Gold nanoparticles in biochemical assays


While most of the research on nanotechnology for medicine is still concentrated in the academic setting, gold nanoparticles are already being used as tags in biochemical assays on the market. Examples vary widely from the simple over the counter pregnancy test, to the highly sophisticated PCR-free genetic testing unit, Verigene by Nanosphere Inc.

For most of the biosensors on the market, the limit of detection does not arise because signals cannot be detected by the detector, but because the signal below the limit of detection, cannot be distinguished from the background signal. This background signal is composed of both the instrument “noise” and the biological “noise” arising from non-specific interactions. While the instrument parameters are usually easily measurable and known, the non-specific interactions from the biological molecules are much more complex and elusive.

Dark Field image of single gold nanoparticles


We have developed an instrument based on dark-field illumination and a CCD camera where single gold nanoparticles can be easily detected in a large field of view (270mm×165mm), without the need for scanning.

The sensitivity of this techniques and the possibility to follow a given area with time, will allow us to follow non-specific adsorption (in the binding step) and non-specific desorption (in the washing step) of DNA-coated and antibody-coated gold nanoparticles. We will determine the kinetic parameters of these two steps, for different surfaces, and different surface coating in order to get a better understanding of how to minimize non-specific adsorption.


If you are interested in this assigment, please contact:

Dr. Ron Gill

Phone: 053 – 489 3161