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801 results on '"Keyes, Tia E"'

1. Metal peptide conjugates in cell and tissue imaging and biosensing

Author

Gkika, Karmel S., Cullinane, David, Keyes, Tia E., Olivucci, Massimo, Editor-in-Chief, Wong, Wai-Yeung, Editor-in-Chief, Bayley, Hagan, Series Editor, Hughes, Greg, Series Editor, Hunter, Christopher A., Series Editor, Hwang, Seong-Ju, Series Editor, Ishihara, Kazuaki, Series Editor, Kirchner, Barbara, Series Editor, Krische, Michael J., Series Editor, Larsen, Delmar, Series Editor, Lehn, Jean-Marie, Series Editor, Luque, Rafael, Series Editor, Siegel, Jay S., Series Editor, Thiem, Joachim, Series Editor, Venturi, Margherita, Series Editor, Wong, Chi-Huey, Series Editor, Wong, Henry N.C., Series Editor, Yam, Vivian Wing-Wah, Series Editor, Yan, Chunhua, Series Editor, You, Shu-Li, Series Editor, Lo, Kenneth Kam-Wing, editor, and Leung, Peter Kam-Keung, editor

Published
2023
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5. Triplet–Triplet Annihilation Upconverting Liposomes: Mechanistic Insights into the Role of Membranes in Two-Dimensional TTA-UC

Author

Prabhakaran, Amrutha, primary, Jha, Keshav Kumar, additional, Sia, Rengel Cane E., additional, Arellano Reyes, Ruben Arturo, additional, Sarangi, Nirod Kumar, additional, Kogut, Mateusz, additional, Guthmuller, Julien, additional, Czub, Jacek, additional, Dietzek-Ivanšić, Benjamin, additional, and Keyes, Tia E., additional

Published
2024
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8. Enhanced Photostability and Photoactivity of Ruthenium Polypyridyl-Based Photocatalysts by Covalently Anchoring Onto Reduced Graphene Oxide

Author

Hennessey, Seán, primary, González-Gómez, Roberto, additional, McCarthy, Kathryn, additional, Burke, Christopher S., additional, Le Houérou, Camille, additional, Sarangi, Nirod Kumar, additional, McArdle, Patrick, additional, Keyes, Tia E., additional, Cucinotta, Fabio, additional, and Farràs, Pau, additional

Published
2024
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13. Surface enhanced resonance Raman and luminescence on plasmon active nanostructured cavities

Author

Lordan, Frances, Rice, James H, Jose, Bincy, Forster, Robert J, and Keyes, Tia E

Subjects
Physics - Optics
Abstract

Presented here are studies of the impact of excitation angle on surface enhanced Raman and luminescence spectroscopy of dye immobilised on a plasmon active nanocavity array support. Results show that both Raman and luminescence intensities depend on the angle of incidence consistent with the presence of cavity supported plasmon modes. Dependence of scattering or emission intensity with excitation angle occurs over the window of observation.

Published
2010
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15. A BODIPY‐Based Molecular Rotor in Giant Unilamellar Vesicles: A Case Study by Polarization‐Resolved Time‐Resolved Emission and Transient Absorption Spectroscopy

Author

Jha, Keshav Kumar, primary, Prabhakaran, Amrutha, additional, Spantzel, Lukas, additional, Sia, Rengel Cane, additional, Pérez, Iván, additional, Arellano‐Reyes, Ruben Arturo, additional, Elmanova, Anna, additional, Dasgupta, Anindita, additional, Eggeling, Christian, additional, Börsch, Michael, additional, Guthmuller, Julien, additional, Presselt, Martin, additional, Keyes, Tia E., additional, and Dietzek‐Ivanšić, Benjamin, additional

Published
2023
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21. Triplet Formation and Triplet‐Triplet Annihilation Upconversion in Iodine Substituted Non‐Orthogonal BODIPY‐Perylene Dyads.

