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Albrecht CS, Scatena LF, von Hippel PH, Marcus AH. Two-photon excitation two-dimensional fluorescence spectroscopy (2PE-2DFS) of the fluorescent nucleobase 6-MI. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2024; 12863:1286305. [PMID: 39149416 PMCID: PMC11326479 DOI: 10.1117/12.3001802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Base stacking is fundamentally important to the stability of double-stranded DNA. However, few experiments can directly probe the local conformations and conformational fluctuations of the DNA bases. Here we report a new spectroscopic approach to study the local conformations of DNA bases using the UV-absorbing fluorescent guanine analogue, 6-methyl isoxanthopterin (6-MI), which can be used as a site-specific probe to label DNA. In these experiments, we apply a two-photon excitation (2PE) approach to two-dimensional fluorescence spectroscopy (2DFS), which is a fluorescence-detected nonlinear Fourier transform spectroscopy. In 2DFS, a repeating sequence of four collinear laser pulses (with center wavelength ~ 675 nm and relative phases swept at radio frequencies) is used to excite the lowest energy electronic-vibrational (vibronic) transitions of 6-MI (with center wavelength ~ 340 nm). The ensuing low flux fluorescence is phase-synchronously detected at the level of individual photons and as a function of inter-pulse delay. The 2PE transition pathways that give rise to electronically excited state populations include optical coherences between electronic ground and excited states and non-resonant (one-photon-excited) virtual states. Our results indicate that 2PE-2DFS experiments can provide information about the electronic-vibrational spectrum of the 6-MI monomer, in addition to the conformation-dependent exciton coupling between adjacent 6-MI monomers within a (6-MI)2 dimer. In principle, this approach can be used to determine the local base-stacking conformations of (6-MI)2 dimer-substituted DNA constructs.
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Affiliation(s)
- Claire S Albrecht
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
- Department of Physics, University of Oregon, Eugene, Oregon 97403
| | - Lawrence F Scatena
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon 97403
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
| | - Peter H von Hippel
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
| | - Andrew H Marcus
- Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon 97403
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403
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2
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Sawyer JM, Passow KT, Harki DA. Synthesis and photophysical characterization of fluorescent indole nucleoside analogues. RSC Adv 2023; 13:16369-16376. [PMID: 37266506 PMCID: PMC10230516 DOI: 10.1039/d3ra03457g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/03/2023] Open
Abstract
Fluorescent nucleosides are useful chemical tools for biochemical research and are frequently incorporated into nucleic acids for a variety of applications. The most widely utilized fluorescent nucleoside is 2-aminopurine-2'-deoxyribonucleoside (2APN). However, 2APN is limited by a moderate Stokes shift, molar extinction coefficient, and quantum yield. We recently reported 4-cyanoindole-2'-deoxyribonucleoside (4CIN), which offers superior photophysical characteristics in comparison to 2APN. To further improve upon 4CIN, a focused library of additional analogues combining the structural features of 2APN and 4CIN were synthesized and their photophysical properties were quantified. Nucleosides 2-6 were found to possess diverse photophysical properties with some features superior to 4CIN. In addition, the structure-function relationship data gained from 1-6 can inform the design of next-generation fluorescent indole nucleosides.
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Affiliation(s)
- Jacob M Sawyer
- Department of Chemistry, University of Minnesota Minneapolis Minnesota 55455 USA
| | - Kellan T Passow
- Department of Medicinal Chemistry, University of Minnesota Minneapolis Minnesota 55455 USA
| | - Daniel A Harki
- Department of Chemistry, University of Minnesota Minneapolis Minnesota 55455 USA
- Department of Medicinal Chemistry, University of Minnesota Minneapolis Minnesota 55455 USA
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3
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V. P. Valverde J, Pelosi AG, H. Zucolotto. Cocca L, Marbello OD, le Bescont J, Breton-Patient C, Piguel S, Silva DL, De Boni L, Mendonça CR. Two-photon absorption in imidazo[1,2-a]pyridine derivatives: study of nonlinear optical response and dipolar properties. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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4
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Zucolotto Cocca LH, Pelosi AG, Piguel S, Mendonça CR, Boni LD. Enhancement of optical properties of new purine nucleobases containing electron-donating and -withdrawing peripheral groups. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 234:112524. [PMID: 35843082 DOI: 10.1016/j.jphotobiol.2022.112524] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 07/04/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
Nowadays, a great deal of attention has been focused on synthesizing highly fluorescent unnatural base analogs. This has been motivated by the need to overcome the lack of fluorescence of nucleic acids' natural bases. Fluorescent unnatural base analogs, such as purines, may be used in several applications, such as DNA or RNA optical spectroscopy studies. Moreover, for purines base analogs, the optical properties, for example, emission, can be tunable through molecular engineering, improving their applications as fluorescent probes. Looking in this direction, the synthesis and optical spectroscopic studies of a new set of purines base analogs are of foremost relevance. Here, an increase in the fluorescence quantum yield was observed in molecules with NH-π-CN arrangement. The two-photon absorption (2PA) cross-sections also increased for the lower energy 2PA state. The enhancement of both properties results in a two-photon brightness of 5 and 10 times higher than in compounds lacking the NH-π-CN arrangement. For the higher energy 2PA state, an excited state absorption contribution to the 2PA cross-section values was observed, that was verified through ultrafast transient absorption measurements. The higher 2PA brightness makes the purines base analogs promising candidates as fluorescent probes in RNA and DNA spectroscopic studies.
