Luminescent supraparticles based on rare earth oxides and plasmonic nanoparticles as multimodal agents for combined optical thermometry and photodynamic and photothermal therapies

• Grant number: 25/09767-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2025
• End date: July 31, 2030
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Paulo Cesar de Sousa Filho
• Grantee: Gabriel Moronari Domingues da Silva
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers, AP.TEM

Abstract

Photodynamic and photothermal therapies are promising strategies in cancer treatment but face several intrinsic challenges, including potential unintended thermal damage to healthy cells. To address these limitations, this project proposes to develop a system combining both therapies with simultaneous temperature sensing in a synergistic approach. Hence, our project aims to create supraparticles (i.e., submicrometric aggregates of nanoparticles with controlled composition, densification, and size) based on rare-earth oxides (RE2O3) and plasmonic nanoparticles capable of acting either simultaneously or orthogonally under near-infrared (NIR) excitation. Different lanthanide ions (Pr3+, Nd3+, Tm3+, and Yb3+) in the RE2O3 nanoparticles will provide both localized generation of reactive oxygen species via Ln3+ excited states and luminescent thermometric response by NIR-NIR downshift processes within biological transparency windows. In addition, the photothermal response of the supraparticles will be provided by gold nanorods (AuNRs) showing plasmonic resonance bands in the NIR. To achieve such systems, we will initially overcome the synthetic challenges concerning the preparation of colloidally stable RE2O3 particles, either through thermolysis of oleates in high-boiling-point solvents or by thermal decomposition of hydroxocarbonate nanoparticles protected by molten salts. Additionally, the conditions for controlled aggregation of different nanoparticles will be investigated using a methodology based on surface ligand photocross-linking. This will allow for the evaluation of the thermometric, photothermal, and photodynamic performance of the prepared supraparticles, as well as their stability and behaviour in both simulated and real biological media. Therefore, the goal is to develop a multifunctional system that not only improves the efficiency of photodynamic and photothermal therapies but also enables precise control of the local temperature, opening new perspectives in theranostic materials.