Australian scientists have developed a biosensor that can detect nano-sized particles of contaminants in just a matter of minutes.
“The biochemiresistor is also more sensitive than the usual biosensor because, as the nanoparticles are dispersed throughout the sample, the entire sample is analyzed, not just a small portion of the solution,” says Professor Justin Gooding of the University of New South Wales’s School of Chemistry, a researcher involved in the development. He was the co-author of a paper describing the innovation that was published in Angewandte Chemie, reports PhysOrg.com.
A biosensor is a portable analytical device that uses biological molecules to detect a desired compound within a mix of many others. Small biosensors are already in use to test pollutants in drinking water, determine the levels of blood sugar in diabetics, and test for pregnancy.
In the paper, the researchers described how they used their sensor to detect tiny traces of the veterinary antibiotic, enrofloxacin, in milk. Gooding says:
Enrofloxacin is an antibiotic used in the agricultural industry that can be transferred to the food chain. Our biochemiresistor was able to detect enrofloxacin in neat milk in 40 minutes, at level as low as one nanogram in a litre of milk. To put that number in perspective, a nanogram is a billionth of a gram and is the mass of a single cell.
“While that is impressive enough, the sensor is a general concept that can be widely applied across many different fields,” he adds. The researchers believe the device has potential uses for detecting drugs, toxins, and pesticides.
The secret to the biochemiresistor are gold-coated magnetic nanoparticles modified with antibodies that are selective for the chemical constituent — or analyte — that is the object of detection. The nanoparticles are dispersed into the sample and, if the analyte is present, some of the antibodies detach from the nanoparticles. According to Gooding:
Using a magnet, the nanoparticles are then assembled into a film between two electrodes and the electrical resistance is measured. The more analyte is present, the more antibodies leave the nanoparticles and the lower the resistance in the nanoparticle film.
“This new type of biosensor is rapid in response because the magnetic nanoparticle biosensors go and get the analyte rather than the usual approach of waiting for the analyte to find the sensing surface,” Gooding says.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.