Analyzing Spin Selectivity in DNA-Mediated Charge Transfer <i>via</i> Fluorescence Microscopy

Abendroth, John M.; Nakatsuka, Nako; Ye, Matthew; Kim, Do Kyun; Fullerton, Eric E.; Andrews, Anne M.; Weiss, Paul S.

doi:10.1021/acsnano.7b04165

Cited by 96 publications

(98 citation statements)

References 73 publications

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“…For this reason, the tunneling probability of an electron through a chiral system depends on its spin. 13 Although the CISS effect has been demonstrated in selfassembled monolayers (SAMs) composed of a wide range of chiral structures that include low-molecular-weight molecules, 16 DNA, 13,14,17,18 oligopeptides, 19 and proteins, 20 spinpolarized currents realized by this mechanism have thus far been transmitted exclusively through chiral molecular insulators. Theoretical treatments, however, suggest the central importance of coherent charge transmission and resonant tunneling in determining CISS effect magnitudes.…”

Section: ■ Introductionmentioning

confidence: 99%

Low-Resistance Molecular Wires Propagate Spin-Polarized Currents

Bullard

Tassinari

et al. 2019

J. Am. Chem. Soc.

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Spin based properties, applications, and devices are typically related to inorganic ferromagnetic materials. The development of organic materials for spintronic applications has long been encumbered by its reliance on ferromagnetic electrodes for polarized spin injection. The discovery of the chirality-induced spin selectivity (CISS) effect, in which chiral organic molecules serve as spin filters, defines a marked departure from this paradigm because it exploits soft materials, operates at ambient temperature, and eliminates the need for a magnetic electrode. To date, the CISS effect has been explored exclusively in molecular insulators. Here we combine chiral molecules, which serve as spin filters, with molecular wires that despite not being chiral, function to preserve spin polarization. Self-assembled monolayers (SAMs) of right-handed helical (L-proline) 8 (Pro 8 ) and corresponding peptides, N-terminal conjugated to (porphinato) zinc or meso-to-meso ethyne-bridged (porphinato)zinc structures (Pro 8 PZn n ), were interrogated via magnetic conducting atomic force microscopy (mC-AFM), spin-dependent electrochemistry, and spin Hall devices that measure the spin polarizability that accompanies the charge polarization. These data show that chiral molecules are not required to transmit spin-polarized currents made possible by the CISS mechanism. Measured Hall voltages for Pro 8 PZn 1−3 substantially exceed that determined for the Pro 8 control and increase dramatically as the conjugation length of the achiral PZn n component increases; mC-AFM data underscore that measured spin selectivities increase with an increasing Pro 8 PZn 1−3 N-terminal conjugation. Because of these effects, spindependent electrochemical data demonstrate that spin-polarized currents, which trace their genesis to the chiral Pro 8 moiety, propagate with no apparent dephasing over the augmented Pro 8 PZn n length scales, showing that spin currents may be transmitted over molecular distances that greatly exceed the length of the chiral moiety that makes possible the CISS effect.

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Section: ■ Introductionmentioning

confidence: 99%

Low-Resistance Molecular Wires Propagate Spin-Polarized Currents

Bullard

Tassinari

et al. 2019

J. Am. Chem. Soc.

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“…Recent studies have shown that, when electrons move through chiral molecules, their transport is spin dependent, with the preferred spin orientation determined by the handedness of the molecule and the direction of motion (12,13). The effect, which by now is well established (14)(15)(16)(17)(18), is known as chirality-induced spin selectivity (CISS). As a corollary, charge redistribution in chiral molecules is also accompanied by enantiospecific spin polarization (19).…”

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confidence: 99%

Separation of enantiomers by their enantiospecific interaction with achiral magnetic substrates

Banerjee-Ghosh

Dor

Tassinari

et al. 2018

Science

366

411

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It is commonly assumed that recognition and discrimination of chirality, both in nature and in artificial systems, depend solely on spatial effects. However, recent studies have suggested that charge redistribution in chiral molecules manifests an enantiospecific preference in electron spin orientation. We therefore reasoned that the induced spin polarization may affect enantiorecognition through exchange interactions. Here we show experimentally that the interaction of chiral molecules with a perpendicularly magnetized substrate is enantiospecific. Thus, one enantiomer adsorbs preferentially when the magnetic dipole is pointing up, whereas the other adsorbs faster for the opposite alignment of the magnetization. The interaction is not controlled by the magnetic field per se, but rather by the electron spin orientations, and opens prospects for a distinct approach to enantiomeric separations.

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“…25,28,29,34 Nonspecific binding was minimized through the use of hydroxyl tri(ethylene glycol)-terminated undecanethiol (TEG) in the functionalized and unfunctionalized regions. 27,30,31 We have previously characterized small-molecule-functionalized substrates using infrared spectroscopy, 26,27 X-ray photoelectron spectroscopy, and electrochemistry.…”

Section: Resultsmentioning

confidence: 99%

Aptamer Recognition of Multiplexed Small-Molecule-Functionalized Substrates

Nakatsuka

Cao

Deshayes

et al. 2018

ACS Appl. Mater. Interfaces

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Aptamers are chemically synthesized oligonucleotides or peptides with molecular recognition capabilities. We investigated recognition of substrate-tethered small-molecule targets, using neurotransmitters as examples, and fluorescently labeled DNA aptamers. Substrate regions patterned via microfluidic channels with dopamine or L-tryptophan were selectively recognized by previously identified dopamine or L-tryptophan aptamers, respectively. The on-substrate dissociation constant determined for the dopamine aptamer was comparable to, though slightly greater than the previously determined solution dissociation constant. Using pre-functionalized neurotransmitter-conjugated oligo(ethylene glycol) alkanethiols and microfluidics patterning, we produced multiplexed substrates to capture and to sort aptamers. Substrates patterned with L-DOPA, L-DOPS, and L-5-HTP enabled comparison of the selectivity of the dopamine aptamer for different targets via simultaneous determination of in situ binding constants. Thus, beyond our previous demonstrations of recognition by protein binding partners (i.e., antibodies and G-protein-coupled receptors), strategically optimized small-molecule-functionalized substrates show selective recognition of nucleic acid binding partners. These substrates are useful for side-by-side target comparisons, and future identification and characterization of novel aptamers targeting neurotransmitters or other important small-molecules.

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Analyzing Spin Selectivity in DNA-Mediated Charge Transfer via Fluorescence Microscopy

Cited by 96 publications

References 73 publications

Low-Resistance Molecular Wires Propagate Spin-Polarized Currents

Low-Resistance Molecular Wires Propagate Spin-Polarized Currents

Separation of enantiomers by their enantiospecific interaction with achiral magnetic substrates

Aptamer Recognition of Multiplexed Small-Molecule-Functionalized Substrates

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