Photosensitization of cellular membrane models mediated by methylene violet photosensitizer

• Grant number: 23/11785-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: August 31, 2025
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Pedro Henrique Benites Aoki
• Grantee: Thais Soares de Oliveira
• Host Institution: Faculdade de Ciências e Letras (FCL-ASSIS). Universidade Estadual Paulista (UNESP). Campus de Assis. Assis , SP, Brazil
• Associated research grant: 22/02189-2 - Plasmonic nanostructures for synergistic photodynamic (PDT) and photothermal (PTT) therapy of cancer cells, AP.PNGP.PI

Abstract

For every three cancers, one is diagnosed as skin cancer, contributing to about 19.3 million cases worldwide in 2020. In the pursuit of less invasive clinical treatments, light-based therapies have gained prominence, such as photothermal therapies (PTT) and photodynamic therapies (PDT). Lipid oxidation is essential for photodynamic therapy (PDT), clinically used in pathologies like skin and esophageal cancer. The method relies on the controlled administration of a photosensitizer molecule (PS), which induces the formation of reactive oxygen species (ROS) capable of triggering cell death in cancer cells. Cellular membranes, especially the singlet oxygen species, are the main targets of ROS due to lipid hydroperoxidation. However, the molecular-level mechanisms responsible for the interaction between PS and lipid membrane, as well as the effects of lipid oxidation, are not fully understood. In project, the interaction between the photosensitizer methylene violet (MV) and membrane models composed of lipid monolayers obtained from A357 and SH-4 melanoma-derived cells will be investigated, along with the photo-oxidative effects on lipid membranes. Langmuir films of melanoma lipid extracts will be produced in a subphase of ultrapure water and in a subphase of varying concentrations of VM. The films will be characterized using surface pressure versus area isotherms (À-A), as well as variations in surface area over time. The interactions will also be studied using Fourier-transform infrared spectroscopy (FTIR) measurements on Langmuir-Schaefer films, formed by multilayers of MV and melanoma lipid extracts. In a subsequent step, the PS incorporated into the monolayers will be photoactivated, monitoring the physicochemical modifications in the lipid membranes through changes in surface area over the irradiation time.