We developed a carbon nanotube biosensor platform that was deployed at the National Cancer Institute and successfully detected the HER2 oncogene in real cancer cells at clinically relevant levels. HER2 is a receptor protein that resides on the surface of certain cancer cells and is associated with higher aggressiveness in breast cancers. Overabundance of HER2 at the chromosomal, cell surface, and intermediate gene expression levels can all indicate a dangerous HER2 status.

At the present, testing for HER2 status requires labor-intensive laboratory procedures using expensive reagents. Cost remains the major barrier to widespread screening. We propose an integrated electronic testing platform based on direct label-free gene detection. The system would integrate the various labor-intensive processes that are usually performed by skilled laboratory technicians. The heart of the system is an array of carbon nanotube field-effect transistors that can detect unlabelled nucleic acids via their intrinsic electric charges.

We developed a scalable fabrication technique for carbon nanotube biosensor arrays, hardware and software for data acquisition and analysis, theoretical models for detection mechanism, and protocols for immobilization of peptide nucleic acid probes and hybridization of nucleic acids extracted from cells. We demonstrated detection of HER2 from real cell lines which express cancer genes, thereby lowering the technological barrier towards commercialization of a low-cost gene expression biosensor. The system is suitable for lab-on-a-chip integration, which could bring rapid, low-cost cancer diagnoses into the clinical setting.