Hyperpolarization techniques based on the use of para-hydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of para-hydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals, and their administration in vivo should be avoided. Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 s) Ir-based catalyst capture by metal scavenging agents can produce pure para-hydrogen-based hyperpolarized contrast agents, as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.
The electrochemical reduction of CO2 to multi-carbon products is a sustainable route for the synthesis of energy dense chemical feedstocks. Cu is the only material known to produce multi-carbon (C2+) products with appreciable selectivity. However, the generation of C2+ products compete with the formation of C1 products and the reduction of water to hydrogen. Here, we tuned the activity of water by using a NaClO4-based water-in-salt-electrolyte with concentrations ranging from 1m to 17m, enabling the activity of water to be tuned from 0.97 to 0.47. Commercial Cu-nanoparticle electrodes evaluated in pH 9 NaClO4 with a water activity of 0.66 achieved a Faradaic Efficiency of ~ 73% for C2+ products (ethylene, ethanol, and propanol) with a C2+ partial current density of −110 mA cm-2 at –0.88 vs. Reversible Hydrogen Electrode. Furthermore, we were able to tune the C2+/C1 ratios between 1 to 20 by altering only the water activity, demonstrating unrivalled tunability between C1 and C2+ products. Analysis of the Tafel slopes and reaction orders on model Cu electrodes revealed that the mechanism for forming C2 products was unchanged across a wide range of water activities, while C1 products and H2 had mechanisms which changed as the activity of water was lowered. We have demonstrated that tuning the activity of water in an aqueous solvent is a powerful new guiding principle for improving the reduction of CO2 to C2 and C3 products.
<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>
<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>
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