Size-dependent impacts of silver nanoparticles on the lifespan, fertility, growth, and locomotion of Caenorhabditis elegans

Abstract

The increased bioavailability of nanoparticles engineered for good dispersion in water may have biological and environmental impacts. To examine this issue, the authors assessed the biological effects in nematodes as they relate to exposure to silver nanoparticles (AgNPs) of different sizes at low (1 mg/L Ag), medium (10 mg/L Ag), and high concentrations (100 mg/L Ag). Over multiple generations, the authors found that the smallest particle, at 2 nm, had a notable impact on nematode fertility. In contrast, the largest particle, at 10 nm, significantly reduced the lifespan of parent nematodes (P0 ) by 28.8% and over the span of 3 generations (F1 -F3). In addition, a computer vision system automatically measured the adverse effects in body length and motility, which were not size-dependent.

Keywords: Caenorhabditis elegans; Escherichia coli; Multigenerational; Silver nanoparticle; Toxicity.

Figure 1

Silver nanoparticle (AgNP) characterization (A) of 2-nm, (B) 5-nm, and (C) 10-nm silver particles. The core diameter was determined from transmission electron microscopy (TEM) images coated with thiolated methoxy-polyethylene glycol (mPEG-SH; nonaggregated, 0.12 mV). From this, the surface area in nm² was calculated. The addition of mPEG-SH via a ligand exchange was measured by dynamic light scattering (DLS) in the organic and aqueous (aq) solutions.

Figure 2

The 24-h dose-dependent viability curve for Escherichia coli exposed to 2 silver ion sources, AgClO4 and AgNO3. The median lethal dose for AgClO4 was 0.02 mg Ag/L, and that for AgNO3 was 0.06 mg Ag/L.

Figure 3

The uptake profile based on body burden of internalized silver for each Ag nanoparticle (AgNP) using inductively coupled plasma–mass spectrometry. The exposure concentration was [Ag] = 100 mg/L. Data shown are mean ± standard error (n = 4).

Figure 4

Lifespan measurement for multiple generations at different concentrations for each treatment of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter Ag nanoparticles (AgNPs). Adverse effects from exposure to AgNPs were size-dependent. P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 5

Brood size significantly decreases over multiple generations after exposure to Ag nanoparticles (AgNPs) of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter. Size-dependent toxicity is evident at higher exposure concentrations. P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 6

Length in nematodes was measured in the present multigeneration study using a worm tracker. Quantitative analysis showed significant changes in length and development, but no size dependence after exposure to (A) 2-nm, (B), 5-nm, and (C) 10-nm diameter Ag nanoparticles (AgNPs) was immediately noted. P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 7

Flex measurements in nematodes quantifying the number of times the body bends. After exposure to Ag nanoparticles (AgNPs) of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter for multiple generations, an adverse effect was seen in parent (P₀) nematodes before acclimation. P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 8

Amplitude measurement of nematode sinusoidal movement after exposure to different Ag nanoparticle (AgNP) treatments of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter AgNP. P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 9

Wavelength measurement of nematode sinusoidal movement at each generation and after treatment of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter Ag nanoparticles (AgNPs). [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]

Figure 10

The velocity of nematodes changed significantly after exposure to treatment of (A) 2-nm, (B) 5-nm, and (C) 10-nm diameter Ag nanoparticles (AgNPs). P₀ = parent generation; F₁ = first-generation progeny; F₂ = second-generation progeny; F₃ = third-generation progeny. [Color figure can be viewed in the online issue which is available at wileyonlinelibrary.com]