Designing a modified electrode based on graphene quantum dot-chitosan application to electrochemical detection of epinephrine

Graphene quantum dots were used for constructing modified carbon paste electrode in a simple way using chitosan as a stabilizing agent. Since these dots are soluble in aqueous solution, chitosan is used to keep the quantum dot into the paste. A triple mixture nanocomposite including graphene quantum dots surrounded by chitosan on the plane of graphite was formed. The graphene quantum dots have plenty of carboxyl groups with the negative charges, which can have a strong electrostatic interaction with amine functional groups in chitosan. This characteristic besides having conjugated pi-pi bonding makes a stable and an excellent electrochemical platform for epinephrine detection. Electrochemical impedance spectroscopy and cyclic voltammetry showed that the prepared graphene quantum dots-chitosan modified carbon paste electrode possesses a fast electron transfer compared with the bare electrode and a noticeable electrocatalytic activity toward electrooxidation of epinephrine. Under optimized experimental conditions, the modified electrode revealed a linear relationship between the peak current and concentrations of epinephrine over a wide range from 0.36 to 380 mu M with the limit of detection of 03 nM (3S(b)/m). The modified electrode, proposed as a new promising nanoplatform is suitable for designing of electrochemical sensors. (C) 2018 Elsevier B.V. All rights reserved.