|
False color scanning electron micrograph
(250,000 times magnification) showing the gold nanoparticles
created by NIST and the National Cancer Institute's Nanotechnology
Characterization Laboratory for use as reference standards in
biomedical research laboratories.
Image by Andras Vladar, NIST
|
Nanosized particles are the subject of a great
deal of biological research, in part because of concerns that in
addition to having unique physical properties due to their size, they
also may have unique biological properties. On the negative side,
nanoparticles may have special toxicity issues. On the positive side,
they also are being studied as vehicles for targeted drug delivery
that have the potential to revolutionize cancer treatments. Research
in the field has suffered from a lack of reliable nanoscale
measurement standards, both to ensure consistency of data from one lab
to the next and to verify the performance of measurement instruments
and analytic techniques.
The new NIST reference materials are citrate-stabilized nanosized gold
particles in a colloidal suspension in water. They have been
extensively analyzed by NIST scientists to assess particle size and
size distribution by multiple techniques for dry-deposited, aerosol
and liquid-borne forms of the material. Dimensions were measured using
six independent methods�including atomic force microscopy (AFM),
transmission electron microscopy (TEM), scanning electron microscopy (SEM),
differential mobility analysis (DMA), dynamic light scattering (DLS),
and small-angle X-ray scattering (SAXS). At the nanoscale in
particular, different measurement techniques can and will produce
different types of values for the same particles.
In addition to average size and size distributions, the new materials
have been chemically analyzed for the concentrations of gold, chloride
ion, sodium and citrate, as well as pH, electrical conductivity, and
zeta potential (a measure of the stability of the colloidal solution).
They have been sterilized with gamma radiation and tested for
sterility and endotoxins. Details of the measurement procedures and
data are included in a report of investigation accompanying each
sample.
NCL examines candidate nanotech cancer drugs developed by biotech
firms and academic labs. NCL and the NCI�s Alliance for Nanotechnology
in Cancer sponsored the NIST work.
Additional technical and ordering information for the new NIST
nanoparticle reference materials is available at:
|
