Silica-porphyrin hybrid nanotubes for in vivo cell tracking by near-infrared fluorescence imaging

Near-infrared fluorescent silica-porphyrin hybrid nanotubes (HNTs) were successfully synthesized by pi-pi stacking, electrostatic interaction and a sol-gel reaction. The HNTs-labeled macrophages were detected in vivo, and the minimum detectable number of cells was 200. Furthermore, the biodistribution of HNTs-labeled macrophages was tracked by fluorescence imaging.