Molecularly-imprinted chloramphenicol sensor with laser-induced graphene electrodes.

Graphene has emerged as a novel material with enhanced electrical and structural properties that can be used for a multitude of applications from super-capacitors to biosensors. In this context, an ultra-sensitive biosensor was developed using a low-cost, simple and mask-free method based on laser-induced graphene technique for electrodes patterning. The graphene was produced on a polyimide substrate, showing a porous multi-layer structure with a resistivity of 102.4 ± 7.3 Ω/square. The biosensor was designed as a 3-electrode system. Auxiliary and working electrodes were made of graphene by laser patterning and the reference electrode was handmade by casting a silver ink. A molecularly-imprinted polymer (MIP) was produced at the working electrode by direct electropolymerization of eriochrome black T (EBT). As proof-of-concept, the MIP film was tailored for chloramphenicol (CAP), a common contaminant in aquaculture. The resulting device was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy readings against a redox standard probe. The limit of detection (LOD) was 0.62 nM and the linear response ranged from 1 nM to 10 mM. These analytical features were better than those produced by assembling the same biorecognition element on commercial graphene- and carbon-based screen-printed electrodes. Overall, the simplicity and quickness of the laser-induced graphene technique, along with the better analytical features obtained with the graphene-based electrodes, shows the potential to become a commercial approach for on-site sensing.