Author

Kumar Jha, Keshav, Prabhakaran, Amrutha, Cane Sia, Rengel, Arellano Reyes, Ruben Arturo, Kumar Sarangi, Nirod, Yang, Tingxiang, Kumar, Krishan, Kupfer, Stephan, Guthmuller, Julien, Keyes, Tia E., and Dietzek‐Ivanšić, Benjamin

Subjects
DYADS, PHOTON upconversion, IODINE, CHARGE transfer, ENERGY transfer, PERYLENE
Abstract

BODIPY‐perylene dyads have emerged as useful metal free sensitizers for triplet‐triplet annihilation upconversion (TTAUC), these dyads are capable of efficient triplet generation via spin‐orbit charge transfer intersystem crossing (SOCT‐ISC). This important route to triplet formation requires dyads in which two moieties are oriented perpendicular to each other. In this contribution, we give a deeper insight on the behavior of recently reported BODIPY‐perylene dyads, where BODIPY‐perylene dihedral exhibits a non‐orthogonal dyad geometry. The intersystem crossing of BODIPY‐perylene dyads with and without iodine are investigated using femtosecond transient absorption (fs‐TA) and nanosecond transient absorption (ns‐TA) spectroscopy. The concurrent decay of the singlet charge transfer state (1CT) and rise of triplet states in both the iodinated and non‐iodinated dyads confirms the SOCT‐ISC as the main intersystem crossing pathway despite the altered geometry of the dyads. The presence of an iodine atom on the BODIPY‐moiety enables intersystem crossing 2.6‐times faster and provides a higher triplet yield with respect to dyad without iodine. The upconversion quantum yield (φSUC ${{\phi{} }_{{\rm S}}^{{\rm U}{\rm C}}}$) is 8.4‐times higher in the sample containing iodinated dyad as sensitizer and perylene as annihilator. The triplet‐triplet energy transfer rate (kTTET) is ~8×108 M−1 s−1 for both iodinated and non‐iodinated sensitizer containing TTAUC systems in 1,4‐dioxane. [ABSTRACT FROM AUTHOR]

Published
2023
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34. Shorter Alkyl Chains Enhance Molecular Diffusion and Electron Transfer Kinetics between Photosensitisers and Catalysts in CO2 -Reducing Photocatalytic Liposomes

Author

Klein, David M, Rodríguez-Jiménez, Santiago, Hoefnagel, Marlene E, Pannwitz, Andrea, Prabhakaran, Amrutha, Siegler, Maxime A, Keyes, Tia E, Reisner, Erwin, Brouwer, Albert M, Bonnet, Sylvestre, Klein, David M [0000-0002-1956-3984], Rodríguez-Jiménez, Santiago [0000-0002-2979-8525], Hoefnagel, Marlene E [0000-0003-1995-4421], Pannwitz, Andrea [0000-0001-9633-0730], Prabhakaran, Amrutha [0000-0003-3400-757X], Siegler, Maxime A [0000-0003-4165-7810], Keyes, Tia E [0000-0002-4604-5533], Reisner, Erwin [0000-0002-7781-1616], Brouwer, Albert M [0000-0002-1731-3869], Bonnet, Sylvestre [0000-0002-5810-3657], and Apollo - University of Cambridge Repository

Subjects
liposomes, Kinetics, CO2 reduction, artificial photosynthesis, Organometallic Compounds, Electrons, Carbon Dioxide, photocatalysis
Abstract

Funder: Nederlandse Organisatie voor Wetenschappelijk Onderzoek; Id: http://dx.doi.org/10.13039/501100003246, Covalent functionalisation with alkyl tails is a common method for supporting molecular catalysts and photosensitisers onto lipid bilayers, but the influence of the alkyl chain length on the photocatalytic performances of the resulting liposomes is not well understood. In this work, we first prepared a series of rhenium-based CO2 -reduction catalysts [Re(4,4'-(Cn H2n+1 )2 -bpy)(CO)3 Cl] (ReCn ; 4,4'-(Cn H2n+1 )2 -bpy=4,4'-dialkyl-2,2'-bipyridine) and ruthenium-based photosensitisers [Ru(bpy)2 (4,4'-(Cn H2n+1 )2 -bpy)](PF6 )2 (RuCn ) with different alkyl chain lengths (n=0, 9, 12, 15, 17, and 19). We then prepared a series of PEGylated DPPC liposomes containing RuCn and ReCn , hereafter noted Cn , to perform photocatalytic CO2 reduction in the presence of sodium ascorbate. The photocatalytic performance of the Cn liposomes was found to depend on the alkyl tail length, as the turnover number for CO (TON) was inversely correlated to the alkyl chain length, with a more than fivefold higher CO production (TON=14.5) for the C9 liposomes, compared to C19 (TON=2.8). Based on immobilisation efficiency quantification, diffusion kinetics, and time-resolved spectroscopy, we identified the main reason for this trend: two types of membrane-bound RuCn species can be found in the membrane, either deeply buried in the bilayer and diffusing slowly, or less buried with much faster diffusion kinetics. Our data suggest that the higher photocatalytic performance of the C9 system is due to the higher fraction of the more mobile and less buried molecular species, which leads to enhanced electron transfer kinetics between RuC9 and ReC9 .

