Voltammetric sensing of oxacillin by using a screen-printed electrode modified with molecularly imprinted polyaniline, gold nanourchins and graphene oxide.

An imprinted electrochemical sensor was developed for the determination of the antibiotic oxacillin (OXC). A screen-printed carbon electrode (SPCE) was modified with gold nanourchin and graphene oxide, and then aniline was electro-polymerized in the presence of OXC to obtain a molecular imprint on the SPCE. The morphologies in sequential modification processes and the electrochemical behavior of the modified SCPE were characterized by field emission scanning electron microscopy and cyclic voltammetry. The performance of the sensor was evaluated by differential pulse voltammetry. At a typical peak potential of 0.82 mV (vs. Ag/AgCl), response is linear in the 0.7-575 nM OXC concentration range. The electrochemical sensitivity is 97.6 nA nM -1 cm -2, and the detection limit is 0.2 nM. The relative of replicate assays is 2.6% (for n = 6) at an OXC concentration level of 200 nM. The sensor is sensitive and selective. It was successfully applied for the detection of OXC in spiked cow's milk. Schematic presentation of electropolymerization of aniline on sreen-printed carbon electrode (SPCE) modified with graphene oxide (GO) and gold nanouchins (GNU) for voltammetric sensing of oxacillin.