 or T2 *), a significant amount of source polarization is maintained after the excitation pulse, even with an excitation pulse angle of 90 degrees. Thus, a large signal can be obtained from the target molecule without significant loss of polarization of the source compound. This can be utilized for repeated measurements before the source compound relaxes back to thermal equilibrium, allowing for signal averaging or multidimensional spectroscopy.

[0160] In some embodiments, the long relaxation times of the source compounds can be used to detect signals of target compounds with short relaxation times, such as, for example, less than 10 seconds, less than 5 seconds, less than 2 seconds, less than 1 second, less than 500 milliseconds, less than 200 milliseconds, less than 100 milliseconds, less than 50 milliseconds, less than 10 milliseconds, or even less. These target compounds are typically very difficult to polarize using methods that result in polarization outside of the NMR spectrometer, such as dissolution DNP, due to the rapid relaxation during transport and detection of the molecule into the NMR spectrometer. However, the disclosed embodiments allow the target compound to remain in constant NOE interaction with the source compound, so that the polarization accumulation of the target compound remains for the relaxation time of the source molecule, thereby allowing the detection of polarization in fast relaxing target compounds. Furthermore, the polarization accumulation maximum can be limited by the short relaxation time of the target compound, so that several excitation pulses close to the accumulation of maximum polarization can be used within the longer relaxation time of the source compound, allowing signal averaging or multidimensional spectroscopy. In some embodiments, ultrafast 2D sequences can be used for two-dimensional spectroscopy, as described in "Ultrafast Two-Dimensional NMR: A New Tool in Analytical Spectroscopy" by P. Giraudeau and L. Frydman, which is incorporated herein by reference in its entirety for all purposes.

[0161] Source and target compounds

[0162] After polarization transfer, the target compound can be separated from the source compound, as described herein with respect to Figure 1. In some embodiments, such a separation step can produce a mixture that includes the target compound, with some trace concentration of the source compound (e.g., less than 1 mM, 500 micromolar (μM), 200 μM, 100 μM, 50 μM, 20 μM, 10 μM, 5 μM, 2 μM, 1 μM, 500 nanomolar (nM), 200 nM, 100 nM, 50 nM, 20 nM, 10 nM, 5 nM, 2 nM, 1 nM, 500 picomolar (pM), 200 pM, 100 pM, 50 pM, 20 pM, 10 pM, 5 pM, 2 pM, or 1 pM) remaining within the mixture. In some embodiments, such separation can involve removal of at least 90% (eg, at least 99%, 99.9%, 99.99% or more) of the source compound from a mixture of source compound and target compound.

[0163] Consistent with the disclosed embodiments, the source compound may not be suitable for use in certain NMR spectroscopy or imaging applications. Separation of the source and target compounds allows for use of the resulting mixture in such applications. For example, the source compound may be or may include a non-biocompatible material, while the target compound may be biocompatible. After polarization transfer, the polarized biocompatible target compound can be separated from the non-biocompatible compound to produce a polarized biocompatible resulting mixture. The resulting mixture can be used as a magnetic resonance probe. As a further example, the target compound can be used to detect tissue metabolism in vitro or in vivo (e.g., hyperpolarized MRI applications). In such applications, toxicity, biocompatibility, or regulatory requirements may require separation of the source compound from the target compound. Additionally, process control and reproducibility requirements may require separation of the source compound from the target compound. As an additional example, the resulting mixture may be used in applications (e.g., NMR spectroscopy) where the magnetic resonance signal of the source compound may otherwise mask the magnetic resonance signal of the target compound, making it difficult to distinguish between the two signals.

[0164] Consistent with disclosed embodiments, because the relaxation times of the target compounds may be short (e.g., on the order of minutes or seconds), the separation of the source and target compounds may be performed in close proximity to the MRI or NMR device. In some embodiments, the target compound may be used in a liquid state (e.g., injection or probe). In such embodiments, the mixture of source and target compounds may be dissolved prior to extraction of the target compound. In some embodiments, the dissolution step may be performed by heating the mixture or by introducing additional solvent that dissolves the target compound. In various embodiments of the invention, the compound may be separated from the solution by filtering out particles of the compound (e.g., using mechanical filtration such as a commercially available sterile filter) or by centrifuging the mixture to remove particles of the compound.

[0165] If the source and target compounds are solutes in solution, the compounds can be removed from the solution using liquid-liquid extraction, high performance liquid chromatography (HPLC) methods (e.g., separation of polar and non-polar molecules), introduction of an agent that undergoes a chemical reaction with the compound that allows for a separation pathway, or other suitable methods. Separation of the source and target compounds can be achieved using methods similar to the separation of the source compounds and hydrogenation catalysts or reaction by-products (e.g., side arms, etc.) when using PHIP, PHIP-SAH, or SABRE polarization methods as described herein. For example, if the source compounds are better soluble in the organic phase and the target compounds in the aqueous phase, liquid-liquid extraction between the aqueous and organic phases can facilitate rapid purification of the target compounds. In some embodiments, one or more rapid iterations of the liquid-liquid extraction can be performed depending on the required purity of the target compounds. In various embodiments, the liquid-liquid extraction can be performed in 2 minutes, 1 minute, 20 seconds, 10 seconds, 5 seconds, or less than 1 second. In some embodiments, the liquid-liquid extraction can be performed as an additional purification step following other extraction and separation methods.

[0166] Exemplary PHIP Polarization and Transfer Apparatus

[0167] 11 illustrates an exemplary PHIP precipitation system and process consistent with disclosed embodiments. A magnetic field generator 1101 (e.g., a permanent magnet, permanent magnet array, or electromagnet) can be configured to generate a magnetic field within a range defined by any two of the preceding values, such as a magnetic field of at least about 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 1000 mT, 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or less, or between 10 mT and 5000 mT. In some embodiments, the magnetic field generated by the magnetic field generating device 1101 may have a magnetic field inhomogeneity of greater than 1 ppm and less than 1000 ppm over a volume of 1 milliliter (mL), 2 mL, 5 mL, 10 mL, 20 mL, 50 mL, 100 mL, or more. The magnetic field inhomogeneity may be measured as the distribution of the magnetic field over the volume or according to any other statistical indicator. In some embodiments, the magnetic field generating device 1101 may generate a magnetic field with the aforementioned inhomogeneity without active shimming.

