Deep-hole transfer leads to ultrafast charge migration in DNA hairpins

Renaud, Nicolas; Harris, Michelle A.; Singh, Arunoday; Berlin, Yu. A.; Ratner, Mark A.; Wasielewski, Michael R.; Lewis, Frederick D.; Grozema, Ferdinand C.

doi:10.1038/nchem.2590

Cited by 63 publications

(75 citation statements)

References 39 publications

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“…50 Our experiments do not provide information about the bases responsible for electron ejection. Regardless, electron holes are expected to be ultimately located on the guanines, possibly after charge transport [51][52][53][54] and undergo deprotonation on the ns timescale. 38 It has been reported that the deprotonated guanine radicals produced in photosensitization experiments survive for hundreds of ms. 23 Moreover, the latter study concerning duplexes with mixed AT/GC sequences correlated a transient absorption decay occurring within a few ms with the reaction intermediate [(8-OH-G):C] leading to 8-oxoG.…”

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confidence: 99%

Radicals generated in alternating guanine–cytosine duplexes by direct absorption of low-energy UV radiation

Bányász

Martínez‐Fernández

Improta

et al. 2018

Phys. Chem. Chem. Phys.

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Recent studies have evidenced that oxidatively damaged DNA, which potentially leads to carcinogenic mutations and aging, may result from the direct absorption of low-energy photons (>250 nm). Herein, the primary species, i.e., ejected electrons and base radicals associated with such damage in duplexes with an alternating guanine-cytosine sequence are quantified by nanosecond transient absorption spectroscopy. The one-photon ionization quantum yield at 266 nm is 1.2 × 10-3, which is similar to those reported previously for adenine-thymine duplexes. This means that the simple presence of guanine, the nucleobase with the lowest ionization potential, does not affect photo-ionization. The transient species detected after 3 μs are identified as deprotonated guanine radicals, which decay with a half-time of 2.5 ms. Spectral assignment is made with the help of quantum chemistry calculations (TD-DFT), which for the first time, provide reference absorption spectra for guanine radicals in duplexes. In addition, our computed spectra predict the changes in transient absorption expected for hole localization as well as deprotonation (to cytosine and bulk water) and hydration of the radical cation.

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confidence: 99%

Radicals generated in alternating guanine–cytosine duplexes by direct absorption of low-energy UV radiation

Bányász

Martínez‐Fernández

Improta

et al. 2018

Phys. Chem. Chem. Phys.

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“…[1][2][3] Researchers have demonstrated how to use Watson-Crick base pairing rules to program the selfassembly of nucleic acids into a diverse array of shapes and structures, and it is now possible to imagine creating a wide range of functional motifs. 4,[8][9][10] Moreover, these various regimes and the transitions between them are known to be sensitive to nucleobase sequence, length, and charge injection energy. [4][5][6][7] Nucleic acids display unusual complexity in their charge transport properties, with mechanisms that range from coherent tunneling at short distances, to incoherent hopping at long distances, and coherent ballistic charge transfer via the flickering resonance mechanism at intermediate distances.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Backbone and Chemical Linker on the Molecular Conductance of Nucleic Acid Duplexes

et al. 2017

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Scanning tunneling microscope break junction measurements are used to examine how the molecular conductance of nucleic acids depends on the composition of their backbone and the linker group to the electrodes. Molecular conductances of 10 base pair long homoduplexes of DNA, aeg-PNA, γ-PNA, and a heteroduplex of DNA/aeg-PNA with identical nucleobase sequence were measured. The molecular conductance was found to vary by 12 to 13 times with the change in backbone. Computational studies show that the molecular conductance differences between nucleic acids of different backbones correlate with differences in backbone structural flexibility. The molecular conductance was also measured for duplexes connected to the electrode through two different linkers, one directly to the backbone and one directly to the nucleobase stack. While the linker causes an order-of-magnitude increase in the overall conductance for a particular duplex, the differences in the electrical conductance with backbone composition are preserved. The highest molecular conductance value, 0.06G, was measured for aeg-PNA duplexes with a base stack linker. These findings reveal an important new strategy for creating longer and more complex electroactive, nucleic acid assemblies.

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“…We note, however, that the reversible hole injection discussed above may complicate the dynamics, and the true mechanism is likely more subtle. 42 Hole Trapping Dynamics. The results of the kinetic modeling of the TA data off er insight into the hole transport dynamics and hole location in the EG-and G-sequences.…”

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confidence: 99%

Tracking Hole Transport in DNA Hairpins Using a Phenylethynylguanine Nucleobase

Brown

Singh

et al. 2017

J. Am. Chem. Soc.

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The hole transport dynamics of DNA hairpins possessing a stilbene electron acceptor and donor along with a modified guanine (G) nucleobase, specifically 8-(4'-phenylethynyl)deoxyguanosine, or EG, have been investigated. The nearly indistinguishable oxidation potentials of EG and G and unique spectroscopic characteristics of EG make it well-suited for directly observing transient hole occupation during charge transport between a stilbene electron donor and acceptor. In contrast to the cation radical G, EG possesses a strong absorption near 460 nm and has a distinct Raman-active ethynyl stretch. Both spectroscopic characteristics are easily distinguished from those of the stilbene donor/acceptor radical ion chromophores. Employing EG, we observe its role as a shallow hole trap, or as an intermediate hole transport site when a deeper trap state is present. Using a combination of ultrafast absorption and stimulated Raman spectroscopies, the hole-transport dynamics are observed to be similar in systems having EG vs G bases, with small perturbations to the charge transport rates and yields. These results show EG can be deployed at specified locations throughout the sequence to report on hole occupancy, thereby enabling detailed monitoring of the hole transport dynamics with base-site specificity.

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Deep-hole transfer leads to ultrafast charge migration in DNA hairpins

Cited by 63 publications

References 39 publications

Radicals generated in alternating guanine–cytosine duplexes by direct absorption of low-energy UV radiation

Radicals generated in alternating guanine–cytosine duplexes by direct absorption of low-energy UV radiation

Effects of the Backbone and Chemical Linker on the Molecular Conductance of Nucleic Acid Duplexes

Tracking Hole Transport in DNA Hairpins Using a Phenylethynylguanine Nucleobase

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