The effect of porphyrin structure on binding to human serum albumin by fluorescence spectroscopy

Olga Rinco, Janet Brenton, Alison Douglas, Amanda Maxwell, Michelle Henderson, Kirsten Indrelie, Jacob Wessels, Joan Widin

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


The efficacy of porphyrin binding to human serum albumin (HSA) is critical to clinical use in photodynamic therapy (PDT). Several porphyrins were utilized to measure the effect of porphyrin structure on its binding to HSA. Two categories of porphyrins were utilized: porphyrins with a hydrophobic and hydrophilic side: Protoporphyrin IX (PPIX), Protoporphyrin IX dimethylester (PPIXDE), and Chlorin e6 (Ce6) and porphyrins with hydrophilic substituents on both sides: Hematoporphyrin IX (Hme), Hematoporphyrin IX dimethylester (HmeDE), and Deuteroporphyrin IX dimethylester (DPIXEG). The following methods were used for the analysis: Stern-Volmer quenching, fluorescence lifetimes, anisotropy, fluorescence binding, and homogeneous studies. The results indicate that PPIX, PPIXDE, and Ce6 bind to HSA efficiently, evidence that porphyrins bind strongly to HSA if they have a hydrophobic and hydrophilic side. Hme is thought to bind to HSA but likely to a lesser degree than the aforementioned three porphyrins. HmeDE and DPIXEG seem not to bind to HSA probably due to the lack of hydrophobic substituents.

Original languageEnglish (US)
Pages (from-to)91-96
Number of pages6
JournalJournal of Photochemistry and Photobiology A: Chemistry
Issue number2-3
StatePublished - Dec 15 2009

Bibliographical note

Funding Information:
The authors thank the Monticello College Foundation and the Iowa College Foundation – R.J. McElroy Trust for partial financial support of this research, as well as Luther College's faculty/student collaborative research grants for allowing numerous students the opportunity to work on this project. The authors also acknowledge the contribution of other group members who were present during this work: Nicholas Gibbons, Alison Rapacz Knutson, Jennifer Miller Meyer and Jay Dicke.


  • Fluorescence
  • Host-guest interactions
  • PDT
  • Porphyrins
  • Singlet excited state


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