[0168] The polarization chamber 1102 may be configured to contain a solution. In use, a precursor of a source compound may be dissolved in the solution and then chemically reacted with parahydrogen (e.g., parahydrogenation) to form a parahydrogenation precursor. In some embodiments, parahydrogen may be bubbled into the solution via a connection (e.g., a gas line, etc.) to a parahydrogen container 1103. In some embodiments, parahydrogenation may be performed outside of the polarization chamber 1102 (and optionally outside of the magnetic field established by the magnetic field generator 1101). For example, in a separate parahydrogenation chamber (not shown in FIG. 11), parahydrogen may be bubbled into the solution via a gas line, or the solution may be sprayed into the parahydrogen environment via a liquid transfer line. The waveform generator 1104 may generate RF pulses (or audio frequency pulses in a relatively low magnetic field), which may be applied to the polarization chamber 1102 using the RF coil 1105. The waveform generator 1104 may be or may optionally include a waveform generator and may generate a sequence of RF pulses suitable for converting spin order in the superhydrogenated precursor to nuclear polarization. In some embodiments, the RF coil 1105 may be, be connected to, or include an NMR probe for performing NMR measurements. Such NMR measurements may be used for monitoring and quality control of the polarization of the source compound. The heating element 1106 may be configured to control the temperature within the polarization chamber 1102. For example, for improved hydrogenation, the solution temperature may be increased beyond 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., or more. In some embodiments, the heating element 1106 utilizes light, microwave, or RF energy to control the temperature. In some embodiments, the heating element 1106 utilizes temperature-controlled flowing air to control the temperature.

[0169] The precipitation chamber 1107 may be configured to separate the polarized source compound from any hydrogenation catalyst or reaction by-products (e.g., side arms, etc.). In use, a solution containing the polarized source compound may be transferred to the precipitation chamber 1107 automatically, semi-automatically, or manually. Precipitation may be initiated in the precipitation chamber 1107 using any of the methods described herein. For example, a compound may be added to the solution to initiate precipitation. In some embodiments, the compound may be a base. If the polarized para-hydrogenation precursor is an ester of the source compound, the added compound may cleave the ester and initiate precipitation of the polarized source compound. The precipitation chamber 1107 may be configured to allow separation of the precipitate from the supernatant, thereby separating the polarized source compound from the catalyst and solvent (e.g., organic solvent) used for hydrogenation and polarization of the precursor, thereby forming the source compound. Additionally, such precipitation may allow for the concentration of the source compound to be changed (e.g., from a low concentration suitable for polarization of the source compound to a high concentration suitable for transfer of polarization to the target compound using NOE).

[0170] In some embodiments, a further purification step can occur in the precipitation chamber 1107, during which the concentration of the hydrogenation catalyst can be reduced from the range of 0.1-100 mM to less than 1 micron, less than 500 nM, less than 200 nM, less than 100 nM, less than 50 nM, less than 20 nM, less than 10 nM, less than 5 nM, less than 2 nM, less than 1 nM, or less than. Such reduction can be achieved by washing the precipitated polarized source compound with a biocompatible solvent. The biocompatible solvent can be selected such that the precipitated polarized source compound is insoluble in this solvent.

[0171] In some embodiments, the hydrogenation, polarization transfer, and precipitation steps of new precursor molecules may be performed repeatedly within a predetermined period of time. In some embodiments, the predetermined period of time may be within the relaxation time of the nuclear spins of the subject in the solid phase. In some embodiments, the hydrogenation, polarization transfer, and precipitation steps may be performed rapidly, such as on the order of minutes or seconds, to allow for the collection of larger quantities of solid polarized particles. In some embodiments, these steps may be performed in a continuous flow system. In some other embodiments, these steps may be performed in several separate steps.

[0172] After precipitation and purification, the hyperpolarized particles may be stored and transported in a transport device 1108. The transport device may include a permanent magnet or an electromagnet for generating a magnetic field of greater than 10 mT. The transport device preferably includes a coolant for cooling the temperature of the hyperpolarized particles to 273.15 K or less, 150 K or less, 80 K or less, 30 K or less. A suitable transport device is described herein with respect to FIG.

[0173] After precipitation and transfer, the source compound 1109 can be mixed with a solution containing the target compound 1110 in a polarization transfer system 1111. In some embodiments, polarization can be transferred from source atoms of the source compound 1109 to target atoms of the target compound 1110 by SPINOE. In some embodiments, the polarization transfer system 1111 can be temperature controlled to increase the polarization transfer efficiency or rate. In some embodiments, the solution containing the source compound and the target compound can then be used by an NMR spectrometer or MRI device 1112 for hyperpolarized NMR or MRI. In some embodiments, the transfer of polarization to the target atom can be followed by another transfer from the target atom to a different nuclear spin on the target compound, for example, by an INEPT sequence. In some embodiments, the polarization transfer system 1111 can be part of the NMR spectrometer or MRI device 1112.

[0174] Exemplary PETS Polarization and Transfer Apparatus

[0175] 12 shows an overview of the setup and components of a PETS polarizer according to disclosed embodiments. The PETS polarizer may include a container 1210 and a solution preparation system 1220. The container 1210 may include a p-polarization chamber 1211 and a magnetic field generator 1212. The solution preparation system 1220 may include a dissolution vessel 1221, a magnetic field generator 1223, and a processing means 1225.

[0176] The polarization chamber 1211 may be configured to contain a solution in the polarization chamber 1211 of the interior volume. In use, a source compound including at least one PETS moiety may be housed in the polarization chamber 1211. In some embodiments, the source compound may be a crystalline host doped with a dopant. In various embodiments, the crystalline host may include at least one of naphthalene, p-terphenyl, or benzoic acid. In some embodiments, the dopant may be pentacene. In some embodiments, the polarization chamber 1211 may include at least one optical window 1213. The optical window 1213 may be configured to couple to a light source (not shown in FIG. 12). In use, the light source may provide light for optical polarization of the at least one PETS moiety. Consistent with disclosed embodiments, the polarization chamber 1211 may include at least one container port 1215. The at least one container port 1215 may allow automated, semi-automated, or manual passage of the source compound from the interior volume, through the at least one container port, and into the solution preparation system. For example, source compounds can exit the polarization chamber 1211 through at least one container port 1215 into a transporter 1216 (e.g., a transporter as illustrated in FIG. 13 or FIG. 14). The transporter 1216 can transport to a solution preparation system 1220 and source compounds disposed within the solution preparation system 1220. As an additional example, a manifold or conveyor can transport source compounds (e.g., automatically or semi-automatically in response to user input) from the polarization chamber 1211 through at least one container port 1215 into the dissolution vessel 1221.

[0177] The magnetic field generator 1213 can at least partially surround the interior volume of the polarization chamber 1211. The magnetic field generator 1213 (e.g., a permanent magnet, a permanent magnet array, or an electromagnet) can be configured to generate a magnetic field of at least about 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 1000 mT, 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or less, or within a range defined by any two of the preceding values, such as between 10 mT and 5000 mT within the interior volume of the polarization chamber 1211. In some embodiments, the magnetic field generating device 1213 may be or include at least one solenoid. In some embodiments, the magnetic field generated by the magnetic field generating device 1213 may have a magnetic field inhomogeneity of greater than 1 ppm, 2 ppm, 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, 1000 ppm, or more, less than 1000 ppm, 500 ppm, 200 ppm, 100 ppm, 50 ppm, 2 ppm, 1 ppm, or less, or within a range defined by any two of the preceding values. In some embodiments, the magnetic field inhomogeneity is measured over a volume of 1 ml, 2 ml, 5 ml, 10 ml, 20 ml, 50 ml, 100 ml, or more. In some embodiments, the magnetic field generating device 1213 may generate a magnetic field with the aforementioned inhomogeneity without active shimming.

