A biosensor for the detection of triazine and phenylurea herbicides designed using Photosystem II coupled to a screen‐printed electrode

A biosensor for the detection of triazine‐ and phenylurea‐type herbicides was constructed using isolated Photosystem II (PS II) complexes as a biosensing element. PSII isolated from the thermophilic cyanobacterium Synechococcus elongatus was immobilized on the surface of a screen‐printed sensor composed of a graphite working electrode and Ag/AgCl reference electrode deposited on a polymeric substrate. The biosensor was mounted in a flow microcell with illumination. The principle of the detection was based on the fact that herbicides selectively block PSII electron transport activity in a concentration‐dependent manner. Changes of the activity were registered amperometrically as the rate of photoreduction of an artificial electron acceptor. The setup resulted in a reusable herbicide biosensor with a good stability (half‐life of 24 h) and limit of detection of approximately 10 −9 M for diuron, atrazine and simazine. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 110–116, 2002; DOI 10.1002/bit.10190