Fiber optic SPR sensor for the detection of melamine using molecular imprinting

Fabrication and characterization of a surface plasmon resonance based fiber optic sensor for the detection of melamine using molecular imprinting are 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 molecular imprinted (MIP) polymer using melamine as template molecule. The MIP layer creates binding sites, complementary of the template molecule on the surface. The template molecules have the capability to bind with these active sites. The performance of the sensor is tested for the melamine concentration range from 10−7 M to 10−1 M. A shift of 19 nm in resonance wavelength is recorded for this concentration range. The sensitivity is maximized by optimizing melamine concentration in MIP layer formation and the pH of the sample solution. The selectivity of the probe is checked using different analytes and is found to be highly selective for melamine. The sensitivity of the sensor is improved by introducing a thin layer of aluminum between silver and MIP layer. The sensor has advantages of fast response, high selectivity and sensitivity, low cost and can be used for online monitoring and remote sensing applications.