Spectroscopic studies of photosensitizer-human serum albumin complexes and their photostability

A. Jasaitis Jr.; Giedre Streckyte; Ricardas Rotomskis

doi:10.1117/12.260770

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4 December 1996 Spectroscopic studies of photosensitizer-human serum albumin complexes and their photostability

A. Jasaitis Jr., Giedre Streckyte, Ricardas Rotomskis

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Proceedings Volume 2924, Photochemotherapy: Photodynamic Therapy and Other Modalities II; (1996) https://doi.org/10.1117/12.260770
Event: BiOS Europe '96, 1996, Vienna, Austria

Abstract

The interaction of haematoporphyrin (Hp), dimethoxyhematoporphyrin IX (DMHp), meso-tetraphenylporphine tetrasulphonate (TPPS₄), photofrin II (PF), chlorin e₆ (Cle₆) and aluminum phthalocyanine tetrasulphonate (AlPcS₄) with human serum albumin (HSA) in aqueous solution and the influence of complexation on the photostability of sensitizers have been investigated by means of steady state absorption spectroscopy. By using the binding isotherm method and graphical Scatchard plot the sequence of affinity of sensitizers to HSA was obtained: TPPS₄ greater than DMHp, Cle₆, Hp, AlPcS₄ greater than PF. The influence of aggregation on the binding ability of sensitizers is discussed. It was observed that complexation with HSA decreases the photostability of sensitizers. The increased rates of sensitizer photobleaching in the presence of photo-oxidizable substrates can be explained by the changes of photophysical properties of sensitizers caused by the interaction with substrates or by the attack of the biomolecules photo- oxidized by the type I mechanism involving electron transfer from excited porphyrin molecule or by the type II mechanism via singlet oxygen on porphyrin microcycle. The sequence of photostability of sensitizers in the presence and in the absence of HSA was established.

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A. Jasaitis Jr., Giedre Streckyte, and Ricardas Rotomskis "Spectroscopic studies of photosensitizer-human serum albumin complexes and their photostability", Proc. SPIE 2924, Photochemotherapy: Photodynamic Therapy and Other Modalities II, (4 December 1996); https://doi.org/10.1117/12.260770

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