In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio)

Abstract

The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP-) coated silver nanoparticles (81 nm) was investigated. NaCl solution series of 100-800 mg L(-1) lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5-8) had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio) was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO(3)). The nanosilver and silver ion 48-hour median lethal concentration (LC(50)) values were 84 μg L(-1) and 25 μg L(-1), respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish.

Figure 1

(a) Representative TEM image of stock nanosilver suspension along with size statistics (insert). (b) PXRD pattern for the nanosilver powder with the indexed diffraction lines of silver.

Figure 2

Dynamic Light Scattering (DLS) size distributions for (a) the nanosilver stock preparation (red line) along with the pH 6.9 200 mg L⁻¹ NaCl solvent condition 5 min (black line), 1 hour (blue line), and 24 hours (green line). (b) The nanosilver mixed with head tank water directly (1 : 1) (black line), after 30 min (blue line), and 24 hours (green line). Data are presented as mean value ± SE.

Figure 3

Toxicity of 81 nm silver nanoparticles (a) and silver ions (b) after 48 hours exposure to adult male zebrafish (Danio rerio) in a static renewal experiment. Black circles (●) represent the mean survival in percent after exposure to a given concentration (n = 10). Solid lines indicate the calculated lethality using probit analysis after exposure to silver nanoparticles and silver ions, respectively. Dashed lines indicate the 95% confidence intervals.