Porphyrinoids for Photodynamic Therapy (PDT) and Antimicrobial PDT

Photodynamic therapy combines light, molecular oxygen and a PS for the production of reactive oxygen species (ROS), such as singlet oxygen (1O2) and free radicals, leading to oxidative stress and eventual cell death. Phthalocyanines (Pcs) fulfil many of the requirements to be applied as photosensitizers for singlet oxygen generation. However, a major drawback of these compounds is their low solubility in physiological media. Functionalization of the macrocycle at the peripheral and/or axial positions with appropriate hydrophilic functions provides compounds with an enhanced solubility in water. In this respect, several strategies have been adopted to increase the hydrophilicity of Pcs and make them more bio-compatible, like their functionalization with charged groups, aminoacids or carbohydrates, or conjugation to appropriate nanocarriers. The introduction of such entities at Pc axial positions reduces the aggregation of the macrocycles in solution, thus improving their 1O2generation efficiency. For recent work of our group, see references 1 and 2, and articles cited therein.1V. Almeida-Marrero, E. van de Winckel, E. Anaya-Plaza, T. Torres, A de la Escosura, "Porphyrinoid biohybrid materials as an emerging toolbox for biomedical light management", Chem. Soc. Rev., 2018; 47: 7369-7400.2 P.-C. Lo, M. S. Rodriguez-Morgade, R. K. Pandey, D. K. P. Ng, T. Torres, F. Dumoulin, "The unique features and promises of phthalocyanines as advanced photosensitisers for photodynamic therapy of cancer", Chem. Soc. Rev. 2020; 49: 1041-1056