Photocatalytic Formation of I−I Bonds Using DNA Which Enables Detection of Single Nucleotide Polymorphisms

Kawai, Kiyoshi; Kodera, Haruka; Majima, Tetsuro

doi:10.1021/ja105850d

Cited by 13 publications

(16 citation statements)

References 48 publications

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“…19,21,62,78 The increasing distance between ATTO 655 and Z resulted in an exponential increase of τ FCS . Charge recombination proceeds within 1 μs for b4 due to the close distance between Z and ATTO 655, is clearly observed for b5, and in the case of b6, τ FCS becomes too long and indistinguishable from the diffusion process ( Figure 7D).…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

Probing the Charge-Transfer Dynamics in DNA at the Single-Molecule Level

et al. 2011

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Photoinduced charge-transfer fluorescence quenching of a fluorescent dye produces the nonemissive charge-separated state, and subsequent charge recombination makes the reaction reversible. While the information available from the photoinduced charge-transfer process provides the basis for monitoring the microenvironment around the fluorescent dyes and such monitoring is particularly important in live-cell imaging and DNA diagnosis, the information obtainable from the charge recombination process is usually overlooked. When looking at fluorescence emitted from each single fluorescent dye, photoinduced charge-transfer, charge-migration, and charge recombination cause a "blinking" of the fluorescence, in which the charge-recombination rate or the lifetime of the charge-separated state (τ) is supposed to be reflected in the duration of the off time during the single-molecule-level fluorescence measurement. Herein, based on our recently developed method for the direct observation of charge migration in DNA, we utilized DNA as a platform for spectroscopic investigations of charge-recombination dynamics for several fluorescent dyes: TAMRA, ATTO 655, and Alexa 532, which are used in single-molecule fluorescence measurements. Charge recombination dynamics were observed by transient absorption measurements, demonstrating that these fluorescent dyes can be used to monitor the charge-separation and charge-recombination events. Fluorescence correlation spectroscopy (FCS) of ATTO 655 modified DNA allowed the successful measurement of the charge-recombination dynamics in DNA at the single-molecule level. Utilizing the injected charge just like a pulse of sound, such as a "ping" in active sonar systems, information about the DNA sequence surrounding the fluorescent dye was read out by measuring the time it takes for the charge to return.

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Section: Journal Of the American Chemical Societymentioning

confidence: 99%

Probing the Charge-Transfer Dynamics in DNA at the Single-Molecule Level

et al. 2011

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“…Since a hole moves much faster through a consecutive A-T sequence rather than through an A-T/T-A repeat sequence due to the closer distance and direct stacking between As [18], the inversion of the A-T base-pair in an A-T stretch was expected to decrease the Φ. Interestingly, the inversion of the A-T basepair adjacent to NI led to an increase in Φ (NTA1) in spite of the unfavorable 1 The electron transfer from NI radical anion to bromouridine dose not takes place in less than 100 μs (see [58]). …”

Section: Charge-separation Triggered By Hole-injection Into the Seconmentioning

confidence: 99%

“…Some Gs within the consecutive G-C base-pairs were replaced with deazaguanine (Z), which have a lower oxidation potential than G (0.98 V vs NHE) [30,[56][57][58], to refine the charge-separation process to achieve a larger Φ. Hence, DNAs were designed so as to have an (A-T) n (n ¼ 0 À 5) spacer and an (X-C) 3 (X¼G or Z) charge pathway between Sens and PTZ.…”

