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Chiral β-HgS quantum dots: Aqueous synthesis, optical properties and cytocompatibility

Yang, Feifei, Gao, Guanbin, Wang, Juncheng, Chen, Rui, Zhu, Wenbo, Wang, Liang, Ma, Zhongjie, Luo, Zhuoying, Sun, Taolei
Journal of colloid and interface science 2019 v.537 pp. 422-430
Oriental traditional medicine, absorption, aqueous solutions, circular dichroism spectroscopy, cytotoxicity, enantiomers, fluorescence, fluorescent dyes, ligands, mercuric chloride, monitoring, optical isomerism, optical properties, photothermotherapy, quantum dots, sodium sulfide, transistors, water solubility
β-HgS quantum dots (QDs) have drawn enormous attention due to the size-tunable bandgap and the lowest quantum state in conduction band which have been applied to semiconductor transistor and photodetector. Though β-HgS is the essential component of Tibetan medicine, the potential toxicity of β-HgS limits its applications, especially in bio-application. Herein, chiral biomolecule enantiomers N-isobutyryl-L(D)-cysteine (L(D)-NIBC) and L(D)-cysteine (L(D)-Cys) were introduced into HgCl2 and Na2S aqueous solution to synthesize chiral β-HgS QDs in one-pot, which significantly improved their water-solubility and cytocompatibility. Notably, all chiral β-HgS QDs showed none cytotoxicity even at high concentration (20 mg·L−1), and the cytocompatibility of D-β-HgS QDs was better than corresponding L-β-HgS QDs at the concentration of 20 mg·L−1. This cytotoxicity discrimination was associated with the chirality inversion of chiral β-HgS QDs compared with the corresponding chiral ligands. In-situ real-time circular dichroism (CD) monitoring indicated that the chirality of β-HgS QDs originated from the asymmetrical arrangement of chiral ligands on the achiral core surface. Their chiroptical activity, near-infrared optical absorption (800 nm), fluorescence emission (900–1000 nm), high-performance photothermal conversion and good cytocompatibility, implied chiral β-HgS QDs could be used as a candidate material for photothermal therapy or a near-infrared fluorescent probe in organism, which brings a novel insight for bio-application of β-HgS QDs.