SPECT/CT imaging of radiolabeled Quantum dots

Quantum dots (QDs) are emerging as a new fluorescent probe for in vivo and in vitro imaging. In comparison with organic dyes and fluorescent proteins, QDs have unique optical and electronic properties, such as size-tunable fluorescence emission, improved signal brightness and resistance against photobleaching. The well-defined in vivo behavior of QDs is prerequisite information for biomedical application. To identify in vivo behavior of QDs, several efforts were done by using in vivo fluorescence imaging and inductively coupled plasma atomic emission spectroscopy (ICPAES). However, in vivo tracking and quantification of QDs by fluorescence imaging is limited by tissue absorption of light and ICP-AES can not be used to measure consecutive and temporal accumulation of QDs in living animals. Scintigraphy is a standard nuclear medicine approach and clinically established to characterize lesions. Radiolabeld QDs will provide quantitative and temporal information of QDs' in vivo behavior. Here we evaluated the feasibility of radioiodination of QDs using Bolton-hunter reagent. The biodistribution of radioiodinated QDs were measured by using gamma counting and in vivo distribution of radiolabeled QDs were evaluated by SPECT/CT imaging