Advanced Materials Letters

Present article describes one-pot, two-stage, in-situ controlled atmosphere method for synthesis of core-shell quantum dots (QDs) comprising of ZnSe, CdS and CdSe combinations e.g. CdS/CdSe, ZnSe/CdS and ZnSe/CdSe. The present method emphasizes on creating an effective surface passivation of core as well as formation of passivated shell via utilization of cyclo-octeno-1, 2, 3-selenadiazole as a precursor for selenium. Synthesis of ZnSe/CdS was compared by using two different selenium precursors viz cyclo-octeno-1, 2, 3-selenadiazole (C8-SDZ) and cyclo-hexeno-1, 2, 3-selenadiazole (C6-SDZ). Optical properties (UV-Visible and PL spectroscopy) indicate narrow peak width with band gap ranging in between 2.30 eV to 2.56 eV. The XRD analysis revealed the formation of respective core-shell QDs with zinc blende crystal structure. TEM analysis showed formation of spherical shaped core-shell QDs with lattice spacing of 0.35 nm due to presence of (111) crystal plane.  By virtue of the excellent optical properties of ZnSe/CdS core shell QDs, this was subjected to bio-evaluation in terms of cytotoxicity and therapeutic efficacy. Approximately, 65% bio-toxicity was observed in MCF-7 with negligible haemolysis by ZnSe/CdS QDs. About, 34% tumour regression was shown by ZnSe/CdS QDs, as against 93% observed by Mitomycin C (Positive control) with respect to placebo (PBS).

Enhanced understanding of diseases at the molecular level has made a paradigm shift towards identifying new biological indicators especially in nanomaterials. It is important to make Quantum Dots (QDs) more than just passive bio-probes/labels for biological imaging and cellular studies as they offers “smart” multifunctional nano-platforms. For any biomedical, optoelectronic device application, evaluation of cytotoxicity coupled with cellular uptake and internalization of QDs are imperative. This paper describes the cytotoxic studies of hydrophilic and hydrophobic QDs, capped with polyvinyl pyrrolidone (PVP) and oleic acid in human breast adenocarcinoma MCF-7, Human Embryonic Kidney (HEK-293) and Ehrlich Ascites Carcinoma (EAC) cancer cells that indicated a concentration and time dependent response in a 48 hr assay. The enhanced fluorescence emitted from the cytoplasm confirmed that the QDs were efficiently internalized by the cells. 35% cytotoxicity was observed by core-shell ZnSe/CdSe QDs in HEK-293 cells, while the hydrophobic CdSe exhibited less cytotoxicity in both MCF-7 and EAC cell lines in 48 hrs. Increased LDH leakage and decreased MTT reduction was observed in a time dependent manner. The decrease rate of LDH was found in PVP-CdSe relative to the value obtained from untreated/control cells post 24 hr. The oleic acid coating renders the core-shell CdSe QDs to be more hydrophobic thus making them less toxic due to possibly weak interaction with the cells, and low ionization of cadmium. Based on our experimental observation the sequence of cytotoxicity of tested QDs was hydrophilic greater than hydrophobic in all three cell lines. 

Gold nanoparticles (AuNPs) are potential candidates for targeted drug delivery, imaging and early detection of cancer cells due to their ability to bind with cancer cells. To ensure their safe use in various possible biomedical applications, it is essential to examine the cytotoxicity and biocompatibility of AuNPs before use. The present work aims to study the cytotoxicity of glucose capped gold nanoparticles (Glu-AuNPs) in several cell lines (HeLa, A549, Jurkat, L929 and HUVEC). The synthesized Glu-AuNPs, using β-D glucose as reducing as well as capping agent, were characterized by SPR and TEM/EDAX analysis. Internalization of Glu-AuNPs in cells was studied by cross sectional TEM imaging. The cytotoxicity of Glu-AuNPs was evaluated by means of colony formation and MTT assays. The present study reveals that Glu-AuNPs (7±2 nm diameter) are non-toxic to the above-mentioned five cell lines, which are cancerous cell lines except HUVEC. Therefore Glu-AuNPs (around 7nm) can be explored for various bio-medical applications and can be of importance for therapeutic applications as evident from enhancement in radiosensitization from our previous work.

The aim of this study is to compare the cyto and genotoxic effects of TiO2 and TiSiO4 nanoparticles on human embryonic kidney cells (HEK-293). The cell viability, induction of oxidative stress, and cell apoptosis induction were assessed after 48 h of cell exposure to TiO2 and TiSiO4 nanoparticles separately. Our results showed that nanoparticles induce the generation of reactive oxygen species (ROS) followed by significant depletion of glutathione levels and increased lipid peroxidation. The cells exhibited apoptotic morphology like condensed chromatin and nuclear fragmentation after 48 h of treatment. Both the particles induce oxidative stress and DNA damage in a dose dependent manner. Oxidative stress is the underlying mechanism by which nanoparticle causes DNA damage and apoptosis. This study further indicate that TiO2 nanoparticles has more toxic effects than TiSiO4 nanoparticles on HEK cells, which demonstrate that larger size may be responsible for retardant of cellular uptake. This might be reducing the toxicity of TiSiO4 nanoparticles.