Technical Highlight - March 2010
Short description: Nanowire transistors act as high-throughput biosensors for detecting protein interactions.
One of the challenges of structural genomics is to see structural data within the context of the cell. For this, protein-interaction information is needed. A recently developed reusable biosensor looks likely to herald a new era of high-throughput interaction mapping.
Usually detecting protein–protein interactions is difficult. Two commonly used techniques — fluorescence resonance energy transfer (FRET) and coimmunoprecipitation — require large protein sample sizes and can be very time-consuming.
The alternative, surface plasmon resonance (SPR), needs less protein, no labelling and provides information on the rates of association and dissociation of biomolecules.
Recently, much attention has been paid to nanowire/nanotube field-effect transistors, because their performances are comparable to those of SPR. And some studies have demonstrated that the sensitivity of a silicon nanowire field-effect transistor for DNA detection is 100 times higher than that of SPR.
Yit-Tsong Chen and colleagues used a silicon nanowire field-effect transistor as a biosensor to investigate protein-protein interactions.
They added the calcium-binding protein calmodulin to the transistor, then looked at the change in conductance through the transistor when calcium and the calmodulin-binding protein troponin I were present. The threshold of calcium needed for the interaction was found to be 1 micromolar.
When they tested their set-up on the calcium channel N-type VGCC expressed in the cell extract of cultured 293T cells they found it still recognized by the calmodulin-modified nanowire.
Silicon nanowire field-effect transistor is an ideal biosensor because it is highly selective, it's sensitive, it can give a real-time response and antibody labels are not needed. In addition, it is reusable and can detect various protein–protein interactions from either purified protein or crude cell extracts.
It shows great potential as a high-throughput detector to identify interacting proteins in physiologically relevant environments.
Label-free detection of protein-protein interactions using a calmodulin-modified nanowire transistor.
Proc. Natl Acad. Sci USA 107, 1047-1052 (2010).