Published
2021

35. Cyclometalated platinum(II) complex as a selective light switch for G-quadruplex DNA.

Author

Saini, Meenaxi and Keyes, Tia E.

Subjects
*PLATINUM, *DNA, *LUMINESCENCE, *GENETIC transduction, *QUADRUPLEX nucleic acids, *TOPOLOGY
Abstract

Cyclometalated 1,3-bis(8-quinolyl) phenyl chloroplatinum(II) (Pt1) shows selective luminescence transduction of G-quadruplex binding over duplex DNA. The effect is enhanced on association with parallel and hybrid G-quadruplex structures over other topologies. The kinetics of binding are studied for c-myc and the response is found to be partially reversible in a displacement assay. [ABSTRACT FROM AUTHOR]

Published
2023
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39. Multimodal Investigation into the Interaction of Quinacrine with Microcavity-Supported Lipid Bilayers

Author

Sarangi, Nirod Kumar, Prabhakaran, Amrutha, and Keyes, Tia E.

Subjects
Cell Membrane, Lipid Bilayers, technology, industry, and agriculture, Surfaces and Interfaces, Condensed Matter Physics, electrical properties, lipids, membranes, raman spectroscopy, vesicles, Cholesterol, Quinacrine, Dielectric Spectroscopy, Electrochemistry, Phosphatidylcholines, lipids (amino acids, peptides, and proteins), General Materials Science, Spectroscopy
Abstract

Quinacrine is a versatile drug that is widely recognized for its antimalarial action through its inhibition of the phospholipase enzyme. It also has antianthelmintic and antiprotozoan activities and is a strong DNA binder that may be used to combat multidrug resistance in cancer. Despite extensive cell-based studies, a detailed understanding of quinacrine’s influence on the cell membrane, including permeability, binding, and rearrangement at the molecular level, is lacking. Herein, we apply microcavity-suspended lipid bilayers (MSLBs) as in vitro models of the cell membrane comprising DOPC, DOPC:Chol(3:1), and DOPC:SM:Chol(2:2:1) to investigate the influence of cholesterol and intrinsic phase heterogeneity induced by mixed-lipid composition on the membrane interactions of quinacrine. Using electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS) as label-free surface-sensitive techniques, we have studied quinacrine interaction and permeability across the different MSLBs. Our EIS data reveal that the drug is permeable through ternary DOPC:SM:Chol and DOPC-only bilayer compositions. In contrast, the binary cholesterol/DOPC membrane arrested permeation, yet the drug binds or intercalates at this membrane as reflected by an increase in membrane impedance. SERS supported the EIS data, which was utilized to gain structural insights into the drug−membrane interaction. Our SERS data also provides a simple but powerful label-free assessment of drug permeation because a significant SERS enhancement of the drug’s Raman signature was observed only if the drug accessed the plasmonic interior of the pore cavity passing through the membrane. Fluorescent lifetime correlation spectroscopy (FLCS) provides further biophysical insight, revealing that quinacrine binding increases the lipid diffusivity of DOPC and the ternary membrane while remarkably decreasing the lipid diffusivity of the DOPC:Chol membrane. Overall, because of its adaptability to multimodal approaches, the MSLB platform provides rich and detailed insights into drug−membrane interactions, making it a powerful tool for in vitro drug screening.

Published
2022

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