Science - September 3, 2009

Quick antibiotics test ready soon

Biosensors can trace antibiotics in food chain quickly.
No longer necessary to send blood from slaughter houses and milk from factories to lab for tests.

RIKILT research scientist Willem Haasnoot states in his thesis that the current practice of sending milk and blood samples to specialist labs for detailed antibiotic testing is no longer necessary. This process takes a few days. 'While this goes on, the products are being sold to consumers; test results are only available afterwards,' he says. 'The new method gives instant results because the test goes to the food, and not the other way round.'
Haasnoot tested the effectiveness of a biosensor with four tiny channels in which special proteins - antibodies - react to antibiotics. This method is quick and, above all, enables large quantities of blood from slaughtered animals and milk samples to be tested automatically in quick succession.
You cannot trace all antibiotics with this method, though. The standard microbial test method can pick out hundreds of antibiotics by using five micro-organisms. 'You can't fit these into this biosensor,' says Haasnoot. 'It can only handle four antibiotics at a time.'
However, a new multiplex biosensor available on the market can perform more than a hundred tests simultaneously. 'That sensor can measure almost all antibiotics. That will get us further', Haasnoot says. In the meantime, the results obtained by the sensor have been published in Analytical Chemistry by PhD candidate Sabina Rebe, with Haasnoot as co-author.
 Haasnoot (56), the cluster leader of the Biomolecular Detection group at RIKILT, completed his own thesis within a year. 'Last year, I supervised a trainee research assistant at the Free University, but was not allowed to present myself as co-defendant at the graduation ceremony. I was not considered as a fully-fledged researcher because I didn't have a PhD. My supervisor then advised me to do a PhD myself. I have now incorporated existing research into a thesis.' Hhasnoot did not mention the success with the new multiplex biosensor in the thesis, though. 'Science keeps advancing.'
Willem Haasnoot will defend his thesis on 11 September in the presence of  Dr. Michel Nielen, professor of Detection of Chemical Food Contaminants, and Dr. Han Zuilhof, professor of Organic Chemistry.

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