Abstract
Negatively charged nitrogen-vacancy (NV-) centers in diamonds are point defects displaying unique optical properties and biocompatibility. In this study, we characterized fluorescent microdiamonds (FMDs) and explored their potential use as fiducial markers for image-guided photothermal therapy. To exploit the excellent thermal conductivity of diamonds, we decorated the surface-functionalized FMDs with hollow gold nanoparticles (HGNs). The dual functions-fluorescent and thermal imaging-of the HGN-FMDs were performed when applying the distinct excitation laser wavelengths of the HGNs and the FMDs, respectively. The HGNs effectively absorbed the excitation near-infrared light to result in excellent light-to-heat conversion; the generated heat is transferred from 70 nm HGNs to 400 mu m FMDs to provide a homogeneous and global heating effect. When we embedded five HGN-FMD particles at a depth of 2 mm in chicken breast, a temperature increase of greater than 20 degrees C was achievable at the site of the HGN-FMDs. Our results highlight the promise of using nitrogen vacancy-containing diamond microcrystals in conjugation with gold nanoparticles for applications involving local hyperthermia.