Investigation of cobalt nanoparticle induced toxicity and hypoxic response in Caenorhabditis elegans

Abstract

The use of nanoparticles, defined as particles smaller than 100 nm, is experiencing a notable surge worldwide. Among these are cobalt nanoparticles (CoNPs) which have applications across various fields including electronics, biotechnology, medicine, and aerospace engineering. With their widespread use, organisms face an elevated risk of exposure to CoNPs. Despite their prevalence, the understanding of the toxicity potential and underlying mechanisms of CoNPs is limited. This study addresses this knowledge gap by investigating the toxic effects of CoNPs compared to those of cobalt chloride (CoCl2) employing the model organism C. elegans.

The CoNPs were characterized with respect to size and surface charge. Transmission electron microscopy (TEM) micrographs revealed a high degree of NP aggregation, with individual particles in the NP suspension measuring smaller than 10 nm. Dynamic light scattering (DLS) determined an NP hydrodynamic diameter of 155 ± 0.8 mm with a polydispersity index of 0.362 ± 0.011. The zeta potential of CoNPs was -16.2 ± 0.3 mV, indicating low suspension stability.

Chronic toxicity tests revealed that CoNPs cause less potent toxicity on growth and reproduction compared to CoCl2. It was demonstrated that CoNP toxicity could to a significant extent be ascribed to ion leaching Additionally, observations of the effects of CoNPs on reproduction suggest there are particle-specific mechanisms that contribute to the toxicity of CoNPs.

CoNPs were shown to induce a hypoxic response in C. elegans following acute exposure. The observations revealed that the assessed hypoxic response, expression of nhr-57, is highly localized to embryos.

Additionally, vulva abnormalities were observed across all exposure concentrations in nematodes subject to acute exposure to CoCl2. Nematodes exposed to CoNPs did not display similar vulva abnormalities.

This project has confirmed the potential toxic effects of CoNPs and their potential risk to the environment. The results indicate unidentified particle-specific mechanisms contribute to the toxicity of CoNPs. Further studies should focus on understanding the particle-specific mechanisms that cause effects on growth, reproduction, and induction of hypoxic response following CoNP exposure.