The use of quantum dots for analysis of chick CAM vasculature

Quantum dots (QDs) are fluorescent semiconductor nanocrystals that possess a number of superior fluorescent properties compared to more established organic dyes and fluorescent proteins. As a result, QDs are being studied for use in a wide range of biological applications. We have examined QDs for one such application, visualization of blood vessels of the chick chorioallantoic membrane (CAM), a popular model for studying various aspects of blood vessel development including angiogenesis. Intravitally injected QDs were found to be biocompatible and were kept in circulation over the course of 4 days without any observed deleterious effects. QD vascular residence time was tunable through QD surface chemistry modification. We also found that use of QDs with higher emission wavelengths (> 655 nm) virtually eliminated all chick-derived autofluorescence and improved depth-of-field imaging. QDs were compared to FITC–dextrans, a fluorescent dye commonly used for imaging CAM vessels. QDs were found to image vessels as well as or better than FITC–dextrans at 2–3 orders of magnitude lower concentration. We also demonstrated that QDs are fixable with low fluorescence loss and thus can be used in conjunction with histological processing for further sample analysis.