Abstract
The authors present in this work, a novel, simple, and disposable electrochemical sensor for the detection of dopamine (DA). Indeed, the proposed sensing system is based on overoxidized polypyrrole (PPyox) modified laser scribed graphene electrode (LSGE). LSGEs were fabricated via direct laser-writing on polyimide (PI) sheets to produce a 3D-porous structure of graphene that offers a large conducting surface area. The morphol-ogy of the electrode surface was analyzed using scanning electron microscopy (SEM). The electrochemical behavior of the developed sensor was investigated using cyclic voltammetry (CV), differential pulse voltamme-try (DPV), and electrochemical impedance spectroscopy (EIS). Compared to conventional screen-printed car-bon electrodes, the results showed that the current responses of DA were drastically enhanced due to the excellent catalytic activity of the LSGE as well as the strong electrostatic attraction of the deposited PPyox film that enables a selective accumulation of DA into the sensor's surface. Furthermore, this sensing strategy demon-strated outstanding adsorption features toward DA detection leading to the detection of subnanomolar levels via preconcentration at an open circuit potential (OCP) system. Under optimal conditions, two linear calibra-tion plots were established in the range of 0.5 mu M-10 mu M at a close circuit potential and 10 nM-500 nM under 5 min of preconcentration at OCP with a lower limit of detection estimated to be 7 nM. The developed sensor demonstrated good selectivity, adaptability, and stability. As a result, it was effectively employed for the detec-tion of DA in human blood serum and tap water samples, with satisfactory recovery values.