title: CdS/ZnS nanocomposites: from mechanochemical synthesis to cytotoxicity issues.
abstract: CdS/ZnS nanocomposites have been prepared by a two-step solid-state mechanochemical synthesis. CdS has been prepared from cadmium acetate and sodium sulfide precursors in the first step. The obtained cubic CdS (hawleyite, JCPDS 00-010-0454) was then mixed in the second step with the cubic ZnS (sphalerite, JCPDS 00-005-0566) synthesized mechanochemically from the analogous precursors. The crystallite sizes of the new type CdS/ZnS nanocomposite, calculated based on the XRD data, were 3-4 nm for both phases. The synthesized nanoparticles have been further characterized by high-resolution transmission electron microscopy (HRTEM) and micro-photoluminescence (μPL) spectroscopy. The PL emission peaks in the PL spectra are attributed to the recombination of holes/electrons in the nanocomposites occurring in depth associated with Cd, Zn vacancies and S interstitials. Their photocatalytic activity was also measured. In the photocatalytic activity tests to decolorize Methyl Orange dye aqueous solution, the process is faster and its effectivity is higher when using CdS/ZnS nanocomposite, compared to single phase CdS. Very low cytotoxic activity (high viability) of the cancer cell lines (selected as models of living cells) has been evidenced for CdS/ZnS in comparison with CdS alone. This fact is in a close relationship with Cd(II) ions dissolution tested in a physiological solution. The concentration of cadmium dissolved from CdS/ZnS nanocomposites with variable Cd:Zn ratio was 2.5-5.0 μg.mL(-1), whereas the concentration for pure CdS was much higher - 53 μg.ml(-1). The presence of ZnS in the nanocrystalline composite strongly reduced the release of cadmium into the physiological solution, which simulated the environment in the human body. The obtained CdS/ZnS quantum dots can serve as labeling media and co-agents in future anti-cancer drugs, because of their potential in theranostic applications.
authors.affiliation: Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice, Slovakia.
authors.forename: Peter
authors.initials: P
authors.lastname: Baláž
authors.affiliation: Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice, Slovakia.
authors.forename: Matej
authors.initials: M
authors.lastname: Baláž
authors.affiliation: Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice, Slovakia. Electronic address: dutkova@saske.sk.
authors.forename: Erika
authors.initials: E
authors.lastname: Dutková
authors.affiliation: Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice, Slovakia.
authors.forename: Anna
authors.initials: A
authors.lastname: Zorkovská
authors.affiliation: Institute of Electronics and Photonics, Slovak University of Technology and International Laser Centre, 81219 Bratislava, Slovakia.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Kováč
authors.affiliation: Institute of Electronics and Photonics, Slovak University of Technology and International Laser Centre, 81219 Bratislava, Slovakia.
authors.forename: Pavol
authors.initials: P
authors.lastname: Hronec
authors.affiliation: Institute of Electronics and Photonics, Slovak University of Technology and International Laser Centre, 81219 Bratislava, Slovakia.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Kováč
authors.affiliation: STU Centre for Nanodiagnostics, Slovak University of Technology, Vazovova 5, 812 43 Bratislava, Slovakia.
authors.forename: Mária
authors.initials: M
authors.lastname: Čaplovičová
authors.affiliation: Faculty of Medicine, P. J. Šafárik University, 04011 Košice, Slovakia.
authors.forename: Ján
authors.initials: J
authors.lastname: Mojžiš
authors.affiliation: Faculty of Medicine, P. J. Šafárik University, 04011 Košice, Slovakia.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Mojžišová
authors.affiliation: Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eliyas
authors.affiliation: Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
authors.forename: Nina G
authors.initials: NG
authors.lastname: Kostova
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D053761:Nanocomposites / Q000737:chemistry* / Q000633:toxicity; D013059:Spectrum Analysis, Raman; D013440:Sulfides / Q000737:chemistry; D013499:Surface Properties; D018675:Toxicity Tests; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; C031238:zinc sulfide
keywords: Cadmium; Cancer; Cytotoxicity; Mechanochemistry; Nanocomposite; Sulfide; Zinc