The different kinetic behavior of two potential photosensitizers for PDT

• The kinetic interaction between BSA and two potential PDT dyes was studied by stopped-flow.
• The two dyes chosen were protoporphyrin IX (PPIX) and a squaraine dye (SQ1).
• Thermodynamic and kinetic binding constants were evaluated for both interactions.
• The kinetic of the interaction of the two dyes is very different.
• Protoporphyrin IX showed a slow kinetic while SQ has a very fast kinetic interaction.

Photodynamic therapy (PDT) efficiency is affected by the nature of the binding between the photosensitizer and serum albumin. The kinetic interaction between two potential PDT dyes with bovine serum albumin was studied providing not only the rate constants but also demonstrating that the kinetic of the interaction of the two dyes is very different.