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Issue 3, 2009
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The localization and photosensitization of modified chlorin photosensitizers in artificial membranes

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Abstract

In this work we investigate the localization and photophysical properties of twelve synthetically derived chlorins in artificial membranes, with the goal of designing more effective photosensitizers for photodynamic therapy (PDT). The studied chlorins incorporate substituents of varying lipophilicity at the C5-meso-position (H to C5H11), while the C13- and C17-positions have carboxylate “anchoring” groups tethered to the tetrapyrrole by alkyl chains (CH2)n (n = 1–3). It was found that as n increases, the chromophoric part of the molecule, and thus the point of generation of singlet oxygen, is located at a deeper position in the bilayer. The vertical insertion of the sensitizers was assessed by two fluorescence-quenching techniques: by iodide ions that come from the aqueous phase and by spin-probe-labeled phospholipids that are incorporated into the bilayer, using the parallax method. These results demonstrate that elongation of the side chains endows the modified molecules with a larger affinity for artificial membranes and also causes the tetrapyrrole ring to be localized deeper in the lipid membrane. This location leads to a higher effective quantum yield for the chemical reaction of singlet oxygen with its chemical target 9,10-dimethylanthracene (DMA).

Graphical abstract: The localization and photosensitization of modified chlorin photosensitizers in artificial membranes

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Publication details

The article was received on 28 Aug 2008, accepted on 05 Dec 2008 and first published on 05 Jan 2009


Article type: Paper
DOI: 10.1039/B814970D
Citation: Photochem. Photobiol. Sci., 2009,8, 354-361
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    The localization and photosensitization of modified chlorin photosensitizers in artificial membranes

    S. B. Dror, I. Bronshtein, Y. Garini, W. G. O'Neal, P. A. Jacobi and B. Ehrenberg, Photochem. Photobiol. Sci., 2009, 8, 354
    DOI: 10.1039/B814970D

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