Investigation of the mechanisms for the methylene blue photochemistry in bile salts aggregates and organic solvents using laser flash photolysis

• Grant number: 22/07342-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Effective date (Start): September 26, 2022
• Effective date (End): June 25, 2023
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Iseli Lourenço Nantes Cardoso
• Grantee: Victor Hladkyi Toledo
• Supervisor: Cornelia Bohne
• Host Institution: Centro de Ciências Naturais e Humanas (CCNH). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Research place: University of Victoria (UVic), Canada
• Associated to the scholarship: 19/26919-7 - Photochemical and photophysical properties of phenothiazinic dyes at the interface of metallic nanoparticles, BP.DD

Abstract

Methylene blue and other phenothiazinic dyes have relevance in various applications in biology, materials, bioelectronics, and energy fields. Previous and ongoing studies in our laboratory have shown that the aggregate states of phenothiazines modulate these dyes' photophysics and photochemistry, favoring the stabilization of cation radicals produced by the type I mechanism. Particularly methylene blue (MB) has specific photochemical behavior modulated by aggregation. According to the medium and aggregation state, the formation of leuco MB can be preceded by the generation of relatively stable radical intermediates. Therefore, understanding the redox processes and the role of aggregation involved in the formation and stabilization of MB free radicals and leuco form generated photochemically is a challenge. The current project proposes the investigation of MB photochemical processes occurring in DMSO and bile salt aggregates, a host-guest system not previously investigated for MB. The availability of laser flash photolysis experiments and other advanced techniques in the laboratory of Professor Cornelia Bohne can unravel the photo-redox processes involved in the formation and stabilization of MB transient species. The data obtained will be relevant for evaluating methylene blue as an electron donor in association with semiconductors, solar light harvesting systems, self-cleaning materials, and other advanced applications. The fundamental studies proposed here can also contribute to a better understanding of the MB photochemical behavior in complex biological structures, like cellular membranes and intracellular compartments relevant for biological applications. (AU)