The Nanomedicine and Nanotoxicology Group at the Universidade de São Paulo's São Carlos Institute of Physics has reported twin advances in biomedical materials, published in ACS Nanoscience Au and ACS Applied Bio Materials. In the first study, the team engineered hydroxyapatite, the mineral that forms bone, so that added carbonate groups create crystal defects that boost the material's intrinsic luminescence, with the highest-carbonate samples glowing most brightly.
Functionalised with citrate for colloidal stability, the particles were taken up by cells and imaged by confocal microscopy and flow cytometry using nothing but their own light, with cytotoxicity assays confirming biocompatibility. That removes the need for separate fluorescent dyes, which can perturb the very processes researchers want to observe, and establishes a cheap, calcium-based alternative to heavy-metal quantum dots for cellular imaging.
The companion study turned the same family of materials into a smart drug carrier. Gemcitabine, a frontline chemotherapy agent, was linked to carboxymethylcellulose and loaded onto calcium phosphate nanoparticles decorated with folic acid, which tumour cells avidly take up. The system stays inert in normal physiological conditions and releases its payload only in the acidic microenvironment characteristic of tumours, a design the team tested against breast and cervical cancer cells. Together the papers sketch a platform in which one biocompatible mineral both finds disease and treats it.