The major objective for this grant continues to be to characterize the properties of the first excited singlet state of molecular oxygen -02(1 delta g) - in media that resemble and model biological environments. Integral to this program are endeavors to characterize and understand the photoproperties of molecules that behave as photodynamic sensitizers and to examine the ways in which such processes depend upon the medium. The methodology used relies upon using lasers for producing pulses of light of various wavelengths for excitation of photosensitizers and subsequent generation of 02(1 delta g) of these transient entities are made using computer-controlled kinetic absorption and emission spectrophotometry with nanosecond time resolution. These allow measurements of the spectral and kinetic properties of the short- lived photo-dynamic intermediates. A new technique to be employed involves time resolved microspectrofluorimetry in individual cells. Investigative areas for the coming period include: (i) Photoproperties of tetrapyrrole (porphyrins, phthalocyanines, naphthalocyanines) and other sensitizers including examination of the effects of structure, presence of co-ordinated metal ion, aggregation state, solvent properties and medium microheterogeneity. (ii) The effects of intercalation by DNA and encapsulation with synthetic polymers and biopolymers upon the yields of sensitizer triplet state, the yields of singlet oxygen and the occurrence of Types I and II photodynamic mechanisms. (iii) A study of the efficiency with which singlet oxygen is formed during the quenching of triplet states of sensitizers. This, together vita the influence of environment on the process, will enhance our knowledge of photodynamic mechanisms. (iv) Demonstrations of the formation of singlet oxygen in cellular populations under photodynamic conditions and correlations of the yields with damage.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Molecular and Cellular Biophysics Study Section (BBCA)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Bowling Green State University
Schools of Arts and Sciences
Bowling Green
United States
Zip Code
Zang, L; Rodgers, M A (1999) Formation of tryptophan radicals in irradiated aqueous solutions of hexachloroplatinate(IV): a flash photolysis study. Photochem Photobiol 70:565-7
Wessels, J M; Foote, C S; Ford, W E et al. (1997) Photooxidation of tryptophan: O2(1 delta g) versus electron-transfer pathway. Photochem Photobiol 65:96-102
Wessels, J M; Charlesworth, P; Rodgers, M A (1995) Singlet oxygen luminescence spectra: a comparison of interferometer- and grating-based spectrometers. Photochem Photobiol 61:350-2
Rodgers, M A (1993) Reflections on type I photodynamic damage. J Photochem Photobiol B 18:296-8
Rakestraw, S L; Ford, W E; Tompkins, R G et al. (1992) Antibody-targeted photolysis: in vitro immunological, photophysical, and cytotoxic properties of monoclonal antibody-dextran-Sn(IV) chlorin e6 immunoconjugates. Biotechnol Prog 8:30-9
Krasnovsky Jr, A A; Rodgers, M A; Galpern, M G et al. (1992) Quenching of singlet molecular oxygen by phthalocyanines and naphthalocyanines. Photochem Photobiol 55:691-6
Gorman, A A; Rodgers, M A (1992) Current perspectives of singlet oxygen detection in biological environments. J Photochem Photobiol B 14:159-76
Specht, K G; Rodgers, M A (1991) Plasma membrane depolarization and calcium influx during cell injury by photodynamic action. Biochim Biophys Acta 1070:60-8
Reddi, E; Valduga, G; Rodgers, M A et al. (1991) Studies on the mechanism of the hematoporphyrin-sensitized photooxidation of 1,3-diphenylisobenzofuran in ethanol and unilamellar liposomes. Photochem Photobiol 54:633-7
Specht, K G; Rodgers, M A (1990) Depolarization of mouse myeloma cell membranes during photodynamic action. Photochem Photobiol 51:319-24

Showing the most recent 10 out of 22 publications