Photodynamic therapy (PDT) presents an interesting alternative for treating skin cancer, offering a significant reduction in the side effects typically seen with radiotherapy and chemotherapy. This technique involves the use of a photosensitizing agent, a light source of a specific wavelength, and molecular oxygen. The interaction between the light-exposed photosensitizer and molecular oxygen leads to producing reactive oxygen species that induce cell death. The success of PDT largely depends on the photosensitizer, which can be hampered by poor solubility, low specificity, or insufficient accumulation in the tumor. Numerous nanosystems have been developed to address these challenges [1]. 

In our studies, we paid particular attention to dendrimers [2], dendrimersomes [3], and polymersomes [4]. We examined four different nanosystems designed to deliver rose bengal, aiming to evaluate their effectiveness in PDT. We assessed various factors: biophysical properties such as hydrodynamic diameter, zeta potential, spectral characteristics, and the ability to either form complexes with or encapsulate rose bengal, the generation of singlet oxygen, production of intracellular reactive oxygen species, intracellular transport, and phototoxic effects. This approach allowed us to evaluate the potential of different nanocarriers for the photodynamic treatment of basal cell carcinoma. 

Our results indicated that the method of interaction between rose bengal and the nanosystems greatly affects its photodynamic potential. Encapsulation was found to be the most efficient delivery method, significantly boosting singlet oxygen production and intracellular transport, ultimately enhancing the phototoxic effect. 

References
[1] Sztandera, K.; Gorzkiewicz, M.; Klajnert-Maculewicz, B. Wiley Interdisciplin. Rev.: Nanomed. Nanobiotech., 2020, 12, 1509 
[2] Sztandera, K; Gorzkiewicz, M.; Dias Martins, A.S.; Pallante, L.; Zizzi, E.A.; Miceli, M.; Batal, M.; Pinto Reis, C.; Deriu, M.A.; Klajnert-Maculewicz, B. J. Med. Chem., 2021, 64, 15758 
[3] Sztandera, K.; Gorzkiewicz, M.; Batal, M.; Arkhipova, V.; Knauer, N.; Sanchez-Nieves, J.; de la Mata, F.J.; Gomez, R.; Apartsin, E.; Klajnert-Maculewicz, B. Int. J. Nanomed., 2022, 17, 1139 
[4] Sztandera, K.; Gorzkiewicz, M.; Wang, X.; Boye, S.; Appelhans, D.; Klajnert-Maculewicz, B. Colloids Surfaces B: Biointerfaces, 2022, 217, 112662