[0178] In some embodiments, the dissolution vessel 1221 can be configured to couple to at least one container port 1215. In various embodiments, the dissolution vessel 1221 is configured to receive a source compound to be transported in a transporter 1216 (e.g., a transporter as shown in Figures 13 and 14). In use, the dissolution vessel 1221 can receive a source compound (e.g., after passage of the source compound through at least one container port 1215 and automatic, semi-automatic, or manual transport of the source compound). The dissolution vessel 1221 can be configured to receive a pressurized gas and a solution. The dissolution vessel 1221 can be configured to receive a solution through port 1227. In use, a target compound can be dissolved in a first solution. The dissolution vessel 1221 can receive a pressurized gas from a gas container 1230. The pressurized gas can be an inert gas. In some embodiments, the pressurized gas can be nitrogen, argon, or any combination thereof. Consistent with disclosed embodiments, the polarization chamber 1211 may include a port 1229 that can allow for automated, semi-automated, or manual passage of the solution from the dissolution vessel 1221 through the port 1229 to the NMR tube. In some embodiments, the port 1129 can be coupled to a flow system. In some embodiments, the flow system can be a tube or manifold that allows or causes (e.g., using a pump) the flow of the solution to the NMR tube (which can be inside or outside the bore of the NMR magnet). For example, the solution can flow from the port 1129 through a manifold into a tube inside the NMR magnet. In another example, the port 1129 can be directly connected to the NMR tube, which can be brought to the NMR magnet or shuttled (e.g., mechanically, pneumatically, by hand, etc.) to it. The disclosed embodiments are not limited to a particular flow system.

[0179] In use, the flow system can be configured to receive a second solution formed by combining the ground source compound with the solution added to the dissolution chamber 1221 and transport this second solution to an NMR tube 1241 (not shown in FIG. 12) located within the NMR spectrometer 1240.

[0180] The magnetic field generator 1223 can at least partially surround the dissolution vessel 1221. The magnetic field generator 1223 (e.g., a permanent magnet, permanent magnet array, or electromagnet) can be configured to generate a magnetic field of at least about 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 1000 mT, 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or less, or within a range defined by any two of the preceding values, such as between 10 mT and 5000 mT within the dissolution vessel 1221. In some embodiments, the magnetic field generating device 1223 may be or include at least one solenoid.

[0181] A processing means 1225 (not shown in FIG. 12) may be disposed at least partially within the dissolution vessel 1221. The processing means 1225 may be configured to process (e.g., break, crush, cut, grind, etc.) the source compound into pieces of a desired size. In use, the processing means 1225 may process the source compound, thereby allowing or accelerating dissolution of the source compound in a solution received through the solution port, thereby generating a second solution.

[0182] In some embodiments, the processing means can be an ultrasonic probe. In some embodiments, the processing means can include a cutting, grinding, or milling head (e.g., processing head) for mechanically processing the source compound. The processing head can be mechanically coupled to the shaft. In some embodiments, the shaft can be configured to permit motion within the dissolution vessel. In some embodiments, the motion can include motion along the axis of the shaft. The shaft advances within the dissolution vessel 1221, causing the processing head to process the source compound (e.g., against the wall of the dissolution vessel 1221). In some embodiments, the motion can include motion about the axis of the shaft and / or about a second axis parallel to the axis of the shaft. This motion can rotate the processing head within the dissolution vessel, causing the processing head to process the source compound. In some embodiments, the processing head can press the source compound against a filter (e.g., a frit) such that particles of the source compound pass through the filter. In some embodiments, the shaft can be mechanically coupled to a rotation motor. The rotation motor can be configured to provide motion to the processing head via the shaft, thereby processing the source compound.

[0183] Examples of transportation devices

[0184] 13 depicts an exemplary transport device 1300 consistent with disclosed embodiments. In some embodiments, the device 1300 may include a base 1310, a container 1320, and a magnet 1330. The device may further include a canister 1340, a cartridge 1350, and a seal 1360.

[0185] The base 1310 may be configured to support the container 1320. The magnet 1330 may be attached to the base 1310 and disposed about the container 1320. In some embodiments, the magnet 1330 may include multiple magnets spaced about the container 1320. The magnet 1330 may be configured to maintain a magnetic field of between 0.1 and 4 Tesla in the container 1320 (or in the receptacle 1327 of the container 1320) when the container 1320 is disposed within the magnet 1330 on the base 1310.

[0186] The container 1320 may include an insulating layer 1321, an absorbent material layer 1323, an inlet 1325, and a receptacle 1327. The insulating layer 1321 may be configured to insulate the inside of the container 1320 from the outside environment. The insulating layer 1321 may be any suitable insulating material. The absorbent material layer 1323 may be configured to absorb a liquid coolant. For example, the absorbent material layer 1323 may be suitable for absorbing liquid nitrogen or a similar cryogenic liquid. The receptacle 1327 may be a void formed in the absorbent material layer 1323 below the inlet 1325. In some embodiments, the void may be cylindrical. The inlet 1325 may allow access to the interior of the container 1320 through the insulating layer 1321.

[0187] The container 1320 may be configured to allow a liquid coolant (e.g., liquid nitrogen) to be poured into the receptacle 1327 and absorbed into the absorbent material layer 1323. As long as enough liquid coolant remains, the temperature within the receptacle 1327 will approximate the temperature of the liquid coolant. In some embodiments, the container 1320 may be a cryogenic, dry shipping container, such as a cryostat (e.g., a Dewar, a vacuum flask, etc.).

[0188] The canister 1340 may be configured to support the cartridge 1350 in the receptacle 1327. In some embodiments, the canister 1340 may include a handle 1341 that allows the canister 1340 to be placed in and removed from the receptacle 1327 through the inlet 1325. The cartridge 1350 may be configured to hold one or more holders 1351. The cartridge 1350 may be configured and arranged such that each holder 1351 may be separately removable from the cartridge 1350. Each holder 1351 may be configured to hold a sample of a polarized compound. The cartridge 1350 may be configured in the canister and lowered into the container 1320. The seal 1360 may be configured to seal the container 1320 and prevent evaporation of the coolant.

[0189] In some embodiments, the device 1300 may not include a base 1310. In such embodiments, the magnet 1330 may be disposed within the container 1320. The magnet 1330 may be disposed about the receptacle 1327. In some embodiments, the absorbent material layer 1323 may be disposed between the magnet 1330 and the receptacle 1327. In various embodiments, the absorbent material layer 1323 may be disposed between the magnet 1330 and the inner surface of the insulating layer 1321. In such embodiments, for example, the receptacle 1327 may be a void defined at least in part by the inner surface of the magnet 1330.

[0190] Exemplary Apparatus for Combining Source and Target Compounds

[0191] 14 illustrates an exemplary system 1400 for automatically combining a solid source compound with a target compound, consistent with disclosed embodiments. In some embodiments, the system 1400 can serve as the solution preparation system 1220 of FIG. 12 or the polarization transfer system 1111 of FIG.

