News and Related Reports

NCL supports new NIST nanoparticulate reference material

In late December 2007, the National Institute of Standards and Technology (NIST) released its first reference standards for nanoscale particles targeted for the biomedical research community. The new nanoparticulate reference materials (RMs) consist of colloidal gold nanoparticles with nominal diameters of 10, 30, and 60 nanometers (nm) in suspension. Production of these RMs was supported in part by the National Cancer Institute (NCI) Alliance for Nanotechnology in Cancer and the Nanotechnology Characterization Laboratory (NCL) at NCI-Frederick.

The new NIST RMs are intended for instrument calibration, method qualification, and in vitro experiments used to characterize nanomaterials. These RMs have been characterized extensively by NIST scientists. Each RM aliquot comes with reference and informational values for a number of properties, including particle size determined by multiple methods, pH, conductivity, gold and citrate concentrations, particle surface charge (zeta potential), optical absorption spectra, and verification of sterility.

Nanotechnology shows great promise for drug delivery and medical diagnostics, but nanoparticles represent a wide variety of material categories, each with unique physicochemical and biological properties. These properties are often highly dependent on synthesis, sample preparation, and environmental conditions, and variations in these conditions are a major cause of inconsistency in both research and preclinical results. Additionally, there is considerable apprehension surrounding risks associated with this new technology. In particular, the toxicity of nanoparticles is a matter of extensive debate, with a wide range of findings in the scientific literature. For example, some initial studies reported that certain nanoparticles were significantly toxic. This toxicity was later found to be due to a synthesis byproduct that in principle could be removed by purification; the nanoparticles themselves were not toxic. An RM (or properly characterized material in the initial study) would have preempted the erroneous conclusions.

Thus, standard RMs allow comparison of the physicochemical and biological properties of newly created nanomaterials to those of well-characterized RMs and allow comparison of results from different laboratories. Without the use of RMs and appropriate standardized tests, the complexity of experimental design (cell type/species/strain, treatment conditions, environmental conditions) often precludes meaningful comparisons. The new NIST RMs are three of five nanoparticle samples used in an American Society for Testing and Materials-sponsored interlaboratory study, which began in January 2008.

The RMs (numbered RM8011, RM8012, and RM8013 for 10-, 30-, and 60-nm diameter particles, respectively) are available for purchase (to recover production and distribution costs) on the NIST Web site:

• RM 8011, Gold Nanoparticles, Nominal 10-nm Diameter
• RM 8012, Gold Nanoparticles, Nominal 30-nm Diameter
• RM 8013, Gold Nanoparticles, Nominal 60-nm Diameter

NIST Standard Reference Materials (SRMs) and Reference Materials (RMs).