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Affiliation(s)
- Leandro H Zucolotto Cocca
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP, Brazil.
| | - André G Pelosi
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP, Brazil
| | - Sandrine Piguel
- Université Paris-Saclay, Faculté de Pharmacie, CNRS UMR 8076, 92296 Châtenay-Malabry, France
| | - Cleber Renato Mendonça
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP, Brazil
| | - Leonardo De Boni
- Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP, Brazil.
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5
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Jena S, Tulsiyan KD, Kumari A, Das R, Biswal HS. Thiolumazines as Heavy-Atom-Free Photosensitizers for Applications in Daylight Photodynamic Therapy: Insights from Ultrafast Excited-State Dynamics. J Phys Chem B 2022; 126:6083-6094. [PMID: 35938784 DOI: 10.1021/acs.jpcb.2c03489] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Finding appropriate photosensitizers (PSs) for daylight photodynamic therapy (dPDT) applications is extremely challenging, even though heavy-atom-free photosensitizers (HAFPSs) such as thiocarbonyl-modified nucleobases have shown a ray of hope. Few attempts have been made to find alternative natural products for dPDT applications. Pteridine heterocycles consisting of a pyrazine ring and a pyrimidine ring, such as lumazine, which exhibit many structural similarities to the alloxazine ring of the flavin molecule, could be an option for HAFPSs. The photophysical and quantum mechanical studies of the thio-modified lumazines revealed that sequential thiomodifications in lumazine result in a bathochromic shift. Additionally, higher tissue penetration depths were observed for thiolumazines. The fluorescence quenching in the case of thiomodified lumazines was explained using triplet state formation, whereas the contribution from the photoinduced electron transfer process cannot be ignored. It was also noticed that a strong one-photon absorption influenced the two-photon absorption (TPA) process, leading to a self-focusing effect in the visible spectral region. The higher tissue penetration and larger TPA cross section are the hallmark characteristics of the thiolumazines to be considered as potential HAFPSs for dPDT applications.
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Affiliation(s)
- Subhrakant Jena
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO- Bhimpur-Padanpur, Via-Jatni, District- Khurda, PIN - 752050, Bhubaneswar, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Kiran Devi Tulsiyan
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO- Bhimpur-Padanpur, Via-Jatni, District- Khurda, PIN - 752050, Bhubaneswar, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Anupa Kumari
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.,School of Physical Sciences, National Institute of Science Education and Research (NISER), PO- Bhimpur-Padanpur, Via-Jatni, District- Khurda, PIN - 752050, Bhubaneswar, India
| | - Ritwick Das
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.,School of Physical Sciences, National Institute of Science Education and Research (NISER), PO- Bhimpur-Padanpur, Via-Jatni, District- Khurda, PIN - 752050, Bhubaneswar, India
| | - Himansu S Biswal
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), PO- Bhimpur-Padanpur, Via-Jatni, District- Khurda, PIN - 752050, Bhubaneswar, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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6
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Pelosi AG, Zucolotto Cocca LH, Piguel S, De Boni L, Mendonça CR. Effect of peripherical groups on the two-photon brightness of (E)-3-benzyl-6-bromo-2-styryl-3H-imidazo[4,5-b]pyridine derivatives. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Determination of two-photon absorption in nucleobase analogues: a QR-DFT perspective. Photochem Photobiol Sci 2022; 21:529-543. [PMID: 35179700 DOI: 10.1007/s43630-022-00182-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 01/27/2022] [Indexed: 10/19/2022]
Abstract
With the prevalence of fluorescence spectroscopy in biological systems, and the benefits of two-photon absorption techniques, presented here is an assessment of the two-photon accessibility of modern fluorescent nucleobase analogues utilising quadratic response DFT. Due to the complex environment experienced by these nucleobases, the two-photon spectra of each analogue has been assessed in the presence of both [Formula: see text]-stacked and hydrogen-bonding interactions involving the canonical nucleobases. Findings suggest that the [Formula: see text]-stacking environment provides a more significant effect on the spectra of the analogues studies than a hydrogen-bonding environment; analogue structures presenting high two-photon cross-section values for one or more states coincide with polycyclic extensions to preserved canonical base structure, as observed in the qA family of analogues, while analogue structures more closely resembling the structure of the base in question present a much more muted spectra in comparison. Results from this investigation have also allowed for the derivation of a number of design rules for the development of potential, two-photon specific, analogues for future use in both imaging and potential photochemical activation.