[0192] In some embodiments, the system 1400 may include a transport container 1410. The transport container 1410 may be configured to store a solid (e.g., crystalline) source compound during transport from the polarizer to the system 1400. The transport 1410 may include a magnet 1411 (e.g., a permanent magnet, an electromagnetic device, etc.) disposed about the transport container 1413 to maintain polarization of the source compound. The magnet 1411 can generate a magnetic field within the transport container 1413 of at least about 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 1000 mT, 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or less, or between 10 mT and 2000 mT, within a range defined by any two of the preceding values. In some embodiments, the transport 1410 can include a temperature control system (e.g., cryogenic storage, Dewar, or other suitable method) for maintaining the temperature of the source compound.

[0193] In some embodiments, the system 1400 may include a dissolution vessel 1420. The dissolution vessel 1420 may be connected to a source compound loading port 1421. The source compound loading port 1421 may be connected to a transport container 1413 and may provide a channel for a solid source compound in the transport container 1413 to move (e.g., gravity drop and / or blown out by compressed gas) to a source compound location 1423 in the dissolution vessel 1420. The target compound loading port 1422 may allow for the addition of a target compound, a solvent, a solution of a target compound and a solvent, pressurized gas, or any combination or sequence of the foregoing to the dissolution vessel 1420. In some embodiments, the target compound loading port 1410 may be connected to a manifold, which in turn is connected to a pressurized gas source, a target compound or target compound solution container, a solvent container, or the like.

[0194] Consistent with disclosed embodiments, the dissolution vessel 1420 can include a mechanism for mechanically breaking down solid source compounds into smaller particles for faster dissolution. As shown in FIG. 14, such a mechanism can be implemented using a grinding head 1424 connected to a shaft 1425 driven by a rotational motor 1426. In some embodiments, the rotational motor 1426, shaft 1425, and grinding head 1423 can be advanced and withdrawn within the dissolution vessel 1420. In this manner, the source compound can be positioned within the source compound location 1423 before advancing and rotating the grinding head 1424 (e.g., for 1-10 seconds, or more), thereby breaking down the source compound. Similarly, the grinding head 1424 can be withdrawn prior to adding the target compound or a solution containing the target compound. Alternatively, a solution containing the target compound can be added through the target compound port 1422 while the grinding head 1424 advances (e.g., while the grinding head 1424 rotates). In such embodiments, rotation of the grinding head 1424 may serve to mix the target solution with the source compound. Although shown with a rotating grinding head 1424 driven by a rotary motor 1426 through a shaft 1425, the disclosed embodiments are not limited to such an arrangement. In some embodiments, the mechanism for mechanically breaking down the solid source compound may be implemented using a mortar and pestle arrangement or an ultrasonic probe.

[0195] Consistent with disclosed embodiments, the separator 1427 may be positioned adjacent to the source compound location 1423 (e.g., below or around the source compound location 1423, or another suitable location). The separator 1427 may be used to separate the solution resulting from the addition of the solvent or target solution to the dissolution vessel 1420 through the target compound loading port 1422. The separator 1427 may be a frit, membrane, filter, or the like. In some instances, the separator 1427 may separate the dissolved source compound (or additionally dissolved target compound) from solid particles (e.g., undissolved particles of the source or target compound). In some embodiments, the solution may be forced through the separator 1427. The solution may be forced through the separator 1427 using a gas (e.g., nitrogen gas, argon gas, and / or another suitable inert gas) introduced through the target compound loading port 1422. The solution may be forced to an outlet port 1428, which may be fluidly connected to the dissolution vessel 1420. In some embodiments, there can be a delay (at least about 1 millisecond (ms), 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, 100 ms, 200 ms, 500 ms, 1000 ms, or more, up to about 1000 ms, 500 ms, 200 ms, 100 ms, 50 ms, 20 ms, 10 ms, 5 ms, 2 ms, 1 ms, or less, or within a range defined by any two of the preceding values) between the cessation of rotation by the grinding head 1424 and the introduction of gas to push the solution through the separator 1427. Such a delay can allow for polarization transfer from source atoms of the source compound to target atoms of the target compound.

[0196] In some embodiments, the outlet port 1428 may be connected to a container for collecting the solution (e.g., an NMR tube, or another suitable container), or to an inlet port of an NMR or MRI machine. In some embodiments, the outlet port 1428 may be connected to an inlet port of an NMR or MRI machine.

[0197] In some embodiments, magnets 1429 may be disposed about or attached to the dissolution vessel 1420 (and optionally at least partially about the source compound loading port 1421 and the target compound loading port 1422, as shown in FIG. 14). Such magnets may be permanent magnets, electromagnets, or the like. Such magnets can generate a magnetic field within the dissolution vessel 1420 of at least about 1 mT, 2 mT, 5 mT, 10 mT, 20 mT, 50 mT, 100 mT, 200 mT, 500 mT, 1000 mT, 2000 mT, 5000 mT, or more, up to about 5000 mT, 2000 mT, 1000 mT, 500 mT, 200 mT, 100 mT, 50 mT, 20 mT, 10 mT, 5 mT, 2 mT, 1 mT, or less, or within a range defined by any two of the preceding values.

[0198] Exemplary polarization transfer from naphthalene doped with pentacene in solution

[0199] Transfer of polarization from naphthalene crystals doped with spin-polarized pentacene dissolved in solution to target compounds via intermolecular NOE was investigated at room temperature and at moderate magnetic fields (1.45 T). NMR signals were enhanced by a factor of 200-1,730 (corresponding to polarizations of up to 0.86%) for a variety of small molecules. The entire polarization process took less than a minute, did not require cryogenic temperatures, and resulted in high-resolution NMR spectra due to the absence of paramagnetic contaminants.

[0200] Hyperpolarization of the source molecule Pentacene-doped naphthalene crystals were optically polarized to 20%-25% proton polarization. The polarized crystals were then transferred to a polarization transfer device at room temperature in a handheld permanent magnet assembly, where they were inserted into a dissolution vessel under inert atmosphere, crushed, and dissolved in the target solution. Finally, the samples were injected into a 1.45T benchtop spectrometer for measurements. For time-dependent studies, small-angle (~1 degree) RF pulses were applied every 3.3 seconds to monitor the source and target signals. Alternatively, one could wait for the polarization transfer and then apply a single 90 degree pulse to obtain maximum signal intensity.

[0201] The proton spins of naphthalene-h8 were polarized via triplet-DNP in single crystals doped with deuterated pentacene (as shown in T. Eichorn et al., "Apparatus for pulsed ESR and DNP experiments with optically excited triplet states up to liquid helium temperatures," J. Magn. Reson. 2013, 234, 58-66, incorporated herein in its entirety by reference for all purposes). The latter photoexcited triplet state exhibited a high electron polarization of about 90%, largely independent of magnetic field and temperature. Naphthalene was extensively purified by zone refinement, in particular to minimize contamination of paramagnetic origin and to maximize T1 relaxation times and triplet-DNP yields. The quality of the material was periodically probed by delayed fluorescence during the purification process. Triplet state lifetimes of naphthalene of more than 300 ms at room temperature were obtained. Naphthalene crystals doped with pentacene were grown using the self-seeded Bridgman technique (see S. Selvakumar et al., "Growth and Characterization of High-Quality Naphthalene Single Crystals by Selective Self-Seeded Vertical Bridgman Technique (SSVBT)," Crystal Growth, 2005, 282, 370-375, incorporated herein by reference in its entirety for all purposes). The pentacene doping concentration was preferentially chosen close to saturation (on the order of 10 ppm to 100 ppm) to maximize the triplet-DNP accumulation rate.

