Novel fiber-optic biosensor for pesticide detection

Detection of toxins such as pesticides in waste water is an important issue today. We have investigated a fiber optical biosensor system utilizing chemiluminescence and molecular self-assembly to detect organophosphorous-based pesticides. Our earlier experiments in the aqueous solution1 and on the inside surface of a capillary2 indicated that chemiluminescent detection of pesticides in waste water can have an extremely high sensitivity (~40 ppb). We report on the development of a fiber optical probe which contains the immobilized enzyme for pesticide detection. The enzyme responsible for chemiluminescent detection is immobilized on the surface of the fiber by a molecular self-assembly technique developed in our lab earlier.3 The detection technique utilizes the fact that enzyme catalyzed chemiluminescent reaction is inhibited in the presence of phosphorous containing pesticides. In a certain range, the decrease in the chemiluminescence signal is proportional to the pesticide concentration. The enzyme used for the detection purpose is alkaline phosphatase (AP) which catalyzes a chemiluminescent reaction when acting on a substrate, called CSPD™. It is a substrate which upon dephosphorylation chemiluminesces.