USC researchers say they have made a big improvement in a new breed of electronic detectors for viruses and other biological materials – one that may be a valuable addition in the battle against epidemics.
The improvement consists of a piece of synthetic antibody attached to a nanowire that is attached to an electrical base sitting in liquid.
If the protein the antibody binds to is present in the liquid, it will bind to these antibodies, immediately creating a sharply measurable jump in current through the nanowire.
The basic principle of nanotube and nanowire biosensors for protein detection was first demonstrated in 2001, but the new design by a team headed by Chongwu Zhou of the USC Viterbi School of Engineering and USC College chemist Mark Thompson uses two new elements.
First, it takes advantage of bioengineered synthetic antibodies – much smaller versions of the natural substances that are designed to bind with a specific protein and only that protein.
Second, it uses indium oxide nanowires instead of silicon and other materials previously tried. Metal oxides, according to an article published in ACS Nano do not, unlike silicon, develop “an insulating native oxide layer that can reduce sensitivity.”
The result, according to the paper, is a device that can detect its target molecules with a sensitivity as great as the best alternative modes and without use of chemical reagents.
It is also potentially cheaper than alternatives.
In addition, the system can be useful in basic research by helping to establish important parameters for two-part biological systems such as the antibody/target protein pair.
The protein the prototype system detects is the SARS (severe acute respiratory syndrome) virus n-protein, which infected more than 8,000 people in 2002-03, killing nearly 10 percent of them. Commercial systems using enzyme-linked immunosorbent assay now exist to test for SARS, but the new system has advantages in time, cost and portability.
The team of researchers included Fumiaki Ishikawa, Hsaio-Kang Chang and Po-Ching Chen from USC Viterbi’s Department of Electrical Engineering; Marco Curreli, Rui Zhang and C. Anders Olson from USC College’s Department of Chemistry; Richard J. Cote of the Keck School of Medicine of USC’s Department of Pathology; and Hsiang-I Liao and Ren Sun of the UCLA Department of Medical Pharmacology.
The Whittier Foundation and the National Institutes of Health funded the research.