Functionalized near-infrared quantum dots for invivo tumor vasculature imaging

In this paper, we report the use of near-infrared (NIR)-emitting alloyed quantum dots (QDs) as efficient optical probes for high contrast invivo imaging of tumors. Alloyed CdTe_{1 - x}Se_x/CdS QDs were prepared in the non-aqueous phase using the hot colloidal synthesis approach. Water dispersion of the QDs were accomplished by their encapsulation within polyethyleneglycol (PEG)-grafted phospholipid micelles. For tumor-specific delivery invivo, the micelle-encapsulated QDs were conjugated with the cyclic arginine-glycine-aspartic acid (cRGD) peptide, which targets the α_vβ₃ integrins overexpressed in the angiogenic tumor vasculatures. Using invivo NIR optical imaging of mice bearing pancreatic cancer xenografts, implanted both subcutaneously and orthotopically, we have demonstrated that systemically delivered cRGD-conjugated QDs, but not the unconjugated ones, can efficiently target and label the tumors with high signal-to-noise ratio. Histopathological analysis of major organs of the treated mice showed no evidence of systemic toxicity associated with these QDs. These experiments suggest that cRGD-conjugated NIR QDs can serve as safe and efficient probes for optical bioimaging of tumors invivo. Furthermore, by co-encapsulating these QDs and anticancer drugs within these micelles, we have demonstrated a promising theranostic, nanosized platform for both cancer imaging and therapy.