Following Oxygen Consumption in Singlet Oxygen Reactions via Changes in Sensitizer Phosphorescence

Abstract

This work reports an examination of singlet oxygen reactions with amino acid substrates by a method involving measurement of the change in phosphorescence intensity of the singlet oxygen sensitizer. The sensitizer, a Ru(II) bipyridyl complex covalently linked to pyrene, has long-lived phosphorescence in N2 purged aqueous solutions (τ0 ~ 20 μs) that is nearly completely quenched by oxygen in aerated solutions. Irradiation of the complex in water containing sub mM concentrations of histidine, tryptophan and methionine results in a dramatic, easily visible increase in the phosphorescence intensity over a period of 10-100 s. Rate constants for singlet oxygen oxidation of each of the substrates can be obtained by using changes in the phosphorescence intensity in initial rate kinetic analysis. Rate constants obtained in this way compare favorably with those reported in the literature. The method represents a very simple approach for obtaining rate constants for singlet oxygen reactions with various substrates and the kinetics can be extended to nonaqueous solvents.

Light‐responsive and Protic Ruthenium Compounds Bearing Bathophenanthroline and Dihydroxybipyridine Ligands Achieve Nanomolar Toxicity towards Breast Cancer Cells†

“…hydrophilic properties (5), the UV‐Vis spectral features (6,7) and whether photodissociation or singlet oxygen formation is the dominant pathway for these ruthenium complexes (8). Many Ru(II) diimine complexes exhibit light‐driven toxicity by producing singlet oxygen in cells (9,10). Light‐induced ligand photodissociation to generate a free site on Ru(II) represents another means of achieving toxicity toward cells via binding of Ru(II) to biological targets or via release of cytotoxic ligands (11–18).…”

Iridium(III) Anthraquinone Complexes as Two‐Photon Phosphorescence Probes for Mitochondria Imaging and Tracking under Hypoxia

“…In recent decades, av ariety of hypoxia-sensitivef luorescent molecular probesh ave been developed to detect hypoxia in living cells. [8][9][10][11][12] However,m ost reported hypoxia probesa re normally aimed at the cellular level, not the organelle level, and have also not been applied to two-photon microscopy (TPM). [13] The TPM technique, which offers an umber of advantages over one-photon microscopy (OPM), including noninvasive excitation, increased penetration depth,l ocalized excitation, and prolonged observation time, is growingi np opularity among biologists.…”

“…However, these commercial probes can barely meet the requirements for hypoxia detection. In recent decades, a variety of hypoxia‐sensitive fluorescent molecular probes have been developed to detect hypoxia in living cells . However, most reported hypoxia probes are normally aimed at the cellular level, not the organelle level, and have also not been applied to two‐photon microscopy (TPM) .…”

Мониторинг Изменения Содержания Кислорода В Тканях По Кинетике Замедленной Флуоресценции Экзогенных Красителей

“…Об относительном изменении количества кислорода в ткани можно судить по тушению кислородом люминесценции ФС, возникающей в результате излучательной релаксации их T 1 -состояний [19][20][21][22][23]. Можно наблюдать как фосфоресценцию:…”

“…Однако в биологических системах подвижность молекул красителей ограничена [21,22], и вкладом процесса T 1 + T 1 в наблюдаемую ЗФ можно пренебречь.…”