At the nanoscale chemistry is different and nanoparticles don’t behave like normal particles. Nanoparticles tend to be more chemically reactive than ordinary-sized particles of the same material making it hard to predict how they will act under different conditions and raising serious questions about the use of such particles – particularly inside the human body. Researchers have now developed a method for predicting the ways nanoparticles will interact with biological systems – including the human body – that could improve human and environmental safety in the handling on nanomaterials, and have applications for drug delivery.

North Carolina State University researchers Dr. Jim Riviere, Dr. Nancy Monteiro-Riviere and Dr. Xin-Rui Xia wanted to create a method for the biological characterization of nanoparticles – a screening tool that would allow other scientists to see how various nanoparticles might react when inside the body.

"We wanted to find a good, biologically relevant way to determine how nanomaterials react with cells," Riviere says. "When a nanomaterial enters the human body, it immediately binds to various proteins and amino acids. The molecules a particle binds with will determine where it will go."

This binding process also affects the particle's behavior inside the body. According to Monteiro-Riviere, the amino acids and proteins that coat a nanoparticle change its shape and surface properties, potentially enhancing or reducing characteristics like toxicity or, in medical applications, the particle's ability to deliver drugs to targeted cells.

To create their screening tool, the team utilized a series of chemicals to probe the surfaces of various nanoparticles, using techniques previously developed by Xia. A nanoparticle's size and surface characteristics determine the kinds of materials with which it will bond. Once the size and surface characteristics are known, the researchers can then create "fingerprints" that identify the ways that a particular particle will interact with biological molecules. These fingerprints allow them to predict how that nanoparticle might behave once inside the body.

"This information will allow us to predict where a particular nanomaterial will end up in the human body, and whether or not it will be taken up by certain cells," Riviere adds. "That in turn will give us a better idea of which nanoparticles may be useful for drug delivery, and which ones may be hazardous to humans or the environment."

With nanoparticles becoming increasingly common in all manner of materials, the work by the NC State researchers will hopefully help us avoid previously unforeseen and potentially devastating problems in the future.

The results of their study will appear in the August 23 online edition of Nature Nanotechnology.