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Zucolotto Cocca LH, Pelosi A, Sciuti LF, M. G. Abegão L, Kamada K, Piguel S, Renato Mendonça C, De Boni L. Two-photon brightness of highly fluorescent imidazopyridine derivatives: Two-photon and ultrafast transient absorption studies. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Parshotam S, Joy M, Rossano-Tapia M, Mora-Gomez VA, Brown A. The thermochemical, structural, and spectroscopic analyses of the tautomers of sulfur and selenium modified emissive nucleobases. CAN J CHEM 2021. [DOI: 10.1139/cjc-2020-0294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, density functional theory (DFT) and time dependent density functional theory (TD-DFT) are used to investigate the stabilities and spectral properties [IR, UV–vis, and two-photon absorption (2PA)] of two sets of modified RNA nucleobase tautomers. The modifications introduce either a sulfur or selenium atom to form an isothiazolo[4,3-d]pyrimidine or isoselenazolo[4,3-d]pyrimidine heterocyclic core, respectively. The relative stabilities of both sets of modified tautomers determined with B3LYP/6-31++G(d,p) reveal that in water (with a polarizable continuum model), the 6-keto-2-amino tautomer of guanine and the rare 4-imino-2-keto tautomer of cytosine may be present at significant populations, whereas the 6-enol-2-amino tautomer of guanine is more common in the gas phase. The identification of these modified tautomers is possible due to the natural differences in their vibrational modes and hence IR spectra. Furthermore, the photophysical properties of both these sets of modified tautomers indicate that excitation and emission energies are shifted relative to their more abundant form in both one photon absorption and emission and 2PA spectra, as determined at the B3LYP/6-31++G(d,p) and CAM-B3LYP/aug-cc-pVDZ levels of theory, respectively. Even though the 2PA cross sections in water for all of the species are small (0.3–2.3 GM), the modified cytosine tautomer shows promise, as its cross section is larger than the more dominant form. The spectral separation between the dominant form and the tautomers of isoselenazole and isothiazole modified cytosine and guanine are relatively similar, suggesting both modifications could be useful in elucidating the tautomers from their more abundant counterparts.
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Affiliation(s)
- Shyam Parshotam
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Megan Joy
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Maria Rossano-Tapia
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - V. A. Mora-Gomez
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
| | - Alex Brown
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2
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10
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The ability of 2,5-disubstituted oxazole dyes derivatives to generate two-photon upconversion photoluminescence and its brightness evaluation. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Ando S, Isozaki T, Xu YZ, Suzuki T. Simultaneous Two-Photon Absorption of the Thioguanosine Analogue 2',3',5'-Tri- O-acetyl-6,8-dithioguanosine with Its Potential Application to Photodynamic Therapy. J Phys Chem A 2020; 124:7024-7030. [PMID: 32786980 DOI: 10.1021/acs.jpca.0c03747] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
2',3',5'-Tri-O-acetyl-6,8-dithioguanosine (taDTGuo) is an analogue of nucleosides and currently under investigation as a potential agent for photodynamic therapy (PDT). Excitation by simultaneous two-photon absorption of visible or near-infrared light would provide an efficient PDT for deep-seated tumors. The two-photon absorption spectrum of taDTGuo was obtained by optical-probing photoacoustic spectroscopy (OPPAS). A two-photon absorption band corresponding to the S5 ← S0 transition was observed at 556 nm, and the two-photon absorption cross-section σ(2) was determined to be 26 ± 3 GM, which was much larger than that of other nucleobases and nucleosides. Quantum chemical calculations suggested that the large σ(2) value of taDTGuo was responsible for large transition dipole moments and small detuning energy resulting from the thiocarbonyl group at 6- and 8-positions. This is the first report on two-photon absorption spectra and cross-sections of thionucleoside analogues, which could be used to develop a more specific PDT for cancers in deep regions.