[0202] For polarization transfer experiments, the crystal axes were identified by optical birefringence, and samples were cut to about 40 mg and placed in a home-built polariscope featuring liquid nitrogen cooling to a temperature near 150 °C. Polariscope control, readout, and analysis were performed with the software suite Qudi. The sample was rotated to its canonical orientation (B0 magnetic field parallel to the pentacene X-axis) and shuttled between the electron spin resonance (ESR) cavity and the NMR coil, both immersed in the field of an electromagnet, typically maintained at 0.22 T for ESR / DNP operation and ramped up to 0.8 T for NMR readout. The crystal was aligned based on the optically detected magnetic resonance (ODMR) of the pentacene fluorescence signal using an optical pump-probe scheme. The photoexcited triplet state was initialized with a pulsed laser and microwaves were synthesized by an arbitrary waveform generator (AWG), allowing the performance of advanced DNP protocols with sweeps of microwave frequency and phase.

[0203] Polarization was constructed using an optimal controlled enhancement transfer scheme, where the initial guess for the optimization algorithm was the "standard" integrated solid effect (as shown in A. Henstra et al., "Enhancement of Dynamic Nuclear Polarization by Integrated Solid Effects," Physics Letters A, 1988, pp. 134-136, incorporated herein in its entirety by reference for all purposes). The optimized sequence typically reaches polarization accumulation rates in the range of 0.1% / min to 1% / min (depending on doping concentration and sample thickness), evened out between 20-25% on average for a 40 mg sample (assuming that it is non-uniformly polarized along the laser direction due to its high extinction cross section). The hyperpolarization values ​​of naphthalene were calibrated by comparison with the thermally relaxed polarization signal.

[0204] Thermal NMR measurement The experiments described herein utilized two benchtop spectrometers, one included in the polarization transfer setup (1.45 T) to monitor polarization transfer and thermal calibration, and one used to perform saturation transfer measurements to measure cross relaxation rates (1.88 T). Intermolecular NOE enhancement was obtained via differential measurements, where the enhanced signal was compared to a reference signal acquired with the same pulse sequence but with the saturation frequency set at an equal offset opposite to the target resonance.

[0205] Polarization transfer to the target compound To bring the polarization source into contact with the selected target compound, the polarized crystals were transported from the optical polarizer to a ceramic grinding and mixing vessel via a hand-held magnet assembly (B0 approximately 150 mT). The crystals were placed on a titanium frit with a pore size on the order of 5 μm. To maximize the polarization transfer efficiency, the average distance between the source and the target compound should be reduced as much as possible. Thus, naphthalene was dissolved in the solution to a concentration of 1.6 molar (M) to 1.8 M, which is not far from its saturation point in chloroform at room temperature. To achieve a concentration close to 20% (v / v) naphthalene, approximately 160 uL of the target solution was injected into the vessel.

[0206] Dissolution of the crystals was accomplished by lowering a motor-controlled ceramic shaft into the ceramic vessel. The grinding shaft began its motor-controlled rotation and was lowered onto the crystals, first just above the frit, and then rotated into position to continue dissolution. Grinding and mixing was continued for 6 seconds until the majority of the polarized naphthalene crystals had dissolved.

[0207] The material was then forced through a titanium frit and injected over 2-8 seconds into a 3 mm NMR tube that was positioned within a benchtop NMR spectrometer to monitor the hyperpolarized signal over time. The hyperpolarized signal was monitored with small flip hard pulse excitations, typically 1-3 degrees, to minimize the effects of radiation decay while providing adequate SNR for the low concentration target compound signal. Pulses were spaced at either 1.7 seconds or 3.3 seconds acquisition periods.

[0208] The following target solutions were used in the experiments described herein: (1) 100 millimolar (mM) propargyl acetate (Sigma Aldrich) in 99.8% D CDCl3, (2) 50 mM TCE in 99.8% D CDCl3, or a mixture of small molecules, (3) 25 mM acetone, 100 mM dichloromethane, 160 mM chloroform, 100 mM THF, 100 mM TCE in 99.8% D CDCl3. Each target solution was bubbled with N2 gas for 120 seconds prior to the nuclear experiment to evacuate any paramagnetic O2 to minimize sources of nuclear spin self-relaxation. An inert atmosphere of N2 gas was maintained during the process of grinding and dissolving the crystals, and pressurized N2 gas was used to inject the hyperpolarized mixture into the NMR spectrometer.

[0209] Results and Analysis 14 shows a series of NMR spectra acquired every 3.3 seconds after injection of the hyperpolarized solution into the spectrometer (i.e., for clarity, every third scan is shown). Three traces are called trace 1410, trace 1420, and trace 1430. The sample considered in this example contained about 1.8 M naphthalene (20% v / v) and 100 mM dichloromethane in deuterated chloroform CDCl3.

[0210] As discussed above with respect to FIG. 10C, the spectrum shows many features related to nuclear magnetization. First, the sample magnetic field produced significant drift of the source and target compound resonances, clearly indicated by the change in position of the dichloromethane and the broadening of the naphthalene resonance over time. The magnetic field of the benchtop NMR spectrometer was 1.45 T, and a shift of -1.00 ppm corresponds to a proton polarization of 5.73%. Second, the spectrum is dominated by a large broad peak centered at the naphthalene resonance frequency. FIG. 16A shows the relationship between the phase of the target resonance and the width of the radiation decay signal. FIG. 16B shows the enhancement curves estimated for each proton site using the preceding procedure according to the disclosed embodiment. FIG. 17 compares the 90 degree excitation of the hyperpolarized dichloromethane signal measured after about 35 seconds and post-processed according to method 1000 with a single shot thermal spectrum.

[0211] The efficiency of the solution NOE polarization transfer approach was benchmarked using a mixture of 20% v / v naphthalene and 300 mM propargyl acetate in CDCl3. The propargyl acetate spectrum consists of three distinct proton resonances that are well separated from the naphthalene resonance. The accumulation curves probed at a 1 degree flip angle are shown in Figure 18A. These curves show the highest enhancement achieved with propargyl acetate, estimated to be -1730 ± 60 times at 1.45 T, corresponding to a polarization of about 1%. The CH protons were observed for a long period of about 60 seconds. 1 The CH2 and CH3 resonances both exhibit HT1 relaxation times of about 10 s, leading to a particularly high degree of polarization transfer, as expected from equation (2). 1 H T1s, reaching maximum signal enhancements of -250±10 and -360±1, respectively.

