A dual-signal sensor based on molecularly imprinted photonic polydopamine for detection of the oxidative stress biomarker allantoin

A novel biomimetic detection method is presented allocating two transducer principles in a molecularly imprinted polymer (MIP)-based sensor. The device was constructed on a transparent three-electrode system of conductive indium tin oxide (ITO) fabricated by laser direct writing on glass substrates. The sensing layer was prepared by electropolymerizing dopamine in the presence of allantoin, on colloidal silica particles that exhibited a structural color due to the short-range ordered structure. This opto-electrochemical dual-signal output was successfully developed for the detection of the oxidative stress biomarker allantoin. The analytical properties were evaluated by electrochemical impedance spectroscopy and reflectance analysis of the structural color. The sensor showed a linear response over a wide range of allantoin concentrations (0.1 nmol L −1 to 10000 nmol L −1 ) measured in synthetic urine. As expected, the lowest limit of detection in urine (0.012 nmol L −1 ) was achieved with the electrochemical signal. In addition, other urinary oxidative stress metabolites tested as interferents, namely uric acid and 8-hydroxy-2′-deoxyguanosine, had no effect on the dual-signal detection of allantoin. The biomimetic and cost-effective properties of the materials in combination with the improved analytical properties of opto-electrochemical detection provide a sensor platform with great potential for the screening of oxidative biomarkers in urinalysis.