Photophysical behaviour of ground state anion and phototautomer of 3-hydroxyflavone in liposome membrane

Abstract

A detailed account of the photophysical behaviour of the phototautomer (PT) and the ground state anion (A-) of 3-hydroxyflavone in liposome membrane at various membrane conditions is presented. A quenching study with a hydrophilic quencher Ag+ suggests that the phototautomeric emission generates from the fraction of 3HF that is located at the inner hydrophobic core, whereas the ground state anionic emission is from the fraction that resides near the water-accessible surface site. However, the biexponential nature of fluorescence decays of both the forms indicates that there is local heterogeneity in the distribution. Temperature dependence studies and experiments in the presence of ethanol reveal that, as the membrane becomes more fluid, redistribution of 3HF takes place between the two sites leading to increase in A- population. The temperature dependence of the fluorescence anisotropy change of PT shows good correlation with the phase change and shows a sharp drop at the transition temperature, whereas the corresponding change in the case of A- is gradual.

A Fluorescence Study of the Interaction of Anticancer Drug Molecule Doxorubicin Hydrochloride in Pluronic P123 and F127 Micelles

“…In the cyclodextrin and nanoparticle environment, almost similar fluorescence lifetimes of DOX were reported [32]. The variation of amplitudes corresponding to shorter (α 1 ) and longer (α 1 ) lifetime components indicates population redistribution of the drug molecule within the site of their location [40]. With increasing concentration of Pluronic, the shorter component amplitude increases with a corresponding decrease in longer component amplitude.…”

“…Fluorescence quenching experiments have normally been performed to confirm the site of the location of fluorophores in microheterogeneous organized systems [39,40]. A fluorescence quenching study has been performed using potassium iodide as a quencher in the Pluronic micelle.…”

Suppression of ESIPT Phenomenon of Flavonoids on Binding Interaction with Double Stranded RNA

“…The nanosecond‐resolved fluorescence decay traces of the flavonoids in aqueous buffer solutions of varying pH are shown in Figure S2 (the deconvoluted decay parameters being compiled in Table ). The decay transient of 3HF ( λ ex =336 nm, λ em =515 nm) at neutral pH (pH=7.4) has typically been fitted in biexponential function . Although the faster component with relatively greater amplitude ( τ 1 ∼ 170 ps; α 1 = 0.98) can be attributed to the PT form of 3HF along with a very nominal contribution from the normal form of 3HF ( τ 2 =3.67 ns; α 2 =0.02) but rationalization of that deconvoluted ultrafast component could not be done with reproducible reliability within the measuring limit of our instrument.…”

A study on the fluorescence quenching of 9-Aminoacridine by certain antioxidants

“…3-Hydroxy flavone is a fluorescent probe, whose quenching by Ag þ is studied. Its photophysical behavior of phototautomer and ground state anion of 3-hydroxy flavone was probed from liposomal studies under different membrane conditions, which were investigated in detail [29]. Solvent dependent fluorescence emission was also reported in the above literature.…”