Functionalized near-infrared quantum dots for in vivo tumor vasculature imaging

Abstract

In this paper, we report the use of near-infrared (NIR)-emitting alloyed quantum dots(QDs) as efficient optical probes for high contrast in vivo imaging of tumors. AlloyedCdTe1 − xSex/CdS QDs were prepared in the non-aqueous phase using the hot colloidal synthesisapproach. Water dispersion of the QDs were accomplished by their encapsulationwithin polyethyleneglycol (PEG)-grafted phospholipid micelles. For tumor-specificdelivery in vivo, the micelle-encapsulated QDs were conjugated with thecyclic arginine–glycine–aspartic acid (cRGD) peptide, which targets theαvβ3 integrins overexpressed in the angiogenic tumor vasculatures. Using in vivo NIR opticalimaging of mice bearing pancreatic cancer xenografts, implanted both subcutaneously andorthotopically, we have demonstrated that systemically delivered cRGD-conjugatedQDs, but not the unconjugated ones, can efficiently target and label the tumorswith high signal-to-noise ratio. Histopathological analysis of major organs of thetreated mice showed no evidence of systemic toxicity associated with these QDs.These experiments suggest that cRGD-conjugated NIR QDs can serve as safeand efficient probes for optical bioimaging of tumors in vivo. Furthermore, byco-encapsulating these QDs and anticancer drugs within these micelles, we havedemonstrated a promising theranostic, nanosized platform for both cancer imaging andtherapy.