[0212] The hyperpolarized spectrum is compared to the averaged 90 degree flip angle thermal spectrum in Figure 18B. The accumulation time selected for this comparison was approximately the time observed to show maximum enhancement of the -CH resonance (e.g., 35-40 s). These curves show the highest enhancement achieved from propargyl acetate, estimated at 1820 ± 60 fold at 1.45 T, corresponding to approximately 1% polarization. The CH protons exhibited a long proton T1 relaxation time of approximately 60 s, resulting in a particularly high degree of polarization transfer. Both the CH2 and CH3 resonances had T1 times the protons of approximately 10 s, reaching maximum signal enhancements of approximately 260 ± 10 and 380 ± 10, respectively.

[0213] To demonstrate the applicability of the polarization transfer method to more complex NMR spectra, the procedure was applied to a CDCl3 solution containing 100 mM 1,1,2,2-tetrachloroethane (TCE), 100 mM dichloromethane (DCM), 100 mM tetrahydrofuran (THF), 5-10 mM toluene, and 25 mM acetone. The polarization enhancement over time for this solution is shown in Figure 18C. The hyperpolarized spectrum is compared to the averaged 90 degree flip angle thermal spectrum in Figure 18D. More than 200-fold signal enhancement for thermal polarization at 1.45 T was observed for all resonances 20-40 s after injection.

[0214] Exemplary polarization transfer from PHIP-polarized diethyl maleate in solution.

[0215] via the intermolecular nuclear Overhauser effect (NOE), spin-polarized deuterated, and 13 C-labeled diethyl maleate 13 CD 10 The transfer of polarization from the NMR spectroscopy to the target compound was investigated at room temperature and at 1.9 T. The NMR signal was enhanced by a factor of about six in solution relative to ethyl acetate.

[0216] 2M Diethyl acetylenedicarboxylate-1- 13 CD 10A 0.5 mL sample of PHIP and 15 mM [1,4-bis(diphenylphosphino)butane](1,5-cyclooctadiene)rhodium(I) tetrafluoroborate was prepared in acetone-d6. 25 uL of ethyl acetate was added to the PHIP precursor solution. A pressurizable 5 mm NMR tube was filled with the solution and sealed with a glass capillary extending to the bottom. The solution was heated to 60°C and parahydrogen gas was bubbled through the capillary at 15 bar into the solution for 15 seconds. The chemical reaction produced diethyl maleate-1- 13 CD 10 Immediately after, the NMR tube containing the solution was placed in a mu-metal shield inside a solenoid electromagnet providing a constant 50 μT magnetic field. A transverse oscillating magnetic field was applied and ramped in strength to obtain the diethyl maleate-1- 13 CD 10 The proton singlet orders of were converted to proton magnetization. The sample was extracted from the mu metal shield and placed in a 1.9 T benchtop NMR spectrometer for signal acquisition after a 2° flip angle rf pulse.

[0217] Results and Analysis Diethyl Maleate 13 CD 10 showed a large, broad resonance at 6.5 ppm, and ethyl acetate showed enhanced NMR resonances centered at 1.3, 2.0, and 4.1 ppm, corresponding to three proton sites. Figure 19 shows the hyperpolarized spectrum 1910 above the thermal equilibrium spectrum 1920 acquired after a 90° flip angle pulse after the hyperpolarized signal has relaxed. The ethyl acetate lines in the hyperpolarized spectrum are negatively enhanced as expected from the NOE effect.

[0218] The foregoing description is presented for illustrative purposes. It is not exhaustive and is not limited to the precise forms or embodiments disclosed. Modifications and adaptations of the embodiments will be apparent from consideration of the specification and practice of the disclosed embodiments. For example, while the described implementation includes hardware, systems and methods consistent with the present disclosure can be implemented using hardware and software. Furthermore, while certain components are described as being coupled to each other, such components may be integrated with each other or distributed in any suitable manner.

[0219] Furthermore, while exemplary embodiments are described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., aspects across various embodiments), adaptations, or alterations based on the present disclosure. The elements of the claims should be interpreted broadly based on the language used in the claims, and not limited to the examples described herein or in the filing of the application, which examples should be interpreted as non-exclusive. Furthermore, the steps of the methods of the present disclosure can be modified in any manner, including reordering steps, or inserting or deleting steps.

[0220] The features and advantages of the present disclosure are apparent from the detailed specification, and therefore, the appended claims are intended to cover all systems and methods that fall within the true spirit and scope of the present disclosure. As used herein, the indefinite articles "a" and "an" mean "one or more." Similarly, the use of a plural word does not necessarily mean a plural, unless ambiguous in a given context. Moreover, since numerous modifications and variations will readily result from the study of this disclosure, it is not desired to limit the exact structure and operation of the present disclosure to that illustrated and described. Thus, all suitable modifications and equivalents may be utilized to fall within the scope of the present disclosure.

[0221] The embodiments may be further described using the following clauses.

[0222] Clause 1 A method for increasing the nuclear spin polarization of a target compound, the method comprising: (a) imparting a first non-thermal equilibrium nuclear spin polarization of at least 1% to at least one source atom of a source compound, such that the source atom has a nuclear gyromagnetic ratio of at least 12 megahertz per Tesla (MHz / T); (b) obtaining a first solution comprising a source compound and a target compound, wherein the at least one source atom is present in the first solution at a source concentration of at least 0.1 molar (M); and (c) imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.01% to at least one target atom of the target compound via Nuclear Overhauser Effect (NOE) transfer of the first non-thermal equilibrium nuclear spin polarization to the at least one target atom.

[0223] Clause 2 13. The method of claim 1, further comprising, prior to (b), disposing the source compound in a first solution.

[0224] Clause 3 3. The method of clause 1 or 2, further comprising, prior to (b), disposing the target compound in a first solution.

[0225] Clause 4 4. The method of any one of clauses 1 to 3, wherein (a) occurs before (b).

[0226] Clause 5 4. The method of any one of clauses 1 to 3, wherein (a) occurs subsequent to (b).

[0227] Clause 6 6. The method of any one of clauses 1-5, further comprising (d) extracting the target compound from the first solution and disposing the target compound in a second solution.

[0228] Clause 7 7. The method of claim 6, wherein (d) comprises performing a liquid-liquid extraction procedure using the first solution and the second solution.

[0229] Clause 8 The method of paragraph 6, wherein (d) comprises crystallizing the target compound from the first solution and disposing the target compound in a second solution.

[0230] Clause 9 9. The method of any one of clauses 1-8, further comprising performing at least one nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) pulse sequence on the target compound.

[0231] Clause 10 10. The method of claim 9, wherein the at least one NMR or MRI pulse sequence includes at least one radiation attenuation procedure configured to reduce radiation attenuation of the target compound by at least 50%, 60%, 70%, 80%, 90%, 95%, or 99% compared to a pulse sequence that does not use the at least one radiation attenuation procedure.

[0232] Clause 11 11. The method of claim 10, wherein the at least one radiation attenuation procedure comprises at least one Q-switching procedure or at least one detuning procedure.

[0233] Clause 12 12. The method of claim 11, wherein at least one Q-switching procedure or at least one detuning procedure is applied to an induction coil configured to receive NMR or MRI signals from the target compound.

