Bioluminescence induced reactive oxygen species generation for photodynamic therapy

Abstract

Photodynamic therapy (PDT) has developed as one of promising systems in cancer therapy for its high-selectivity and low systemic cytotoxicity. However, the accessibility of external light limits the application on deeper tumor because of tissue-penetrating properties. In this study, bioluminescence (BL) enzyme protein- photosensitizer (PS) conjugates were synthesized using covalent bonging. Renilla luciferase8 (Rluc8), mutant of enzyme protein that has stability and high intensity BL, was employed as an internal light source. Chlorin e6, photosensitizer that has high singlet oxygen quantum yield, was covalently attached to Rluc8. Generation of reactive oxygen species (ROS) could be achieved through bioluminescence resonance energy transfer (BRET) from BL to photosensitizer. The amount of ROS produced from Rluc8-e6 conjugates was detected using singlet oxygen sensor green (SOSG), which shows fluorescence increase as ROS is generated. Our results show that Rluc8-e6 conjugates could be synthesized without distorting of properties of both materials and conjugates could generate ROS, which may be applied for PDT.