Polymer nanowires detect cancer biomarker

Investigators at the University of California, Riverside, have developed a simple and cost-effective method of building conducting polymer nanowires that can detect a wide range of levels of a cancer biomarker. This work, which was published in the journal Analytical Chemistry, could serve as a model for portable cancer detection equipment suitable for use in a doctor's office.

Ashok Mulchandani, Ph.D., led the research team that developed this new device. At its heart lies polypyrrole nanowires connected to a pair of gold electrodes spaced a mere 3 microns apart. The researchers use an applied electric field to move individual nanowires into proper alignment on the gold electrodes. They then coat the nanowires with a material known as EDC that can serve as an attachment point for antibodies and other molecules that bind to specific cancer biomarkers. In the work reported in their recent paper, the investigators attached an antibody that binds to the cancer biomarker CA 125.

When solutions with known concentrations of CA 125 were applied to the biosensor, the device accurately measured concentrations as low as 1 "enzymatic unit" per milliliter (U/mL) of solution to as high as 1,000 U/mL. The maximal normal blood level of CA 125 is considered to be 35 U/mL. The researchers obtained identical results when they tested human blood plasma for CA 125 levels.

The researchers note that their next step will be to create a device capable of measuring a panel of disease markers simultaneously. They also plan to incorporate their biosensor into a microfluidic device that would be suitable for use in a portable disease detection system.

This work is detailed in the paper "Single conducting polymer nanowire chemiresistive label-free immunosensor for cancer biomarker." An abstract of this paper is available at the journal's Web site. View abstract