Mechanism of in-vivo photodynamic effects

Peter Strizhak; Tamas Kriska; Dezso Gal

doi:10.1117/12.230962

31 January 1996 Mechanism of in-vivo photodynamic effects

Peter Strizhak, Tamas Kriska, Dezso Gal

Proceedings Volume 2625, Photochemotherapy: Photodynamic Therapy and Other Modalities; (1996) https://doi.org/10.1117/12.230962
Event: BiOS Europe '95, 1995, Barcelona, Spain

Abstract

In order to compare the efficiency of the three different mechanisms suggested for photosensitization in biology and medicine: the sensitizer radical, (Type I), the singlet oxygen (Type II), and the native free radical-triplet sensitizer interaction (MTO mechanism) mediated effects, a possible mechanism is suggested including the primary steps of all three mechanisms. Simulation and sensitivity tests based on this mechanism have revealed: that (i) the main contributing elementary steps to the overall photodynamic effect are the decay of the triplet sensitizer; the interaction of sensitizer radicals with biomolecules and the interactions of native free radicals with biomolecules. (ii) The extent of the contribution of the latter is determined by the concentration of the native free radicals in the tissue preceding illumination. (iii) By changing the assumed rate constants of the triplet-doublet interactions it has been established, that with the decrease of their rate constants the overall photodynamic effect decreases. And (iv) its contribution might become negligible. Kinetic consideration has shown, that while continuous illumination results in steady states, illumination by pulsing light leads to non-steady states of the transient species and the latter enables the distinction between the mechanisms provided one of them is predominant under conditions of the measurements.

Citation Download Citation

Peter Strizhak, Tamas Kriska, and Dezso Gal "Mechanism of in-vivo photodynamic effects", Proc. SPIE 2625, Photochemotherapy: Photodynamic Therapy and Other Modalities, (31 January 1996); https://doi.org/10.1117/12.230962

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available