The team made an exhaustive set of measurements so they could thoroughly describe their custom-made dendron-coated nanoparticles. "There aren't a lot of protocols around for characterizing these materialstheir physical and chemical properties, stability, et cetera," Hackley says, "so, one of the things that came out of the project is a basic series of measurement protocols that we can apply to any kind of gold-based nanoparticle."
Any single measurement technique, he says, is probably inadequate to describe a batch of nanoparticles, because it likely will be insensitive to some size ranges or confused by other factorsparticularly if the particles are in a biological fluid.
The new NIST/NCL paper provides the beginnings of a catalog of analysis techniques for getting a detailed lowdown on nanoparticles. These techniques include nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization mass spectrometry, dynamic light scattering, ultra-violet/visible spectroscopy and X-ray photoelectron spectroscopy. The dendron-coated nanoparticles also were tested for stability under "biologically relevant" conditions of temperature, acidity and some recognized forms of chemical attack that would take place in the bloodstream. In vitro biological tests are pending.
|Contact: Michael Baum|
National Institute of Standards and Technology (NIST)