SPR based fibre optic biosensor for phenolic compounds using immobilization of tyrosinase in polyacrylamide gel

We present a surface plasmon resonance (SPR) based fibre optic biosensor for the detection of phenolic compounds (potentially bio-hazardous) in aqueous solution. The sensing probe was prepared by depositing silver film onto optical fibre core via thermal evaporation technique followed by the immobilization of enzyme, tyrosinase, also known as poly phenol oxidase (PPO), using gel entrapment technique. The response characteristics of the biosensor towards different phenolic compounds were determined using wavelength interrogation technique. Experimental results of SPR spectra show a red shift in the resonance wavelength on increase in the concentration of the phenol compounds in aqueous samples. Further, the sensitivity of the sensor decreases as the concentration of the phenolic compounds increases. The biosensor also manifests optimum activity at pH 7. The sensor has high sensitivity, wider operating range, reusability and reproducibility of results which make the sensor compatible for practical applications. Since the sensor is based on wavelength interrogation it is immune to source intensity fluctuation. Further, the probe is fabricated on optical fibre it has additional advantages such as probe miniaturization, low cost, capability of online monitoring and remote sensing, immunity to electromagnetic field and biocompatibility.