A molecular engineering strategy based on rational variations of the bromine substitution pattern in two-photon absorbing singlet oxygen sensitizers allows studying the relations that exist between the positioning of an inter-system crossing promoter on the charge-transfer chromophore and its ability to generate singlet oxygen.

The effect of various abiotic stresses on photosynthetic apparatus is inevitably associated with formation of harmful reactive oxygen species (ROS). In this review, recent progress on ROS production by photosystem II (PSII) as a response to high light and high temperature is overviewed. Under high light, ROS production is unavoidably associated with energy transfer and electron transport in PSI...

Reactive oxygen species comprise oxygen-based free radicals and non-radical such as peroxynitrite electronically excited (singlet) oxygen. These reactive often have short lifetimes, much of our understanding their formation reactivity in biological especially medical environments has come from complimentary fast reaction methods involving pulsed lasers high-energy radiation techniques. related ...

A molecular dyad that can photosensitize and visualize singlet oxygen ((1)O2) was developed. The dual photofunction enables ratiometric photoluminescence monitoring of the progress of (1)O2-induced cell death.

Reactive oxygen species (ROS) are formed enzymatically, chemically, photochemically, and by irradiation of food. They are also formed by the decomposition and the inter-reactions of ROS. Hydroxy radical is the most reactive ROS, followed by singlet oxygen. Reactions of ROS with food components produce undesirable volatile compounds and carcinogens, destroy essential nutrients, and change the fu...

The photodynamic therapy of cancer is contingent upon the sustained generation of singlet oxygen in the tumor region. However, tumors of the most metastatic cancer types develop a region of severe hypoxia, which puts them beyond the reach of most therapeutic protocols. More troublesome, photodynamic action generates acute hypoxia as the process itself diminishes cellular oxygen reserves, which ...

Different wavelength light sources are used in photodynamic therapy (PDT) of the skin to treat different conditions. Clinical studies show inconsistent results for the effectiveness of aminolevulinic acid (ALA)-PDT performed at different wavelengths. In order to understand the effect of treatment wavelength, a theoretical study was performed to calculate time-resolved depth-dependent distributi...

Hematoporphyrin derivative and light in the presence of cysteine or glutathione were found to convert oxygen to superoxide and hydrogen peroxide at pH less than approx. 6.5, while at pH greater than 6.5 no superoxide or hydrogen peroxide production was observed. However, at pH values greater than 6.5 the rate of oxygen consumption increased. This rate paralleled the acid dissociation curve of t...

The main photophysical properties of a series of recently synthetized 1,2- and 1,3-squaraines, including absorption electronic spectra, singlet-triplet energy gaps, and spin-orbit matrix elements, have been investigated by means of density functional theory (DFT) and time-dependent DFT approaches. A benchmark of three exchange-correlation functionals has been performed in six different solvent ...