Photophysical evaluation of mTHPC-loaded HSA nanoparticles as novel PDT delivery systems

Controlled drug release is one of the main goals of recent developments in drug carrier systems. In this work human serum albumin (HSA) nanoparticles as carriers for 5-, 10-, 15-, 20-Tetrakis (3-hydroxyphenyl)-chlorin (mTHPC) were investigated. The photophysical properties of mTHPC-HSA nanoparticles in dependence of loading ratio and level of HSA cross-linking were determined. Further the drug release after uptake by Jurkat cells and in vitro singlet oxygen kinetics were examined. The loading ratio of the mTHPC-HSA nanoparticles turned out to be of major importance for the PDT relevant electronic parameters in solution. Therefore, only HSA nanoparticles with low mTHPC-loading ratio generate singlet oxygen in D(2)O. However, after cellular uptake all mTHPC-HSA samples generate singlet oxygen in Jurkat cells, but the decomposition rate depends on the level of HSA cross-linking.