A review on the application of molecularly imprinted polymers in the detection of pollutants: A case study of optical sensors

Optical sensors and biosensors have the great potential to detect metal cations, anions, organic dyes, drugs, pesticides and other contaminants. These sensors are considered for their easy preparation, fast sensing, high sensitivity and selectivity, as well as naked eye detection. Optical sensors are divided into two categories of colorimetric and fluorescent sensors. In this regard, molecularly imprinted polymers, indicators, nanomaterials (metal nanoparticles, metal oxides, quantum dots) and etc. are used for the designation of optical sensors. The fabrication of MIP-based optical sensors is one of the considerable methods for the preparation of optical sensors. This method, known as the molecular lock-key method, for creating molecularly imprinted polymers (MIPs) which are complement to template molecules in shape, size, and functional groups. These materials are similar to biological systems in structure and application that result from the copolymerization of functional monomers and crosslinkers in the presence of the target molecule. These polymers are used for the detection, separation and removal of trace amount of various contaminants in complex substrates. For the preparation of MIP-based sensors, fluorescent functional monomers and dyes including coumarins, xanthenes, naphthalimides, carbazoles, boron dipyrromethenes, azo dyes, schiff bases and etc. are used. Therefore, in this study, various applications of MIPs including environmental, pharmaceutical and medical usage through separation, biomimetic assays, sustained delivery and release, new application areas and specially, optical sensors (synthesis process and its mechanism), will be expressed. In addition, recent developments and commercialization of MIPs and MIP based sensors, will be discussed as well as the introduction of some active companies in this field.