Scottish scientists were able to detect sub-femtomolar (10-12) concentrations of thrombin in human serum by using gold nanoparticles and lasers. This could eventually be used to detect blood clots and other disorders in-vivo by injecting patients with the gold nanoparticles, which bind to thrombin in the blood, and then using non-invasive laser sensors on the skin to assess concentration changes. In the near term, the scientists hope to use the technique to examine intracellular protein interactions without damaging the cell.
From an abstract in ChemComm:
We demonstrate a strategy for label-free protein detection through monitoring the Surface Enhanced Raman Spectrum of an aptamer probe attached to a gold nanoshell. Low limit of detection and minimal non-specific binding show potential for in vitro and in vivo assays.
Image: Gold nanoshells, shown in black, cluster in the cytoplasm of a fibroblast cell.
Press release from The University of Edinburgh: Tiny gold probes to help track disease…
Abstract in Chemical Communications: Probing biomolecular interactions using surface enhanced Raman spectroscopy: label-free protein detection using a G-quadruplex DNA aptamer
(hat tip: Technology Review)