Low cost sensor measures small amounts of antibodies

A new sensor has been developed that measures extremely small amounts of antibodies, the disease-fighting antitoxins found in blood that indicate whether a person is sick.

Brian Geiss holds a wire that is one-fourth the size of a human hair (Credit: John Eisele/CSU Photography)

Using a small wire that is one-fourth the size of a human hair, the researchers from Colorado State University developed a sensor that can detect as few as 10 antibody molecules within 20 minutes. Standard medical testing requires billions or trillions of antibody molecules for detection and can take up to a day to process.

According to the university, this type of cost-effective instrument could help clinicians treat diseases sooner in people and could be used in low-resource settings.

Results from the team’s research will be published April 15 in Biosensors and Bioelectronics. The study, titled: An ultra-sensitive capacitive microwire sensor for pathogen-specific serum antibody responses, is published in advance online.

Currently, most US medical offices and hospitals use the ELISA (enzyme-linked immunosorbent assay) test to determine whether a person has a viral infection.

It’s a common test, but ELISA’s sensitivity is relatively low, said Brian Geiss, a senior author on the study and an associate professor in the Department of Microbiology, Immunology, and Pathology. This means that clinicians need a fairly high number of antibodies in a person’s blood to get a positive test result. It also often takes seven to 10 days after infection for the test to register.

To make the sensor, the research team chemically attached proteins related to Zika and chikungunya viruses to gold wires. These viruses, along with West Nile and dengue, are transmitted by infected mosquitoes. Medical laboratories use these proteins in ELISA tests to look for antibodies that have developed to fight infections.

Next, they ran an electrical current through the wire. The researchers then added antibodies to bind to the viral proteins on the wire, which increased the mass on the outside of the wire. The university said that this also increased the ability of the wire to hold the charge. They then measured the change in mass to quantify the number of antibodies on the surface of the wire.

“We found that we could get very high specificity for confirming a viral infection,” said Professor David Dandy, a senior author on the paper and head of the Department of Chemical and Biological Engineering. In addition, the research team did not see any reaction or reactivity from antibodies targeting other viruses, which can sometimes lead to false positive test results.

The research team now hopes to combine this discovery with viral detection research they previously published to create a single system that can detect viruses and antibodies against the viruses in patient samples.