Mathematical model for isosbestic points of porphyrins. Implications in cryotherapy and photodynamic therapy

摘要

- 5, 10, 15, 20-sulfonatophenyl porphine (TSPP or H_2TPPS_4~(4-)) is a water-soluble tetrapyrrolic dye. It has been shown that this porphyrin can self-associate to form J-aggregates depending on the dye concentration, pH and ionic strength. In an acidic medium (pH < 5), the nitrogen atoms of porphyrin can be protonated resulting in a diprotonated form, which shows, in contrast to its neutral form, a near to coplanar conformation of the phenyl rings to the tetrapyrrolic ring. In this paper will be studied the transformation of TSPP from J-aggregates to monomer forms in the temperature range -10°C to +24°C, putting into evidence the generated isosbestic points. With a mathematical calculus, will be possible to evaluate the main transitions from the vibrational levels, responsible for singlet oxygen generation and photodynamic activity, especially.