Exposure of nano- and ultrafine Ni particles to synthetic biological solutions: predicting fate-related dissolution and accumulation

The growing production and use of nickel (Ni) nanopowders with low biopersistence makes dissolution and accumulation degree in a body an important parameters needed for the risk assessment of nanoparticles. We propose an experimental approach for rapid determination of the dissolution degree of nanoscale (77 nm) and ultrafine (275 nm) Ni particles in synthetic biological solutions. It has been shown that after 2 h of exposure to simulating saliva and lysosomal liquid the dissolution degree of nanoparticles can reach 30 and 60 wt.%, respectively. With decreasing of the particle’s size, they are characterized by increased solubility in saliva and the pulmonary tract; and the particles completely dissolve in 24 h. There was an attempt to predict the potential extent of accumulation of nickel compounds in the human body with particles entering the body by saliva or with breathing: with 3.8 times size decrease the probability of nickel accumulation in a body can rise in 3.5 times.

Considerable Variation of Antibacterial Activity of Cu Nanoparticles Suspensions Depending on the Storage Time, Dispersive Medium, and Particle Sizes

Suspensions of Cu nanoparticles are promising for creating the new class of alternative antimicrobial products. In this study we examined copper nanoparticles of various sizes obtained by the method of wire electric explosion: nanopowder average size 50 nm (Cu 50) and 100 nm (Cu 100). The paper presents the complex study of the influence of physicochemical properties such as particle size and concentration of the freshly prepared and 24-hour suspensions of Cu nanoparticles in distilled water and physiological solution upon their toxicity to bacteria E. coli M-17. Ionic solution of Cu²⁺ and sodium dichloroisocyanurate was used for comparison study. It has been shown that decrease in the nanoparticle size leads to changes in the correlation between toxicity and concentration as toxicity peaks are observed at low concentrations (0.0001⋯0.01 mg/L). It has been observed that antibacterial properties of Cu 50 nanoparticle suspensions are ceased after 24-hour storage, while for Cu 100 suspensions no correlation between antibacterial properties and storage time has been noted. Cu 100 nanoparticle suspensions at 10 mg/L concentration display higher toxicity at substituting physiological solution for water than Cu 50 suspensions. Dependence of the toxicity on the mean particle aggregates size in suspension was not revealed.