NAC-capped quantum dot as nuclear staining agent for living cells via an in vivo steering strategy

We describe a new nuclear staining strategy by in vivo anchoring Hoechst 33342, a commonly used nuclear staining organic dye, onto water-soluble N-acetylcysteine (NAC)-capped CdTe quantum dots (QDs). The strong H-bonding and electrostatic interaction between the organic dye and the QDs entice the positively charged nuclear staining agent in carrying effectively the bright QDs into the nucleus of living cells. Dynamic confocal imaging studies indicated that all visible light emitting NAC-capped QDs with emitting wavelength ranging from 530 to 602 nm can be successfully targeted to the nucleus of the living cells within 30 min. The minimum quantity of Hoechst 33342 as the anchoring agent required in carrying QDs to the nucleus is found to be 5 μg/mL. In essence, a simple, fast, and specific bioimaging of the nucleus in living cells by QDs is accomplished.