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

ß-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 ß-HgS is the essential component of Tibetan medicine, the potential toxicity of ß-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 ß-HgS QDs in one-pot, which significantly improved their water-solubility and cytocompatibility. Notably, all chiral ß-HgS QDs showed none cytotoxicity even at high concentration (20 mg·L-1), and the cytocompatibility of D-ß-HgS QDs was better than corresponding L-ß-HgS QDs at the concentration of 20 mg·L-1. This cytotoxicity discrimination was associated with the chirality inversion of chiral ß-HgS QDs compared with the corresponding chiral ligands. In-situ real-time circular dichroism (CD) monitoring indicated that the chirality of ß-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 ß-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 ß-HgS QDs.

Synthesis and Cell Imaging of a Near-Infrared Fluorescent Magnetic "CdHgTe-Dextran-Magnetic Layered Double Hydroxide-Fluorouracil" Composite.

In this article, a water-soluble near-infrared quantum dots of CdHgTe were prepared and subsequently combined with the drug delivery system "dextran-magnetic layered double hydroxide-fluorouracil" (DMF) to build a new nanostructure platform in form of CdHgTe@DMF, in which the fluorescent probe function of quantum dots and the magnetic targeting transport and slow-release curative effect of DMF were blended availably together. The luminescent property particle size, and internal structure of the composite were characterized using fluorescence spectrophotometer, ultraviolet spectrophotometer, laser particle size distribution, TEM, X-ray diffraction, and Fourier transform infrared. The experimental study on fluorescent tags effect and magnetic targeting performance of the multifunctional platform were performed by fluorescent confocal imaging. The results showed that the CdHgTe could be grafted successfully onto the surface of DMF by electrostatic coupling. The CdHgTe@DMF composite showed super-paramagnetic and photoluminescence property in the near-infrared wavelength range of 575-780 nm. Compared with CdHgTe, the CdHgTe@DMF composite could significantly improve the cell imaging effect, the label intensity increased with the magnetic field intensity, and obeyed the linear relationship Dmean = 1.758 + 0.0075M under the conditions of magnetic field interference. It can be implied that the CdHgTe@DMF may be an effective multifunction tool applying to optical bioimaging and magnetic targeted therapy.

Aqueous synthesis and characterization of glutathione-stabilized ß-HgS nanocrystals with near-infrared photoluminescence.

A simple, rapid and green aqueous approach to near-infrared (NIR)-emitting ß-HgS nanocrystals (NCs) was demonstrated for the first time by using glutathione (GSH) as the stabilizer at room temperature. The resulting HgS NCs with zinc blend structure exhibited strong quantum size effect, and the emission peak could be tuned in a wide NIR region from ca. 775 to 1041 nm. As compared with early achievements, the emission intensity of GSH-stabilized HgS NCs enhanced, with the maximum quantum yield reaching ~2.8%. It was also found that the stability of the GSH-HgS NCs was improved noticeably, the PL peak red-shifting only 9 nm and 23 nm after stored at 4°C for 4 months and 25°C for 7 days, respectively. The better stability of the HgS NCs was elucidated by FT-IR due to the multiple coordination of GSH molecule to surface Hg of the NCs. The emission range of GSH-stabilized HgS NCs was located between the visible region (500-800 nm) and IR region (1000-1600 nm) of HgS NCs as reported previously, extending the emission region of HgS nanomaterial. Therefore, the continuous emission from visible to IR spectral ranges provided HgS material more potential applications.

In vivo monitoring of organ-selective distribution of CdHgTe/SiO2 nanoparticles in mouse model.

CdHgTe/SiO(2) nanoparticles were prepared by SiO(2) capping on the surface of CdHgTe QDs. The characteristics, such as optical spectra, photostability, size and cell toxicity were investigated. The dynamic distribution of CdHgTe/SiO(2) nanoparticles was in vivo monitored by near infrared fluorescence imaging system. CdHgTe/SiO(2) nanoparticles acted as a novel fluorescence probe have a maximum fluorescence emission of 785 nm and high photo-stability. The hydrodynamic diameter of CdHgTe/SiO(2) nanoparticles could be adjusted to 122.3 nm. Compared to CdHgTe QDs, inhibitory effects of CdHgTe/SiO(2) nanoparticles on proliferation of HCT116 cells decreased to a certain extent. CdHgTe/SiO(2) nanoparticles had their specific dynamic distribution behavior, which provided new perspectives for bio-distribution of nanoparticles.

Synthesis and characterization of self-assembled CdHgTe/gelatin nanospheres as stable near infrared fluorescent probes in vivo.

This work presented a kind of novel near infrared emitting CdHgTe/gelatin nanospheres which were synthesized with Cd(NO(3))(2), Hg(NO(3))(2), NaHTe and a thiol stabilizer in gelatin solution. The self-assembled nanospheres were megranate-like and nearly 40 nm in diameter, with CdHgTe QDs uniformly embedded in gelatin matrix. They exhibited strong fluorescence ranging from 580 to 800 nm that could be tuned by molar ratios of Hg(2+) and gelatin. The full widths at half-maximum of the emission spectra were in the range of 60-80 nm. Compared with bare CdHgTe QDs, the photostability of this compact complex nanostructure remarkably improved. Moreover, the fluorescence of CdHgTe/gelatin nanospheres was much more resistant to the interference from certain kinds of endogenous biomolecules such as HSA, transferrin and hemoglobin. Further applications of living cells and mouse imaging were demonstrated with an in vivo near infrared fluorescence imaging system. The inherent advantages of high stability as well as high fluorescence intensity make the nanospheres particular interested NIR bioprobe candidates for in vivo imaging studies.

Zinc, cadmium, and mercury 1,2-benzenedithiolates with intramolecular NH...S hydrogen bonds.

Mononuclear Zn, Cd, and Hg 1,2-benzenedithiolates with intramolecular NH...S hydrogen bonds, [M(II){1,2-S2-3,6-(RCONH)2C6H2}2](2-) (R = CH 3, t-Bu; M = Zn, Cd, Hg), were synthesized and characterized by X-ray analysis and spectral measurements. The presence of intramolecular NH...S hydrogen bonds was established by the IR spectra. (199)Hg and (113)Cd nuclear magnetic resonance showed a stabilized four-thiolate coordinated structure and suggested the influence of the NH...S hydrogen bonds to ppi(Hg)-ppi(S) interactions. The NH stretching bands show that the NH...S hydrogen bonds in Cd and Hg complexes are stronger than those in the corresponding Zn complex. These results are supported by theoretical calculations. The experimental and theoretical results suggested that the NH...S hydrogen bond influences the efficient capture of toxic Cd and Hg ions by metallothioneins.