Surface plasmon resonance based fiber-optic sensor for the detection of pesticide

Fabrication and characterization of a surface plasmon resonance based fiber-optic sensor for the detection of organophosphate pesticide, chlorphyrifos, have been reported. The probe is prepared by immobilizing acetylcholinesterase (AChE) enzyme on the silver coated core of a plastic-cladded silica (PCS) fiber. The detection is based on the principle of competitive binding of the pesticide (acting as inhibitor) for the substrate (acetlythiocholine iodide) to the enzyme AChE. The spectral interrogation method has been used to characterize the sensor. It has been observed that the SPR wavelength decreases with the increase in the concentration of the pesticide for the fixed concentration of substrate in the fluid around the probe. Further, the effect of the concentration of the substrate in the fluid on the resonance wavelength has been studied. The sensitivity, detection accuracy, reproducibility and stability of the sensor have been also determined. It has been found that the sensitivity decreases with the increase in the concentration of the pesticide while reverse is the case for detection accuracy.