Labeling tumor cells with fluorescent nanocrystal–aptamer bioconjugates

Aptamers that bind to prostate specific membrane antigen (PSMA) were conjugated to luminescent CdSe and CdTe nanocrystals for cell-labeling studies. The aptamer–nanocrystal conjugates showed specific targeting of both fixed and live cells that overexpressed PSMA. More importantly, aptamers were able to label cells dispersed in a collagen gel matrix simulating tissue. The specific binding abilities and synthetic accessibility of aptamers combined with the photostability and small size of semiconductor nanocrystals offers a powerful and general tool for cellular imaging.