Section: •àmentioning

confidence: 99%

Photoinduced Charge-Separation in DNA

Kawai

Majima

2014

Photoinduced Phenomena in Nucleic Acids II

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DNA site-specifically modified with a photosensitizer (Sens) was synthesized and the charge-separation and charge-recombination dynamics in DNA were studied. We specifically focused on the formation of the long-lived charge-separated state whose lifetime (τ) is longer than 0.1 μs. The quantum yields of the formation of the charge-separated states (Φ) upon the photoexcitation of the Sens, and the τ were measured using the laser flash photolysis technique. We utilized naphthalimide (NI), naphthaldiimide (ND), and anthraquinone (AQ) as a Sens to investigate the mechanism of the formation of the charge-separated state in DNA via rapid positive charge (hole) transfer between adenine and thymine (A-T) base-pairs. By replacing some T bases in the A-T stretch with 5-bromouracil ((br)U), the charge-separation was shown to occur via the photoinduced charge-injection into the second and further neighboring As to the Sens. On the other hand, the generation of a hole on A nearest to Sens ends up with the rapid charge-recombination within a contact ion pair. A long-lived charge-separated state was also generated in DNA when a commonly used fluorophore such asTAMRA, Alexa 532, and ATTO 655, which can only oxidize guanine-cytosine (G-C) base-pair, but not A-T, was used as a Sens. These results suggested that the charge-separation in DNA is a general phenonmenon for fluorescent dyes which fluorescence is quenched only by G-C.

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“…DNA duplexes can also transport holes and excess electrons over a distance,3–23 and such charge‐transfer reactions in DNA might be involved in the recognition of damaged DNA bases by DNA repair enzymes 24. In addition, it has been demonstrated that electron‐transporting DNA could be used as a device for genotyping and for single‐nucleotide polymorphism analysis 25–29…”

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Transporting Excess Electrons along Potential Energy Gradients Provided by 2′‐Deoxyuridine Derivatives in DNA

et al. 2012

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Charge transfer through peptides and proteins is one of the most important reactions in the processes of photosynthesis, signal transduction, respiration, and some enzymatic activities. [1][2][3][4][5] DNA duplexes can also transport holes and excess electrons over a distance, and such charge-transfer reactions in DNA might be involved in the recognition of damaged DNA bases by DNA repair enzymes. [24] In addition, it has been demonstrated that electron-transporting DNA could be used as a device for genotyping and for singlenucleotide polymorphism analysis. [25][26][27][28][29] To date, studies on hole transfer (HT) through the highest occupied molecular orbital (HOMO) of DNA bases have demonstrated that holes on DNA migrate over long distances mainly between guanine-cytosine (G-C) base pairs and partially between adenine-thymine (A-T) base pairs. Recently, highly efficient HT was achieved by replacing the A-T base pair with the 7-deazaguanine-T base pair, which has a higher HOMO energy level than the A-T base pair. [13] Electrons injected into DNA also migrate along the duplex through the lowest unoccupied molecular orbital (LUMO), most likely between C and T by means of a thermally activated hopping mechanism at ambient temperature. [17] In contrast with the HT in DNA, the efficiency of excess electron transfer (EET) from a photoinduced electron donor over a distance through DNA bases has been reported as being low. This is partly explained by the fast charge recombination between the DNA-tethered electron donor and the excess electron, and kinetically competitive proton transfer between the radical anion of C (C À C) and its complementary G. [30,31] If one considers the redox stability of DNA bases, nanoscale electronic devices based on EET chemistry are seemingly preferable, because HT in DNA results in the oxidation of G. Although many issues remain regarding the durability of redox chemical reactions, one of the strategies for developing novel DNA-based devices is to use modified DNA analogues that overcome the aforementioned shortcomings of natural DNA bases.In this study, we developed DNA containing uracil (U) derivatives with different LUMO energy levels, and examined the regulation and directional control of EET in DNA. Our temporal goal is to construct molecular diode-like DNA nanostructures [32][33][34] in which the direction and efficiency of EET could be arbitrarily controlled depending on the chemical structures of the intervening DNA bases. We investigated photoinduced electron transport from the DNA-tethered photoinduced electron donor phenothiazine (PTZ; E ox * = À2.7 V vs SCE) [35] to the co-inserted 5-bromouracil ( Br U) through the intervening U derivatives. Product analysis clearly showed that injected electrons migrated according to the potential energy gradient of the LUMOs of U derivatives, which is, to the best of our knowledge, the first example of the manipulation of the direction of EET using DNA analogues.

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Photocatalytic Formation of I−I Bonds Using DNA Which Enables Detection of Single Nucleotide Polymorphisms

Cited by 13 publications

References 48 publications

Probing the Charge-Transfer Dynamics in DNA at the Single-Molecule Level

Probing the Charge-Transfer Dynamics in DNA at the Single-Molecule Level

Photoinduced Charge-Separation in DNA

Transporting Excess Electrons along Potential Energy Gradients Provided by 2′‐Deoxyuridine Derivatives in DNA

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