PHOTODYNAMIC ACTION OF MEROCYANINE 540 IN ARTIFICIAL BILAYERS AND NATURAL MEMBRANES: ACTION SPECTRA AND QUANTUM YIELDS

RAVINDER J. SINGH, JIM B. FEIX, THOMAS J. PINTAR, ALBERT W. GIROTTI, B. KALYANARAMAN

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

The action spectra and quantum yields for singlet oxygen (1O2) generation by merocyanine 540 (MC540) in liposomes and isolated erythrocyte membranes were obtained using electron spin resonance techniques. Oxygen consumption was measured by spin label oximetry in the presence of histidine for fully‐saturated dimyristoylphosphatidylcholine vesicles, mono‐unsaturated 1‐palmitoyl‐2‐oleoylphosphatidylcholine vesicles and erythrocyte membranes. The quantum yield for the photogeneration of 1O2 by membrane‐bound MC540 in aqueous buffer was determined to be 0.065 ± 0.005, which is approx. 1/10 of the value determined for Rose Bengal under similar conditions. Using unilamellar liposomes and isolated erythrocyte membranes containing MC540 at different monomer/dimer ratios, we have observed that the action spectra of 1O2 generation closely overlap the absorption spectra of the monomeric dye in these systems. It is likely that factors which affect the monomer‐dimer equilibrium of MC540 will influence the production of 1O2. These findings have important implications for the phototherapeutic efficacy of MC540.

Original languageEnglish (US)
Pages (from-to)493-500
Number of pages8
JournalPhotochemistry and Photobiology
Volume53
Issue number4
DOIs
StatePublished - Apr 1991

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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