Biosensor Breakthrough Means Better Chemical Detection
- Published on Thursday, 28 June 2012 00:01
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A new biosensor with an improved response time and a heightened sensitivity to chemicals has been developed by researchers from the University of New South Wales (UNSW). This “biochemiresistor” is able to find contaminants in liquids in 40 minutes, faster than any previous biosensor, according to a UNSW news release. The biosensor will be used for detecting drugs, toxins, and pesticides for biomedical research.
Published in the journal Angewandte Chemie, the UNSW team’s research has been successful in developing biosensors that are sensitive enough to uncover chemical compounds much quicker than previous biosensors. The journal editors have characterized the research as “very important,” a term they say is given to just 5 percent of the research published.
The development is important to Earth observation because biosensors are able to detect potentially harmful biological organisms that can destroy plants, animals, and the overall environment. Biosensors also are able to provide an early warning capability that in turn can help policymakers, farmers, and others respond faster in combating these harmful organisms.
The researchers were able to find the veterinary antibiotic enrofloxacin in milk by using a new, innovative process. In their experiment, a biosensor using gold-coated magnetic nanoparticles enhanced with antibodies was used. The antibodies acted as the selectors for recognizing a chemical constituent, called analyte. If analyte was present in the sample, the antibodies detached themselves from the nanoparticles. The nanoparticles were then placed on a film (using a magnet) between two electrodes; the electrical resistance was then measured, which in turn showed the amount of analyte within the sample. Therefore, the more of the antibodies that removed themselves from the nanoparticles, the higher the amount of analyte was present. This caused the electrical resistance to decrease.
Using this method involving magnetic nanoparticles, the biochemiresistors are different than other sensors and have a much more rapid response time at detecting analyte within a sample. Instead of waiting for analyte to find the sensing surface, these biosensors find the analyte themselves. Another advantage of the biochemiresistor is that it is more sensitive to uncovering analyte because of the dispersion of the nanoparticles throughout the entire sample. This allows the entire sample to be tested for analyte, rather than simply a concentrated part.
“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,” according to co-author Justin Gooding, of the UNSW School of Chemistry and the Australian Centre for Nanomedicine (ACN).
“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.”
Biosensors are genetically engineered sensors that use B cells to identify pathogens and shine a light if there is detection, by converting a biological stimulus to an electrical response. According to Dr. Bernhard Weigl of the National Institutes of Health (NIH), there are four characteristics of a biosensor:
• Linearity, which measures substrate concentration;
• Sensitivity, which measures electrode response per substrate concentration;
• Selectivity, which measures the amount of chemical interference; and
• Response time, which measures the time necessary for 95 percent of the response to go through.
The lead author of the research was Leo M.H. Lai of UNSW’s School of Chemistry and the ACN. Other researchers were from the ACN and the former Australian Research Council’s (ARC) Centre of Excellence for Functional Nanomaterials at UNSW.