In Vivo Toxicity of Silver Nanoparticles in the Marine Rotifer Brachionus plicatilis: Integrating Metabolic Activity and Generation of Reactive Oxygen Species

Abstract

Silver nanoparticles (AgNPs) have been widely employed across various industrial, medical,and consumer applications due to their unique biocidal properties, raising concernsabout their potential impact on biota such as planktonic microinvertebrates, which, inturn, necessitates the rapid development of in vivo nanotoxicological bioassays. Here, wecombined physicochemical particle characterization with organismal responses to assessthe in vivo nanotoxicity of chemically synthesized AgNPs in the marine rotifer Brachionusplicatilis (Ploimida, Brachionidae). Particles were fully characterized by dynamic light scattering(hydrodynamic diameter and polydispersity), zeta potential, transmission electronmicroscopy, and UV–Vis spectroscopy in both stock and exposure media. Rotifers wereexposed to low AgNP concentrations: 0 (control), 2, and 20 μg/L. After a 24 h exposure,in vivo metabolic activity was quantified via resazurin reduction. Reactive oxygen species(ROS) were measured using the fluorescent probe H2DCF-DA (excitation 485 nm, emission530 nm), quantified by fluorimeter and fluorescence microscopy. Results showed thatAgNP exposure decreased ROS levels at both tested concentrations, a finding that can belinked to reduced aerobic metabolic activity in the rotifers. These findings demonstratethat B. plicatilis provides a rapid and sensitive in vivo toxicity assessment that integratesmetabolic and ROS endpoints for nano-ecotoxicity evaluations.