Synthesis of CuInS2 and CuInS2@ZnX (X = S, Se) nanoparticles for bioimaging of cancer cells using electrochemically generated S2- and Se2-

Abstract An electrochemical approach has been used for the aqueous synthesis of low-toxicity and eco-friendly copper indium sulfide (CuInS2) nanocrystals, and related core@shell systems (CuInS2@ZnX, where X = S2- and Se2-). The chalcogenide precursors (S2-, Se2-) were generated in electrochemical cavity cell, using a constant current electrolysis (i = 30 mA and Q = 11.5C), in the presence of metallic precursors (In3+, Cu+, Zn2+), room temperature and argon atmosphere. Firstly, In2S3 seeds were obtained in the intermediate compartment of the cell and converted to CuInS2 by thermoactivated diffusion (colloidal solution under reflux) of Cu+ ions into the In2S3 lattice. Cu+/In3+ ratios = 0.25 and 0.125 were tested for the production of CuInS2 stabilized by l -glutathione (GSH), and characterized by UV–vis and emission spectroscopy, XRD, HRTEM and zeta potential. CuInS2@ZnX nanoparticles were prepared by using the same electrochemical system, paired electrolysis and Zn sacrificial anode. Nanocrystals prepared under Cu+/In3+ = 0.125 reached 3.1% (CuInS2), 4.6% (CuInS2@ZnSe), and 9.6% (CuInS2@ZnS) quantum yields. The CuInS2@ZnX systems presented high cell viability (85%–94%) and internalization in cytosol region of HeLa cells, showing high potential for biological labeling.