Fast Biosensor for Detection of Harmful Substance in Food

Concern about traces of beta-lactam antibiotics (e.g. penicillins and cephalosporins) in food and in the environment is spurring the search for simple, specific, sensitive, and rapid methods of detection. We have designed a biosensor for detecting antibiotics based on enzymes (beta-lactamases) secreted by pathogenic bacteria to destroy antibiotics. The biosensor works on the principle of gross conformational changes in the enzyme when it ‘sees’ antibiotic substrate. We attached an environment-sensitive fluorescent molecule to a flexible loop close to the enzyme’s active site. When the enzyme binds a beta-lactam antibiotic, the loop moves, changing the environment of the probe and causing the probe to fluoresce strongly. Our technology allows the fine-tuning of fluorescence color from the biosensor for different purposes. The sensor responds to beta-lactam antibiotics and beta-lactamase inhibitors. It can detect penicillin G at nanomolar levels. It can also be used for screening enzyme inhibitors and hence finds its application in drug screening.