Synthesis and application of chiral functionalized quantum dots

Recent progresses in design and preparation of new chiral materials resulted in the development of molecular recognition methods [1]. Chiral receptors can discriminate between left- and right-handed enantiomers of target analytes resulting in the chiral recognition. This discrimination takes place if the analyte species can interact differently with the chiral receptor sites. A measurable difference in the interaction between the chiral receptor sites and analyte species is necessary for chiral recognition. Chiral colloidal quantum dots (QDs) have been appeared as new nanomaterials with extensive potential applications [2]. Functionalization of QDs with desired chiral groups is a promising method for tailoring tunable chiral QDs with potential uses in chemical or biological applications. The QDs core with appropriate optical absorption or emission properties may be designed and prepared separately and then functionalized with appropriate chiral ligands. Chiral amino acids containing thiol groups such as cysteine are appropriate capping groups and their use have provided new pathways for the preparation of chiral QDs [3]. In spite of the importance of chiral QDs in chiral analysis, there are few reports on their preparation and utilization in practical chiral recognition and analysis of chiral species [4]. Moreover, the selective interaction of different enantiomers of chiral QDs with chiral molecules has not been well-described. Here, the design and characterization of optically active chiral QDs is described with functionalization of achiral QDs with chiral l- and d-cysteine groups. According to the results of fluorescence spectroscopy, the prepared chiral functionalized QDs exhibited selective interaction with chiral analytes. Thus, the chiral recognition of analytes is possible by their enantioselective interaction with the functionalized chiral QDs. Some of the chiral analytes quenched the fluorescence intensity of the functionalized chiral QDs more efficient than the other.