Surface Plasmon Resonance-Based Fiber Optic Sensor for the Detection of Ascorbic Acid Utilizing Molecularly Imprinted Polyaniline Film

An effort for the fabrication and characterization of a fiber optic sensor based on surface plasmon resonance for the detection of ascorbic acid utilizing molecularly imprinted (MIP) polyaniline film has been reported. The probe is fabricated by coating a thin film of silver over the unclad core of an optical fiber which is further coated with the molecularly imprinted polyaniline film using ascorbic acid as template molecule. The MIP layer creates binding sites complementary of the shape and size of the template molecule on the surface. The sensor is characterized for ascorbic acid concentration solution in the range from 10(-8) to 10(-4) M. A shift of 22 nm in resonance wavelength for this concentration range has been obtained. The concentration of ascorbic acid in the MIP preparation solution is optimized to maximize the sensitivity of the sensor. In addition, the effect of pH of the sample solution of ascorbic acid on the performance of the sensor has been studied and it has been found that the proposed sensor is most sensitive at pH 7.0. The selectivity of the probe has been checked by using different analytes and has found that the probe is highly selective for ascorbic acid. The sensor has various advantages such as fast response, high selectivity and sensitivity, low cost, and can be used for online monitoring and remote sensing applications.