Investigation of the photophysical properties of porphyrins coordinated with metals and effects in photoinduced damage in cell membranes

• Grant number: 20/15400-8
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2021
• Effective date (End): February 28, 2022
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal researcher: Mauricio da Silva Baptista
• Grantee: Otávio Augusto de Oliveira Reis
• Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

This project aims to study the photophysical properties of three types of platinated tetrapyridylporphyrins, coordinated in its porphyrin ring to three different metals: Cu(II), Zn(II) and Ni(II). Along with that, we shall provide experiments to determine the phototoxicity of these three compounds, analysing the membrane damage generated by these molecules after irradiation and comparing them in terms of photoinduced membrane damage. The importance of this project is given not only to the study of the relation structure-property of these modified porphyrins, but also to the elucidation of the mechanisms of photoinduced damage generation in cell membranes. Such studies are essential for the development of photosensitizers (PSs) and consequently for the improvement of photodynamic therapy, which has been showing itself to be a innovative modality in the treatment of several types of cancer and infectious diseases through the combination of light, oxygen and PS, which shall damage the target cells due the excitation of the PS by light and transference of the absorbed energy to nearby oxygen molecules, generating reactive oxygen species (ROSs) that will damage the membranes. It's noteworthy that there's the possibility of contact-dependent reactions between the PS and the cell membrane, where the energy liberated by the PS will be directly transfered to the biomolecules of the membrane, without having the generation of ROSs. Spectrometrical analysis will be performed for the study of the photophysical properties of the modified porphyrins, such as spectrophotometric and fluorimetric characterization of the compounds, while also investigating the photoinduced damage on cell membranes through carboxyfluorescein leakage tests in GUV's and SUV's after irradiation of the compounds, and EPR and UHPLC analysis for characterization of the products derived from the oxidation of the membranes lipids.