SABRE-SHEATH Hyperpolarization at MicroTesla Fields
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for hyperpolarizing heteronuclei, such as dissolution dynamic nuclear polarization (d-DNP) and Signal Amplification by Reversible Exchange (SABRE), are expensive, complex, and inefficient, particularly for achieving significant hyperpolarization of heteronuclei like 15N, which have long polarization lifetimes but require efficient transfer of spin order from parahydrogen at low magnetic fields.
Innovation Solution
A method called SABRE-SHEATH, which involves combining parahydrogen with a compound containing hyperpolarizable heteronuclei and a catalyst, and applying a magnetic field of less than 50 μT to transfer spin order from parahydrogen to the heteronuclei, enabling efficient hyperpolarization without the need for rf irradiation or pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dissolution dynamic nuclear polarization (d-DNP) is used for hyperpolarization, then NMR signal enhancement is achieved, but the method becomes expensive and complex
Solution Approach 1:
The patent uses parahydrogen as an intermediary carrier of spin order. Instead of directly polarizing heteronuclei through complex d-DNP processes, the method transfers spin order from parahydrogen to heteronuclei via a catalyst-mediated reversible exchange process, simplifying the overall system while achieving high polarization
Solution Approach 2:
The patent replaces the complex mechanical and thermal systems required for d-DNP (including cryogenic temperatures and high magnetic fields) with a chemical exchange mechanism operating at ambient conditions. The SABRE process uses scalar couplings in low magnetic fields instead of the mechanical complexity of dissolution DNP equipment
2Measurement precision
If traditional PHIP is used to transfer spin order from parahydrogen to substrate, then hyperpolarization is achieved, but the method is limited to protons which depolarize quickly
Solution Approach 1:
The patent changes the target nucleus parameter from protons (1H) to heteronuclei (15N, 13C, 29Si, 31P, 19F). Heteronuclei have inherently longer T1 relaxation times, providing polarization lifetimes extending from minutes to hours compared to seconds for protons, enabling long-term metabolic tracking
3Productivity
If SABRE is used at low field (5-7 mT) for proton hyperpolarization, then spin order transfer is achieved, but efficiency for heteronuclei is low
Solution Approach 1:
The patent changes the magnetic field strength parameter from millitesla (5-7 mT) to microtesla (<50 μT) range. This parameter change is critical for heteronuclei hyperpolarization because it allows the Larmor frequency of heteronuclei to match the scalar coupling frequencies, enabling efficient spin order transfer that cannot be achieved at higher fields
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
SABRE-SHEATH achieves up to 10% polarization of 15N, corresponding to a 30,000-fold signal enhancement, facilitating broader applicability in biophysical and biomedical imaging with improved efficiency and shorter timescales compared to existing methods.
Implementation Method 1
In low field (e.g., 5-7 mT), net spin order can be transferred from the para-H2 to the spins of the substrate via scalar couplings
Implementation Method 2
Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MM) sensitivity can be enhanced through hyperpolarization by temporarily increasing the relatively low nuclear spin polarization
Implementation Method 3
SABRE generally uses an organometallic catalyst to transiently co-locate para-H2 and the target substrate molecule in a low-symmetry complex in solution
Data Source
AI summary
Provided are methods for nuclear spin polarization enhancement via signal amplification by reversible exchange at very low magnetic fields.