With so much research being done on the affects of nanoparticles in biological studies, the field has been in need of marker or set of standards to measure against. NIST, together with the National Cancer Institute's Nanotechnology Characterization Laboratory, has come up with just such a standard in the form of three different sizes of gold nanoparticles.

While things like nanoparticle cancer-killing bombs might sound like a boon to science and medicine, some experts worry that the toxicity of nanoparticles could cause severe problems in the future. The problem has been a lack of standards for nanoparticles, such as the measurement of toxicity, as well as a way to ensure that instruments and analytic techniques are accurate from one study or lab to the next.

NIST's work towards a standard has materialized in the form of three sizes of citrate-stabilized gold nanoparticles. The 10nm, 30nm, and 60nm particles can be purchased in a colloidal suspension in water in sets of 5mL ampoules for the small sum of $225. The particles' size and distribution have been extensively tested with multiple techniques for dry-deposited, aerosol and liquid-borne forms.

Particle size was measured using six different methods including atomic force microscopy, transmission electron microscopy, scanning electron microscopy, differential mobility analysis, dynamic light scattering and small-angle X-ray scattering

Along with the fundamental tests for nominal dimensions, tests were performed to measure toxicity and chemical composition. The particles were analyzed for concentrations of gold, chloride ion, sodium and citrate along with pH, electrical conductivity and zeta potential, or the measure of stability in a colloidal solution.

Each sample is also tested for sterility and endotoxins and a report of measurements accompanies them to their destination.