Preparation and characterization of molecularly imprinted mussel inspired film as antifouling and selective layer for electrochemical detection of sulfamethoxazole

The present work describes the development of a novel simple and cheap electrochemical sensor based on molecularly imprinted polydopamine, for the detection of sulfamethoxazole (SMX) an antibiotic widely used in food industry. A double step procedure is used for sensor fabrication consisting in molecularly imprinted polydopamine (PDA-MIP) electropolymerization on a gold electrode and template removal through a simple washing procedure with diluted acetic acid. SMX detection was then performed amperometrically. A deep investigation of PDA-MIP electropolymerization was performed combining electrochemical, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization and comparing the obtained results with the corresponding non-imprinted polymer (PDA-NIP), evidencing, for the first time, the possibility of secondary reaction that can occur between template molecule and polymer during material synthesis. Antifouling properties of here prepared PDA-MIP film were observed avoiding the use of complex cleaning procedure of electrode surface during the measurements. Under the selected optimum conditions, MIP sensor evidenced a linear range from 0.8 to 170 ?M and a good selectivity in presence of other structurally related molecules such as sulfadimethoxine. The PDA-MIP film was then used for the first time in food analysis to determine SMX in spiked milk samples at two different concentrations (3.4 ?M and 9.8 ?M) obtaining satisfactory recovery results (103 ± 6% and 99 ± 8% respectively).