Singlet oxygen generation by different photosensitizers excited by nanoparticle presenting upconversion and biological applications

• Grant number: 19/17363-5
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: September 01, 2019
• End date: July 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Paolo Di Mascio
• Grantee: Amanda da Annunciação Farhat
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 13/07937-8 - Redoxome - Redox Processes in Biomedicine, AP.CEPID

Abstract

Electronically excited molecular oxygen at the singlet state 1Δg (1O2) is known for its reactivity in proximity to high electron density organic molecules. 1O2 reactions with biomolecules have been studied in recent decades as a source of study of lesions related to cytotoxic and pathophysiological processes, which is indicative of the importance of studying this molecule in complex systems.Trivalent rare earth ion (TR3+) doped nanoparticles may present the upconversion phenomenon, which consists of the excitation of the material with two or more photons and a subsequent emission of a higher energy photon. Similarly, an excitation source can be applied to the biological window region and UV-visible emissions can be obtained using these nanoparticles. In addition, TR3 + doped materials exhibit emissions across the UV and visible spectrum under varying excitation wavelengths.Therefore, this project envisages using β-NaErF4:Tm3+@β-NaYF4 e β-NaYF4:Yb3+,Tm3+@β-NaYF4 nanoparticles excited in the near infrared (red window region) and emitted in red for methylene blue sensitization. , capable of generating high quantum yield 1O2 and UVA-emitting nanoparticles for internal and local sensitization of 6-thioguanine incorporated into nucleic acids for the study of oxidative processes through photosensitization of this molecule that generates 1O2 in cells. Studies on the generation and kinetics of monomolecular emission of 1O2 (1270 nm) by photosensitization of methylene blue will be performed in different solvents (H2O, D2O e CHCl3). (AU)