Biochemistry & Organic Chemistry

Chirality-Induced Magnetization of Magnetite by an RNA Precursor

By Keith Cowing
Press Release
June 18, 2023
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Chirality-Induced Magnetization of Magnetite by an RNA Precursor
Chiral molecules can spin polarize magnetic surfaces due to the CISS effect. A. Electron density of a molecule approaching a surface is asymmetrically distributed and a transient charge dipole is created. Charge transport through chiral molecules is spin selective due to the CISS effect and therefore a spin-dipole along the chiral molecular axis accompanies this charge dipole. This transient spin dipole can couple with surface spins due to the spin-exchange interaction (J ≡ [E(↑↑) − E(↑↓)]) and spin polarize the surface along the chiral molecular axis. B. Schematic of the setup used in crystallization experiments for CD detection. Homochiral crystals of RAO are formed on magnetite from their enantiopure solution. These crystals align the magnetic domains under them and interact with the surface spins due to magnetic dipolar coupling—a weaker but longer range coupling compared to the spin-exchange interaction C. A sequence showing the effect of chiral molecules on the magnetic domains. 1 Initially, there is no net magnetization of the magnetic domains. 2 As a layer of RAO is forming, the spins underneath the layer align due to the strong spin-exchange interaction. This is an avalanche magnetization process: molecules align the surface spins and the aligned regions attract more molecules and get larger. 3 The mono-layer grows and covers more surface due to the attraction of chiral molecules to the aligned regions and crystal seeds start forming. 4 Crystals get larger and couple with the magnetic domains due to magnetic dipole-dipole interaction, Edd. D. If an external magnetic field, −→B, is applied, the domains outside the area covered by crystals magnetize. Yet the crystals preserve the magnetization of the domains under them as long as the energy of the dipolar coupling is larger than the magnetic energy. — physics.chem-ph

Life is homochiral and homochirality is a fundamental feature of living systems on Earth. While the exact mechanism that led to homochirality is still not fully understood, any realistic scenario on the origins of life needs to address the emergence of homochirality. In order to impose and maintain chirality in a prebiotic network, an environmental factor functioning as a chiral agent is demanded.

Magnetized surfaces are prebiotically plausible chiral agents, shown to be effective in enantioseparation of ribose-aminooxazoline (RAO), a ribonucleic acid (RNA) precursor, due to the chiral-induced spin selectivity (CISS) effect. As such, mechanisms for breaking the magnetic symmetry of magnetic minerals are of the utmost importance.

Here we report the avalanche magnetization of magnetite (Fe3O4) by the crystallization of enantiopure RAO. The observed breaking of the magnetic symmetry is induced by the chiral molecules due to the CISS effect and spreads out across the magnetic surface like an avalanche, providing a way to uniformly magnetize a magnetic surface without fully covering it. Considered together with our previous results on enantioseparation by crystallization on a magnetic surface, chirality-induced avalanche magnetization paves the way for a cooperative feedback between chiral molecules and magnetic surfaces.

With this feedback, a weak natural bias in the net magnetization can be amplified and spin-selective processes can be accommodated on magnetic minerals on a persistent basis.

S. Furkan Ozturk, Deb Kumar Bhowmick, Yael Kapon, Yutao Sang, Anil Kumar, Yossi Paltiel, Ron Naaman, Dimitar D. Sasselov

Comments: 19 pages, 6 figures
Subjects: Chemical Physics (physics.chem-ph)
Cite as: arXiv:2304.09095 [physics.chem-ph] (or arXiv:2304.09095v1 [physics.chem-ph] for this version)
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Submission history
From: Sukru Furkan Ozturk
[v1] Thu, 13 Apr 2023 22:01:24 UTC (20,298 KB)

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