Abstract
The near-infrared (NIR)-emitting quantum dots (Qdots) have great potential for the use in biological imaging and
diagnostic applications. In our work, a facile method was developed for the preparation of high quality, water-soluble,
and NIR-emitting CdSeTe alloyed Qdots (A-Qdots) with L-cysteine (L-cys) as capping agent. By changing the size and
the composition of the A-Qdots, the photoluminescent quantum yields (QYs) can reach as high as 53% and the emission
color can be tuned between visible and NIR regions. Based on the fluorescence of the A-Qdots selectively quenched in
the presence of Cu2+, the NIR-emitting CdSeTe A-Qdots were applied in ultrasensitive Cu2+ sensing. Furthermore, the
prepared CdSeTe A-Qdots have been successfully applied for cell imaging, glucose and cholesterol assay, which
demonstrates the great potential of the Qdots for biological applications. In order to improve the biocompatibility of the
CdSeTe A-Qdots, new water-soluble CdSeTe/ZnS core-shell Qdots (CS-Qdots) with excellent NIR emission were
synthesized in aqueous solution. The prepared CS-Qdots not only possessed high QYs but also exhibited excellent
photobstability and favorable biocompatibility. Moreover, the CS-Qdots showed high electrogenerated
chemiluminescence (ECL) signal. These characteristics showed their potential applications in cell imaging and
biosensing with high sensitivity.
