Does the environment hate vampires?

Silver nanoparticles
Nanoparticles of silver

Silver nanoparticles are increasingly being found in the environment. Because they have a variety of useful properties, especially as antibacterial and antifungal agents, silver nanoparticles are enjoying a surge in popularity in environmental science laboratories as well as a variety of industrial and consumer products.

The growing use of silver nanoparticles has sparked concerns about what happens to them once they are released into the environment. New research, however, indicates that man isn’t the only source for nanoparticles of silver. Nature, it seems, is creating more of them too.

A team of researchers from Florida Institute of Technology (FIT), the State University of New York (SUNY), Buffalo and the National Institute of Standards and Technology (NIST) reports that, given a source of silver ions, naturally occurring humic acid will synthesize silver nanoparticles. Humic acid is a principal component of soil and humic or soil-like substances. It is a complex mixture of multiple organic acids formed naturally by the microbial breakdown of dead plant matter. Although the exact composition varies from place to place, humic acid is ubiquitous in the environment.

“This caught us by surprise because a lot of our work is focused on how silver nanoparticles my dissolve when they’re released into the environment and release silver ions,” says Robert MacCuspie at NIST. “[But] this creates the idea that there may be some sort of natural cycle returning some of the ions to nanoparticles.”

What the team discovered was that when silver ions were mixed with humic acids from river water or sediments detectable silver nanoparticles would form at room temperature in as little as two to four days. If there is good news for vampires about this discovery it is that the humic acid appears to stabilize the nanoparticles by coating them and preventing the nanoparticles from clumping together and forming larger masses of silver.

Is this a sign that the environment is turning against vampires and other creatures suffering from severe “silver allergies”? Could this natural cycle possibly explain why such a top predator is historically found in such limited numbers? Either way, further research is needed.

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