Abstract
The complexation behavior of pyropheophorbide-a methyl ester (PPME) with transition metal ions as well as other biologically relevant metal ions has been investigated in water-DMF (2:1 v/v) solution. PPME was found to selectively complex Cu2+ ions, which leads to a distinct change in its absorption spectrum as well as efficient fluorescence quenching. The degree of fluorescence quenching by Cu2+ depended on concentration and time. Upon addition of Cu2+, the fluorescence showed a time-resolved decay on the time scale of minutes to hours, with the decay rate being dependent on the cation concentration. Fitting according to a bimolecular reaction rate law provided a rate constant of 650 ± 90 M-1 s-1 at 298 K for metallochlorin formation. The potential implications of Cu2+ binding for the use of PPME in photodynamic therapy are discussed, along with its use as a fluorescent sensor for detection of micromolar concentrations of Cu2+.
Original language | English |
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Pages (from-to) | 649-654 |
Number of pages | 6 |
Journal | Photochemical and Photobiological Sciences |
Volume | 9 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2010 |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry