PVA-AWP/tyrosinase functionalized screen-printed electrodes for dopamine determination†
The development of highly sensitive amperometric biosensors for dopamine determination using commercially available SPEs in combination with the PVA-AWP photopolymer as the enzyme immobilization matrix is described in this work. This research focuses on (i) the optimization of the conditions for SPE biofunctionalization by tyrosinase entrapment in PVA-AWP and of the working conditions for dopamine determination by mathematical model application, and (ii) the evaluation of the analytical performances of the PVA-AWP/tyrosinase functionalized SPEs. Dopamine determination under optimum conditions for electrode biofunctionalization (PVA-AWP 3%, 60 min UV light exposure) and under optimum working conditions (pH 6.5, 25 °C) was performed in the dynamic concentration range of 0.9–500 μmol L−1, 0.2–400 μmol L−1, and 0.03–150 μmol L−1, using respectively C SPE, MWCNT-GNP/C SPE, and graphene-GNP/C SPE. The LOD was found to be 300 nmol L−1, 60 nmol L−1, and as low as 10 nmol L−1, correspondingly. The excellent analytical performances of the graphene-GNP C SPE and MWCNT-GNP C SPE were associated with their large active area (19.72 mm2 and 15.3 mm2) and enhanced electrocatalytic properties (ko = 8.1 × 10−3 cm s−1 and 4.4 × 10−3 cm s−1) compared with the bare C SPE (12.47 mm2 and ko = 3.0 × 10−3 cm s−1). The developed biosensors were stable, reproducible, and more sensitive than most of the known biosensors for dopamine determination. They were successfully applied for dopamine determination in injections. Taking into consideration the fact that the selected enzyme immobilization approach using a water-soluble photopolymer opens the possibility of SPE biofunctionalization by photolithography, the developed biosensors are promising for fast, simple, sensitive, selective, and cost effective analysis of dopamine.