[0234] Clause 13 13. The method of claim 12, wherein the at least one Q-switching procedure or the at least one detuning procedure includes changing a quality (Q) factor of the induction coil from (i) a first value of at least 20 during application of a hard excitation pulse to the molecule, and (ii) a second value of up to 1 during application of a frequency selective pulse to the molecule.

[0235] Clause 14 14. The method of any one of clauses 1-13, wherein the source compound comprises at least one photoexcited triplet state (PTS) moiety.

[0236] Clause 15 15. The method of claim 14, wherein (a) comprises optically exciting the triplet state of the PETS moiety.

[0237] Clause 16 16. The method of any one of clauses 1 to 15, wherein the source compound comprises a crystalline host doped with a dopant.

[0238] Clause 17 17. The method of claim 16, wherein the crystalline host comprises naphthalene, p-terphenyl, or benzoic acid.

[0239] Clause 18 18. The method of claim 16 or 17, wherein the dopant comprises pentacene.

[0240] Clause 19 19. The method of any one of clauses 1-18, wherein the source compound comprises a para-hydrogenated or para-tritiated source compound.

[0241] Clause 20 20. The method of claim 19, wherein the source compound comprises a PHIP polarized para-hydrogenated or para-tritiated source compound.

[0242] Clause 21 20. The method of claim 19, wherein the source compound comprises a PHIP-SAH-polarized para-hydrogenated or para-tritiated source compound.

[0243] Clause 22 20. The method of claim 19, wherein the source compound comprises a SABRE-polarized para-hydride or para-tritiated source compound.

[0244] Clause 23 20. The method of clause 19, further comprising repeating (a) and (c) to impart additional polarization to the target compound.

[0245] Clause 24 23. The method of any one of clauses 1-22, wherein at least one source atom comprises hydrogen, tritium, fluorine-19, or phosphorus-31.

[0246] Clause 25 25. The method of any one of clauses 1-24, wherein at least one target atom has a nuclear spin equal to 1 / 2.

[0247] Clause 26 26. The method of clause 25, wherein the at least one target atom comprises hydrogen, tritium, carbon-13, nitrogen-15, fluorine-19, silicon-29, phosphorus-31, iron-57, selenium-77, yttrium-89, rhodium-103, silver-107, silver-109, cadmium-111, cadmium-113, tin-117, tin-119, tellurium-123, tellurium-125, thulium-169, ytterbium-171, tungsten-183, osmium-187, platinum-195, mercury-199, thallium-203, thallium-205, lead-207, polonium-209, or plutonium-239.

[0248] Clause 27 27. The method of any one of clauses 1-26, wherein at least one target atom has a nuclear spin greater than 1 / 2.

[0249] Clause 28 At least one target atom is selected from the group consisting of deuterium, lithium-6, lithium-7, beryllium-9, boron-10, boron-11, nitrogen-14, oxygen-17, sodium-23, magnesium-25, aluminum-27, sulfur-33, chlorine-35, chlorine-37, potassium-39, potassium-41, calcium-43, scandium-45, titanium-47, titanium-49, vanadium-50, vanadium-51, chromium-53, manganese-55, cobalt-59, nickel-61, copper-63, copper-65, zinc-67, gallium-69, gallium-71, germanium-73, arsenic-75, bromine-79, bromine-81, rubidium-85, rubidium-87, strontium-89, strontium-90, strontium-91, strontium-92, strontium-93, strontium-94, strontium-95, strontium-96, strontium-97, strontium-99, strontium-98, strontium-99, strontium-99, strontium-100, strontium-101, strontium-102, strontium-103, strontium-104, strontium-105, strontium-106, strontium-107, strontium-108, strontium-109, strontium-1109, strontium-111, strontium-112, strontium-113, strontium-114, strontium-115, strontium-116, strontium-117, strontium-118, stro 28. The method of claim 27, comprising rontium-87, zirconium-91, niobium-93, molybdenum-95, molybdenum-97, ruthenium-99, ruthenium-101, palladium-105, indium-113, indium-115, antimony-121, antimony-123, iodine-127, cesium-133, barium-135, barium-137, lanthanum-138, lanthanum-139, hafnium-177, hafnium-179, tantalum-181, rhenium-185, rhenium-187, osmium-189, iridium-191, iridium-193, gold-197, mercury-201, bismuth-209, or uranium-235.

[0250] Clause 29 29. The method of any one of clauses 1-28, wherein the at least one source atom is present in the first solution at a source concentration of at least 0.2M, 0.5M, 1M, 2M, 5M, or 10M.

[0251] Clause 30 30. The method of any one of clauses 1-29, wherein (a) comprises imparting a first non-thermal equilibrium nuclear spin polarization of at least 2%, 5%, 10%, 20%, or 50% to at least one source atom of the source compound.

[0252] Clause 31 31. The method of any one of clauses 1-30, wherein (c) comprises imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, or 10% to at least one target atom of the target compound.

[0253] Clause 32 32. The method of any one of clauses 1-31, wherein the cross relaxation term between the source atom and at least one target atom is at most 1 Hertz (Hz), 0.5 Hz, 0.2 Hz, 0.1 Hz, 0.05 Hz, 0.02 Hz, 0.01 Hz, 0.005 Hz, 0.002 Hz, or 0.001 Hz.

[0254] Clause 33 33. The method of any one of clauses 1-32, wherein the target compound is present in the first solution at a target concentration of up to 1,000 millimolar (mM), 500 mM, 200 mM, 100 mM, 50 mM, 20 mM, 10 mM, 5 mM, 2 mM, 1 mM, 500 micromolar (μM), 200 μM, 100 μM, 50 μM, 20 μM, 10 μM, 5 μM, 2 μM, 1 μM, 500 nanomolar (nM), 200 nM, 100 nM, 50 nM, 20 nM, 10 nM, 5 nM, 2 nM, 1 nM, or less.

[0255] Clause 34 34. The method of any one of clauses 1-33, wherein the target compound is incorporated into a surface, solid, membrane, nanoparticle, or microparticle.

[0256] Clause 35 35. The method of any one of clauses 1-34, wherein the target compound comprises a small molecule, a peptide, a polypeptide, a protein, a nucleic acid, a ribonucleic acid, a deoxyribonucleic acid, a carbohydrate, or a polymer.

[0257] Clause 36 1. A system for increasing the nuclear spin polarization of a target compound, the system comprising: a first solution receiving module configured to receive a first solution comprising a source compound dissolved therein, the source compound comprising at least one source atom, the at least one source non-carbon atom being present in the first solution at a source concentration of at least 0.1 molar (M); a polarization module coupled to the first solution receiving module, the polarization module configured to impart a first non-thermal equilibrium nuclear spin polarization of at least 1% to the at least one source atom of the source compound; a second solution receiving module configured to receive a second solution comprising a target compound dissolved therein; and a mixing module fluidly coupled to the polarization module and the second solution receiving module, the mixing module configured to mix the first solution and the second solution, thereby allowing the first non-thermal equilibrium nuclear spin polarization to be transferred to at least one target atom of the target compound via Nuclear Overhauser Effect (NOE) transfer, thereby imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.01% to at least one target atom of the target compound.

