Quantum yields of photodegradation of protoporphyrin IX in solution: luminescent spectrophotometric and biological testing of photobleaching

摘要

In the present study, the biological testing of the photodegradation of protoporphyrin IX (PP IX) is proposed. The method implies preirradiation of PP IX ($lambda $LS 415 nm) in buffer solution (with or without serum) with the following adding to cells and irradiation of this mixture ($lambda $LS 415 nm). The increase in survival with increase in preirradiation fluence was used for estimation of rate and quantum yield of PP IX photobleaching in solutions. The quantum yield estimated by the proposed method was compared with quantum yields of photodegradation of PP IX by decay in absorbance and decay in fluorescence. The highest quantum yield of photodegradation of PP IX was obtained by the test of cells photoinactivation, the lowest by the decay monitored by absorbance. The different values of quantum yield of photodegradation are discussed in the view of photobleaching of monomeric forms which are much more photolabile than aggregates and of photoproduct formation. Biological testing of photodegradation of monomeric species of PP IX seems to be the most specific.