UNIVERSITY OF NEW SOUTH WALES, SYDNEY, NEW SOUTH WALES, AUSTRALIA: A UNSW-led team of researchers has developed a biosensor that can spot remarkably small traces of contaminants in liquids in just 40 minutes.

Biosensors are otherwise called biochemiresistors among the scientists.  It meets a long-standing challenge for scientists to create a sensor that is not only super-sensitive to the presence of chemical compounds but also responds to their presence quickly. The new invented biochemiresistor can be used in detecting drugs, toxins and pesticides for biomedical or environmental analysis.

A biosensor is a portable analytical device that uses biological molecules to detect selectively just one compound within a mix of many others. Small biosensors are already in daily use testing the safety of drinking water, for checking diabetic blood-sugar levels and for pregnancy tests.

This recently developed biochemiresistor uses gold-coated magnetic nanoparticles modified with antibodies that are selective for the chemical constituent – or analyte – of interest. The nanoparticles are dispersed into the sample for analysis and if the analyte is present some of the antibodies detach from the nanoparticles and attach to the analyte of interest. This biosensor was successfully experimented for the first time by detecting tiny traces in milk of the veterinary antibiotic enrofloxacin. Enrofloxacin is an antibiotic used in the agricultural industry that can be transferred to the entire food chain. The biochemiresistor was able to detect enrofloxacin in neat milk in 40 minutes, at a level as low as one nanogram in a litre of milk.

This new type of biosensor is more rapid in response because of the magnetic nanoparticle biosensors that go and attach to the analyte rather than the usual approach of waiting for the analyte to find the sensing surface. 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. The study’s lead author is Leo M.H. Lai. The team included other researchers from the Australian Centre for NanoMedicine and the former ARC Centre of Excellence for Functional Nanomaterials at UNSW.