Enhanced Blue Emission in SrF2@X (X = SrF2, CaF2, and/or BaF2) Core-Shell Nanoscintillators for the Development of Radiodynamic Therapy in Nuclear Medicine

• Grant number: 24/18895-9
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: May 01, 2025
• End date: February 28, 2029
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Éder José Guidelli
• Grantee: Jezabel Melo Teixeira
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Scintillating nanoparticles (ScNPs) are considered promising due to their potential to be coupled with photosensitizers (PS) for use in X-ray-activated photodynamic therapy (X-PDT) and/or radionuclide-activated therapy. However, most PSs with high capacity for reactive oxygen species (ROS) generation absorb light mainly in the blue region, and there are few ScNPs with high scintillation efficiency in this spectral range.In a recent study by our group, we synthesized and characterized SrF2:Eu nanoparticles, which exhibited emission bands in the blue and red regions. When these nanoparticles were combined with porphyrins and irradiated with X-rays, they demonstrated potential to reduce the required radiation dose compared to the control group. However, the results indicated that the Eu2+ ions, responsible for the blue emission, were located in the inner regions of the ScNPs, probably due to charge compensation and the high oxidation potential of Eu2+ in the presence of oxygen. In contrast, the Eu3+ ions, responsible for the red emission, were stabilized at surface defects, establishing a correlation between particle size and blue emission: the smaller the particle, the lower the blue emission due to the increased availability of surface sites hosting Eu3+ ions.To address this, the proposed project aims to grow a shell of SrF2, CaF2, and/or BaF2 around the SrF2:Eu ScNPs to promote the reduction of surface Eu3+ ions into Eu2+, thus enhancing blue emission. Morphological and structural characterizations, along with luminescence studies and energy transfer mechanisms to the photosensitizer, will be investigated to maximize ROS production under ionizing radiation. In addition to exploring X-PDT with X-ray activation, the project will evaluate the use of gamma and/or beta radiation emitted by radioisotopes to develop radiodynamic therapy for nuclear medicine applications.