Dependence of the Lifetime upon the Excitation Energy and Intramolecular Energy Transfer Rates: The5D0EuIIIEmission Case

2012 ◽  
Vol 18 (38) ◽  
pp. 12130-12139 ◽  
Author(s):  
Rute A. S. Ferreira ◽  
Mariela Nolasco ◽  
Ana C. Roma ◽  
Ricardo L. Longo ◽  
Oscar L. Malta ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Intramolecular Energy Transfer ◽  
Transfer Rates

scholarly journals FLUORESCENT PROPERTIES OF DOXYCYCLINE IN PRESENCE OF SILVER NANOCLUSTERS

2020 ◽  
Vol 64 (1) ◽  
pp. 34-40
Author(s):  
Tatyana D. Smirnova ◽  
Elens A. Zhelobitskaya ◽  
Tatyana G. Danilina ◽  
Natalya A. Simbireva
Keyword(s):  
Silver Nanoparticles ◽  
Energy Transfer ◽  
Excitation Energy ◽  
Surface Plasmon ◽  
Limit Of Detection ◽  
Silver Nanoclusters ◽  
Complexing Agent ◽  
Intramolecular Energy Transfer ◽  
Sensitized Fluorescence ◽  
Wide Range

The paper shows that in the presence of silver nanoparticles the efficiency of intramolecular energy transfer in the complex of europium with doxycycline increases. It is proved that sensitivity of determination increases and limit of detection of doxycycline decreases by the method of sensitized fluorescence. The justification of the observed effects is given. The amplification of the signal of sensitized fluorescence in the presence of silver nanoparticles (energy donor) is the result of resonant transfer of excitation energy between the nanoparticle and the antibiotic ion, which is implemented under conditions of overlapping of the local surface plasmon resonance spectrum and excitation of the doxycycline ligand located near the surface of the nanoparticle. As a result of exposure to the antibiotic external radiation source and the local field of the surface plasmon increases the efficiency of tetracycline excitation, which contributes to the effectiveness of intramolecular energy transfer in europium chelate with doxycycline, doubling the intensity and lifetime. Modification of the surface of silver nanoparticles by europium ions allows to reduce the distance between the surface of a nanoparticle and an antibiotic, to increase the intensity of the signal of sensitized fluorescence by more than 100 times. The role of the stabilizer of a non-chromophore-containing ligand, − citrateion, in the formation of the analytical signal lies in its participation in the formation of a multi-ligand Eu3+ complex on the surface of a nanoobject, which reduces the distance between the donor and the acceptor, as well as the additional removal of water molecules from the immediate environment of the complexing agent ion, suppressing the process of excitation energy dissipation. On the basis of the conducted researches the fluorimetric technique of definition of doxycycline in medicines is offered. It differs in a low limit of detection (6.0·10-9 M) and a wide range of the defined concentrations from 1.0·10-8 to 1.0·10-5 M.

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

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