Chitosan-based Molecularly Imprinted Polymers for the detection of compounds of interest in the food industry

Abstract

The use of sensors in the food industry is essential to control and guarantee the organoleptic properties of their products. For this purpose, the preparation of sensors to easily measure the different compounds present in food has generated an enormous interest. Molecularly imprinted polymers (MIPs) can act as electrochemical sensors purposely designed to have specific recognition cavities. This cavities are shaped by the use of a definite template molecule present during the formation of the sensor. Once the molecularly imprinted polymer is formed, the template molecule is eluted leaving behind the specific cavities. The presence of this cavities will later be crucial in the selective detection of a specific concentration range of solutions containing the template molecule. In this work, MIP sensors have been developed using the electrodeposition of a biopolymer, chitosan, via cyclic voltammetry in a glassy carbon electrode. The parameters of this electrodeposition have been optimized in this work, modifying mainly the use of cross-linking agent as well as the pH of the chitosan solution. For the optimization, the response of the sensor towards catechol using cyclic voltammetry was evaluated in comparison to the use of a non-imprinted polymer (NIP), prepared under the same conditions but in the absence of template molecule. Also, the effect of introducing metallic nanoparticles has been tested in order to see how they affect the intensity of response of the sensors. In this case gold (AuNPs) and silver (AgNPs) nanoparticles have been used. Once optimized, MIP sensors have been developed to detect organic acids present in the food industry, successfully obtaining sensors for the detection of lactic, malic and tartaric acid. All of the prepared MIP sensors gave a limit of detection in the order of 10-5M or lower in the detection of the compound they were designed for. The addition of nanoparticles, even though it gave positive results, was discarded due to the balance between the higher cost of operation and the improvement of the results