Dual-function probe for PET and near-infrared fluorescence imaging of tumor vasculature

To date, the in vivo imaging of quantum dots (QDs) has been mostly qualitative or semiquantitative. The development of a dual-function PET/near-infrared fluorescence (NIRF) probe can allow for accurate assessment of the pharmacokinetics and tumor-targeting efficacy of QDs. Methods: A QD with an amine-functionalized surface was modified with RGD peptides and 1,4,7,10-tetraazacyclodocecane-N,N9,N$,N%-tetraacetic acid (DOTA) chelators for integrin avb3–targeted PET/NIRF imaging. A cell-binding assay and fluorescence cell staining were per-formed with U87MG human glioblastoma cells (integrin avb3– positive). PET/NIRF imaging, tissue homogenate fluorescence measurement, and immunofluorescence stainingwere performed with U87MG tumor–bearing mice to quantify the probe uptake in the tumor and major organs. Results: There are about 90 RGD peptides per QD particle, and DOTA–QD–RGD exhibited integri