Singlet oxygen generation by photosensitizers excited by upconverting nanoparticles

• Grant number: 18/07737-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2018
• End date: April 30, 2019
• Field of knowledge: Biological Sciences - Biophysics - Radiology and Photobiology
• 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 1”g (1O2) is known for its reactivity in proximity to organic molecules with high electronic density. Reactions of 1O2 with biomolecules have been studied in the last decades due to lesions related to cytotoxic and pathophysiological, which is indicative of the importance of this molecule in complex systems. Nanoparticles doped with trivalent rare earth ions (TR3+) may present the upconversion phenomenon, which consists in 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 in the region of the biological window and obtain UV-visible emissions using these nanoparticles. In addition, materials doped with TR3+ exhibit emissions throughout the UV and visible range under different excitation wavelengths. Therefore, this project aims to use nanoparticles ²-NaErF4:Tm3+,Dy3+@²-NaYF4 excited in the near infrared (biological window region) and emitting blue and red light for acridine yellow and methylene blue sensitization, respectively, capable of generating 1O2 with high quantum yield. Studies of generation and emission kinetics of 1O2 monomolecular transition (1270 nm) by the photosensitization of methylene blue and acridine yellow will be carried out in different solvents (H2O, D2O and CHCl3). (AU)