Physical Characterization and Cellular Toxicity Studies of Commercial NiO Nanoparticles

Abstract

Nickel oxide (NiO) nanoparticles from several manufacturers with different reported sizes and surface coatings were characterized prior to assessing their cellular toxicity. The physical characterization of these particles revealed that sizes often varied from those reported by the supplier, and that particles were heavily agglomerated when dispersed in water, resulting in a smaller surface area and larger hydrodynamic diameter upon dispersion. Cytotoxicity testing of these materials showed differences between samples; however, correlation of these differences with the physical properties of the materials was not conclusive. Generally, particles with higher surface area and smaller hydrodynamic diameter were more cytotoxic. While all samples produced an increase in reactive oxygen species (ROS), there was no correlation between the magnitude of the increase in ROS and the difference in cytotoxicity between different materials.

Keywords: characterization; nickel oxide; oxidative stress; size; toxicity.

Figure 1

Representative TEM micrographs of NiO nanoparticles dispersed by sonication in water and deposited on TEM grids.

Figure 2

Representative ¹H NMR spectrum of PVP removed from the nanoparticle surface for Ni-05; note that the region between 4.1 and 5.6 ppm was removed for clarity and the signal due to internal standard being at 7.3 ppm. a and b denote different regions of the proton NMR spectrum and the positions of the polymer to which they correspond.

Figure 3

MTT toxicity data from Ni-01 and Ni-04 in both cell lines to show the contrast in toxicity profiles between both samples and cell lines that results in changes in their respective IC₅₀ values.