[0258] Clause 37 37. The system of claim 36, further comprising a chamber fluidly coupled to the first solution receiving module, the chamber configured to receive a source compound and a liquid and to mix the source compound and the liquid, thereby forming a first solution.

[0259] Clause 38 38. The system of claim 36 or 37, wherein the polarization module comprises a parahydrogen polarization module.

[0260] Clause 39 38. The system of claim 36 or 37, wherein the polarization module includes a PETS module.

[0261] Clause 40 A system according to any one of clauses 36 to 39, wherein the system is further configured to carry out a method according to any one of clauses 1 to 35.

[0262] Clause 41 10. A system for increasing the nuclear spin polarization of a target compound, the system comprising: a container including an internal volume configured to contain a source compound comprising at least one PETS moiety therein; a first magnetic field source at least partially surrounding the internal volume and configured to generate a first magnetic field within the internal volume; at least one optical window configured to couple to a light source thereby to allow optical polarization of the at least one PETS moiety and at least one container port configured to allow passage of the source compound; a dissolution vessel coupled to the at least one container port and configured to receive the source compound after passage of the source compound through the at least one container port and receive a first solution comprising a pressurized gas and a compound dissolved therein; a second magnetic field source at least partially surrounding the dissolution vessel and configured to generate a second magnetic field within the dissolution vessel; and a solution preparation system including a grinding head located within the dissolution vessel and configured to grind the source compound thereby allowing dissolution of the source compound in the first solution, thereby generating a second solution, and at least one solution port configured to allow passage of the second solution therethrough.

[0263] Clause 42 42. The system of claim 41, wherein the source compound comprises a crystalline host doped with a dopant.

[0264] Clause 43 43. The system of claim 42, wherein the crystalline host comprises naphthalene, p-terphenyl, or benzoic acid.

[0265] Clause 44 44. The system of claim 42 or 43, wherein the dopant comprises pentacene.

[0266] Clause 45 45. The system of any one of clauses 41-44, wherein the first magnetic field source or the second magnetic field source includes at least one solenoid.

[0267] Clause 46 46. ​​The system of any one of clauses 41-45, wherein the first magnetic field or the second magnetic field has a strength of at least about 1 mT, 2 mT, 5 mT, or 10 mT.

[0268] Clause 47 47. The system of any one of clauses 41-46, wherein the first magnetic field or the second magnetic field has a strength of up to about 5000mT, 2000mT, 1000mT, 500mT, 200mT, or 100mT.

[0269] Clause 48 48. The system of any one of clauses 41-47, wherein the pressurized gas comprises nitrogen, argon, or any combination thereof.

[0270] Article 49 49. The system of any one of clauses 41-48, further comprising a shaft mechanically coupled to the grinding head and configured to permit movement of the grinding head, thereby grinding the source compound.

[0271] Article 50 50. The system of claim 49, further comprising a rotational motor mechanically coupled to the shaft and configured to provide motion to the grinding head via the shaft, thereby grinding the source compound.

[0272] Article 51 51. The system of any one of clauses 41-50, wherein the solution port is configured to couple to an NMR tube configured to receive a second solution therein.

[0273] Clause 52 52. The system of any one of clauses 41-51, wherein the solution port is configured to couple to a flow system configured to receive a second solution and transport the second solution to an NMR tube located within an NMR spectrometer.

[0274] As used herein, unless otherwise stated, the term "or" includes all possible combinations unless impracticable. For example, if it is stated that a component may include A or B, the component may include A, or B, or A and B, unless otherwise stated or impracticable. As a second example, if it is stated that a component may include A, B, or C, the component may include A, or B, or C, or A and B, or C, or C, or B, unless otherwise stated.

Claims

1. 1. A method for increasing the nuclear spin polarization of a target compound, comprising: (a) using a method for polarizing nuclear spins, imparting a first non-thermal equilibrium nuclear spin polarization of at least 1% to at least one source atom of a source compound, such that the source atom has a nuclear gyromagnetic ratio of at least 12 megahertz per tesla (MHz / T); (b) the source compound, wherein the at least one source atom is present in the first solution at a source concentration of at least 0.1 molar (M); obtaining a first solution comprising the target compound; (c) imparting a second non-thermal equilibrium nuclear spin polarization of at least 0.01% to at least one target atom of the target compound via intermolecular Nuclear Overhauser Effect (NOE) transfer of the first non-thermal equilibrium nuclear spin polarization to the at least one target atom; A method comprising:

2. 10. The method of claim 1, further comprising: (d) extracting the target compound from the first solution and placing the target compound in a second solution.

3. 3. The method of claim 2, wherein (d) comprises performing a liquid-liquid extraction procedure using the first solution and the second solution.

4. 3. The method of claim 2, wherein (d) comprises crystallizing the target compound from the first solution and disposing the target compound in the second solution.

5. 10. The method of claim 1, further comprising performing at least one nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) pulse sequence on the target compound.

6. 6. The method of claim 5, wherein the at least one NMR or MRI pulse sequence includes at least one radiation attenuation procedure configured to reduce radiation attenuation of the target compound by at least 50% compared to a pulse sequence that does not use the at least one radiation attenuation procedure.

7. The method of claim 6 , wherein the at least one radiation attenuation procedure comprises at least one Q-switching procedure or at least one detuning procedure.

8. 8. The method of claim 7, wherein the at least one Q-switching procedure or the at least one detuning procedure is applied to an induction coil configured to receive NMR or MRI signals from the target compound.

9. 9. The method of claim 8, wherein the at least one Q-switching procedure or the at least one detuning procedure comprises changing a quality (Q) factor of the induction coil from (i) a first value of at least 20 during application of a hard excitation pulse to the molecule, and (ii) a second value of up to 1 during application of a frequency selective pulse to the molecule.

10. 2. The method of claim 1, wherein the source compound comprises at least one photoexcited triplet state (PETS) moiety, and the method of polarizing the nuclear spins comprises optically exciting the triplet state of the PETS moiety.

11. The method of claim 1 , wherein the source compound comprises a crystalline host doped with a dopant.

12. The method of claim 11, wherein the crystalline host comprises naphthalene, p-terphenyl, or benzoic acid and the dopant comprises pentacene.

13. 2. The method of claim 1, wherein the source compound comprises a para-hydrogen induced polarization (PHIP) polarized para-hydride or para-tritide source compound, a para-hydrogen induced polarization by side-arm hydrogenation (PHIP-SAH)-polarized para-hydride or para-tritide source compound, or a signal amplification by reversible exchange (SABRE) polarized para-hydride or para-tritide source compound, and the method of polarizing the nuclear spins comprises a PHIP method, a PHIP-SAH method, or a SABRE method.

14. 10. The method of claim 1, further comprising repeating (a) and (c) to impart additional polarization to the target compound.

15. 2. The method of claim 1, wherein the at least one source atom comprises hydrogen, tritium, fluorine-19, or phosphorus-31.

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