ANALYSIS OF PHOTOGEM SONODEGRADATION IN DIVERSE SOLVENTS

Cutaneous melanoma is one of the most aggressive and deadly forms of skin cancer. Standard treatments rely on surgical removal, which can cause irreversible side effects and may be unsuitable for patients with comorbidities. In such cases, alternative approaches such as sonodynamic therapy (SDT) have emerged as a promising non-invasive cancer treatment. SDT combines a sonoactive molecule, known as sonosensitizer (SS), low intensity ultrasound, and molecular oxygen to promote sonomechanical and sonochemical effects via acoustic cavitation, generating reactive oxygen species (ROS) and causing targeted cell damage. Several sensitizers, such as hematoporphyrin derivatives, have shown cytotoxic dynamic effects in both in vitro and in vivo SDT studies. Although the therapeutic potential of SDT has been demonstrated, the mechanisms underlying this technique are not yet fully understood. Therefore, studies investigating the sonobleaching effects of a sonosensitizer (SS) under various conditions are crucial. In this context, the present study aims to investigate the interaction between Photogem (PG), a hematoporphyrin derivative, and ultrasound through sonodegradation experiments in different solvents, in order to evaluate the medium influence. PG 10 μM solutions were prepared in water, DMSO, PBS and surfactant (1% Triton X-100) solution, then irradiated with ultrasound (1MHz, 50% duty cycle, 100Hz, 1.5 W/cm²). Absorption spectra were recorded during irradiation to monitor PG degradation over time and to determine the corresponding decay rate constant (k). The obtained results were: k_water = 1,2E-2 1E-3, k_DMSO = 6E-4 1E-4, k_PBS = 2,54E-3 6E-5 and k_surfactant = 1,2E-3 2E-4. These results showed that PG degradation rates vary depending on the solvent, suggesting that nucleation and cavitation are influenced by the medium’s physicochemical properties, such as viscosity, surface tension, and the presence of salts in the solution, which affect both ROS generation and PG sonobleaching.