Nanoscale MRI Using Electron-Spin Probe for Single-Molecule Imaging
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Solution Overview
Problem
Current methods for determining the atomic structure of bio-molecules rely on averaging over large ensembles, failing to provide direct imaging of single molecules due to limitations in spatial resolution and noise levels.
Innovation Solution
A nanoscale magnetic resonance imaging system using an electron-spin probe as both sensor and generator of a spatially varying magnetic field, allowing for precise determination of multiple nuclei's spatial configuration through dipole-dipole interactions and decoupling signals, achieving high spatial resolution and low noise imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional x-ray crystallography, NMR, or free electron laser femtosecond crystallography is used, then structure determination is achieved through averaging over large ensembles, but spatial resolution at the single-molecule level is lost
Solution Approach 1:
The patent extracts the measurement process from ensemble averaging to single-molecule detection by positioning a nitrogen-vacancy center in diamond near individual molecules. This allows direct imaging of atomic structures at the single-molecule level without requiring large ensembles, thereby achieving high spatial resolution while reducing the quantity of substance needed.
Solution Approach 2:
The nitrogen-vacancy center acts as an intermediary sensor that mediates between the external measurement system and the target nuclei. Through dipole-dipole interactions, the NV center enables detection of nuclear spin states and spatial configuration of individual molecules, bridging the gap between conventional ensemble methods and single-molecule imaging.
2Measurement precision
If the electron-spin probe generates a spatially varying magnetic field for high spatial resolution, then the magnetic field gradient becomes extremely steep, but the frequency range becomes constrained between upper and lower frequency limits
Solution Approach 1:
The patent changes the operating parameters by tuning the microwave frequency and magnetic field strength to match the constrained frequency range imposed by the steep magnetic field gradient. This allows the system to operate effectively within the limited frequency window between the upper frequency (set by surface interaction) and lower frequency (set by minimal coupling), achieving high spatial resolution while adapting to the frequency constraints.
3Loss of information
If dipole-dipole interaction is used for sensing nuclei, then phase information indicates number of resonant nuclei, but interaction between multiple nuclei creates coupling that complicates measurement
Solution Approach 1:
The patent extracts the nuclear spin information from the complex many-body interaction by using the nitrogen-vacancy center as a selective sensor. The NV center couples to individual nuclei through dipole-dipole interactions, allowing the phase information to be read out without requiring full characterization of all nuclear-nuclear couplings, thereby simplifying the measurement while preserving the essential spatial configuration data.
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
Enables the determination of nuclear structure with atomic resolution and low noise, overcoming the limitations of existing methods by providing detailed imaging of individual molecules.
Implementation Method 1
the electron-spin probe is configured to generate a spatially varying magnetic field such that each of the multiple nuclei is resonant at a respective resonance frequency defined by the magnetic field at a location of that nucleus
Implementation Method 2
as a result of dipole-dipole interaction between the electron-spin probe and a subset of the multiple nuclei that are resonant at the first signal frequency, a phase of the electron-spin probe is indicative of a number of nuclei that are resonant at the first signal frequency
Implementation Method 3
a second signal generator to generate a second signal that decouples the multiple nuclei from each other to reduce interaction between the nuclei
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3a~3b
AI summary
This disclosure relates to determining a spatial configuration of multiple nuclei. An electron dipole generates a spatially varying magnetic field such that each of the multiple nuclei is resonant at a respective resonance frequency defined by the magnetic field at a location of that nucleus. A first signal generator generates a first signal at a first signal frequency such that, as a result of dipole-dipole interaction between the electron dipole and a subset of the multiple nuclei that are resonant at the first signal frequency, a phase of the electron dipole is indicative of a number of nuclei that are resonant at the first signal frequency. A readout module determines the phase of the electron dipole, and determines the spatial configuration of the multiple nuclei based on the phase of the electron dipole. As a result of the high spatial resolution of the sensing the nuclear structure of molecules can be determined with low noise.