Fuel mediated solution combustion synthesis of ZnO supported gold clusters and nanoparticles and their catalytic activity and in vitro cytotoxicity

Abstract

Nanocomposites of gold nanoparticles and semiconductor ZnO with wurtzite structure, made by solution combustion synthesis (SCS), as a function of the Zn/fuel ratio with polyethylene glycol (PEG) as fuel exhibit the presence of both nanoparticles and clusters. Atomic gold clusters present on the surface of ZnO nanorods which can be identified by XPS and SEM are easily monitored and characterized by positive ion MALDI experiments as mostly odd numbered clusters, Au3 to Au11 in decreasing amounts. Low concentrations of the fuel produce AuClO and nanoparticles (NPs), with no clusters. Au-ZnO nanocomposites at all [Au] exhibit single blue shifted plasmon absorption and corresponding photoluminescence (PL). Increasing particle size prefers surface plasmon resonance (SPR) scattering of metal that could lead to PL enhancement; however, available ZnO surface in the Au-ZnO composite becomes more important than the particle size of the composite with higher [Au]. The catalytic activity of these Au-ZnO nanocomposites tested on 4-nitrophenol clearly revealed the presence of an intermediate with both NPs and clusters playing different roles. An in vitro study of cytotoxicity on MCF-7 cell lines revealed that these gold nanostructures have turned out to be powerful nanoagents for destruction of cancer cells even with small amounts of gold particles/clusters. The nanorods of ZnO, known to be nontoxic to normal cells, play a lesser role in the anticancer activity of these Au-ZnO nanocomposites.

Inclusion of supported gold nanoparticles into their semiconductor support

“…This is in agreement with Chanu et al who integrated Au clusters into ZnO. 32 In similar, the preservation of the plasmon resonance for the integrated plasmonic silver nanoparticles into TiO 2 and the related photocatalytic activity was demonstrated by Awazu et al 33 The Au NPs integrated into ZnO SMS also possess plasmonic properties, as shown in Fig. 3(d).…”

“…The diffuse reflection spectra show that increased extinction at wavelengths above 600 nm results from light scattering 29 . 3 32 . That such spheres reflect light wavelengths in their size regime is confirmed here by scattering measurement of the dried particle powders.…”

Oxygen vacancies and intense luminescence in manganese loaded Zno microflowers for visible light water splitting

“…Such a kind of transformation during such an addition of metal ions has been rarely observed, for example during the addition of Ag and Au in our own earlier work. 10,11 The most interesting aspect comes from our current observation of H 2 generation from the Mn containing ZnO materials, which is a new one and we believe it is probably the first such report using Mn. Furthermore there seems to be a relationship between the presence of oxygen vacancies and the introduction of Mn.…”

Enhancement of antibacterial and anticancer properties of pure and REM doped ZnO nanoparticles synthesized using Gymnema sylvestre leaves extract

“…14a, b). Table 5 shows a comparison between our and earlier reported IC 50 values of ZnO NPs [42,[52][53][54][55][56][57][58]. Cell morphological changes were observed for light microscope with different concentrations 10, 50 and 100 μg/ml (Fig.…”