A microscopic image of gold nanoparticles. / Photo by: Roberto Lo Savio via 123RF


Biocompatible gold nanoparticles have been widely used in many applications, such as in biomedicine. Meanwhile, surfactants have been considered safe for producing commercial products. However, a recent study found that if the substances are combined, they are toxic to embryos of zebrafishes.

Surfactants are known compounds with properties that lower the surface tension between a gas and a liquid, between a liquid and a solid or between two liquids. With these, many industries utilize the compounds to produce detergents, emulsifiers, foaming agents, and wetting agents.

But in a study conducted by chemists and toxicologists at the University of Oregon and Oregon State University, a poisonous multiplicative or synergistic effect occurs while testing nanomaterials. The effect has been found in the combination of the two substances.

The experts manually delivered the nanoparticles to zebrafishes using pipettes, a laboratory instrument used in biology, chemistry, and medicine to transport a volume of liquid. The nanoparticles on its own posed no threat to the health of the marine animals, but when they injected a small amount of surfactant to control the size of the particles, it led to an 88-percent mortality rate of the zebrafish embryos that have been exposed to the gold particles, compared to the three percent toxicity of the nanoparticles alone.

"Our new study gives us a wakeup call. This isn't the first time that people have seen mixture toxicity, but it does remind us that two safe things mixed together doesn't mean that the mixture is safe," said Jim Hutchinson, a co-author of the study from the department of chemistry and biochemistry at UO.

They found the synergistic toxicity from the analysis made on a diffusion-ordered spectroscopy, which showed how particles diffuse or move in a particular solution. The experts are unsure if the same problem will occur in human embryos.