It is widely recognized that physico-chemical characterization of engineered nanomaterials (ENMs) is essential to nanotechnology–enabled product (NEP) development and commercialization, and to evaluate toxicity of and exposure to ENMs and NEPs. There are numerous lists of key physico-chemical properties of ENMs; see, for example, pp. 12-14 of the 2011 National Nanotechnology Initiative Environmental, Health, and Safety Research Strategy.
The development of a physico-chemical measurement protocol is challenging for a number of reasons. Measurements must be conducted in relevant media, including complex environmental and biological matrices; however, the media capabilities of many commercial instruments are limited to air, vacuum, and/or simple aqueous solutions. Different measurement techniques will yield different values for a given property because each technique measures different aspects of that property. This is well-illustrated by NIST reference material 8012, Gold Nanoparticles, Nominal 30 nm Diameter, for which particle diameters determined by six different techniques ranged from (24.9 ± 1.1) nm to (28.6±0.9) nm. Transformations such as agglomeration and dissolution may occur during a measurement, complicating interpretation of the results.
Following is a list of physico-chemical measurement protocols:
NIST SP 1200-25: Protocol for Collecting and Quantifying Release from Weathered Epoxy-Nanosilica Coatings: Using a Simulated Rain Method and Inductively Coupled Plasma-Optical Emission Spectrometry
NIST SP 1200-26: Assessing the Chemical and Colloidal Stability of Functionalized Gold Nanoparticles
Numerous protocols were developed in conjunction with the Nanotechnology Characterization Laboratory, National Cancer Institute, National Institutes of Health. Some of these protocols will form the basis for future NIST Special Publications to be posted.