The Nanomedicine and Nanotoxicology Group at the University of São Paulo's São Carlos Institute of Physics announced on Mar. 18 that it has developed a new method to enhance the luminescence of hydroxyapatite nanoparticles, paving the way for their use in biomedical imaging and targeted cancer drug delivery.
This development is significant because it could lead to safer, more effective ways to diagnose diseases and deliver chemotherapy drugs directly to tumor cells, potentially reducing side effects for patients.
Thales Rafael Machado, a participant in the study and a FAPESP scholarship recipient, said, "We've demonstrated that the incorporation of carbonate groups into the hydroxyapatite structure increases the concentration of crystal defects, which are responsible for enhancing the intrinsic luminescence of the material. After functionalization with citrate, which improves colloidal stability in aqueous media, these calcium phosphate nanoparticles can be used as luminescent agents for cellular bioimaging." The research was coordinated by Professor Valtencir Zucolotto and involved collaboration with the Center for Molecular Engineering of Advanced Materials at CNPEM in Campinas.
Machado explained that by controlling carbonate levels during synthesis, researchers increased structural defects in hydroxyapatite nanoparticles. The sample with the highest carbonate content showed the strongest luminescence. He added, "The bioimaging capability was demonstrated by visualizing the internalization of the nanoparticles into cells using confocal fluorescence microscopy, relying exclusively on their intrinsic luminescence. Cellular internalization was also confirmed by flow cytometry... while biocompatibility was assessed through cellular cytotoxicity assays." Machado also noted that this research could help develop new materials for environmental applications and tissue engineering: "This knowledge can also be applied to producing luminescent scaffolds for tissue engineering."
In related work published in ACS Applied Bio Materials, GNano and CEMol created a dual pH-responsive system using calcium phosphate nanoparticles to deliver gemcitabine—a chemotherapy drug—so it remains inactive in normal conditions but releases its active form in acidic tumor environments. Machado said this approach promotes greater bioavailability and therapeutic potential: "The system was designed to be dual pH-responsive... promoting higher drug concentrations in tested tumor cells – from breast and cervical cancer – potentially reducing unwanted side effects in healthy tissues." The team also functionalized nanoparticle surfaces with folic acid to target tumor cells more effectively.
Machado emphasized that these advances could make chemotherapy more efficient: "By keeping the drug inactive while it circulates in the body and releasing it preferentially in the tumor environment, the system has the potential to reduce side effects and enhance the action of the drug directly on tumor cells." He concluded that such systems may improve quality of life during treatment: "Systems like these could make chemotherapy more efficient with lower doses and less damage to healthy tissues, improving patients' quality of life during treatment."
GNano continues developing nanostructured materials aimed at advanced diagnostics and therapies for cancer as well as safer delivery systems for agricultural uses.
