Role of the amine and phosphine groups in oleylamine and trioctylphosphine in the synthesis of copper chalcogenide nanoparticles.

The effect of the functional groups of capping agents was investigated in the synthesis of copper selenide, copper sulphide and copper oxide nanoparticles using oleylamine (OLA) and trioctylphosphine (TOP). These capping molecules have demonstrated their ability to act as reducing agents, surfactants, solvents and enhancement of colloidal stabilization. They also offer electron donating abilities from the two group 5A elements, P and N. Nitrogen atom in an amine group possess stronger surface interactions and higher basicity than P atom in the phosphines. Copper chalcogenide nanoparticles were prepared using Hot-injection method and characterized using UV/Vis spectroscopy, TEM and XRD. The optical and structural properties of the yielded nanoparticles showed dependence on the type of capping interactions from the two agents. Nanoparticles synthesized using TOP produced two phases whereas a single phase was observed from OLA as confirmed by XRD. Although TOP and OLA exhibit similar features, but their affinity to metals differs resulting to significant different morphology and crystallinity of the produced nanoparticles. Amine group has higher affinity for protons than phosphine due to the lone pair of electrons it possesses which it easily donates to H+ compared to phosphine. The high proton affinity of oleylamine makes it interact faster than trioctylphosphine. OLA in overall produced larger particle sizes compared to TOP but generated a wider variety of shapes.

Synthesis, characterization and cytotoxicity of alanine-capped CuS nanoparticles using human cervical carcinoma HeLa cells.

Nanoparticles in biomedicine, requires a detailed understanding of the biocompatibility and toxicity of nanoparticles in human beings. The biological and physicochemical properties of nanoparticles bring new challenges with regards to management of potential adverse health effects following exposure. This work reports on the synthetic optimization of condition of copper sulphide nanoparticles and the cytotoxicity effects of the particles on the human cervical carcinoma cells. CuS nanoparticles synthesized produced a single and different XRD phases in basic and acidic media, respectively. Temperature variation influenced both the optical and morphological properties of the nanoparticles. The highest temperature (95 °C) resulted in particles with superior properties compared to the ones synthesized at lower temperatures. The cytotoxicity tests showed that the particles were nontoxic at low to moderate concentrations and only induced toxicity at higher concentrations. Particles synthesized at 95 °C were less toxic compared to other nanoparticles as determined by their CC50 values.

The study on the time dependency and the stability of cobalt sulphide nanoparticles under an electron beam.

We report on the synthesis and characterization of cobalt sulphide (CoS(1.097)) nanoparticles using a cobalt tetramethylthiuram disulphide complex as a single-source precursor. To study the effect of reaction time on the optical and morphological properties of the synthesized nanoparticles, aliquots from the reaction mixture were collected after different intervals of time. The absorption spectra were time dependent, with the 5 min aliquot being the most blue-shifted from bulk and the subsequent samples showing a slight shift towards the bulk. Photoluminescence of the nanoparticles showed a single emission wavelength of 341 nm, however, the peak intensity of nanoparticles decreased with reaction time. The morphology of the synthesized nanoparticles was investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM). Results from the SEM images showed the formation of spherical CoS(1.097) nanoparticles and the size of the observed nanoparticles increase with increasing reaction time. However, the TEM results showed a change in the morphology of the particles from spherical to wire-like. The change in morphology was thought to be induced by the high voltage electron beam and this was supported by the HR-TEM and optical results.

The effect of precursor concentration, temperature and capping group on the morphology of CdS nanoparticles.

A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The CdS nanoparticles were synthesized under various conditions and were characterized using UV/Vis, PL, XRD and TEM. The influence of the precursor concentration, temperature and capping environment as factors affecting the morphology and size of the nanoparticles was investigated. We observed that with an increase in precursor concentration, there was an increase in particle sizes and the morphology evolved from spherical to rod-shaped nanoparticles. An increase in temperature showed only evidence of increasing the particle sizes whilst the capping environment had a profound influence on the morphology of the nanoparticles. The work reported in this paper demonstrate that factors such as temperature, concentration and the capping group affects the growth of nanoparticles either in size and/or shape.