Porphyrin Containing Polymersomes with Enhanced ROS Generation Efficiency: In Vitro Evaluation

Porphyrins are molecules possessing unique photophysical properties making them suitable for application in photodynamic therapy. The incorporation of porphyrins into natural or synthetic nano-assemblies such as polymersomes is a strategy to improve and prolong their therapeutic capacities and to overcome their limitations as therapeutic and diagnostic agents. Here, 5,10,15,20-tetrakis(1-(6-ethoxy-6-oxohexyl)-4-pyridin-1-io)-21H,23H-porphyrin tetrabromide porphyrin is inserted into polymersomes in order to demonstrate that the encapsulation enhances its ability to generate highly reactive singlet oxygen (¹ O₂ ) upon irradiation in vitro. The photoactivation of the free and polymersome-encapsulated porphyrin is evaluated by electron spin resonance and cell viability assays on three different mammalian cell lines. The results indicate that by encapsulating the porphyrin, a controlled ROS delivery within the cells is achieved, at the same time avoiding side effects such as dark toxicity, non-specific porphyrin release and over time decreased activity in vitro. This work focuses on showing a not-toxic model system for modern therapeutic nanomedicine, which works under mild irradiation and dosage conditions.