Here, a needle-shaped electrode based on commercial acupuncture needle was fabricated and functionalized with dendritic gold nanostructures (AuNDs) and ion-exchange polymer (Nafion) for voltammetric speciation analysis of copper (Cu) in seawater. To achieve the enhanced performance for voltammetric determination of Cu in seawater, the acupuncture needle electrode (ANE) was functionalized with AuNDs via electrochemical deposition and covered with Nafion. AuNDs facilitate the electrochemical responses of Cu due to their excellent catalytic and electroconductive properties, whereas Nafion can stabilize the AuNDs deposited on the surface of the needle tip and enhance the voltammetric responses through its specific cation-exchange ability with Cu2+. The so-designed AuNDs/Nafion/ANE showed excellent performance for the determination of Cu in complex matrix like seawater. Under the optimal conditions, the response of Cu at this functional needle-shaped electrode was linear in the concentration range from 0.05 to 1 nmol L-1 with an ultralow detection limit of 15.4 pmol L-1. Additionally, the functional needle-shaped electrode has been successfully used for the direct determination of different Cu species in seawater via anodic stripping voltammetry. (C) 2018 Elsevier Ltd. All rights reserved.