Luminescent Ge3+, Cr3+ and Ln3+ doped zinc gallate nanoparticles: synthesis and applications in bioimaging

• Grant number: 24/15166-6
• Support Opportunities: Scholarships in Brazil - Master
• Start date: December 01, 2024
• End date: March 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Rogéria Rocha Gonçalves
• Grantee: Marco Aurélio Teodoro da Silva
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers, AP.TEM

Abstract

Persistent luminescent nanoparticles (PLNPs) are the focus of research in materials science and medicine, acting as "optical batteries" that store and emit light energy after initial excitation. This ability to emit light for a prolonged period post-excitation makes PLNPs valuable tools for photonic applications such as security marking, biomarking and bioimaging, sensors, among others.Among PLNPs, chromium-doped zinc gallate (ZnGa2O4:Cr3+) is notable for its intense persistent luminescence emission at approximately 700 nm. This emission, located in the "first optical window of biological transparency", minimizes the need for continuous excitation, allows both signal acquisition and excitation penetration into deeper layers of biological tissues, reduces the autofluorescence signal, improving the ratio signal-to-noise. These characteristics make this a potential material for application as a marker or emission source in biological systems, whether for diagnosis or therapy using some photo-stimulated process.The synthesis of ZnGa2O4:Cr3+ has been explored through various methodologies, but the precise control of morphological and optical properties still represents a major challenge. This master's project focuses on the development of ZnGa2O4 nanoparticles: Ge4+, Cr3+ and Ln3+ through solvothermal synthesis, using oleic acid and oleylamine as stabilization agents. Detailed investigation of synthetic parameters aims to improve control over nanoparticle morphology and redispersion. In addition, it will be considered doping with lanthanide ions (Ln3+) to induce persistent luminescence at different and specific wavelengths, and codoping with germanium ions (Ge4+) to monitor the impact on changes in the electronic structure and properties of persistent luminescence.Morphological and optical properties will be evaluated to select particles with the most promising characteristics, ensuring redispersion and colloidal stability in aqueous and biological systems. The second part of this proposal focuses on the biological applications of these nanoparticles. Grade IV glioblastoma multiforme cell lines: T98G and U87MG and infantile glioblastoma KNS42 will be cultivated for imaging and treatment of these neoplasms. Analysis of toxicity, cell viability and cell death mechanisms will be explored.As activities of this project, it is also intended to carry out adaptations to adapt the instrumental part of equipment with Mater Lumen and CNET to obtain images and spectra of particles in cells, and, therefore, validation of future medical and biological applications.