Biocompatible Near-Infrared Quantum Dots as Ultrasensitive Probes for Long-Term in vivo Imaging Applications

A facile synthesis method to produce monodisperse, biocompatible, lysine crosslinked mercaptoundecanoic acid (MUA) CdSe(0.25)Te(0.75)/CdS near-infrared (NIR) quantum. dots and use them as probes to study their long term in vivo distribution, clearance, (aid toxicity is presented. Large signal enhancements are demonstrated by these quantum dots, which enables their use as efficient and sensitive probes for live-animal imaging. An important finding is that mice intravenously injected with approximate to 10.5 mg kg(-1) of NIR QDs survive for more than three months without any apparent adverse effect to their health. Furthermore, it is determined that there is a significant reduction. in the number of the QDs in the liver and spleen three months post injection. In addition., histological analysis of heart, kidney, liver, spleen, and lung tissue indicates that there are no acute toxic effects from these lysine crosslinked MUA NIR QDs. This study suggests that these NIR QDs call be potentially used for long-term targeted imaging and therapy studies in vivo.