Development of a fiber optic enzymatic biosensor for 1,2-dichloroethane

There is a significant need for devices capable of measuring water contaminant concentrations in situ--continuously, rapidly, and without reagents, extraction, or other pretreatment. Toward this goal, we constructed and tested fiber optic biosensors for measurement of 1,2-dichloroethane (DCA) in aqueous solutions. The biocomponent was the haloalkane dehalogenase, DhlA, in whole cells of Xanthobacter autotrophicus GJ10. These cells were immobilized in calcium alginate on the tip of a fiber optic fluoresceinamine-based pH optode. The resulting biosensor could quantify DCA at 11 mg/l and had a linear response up to at least 65 mg/l. Total signal change was reached in 8-10 min, and measurements were reproducible (SE <9%). The sensor's small size, potential for remote operation, and low cost make it of interest for further development.