Near-infrared fluorescent imaging can be used for rapid and sensitive detection of cells deep within the body. However, common NIR dyes and quantum dots are expensive and/or toxic.
Porphyrins are economical fluorescent dyes, but their emission and excitation wavelengths are shorter than the NIR region and they can be toxic and poorly water-soluble. Scientists in Japan have made silica–porphyrin hybrid nanotubes that have no acute toxicity and higher water solubility compared to porphyrin. They used them to label macrophages, injected them into mice and tracked their distribution by fluorescence imaging with good results.
Link to journal article
Silica/Porphyrin Hybrid Nanotubes for In Vivo Cell Tracking by Near-Infrared Fluorescence Imaging
K Hayashi, M Nakamura and K Ishimura
Chem. Commun., 2012, DOI: 10.1039/c2cc17444h
