Gabriel Abrahams
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gabriel-abrahams.bsky.social
Gabriel Abrahams
@gabriel-abrahams.bsky.social
630 followers 880 following 26 posts
DPhil student in the Engineered Biotechnology Group, University of Oxford. https://steel.ac/

ORCID: 0000-0002-2360-7150
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gabriel-abrahams.bsky.social
MagLOV quantum sensing update! Much improved imaging (>10% single cell ODMR contrast), detailed characterisation and simulation, and new experimental demonstrations taking us a step closer to applications.
www.biorxiv.org/content/10.1...

SI: www.biorxiv.org/content/10.1...
A. Structure of AsLOV2 PDB~2V1A (Halavaty, 2007) with mutations resulting in MagLOV~2 highlighted. Spin transitions driven by radio-frequency (RF) fields in the presence of a static magnetic field are optically detected via fluorescence measurements on an otherwise standard widefield microscope. Similar effects have recently been observed in other protein systems (Burd 2025, Meng 2025, Feder 2025). B. Simplified photocycle diagram in the case of a large external magnetic field. C. A single cell expressing MagLOV 2 displaying an MFE of ~50% (measured as a change in fluorescence intensity in the presence of an applied field). For MFE measurements, the magnetic field was switched between 0 mT and 10 mT. D. Black dots: data from a single cell expressing MagLOV 2 displaying an ODMR signal with ~10% contrast. The static field B_0 is ~21.6 mT. Blue line (shade): the mean (std) of all single cell data in a field of view (~1000 cells). E. The static magnetic field B_0 was varied by adjusting the magnet's position, and ODMR spectra recorded. Red-lines are Lorentzian fits. Blue line is a theoretical prediction (i.e. is not a fit) of the expected resonance frequency of an electron spin with $\bar\gamma_e$=28 MHz/mT. Electronics, radio electronics, optical parts, and an animal sized MRI coil are assembled to perform fluorescence MRI measurements using MagLOV.
August 21, 2025 at 1:59 PM
gabriel-abrahams.bsky.social
MFPs can be used today for lock-in detection - measuring a weak signal in a noisy environment, and tomorrow high dimensionality multiplexing - expanding the number of orthogonal signals from a cell to (different-colors) X (magneto-responses) X (ODMR-responses).
Multiplexing and Lock-in Applications using MFE. A. Illustration of the preparation of multiple variants on a coverslip. B, C. Exponential curves were fit to the MFE of each cell in each field of view. In B, the separate populations are shown, illustrating MagLOV 2 has a greater exponential parameter tau_on,off and that overlaying the two populations produces a bi-modal distribution with small overlap. C. A two-Gaussian function is fit to the bi-modal distribution of a sample with 1:1 mixture of the variants. The ratio of areas under the Gaussians is AsLOV-R3:MagLOV 2=0.82:1, consistent with 0.92:1 found from the area under the Gaussian fits in B. D. Schematic illustration of the microfluidic setup. Cells expressing either MagLOV and EGFP fluoresce green under 450nm illumination, whereas only cells expressing MagLOV are visible under 565~nm illumination, since they co-express mCherry. The chip is composed of two rows of trenches (vertical lines) connected by a channel bringing fresh media into the system and carrying old cells out. E. Cropped view of single trenches, with cells circled in red as identified by a cell-segmentation algorithm. F. Time-series of the 450nm illumination fluorescence response for the individual cells depicted in E over time, as a magnetic field B0=10mT is switched on and off (red line). Both the traces for each cell in the trench (grey lines), and the average trace over all the cells in the trench (black line) are shown. G. Confusion scatter plot for classifying whether cells express MagLOV or EGFP based on magnetic response, taking the 565nm fluorescence as ground-truth and using the lock-in value as the predictor. H. The standard deviation of the lock-in values in G is calculated between cells in each trench (blue histogram) and between all cells in all trenches (mean value in red dashed line).
November 28, 2024 at 3:15 PM
gabriel-abrahams.bsky.social
Quantum sensing with magneto-fluorescent proteins (MFPs) could lead to a whole bunch of new technologies, for example 3D spatial localisation using gradient fields: MRI using only an endogenous protein. Down the line a spatially controllable magneto-genetic switch?
Optically Detected Magnetic Resonance of MagLOV expressing E. Coli. To acquire an ODMR spectrum, a radio frequency is swept linearly with interleaved RF-on and RF-off periods, while the fluorescence is monitored under constant 450 nm excitation. A. Single field of view with MagLOV and negative control cells present as used in panels B/C. Scale bar is 100 um. B. ODMR trace of bulk MagLOV cells and negative control cells in the same field of view, found by integrating horizontal regions 1 and 2 of panel A. C. Treating the negative control signal as reference (i.e. not carrying an ODMR signal, but carrying other signals due to resonant heating etc.) we subtract it from the MagLOV signal, yielding a sharp ODMR peak and hyperfine structure (side peaks). D. ODMR of bulk MagLOV 2 cells (similar to A, but only one type of cell), performed in biological triplicates at the same magnetic field B0 = 24.3 mT to compare peak ODMR contrast measured at the resonant frequency 680 MHz E. The static magnetic field B0 was varied by adjusting the magnet's z-position, and ODMR spectra recorded. The red-dashed line is not a fit; it is a line drawn with slope equal to the electron gyromagnetic ratio.
November 28, 2024 at 3:14 PM
gabriel-abrahams.bsky.social
Some exciting results to share! The MagLOV and related proteins from @andrewgyork.bsky.social and @mariaingaramo.bsky.social are quantum. We measured 4% optically detected magnetic resonance contrast in living bacterial cells at room temperature. www.biorxiv.org/content/10.1...
A. Structure of AsLOV2 [PDB 2V1A] with mutations resutling in MagLOV~2 highlighted. For the first time, quantum sensing in living cells using a fluorescent protein-based sensor can be performed by driving spin transitions using radio-frequency (RF) fields in the presence of a static magnetic field. B. Simplified photocycle diagram in the case of a large external magnetic field. C. Microscope image cropped to a single cell expressing MagLOV 2. Scalebar is 1 um. D. For MFE measurements the magnetic field was modulated between 0 mT and 10 mT, here with a period 10 seconds. The intensity over time is integrated over pixels covering the single cell, with an exponential decay (due to photobleaching) removed. E. A single cell expressing MagLOV 2 displaying an ODMR signal 4% contrast.
November 28, 2024 at 3:13 PM