Nonlinear absorption measurements of porphyrins in aqueous solutions with macromolecules

Summary form only given. The application of porphyrins in medicine has increased over the last decade due to their efficacy in photodynamic therapy (PDT) of cancer. The porphyrin efficacy in PDT is due to energy transfer from the porphyrin triplet state to the oxygen ground state and thus depends on porphyrin triplet state characteristics (lifetime and quantum yield). The interaction of porphyrin molecules with biological structures (membranes, macromolecules, etc.) changes the characteristics of their excited states. On the other hand the interaction with microheterogeneous systems affects the porphyrin non-linear optical properties. Thus, the changes of the non-linear characteristics should give information about the mechanisms of the interaction between porphyrin molecules and microheterogeneous systems, biological structures in particular. In this work we study the changes of the nonlinear optical absorption of water soluble porphyrins due to their interaction with bovine serum albumin (BSA) and DNA.