Effect of Toxic Metal Ions on Photosensitized Singlet Oxygen Generation for Photodegradation of Polyaromatic Hydrocarbon Derivatives and Inactivation of Escherichia coli

Abstract

Here, we report an experimental study of the effect of toxic metal ions on photosensitized singlet oxygen generation for photodegradation of PAH derivatives, Anthracene‐9,10‐dipropionic acid disodium salt (ADPA) and 1,5‐dihydroxynapthalene (DHN) and photoinactivation of Escherichia coli bacteria by using cationic meso‐tetra(N‐methyl‐4‐pyridyl)porphine tetrachloride (TMPyP) as a singlet oxygen photosensitizer. Three s‐block metals ions, such as Na+, K+ and Ca2+ and five toxic metals such as Cd2+, Cu2+, Hg2+, Zn2+ and Pb2+ were studied. The s‐block metal ions showed no change in the rate of photodegradation of ADPA or DHN by TMPyP, whereas a dramatic change in the photodegradation of ADPA and DHN was observed in the presence of toxic metals. The maximum photodegradation rate constants of ADPA and DHN were observed for Cd2+ ions [(3.91 ± 0.20) × 10−3 s−1 and (7.18 ± 0.35) × 10−4 s−1, respectively]. Strikingly, the photodegradation of ADPA and DHN was almost completely inhibited in the presence of Hg2+ ions and Cu2+ ions. A complete inhibition of growth of E. coli was observed upon visible light irradiation of E. coli solutions with TMPyP and toxic metal ions particularly, Cd2+, Hg2+, Zn2+ and Pb2+ ions, except for Cu2+ ions where a significantly slow inhibition of E. coli's growth was observed.

Photodynamic Inactivation of Legionella pneumophila Biofilm Formation by Cationic Tetra- and Tripyridylporphyrins in Waters of Different Hardness

“…In our previous work, we have observed small spectroscopic changes of tested porphyrins in tap water [19]; thus, we wanted to investigate in more detail the impact of water hardness on our porphyrins and their antibacterial activity. Herschmann et al, for example, investigated the physicochemical properties of tetracationic pyrid-4-ylporphyrin and its activity against E. coli in presence of various monovalent and bivalent cations [21]. They observed a high impact on singlet oxygen production and PDI only in presence of toxic metals; however, this motivated us to investigate the effect of ions naturally present in the raw groundwater in the treatment against L. pneumophila by PDI.…”