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Affiliation(s)
- Saki Ando
- Department of Chemistry and Biological Science, Aoyama Gakuin University, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Tasuku Isozaki
- Division of Natural Sciences, College of Arts and Sciences, J. F. Oberlin University, Tokiwa-machi, Machida, Tokyo 194-0294, Japan
| | - Yao-Zhong Xu
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, U.K
| | - Tadashi Suzuki
- Department of Chemistry and Biological Science, Aoyama Gakuin University, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
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Nobis D, Fisher RS, Simmermacher M, Hopkins PA, Tor Y, Jones AC, Magennis SW. Single-Molecule Detection of a Fluorescent Nucleobase Analogue via Multiphoton Excitation. J Phys Chem Lett 2019; 10:5008-5012. [PMID: 31397575 PMCID: PMC7024020 DOI: 10.1021/acs.jpclett.9b02108] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The ability to routinely detect fluorescent nucleobase analogues at the single-molecule level would create a wealth of opportunities to study nucleic acids. We report the multiphoton-induced fluorescence and single-molecule detection of a dimethylamine-substituted extended-6-aza-uridine (DMAthaU). We show that DMAthaU can exist in a highly fluorescent form, emitting strongly in the visible region (470-560 nm). Using pulse-shaped broadband Ti:sapphire laser excitation, DMAthaU undergoes two-photon (2P) absorption at low excitation powers, switching to three-photon (3P) absorption at high incident intensity. The assignment of a 3P process is supported by cubic response calculations. Under both 2P and 3P excitation, the single-molecule brightness was over an order of magnitude higher than reported previously for any fluorescent base analogue, which facilitated the first single-molecule detection of an emissive nucleoside with multiphoton excitation.
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Affiliation(s)
- David Nobis
- WestCHEM School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, U.K
| | - Rachel S. Fisher
- EaStCHEM School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Mats Simmermacher
- EaStCHEM School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Patrycja A. Hopkins
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Anita C. Jones
- EaStCHEM School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
- Corresponding Authors (A.C.J.)., (S.W.M.)
| | - Steven W. Magennis
- WestCHEM School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, U.K
- Corresponding Authors (A.C.J.)., (S.W.M.)
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Fisher RS, Nobis D, Füchtbauer AF, Bood M, Grøtli M, Wilhelmsson LM, Jones AC, Magennis SW. Pulse-shaped two-photon excitation of a fluorescent base analogue approaches single-molecule sensitivity. Phys Chem Chem Phys 2018; 20:28487-28498. [PMID: 30412214 DOI: 10.1039/c8cp05496g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fluorescent nucleobase analogues (FBAs) have many desirable features in comparison to extrinsic fluorescent labels, but they are yet to find application in ultrasensitive detection. Many of the disadvantages of FBAs arise from their short excitation wavelengths (often in the ultraviolet), making two-photon excitation a potentially attractive approach. Pentacyclic adenine (pA) is a recently developed FBA that has an exceptionally high two-photon brightness. We have studied the two-photon-excited fluorescence properties of pA and how they are affected by incorporation in DNA. We find that pA is more photostable under two-photon excitation than via resonant absorption. When incorporated in an oligonucleotide, pA has a high two-photon cross section and emission quantum yield, varying with sequence context, resulting in the highest reported brightness for such a probe. The use of a two-photon microscope with ultrafast excitation and pulse shaping has allowed the detection of pA-containing oligonucleotides in solution with a limit of detection of ∼5 molecules, demonstrating that practical single-molecule detection of FBAs is now within reach.
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Affiliation(s)
- Rachel S Fisher
- EaStCHEM School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, UK.
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14
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Passow KT, Harki DA. 4-Cyanoindole-2'-deoxyribonucleoside (4CIN): A Universal Fluorescent Nucleoside Analogue. Org Lett 2018; 20:4310-4313. [PMID: 29989830 PMCID: PMC6168291 DOI: 10.1021/acs.orglett.8b01746] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The synthesis and characterization of a universal and fluorescent nucleoside, 4-cyanoindole-2'-deoxyribonucleoside (4CIN), and its incorporation into DNA is described. 4CIN is a highly efficient fluorophore with quantum yields >0.90 in water. When incorporated into duplex DNA, 4CIN pairs equivalently with native nucleobases and has uniquely high quantum yields ranging from 0.15 to 0.31 depending on sequence and hybridization contexts, surpassing that of 2-aminopurine, the prototypical nucleoside fluorophore. 4CIN constitutes a new isomorphic nucleoside for diverse applications.
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Affiliation(s)
- Kellan T. Passow
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Daniel A. Harki
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
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15
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Rebane A. Multiphoton spectroscopy: An optical window into molecular electrostatics. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201819002009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantitative knowledge about static molecular electric dipole moments is essential for understanding of intramolecular charge transfer as well as nanometer-scale static electric interactions. However, measuring or determining the molecular electrostatic properties with sufficient accuracy remains a challenging task. In our experiments, we measure the femtosecond two-photon absorption spectra- and cross sections of a range of organic- and organometallic chromophores in solution and use these data to determine the electric dipole moment change in corresponding lowest-energy dipole-allowed transition. Good correspondence of our experimental dipole moments with the quantum-chemical calculations as well as reports by other groups using conventional dipole moment measurement methods suggests that quantitative multiphoton spectroscopy may offer all-optical alternative to the traditional techniques such as Stark effect and electrochromism.
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