Donor Optimizing to Boost Type I and Type II Photosensitization for Solid Tumor Therapy.

Area of Science:

• Biomedical Engineering
• Photochemistry
• Oncology

Background:

• Solid tumors present heterogeneous oxygen environments, with normoxia near blood vessels and hypoxia internally.
• Traditional photodynamic therapy (PDT) faces challenges in effectively treating these diverse tumor regions.
• Oxygen-dependent Type I photosensitizers (PSs) are crucial for enhancing PDT in hypoxic tumors.

Purpose of the Study:

• To develop a novel photosensitizer (PS) strategy that optimizes both Type I and Type II reactive oxygen species (ROS) generation.
• To enhance the utilization of oxygen within solid tumors for improved PDT efficacy.
• To create a PS effective in both normoxic and hypoxic tumor environments.

Main Methods:

• A viable donor optimizing approach was employed to enhance PS performance.
• The optimized PS (DE) was compared against commercial Type II PS (Chlorin e6) for singlet oxygen (¹O₂) generation.
• The optimized PS (DE) was compared against commercial Type I PS (Rose Bengal) for hydroxyl radical (•OH) generation under hypoxia.

Main Results:

• The optimized PS (DE) generated 9 times more ¹O₂ than Chlorin e6 under white light irradiation.
• DE exhibited 2.9 times greater •OH generation than Rose Bengal under hypoxic conditions.
• DE demonstrated efficient Type I and Type II ROS generation in both normoxia and hypoxia.

Conclusions:

• The optimized PS (DE) shows significant potential as an efficient agent for solid tumor treatment via PDT.
• DE's ability to leverage both Type I and Type II pathways in varying oxygen conditions offers a promising advancement in PS development.
• This approach provides a viable strategy for enhancing PDT efficacy in complex tumor microenvironments.