Lipid nanoparticles as efficient verteporfin nanocarriers for photodynamic therapy of cancer

Abstract

Photodynamic therapy (PDT) is a non-invasive procedure used in cancer treatment that requires the interplay of a photosensitizer (PS), a light source, and molecular oxygen. When the cell internalizes the PS, light irradiation will trigger the production of reactive oxygen species (ROS), which induces cancer cell death. Currently, efforts are being made to improve the properties of different PSs, namely their light absorption parameters, pharmacokinetics, and tumor accumulation. Verteporfin (VP) is a protoporphyrin derivative that is under clinical trials for the management of several types of cancer. Despite being approved as a PS in other pathologies, such as age-related macular degeneration, issues related to VP's poor water solubility and tumor accumulation may compromise its efficacy and clinical application. In this work, solid lipid nanoparticles (SLNs) were proposed as suitable nanocarriers of VP. Nanoparticles were produced using a low-cost method and presented high encapsulation efficiency (EE%) and adequate physiochemical properties for efficient delivery into the tumor benefiting from the enhanced permeability and retention (EPR) effect. In addition, SLNs were non-hemolytic and exhibited negligible toxicity under dark conditions in both normal (L929) and cancer (MCF-7) cells. After light irradiation with a LED light source at 690 nm, 6.7 mW cm⁻² for 5 min, a dose-dependent anti-cancer activity was achieved. These results were corroborated by an enhancement in the production of ROS and a higher degree of apoptosis. Overall, the presented study demonstrated that SLNs are promising candidates to improve the water solubility of VP while maintaining its high therapeutic effect.