Biocompatible gallic acid (GA) was conjugated on the shell of gamma-Fe2O3 encapsulated with bio-inspired polydopamine (PDA) to form novel environment friendly magnetic nanoparticles, gamma-Fe2O3/PDA/GA. To elucidate the effect of the grafted GA, gamma-Fe2O3/PDA and gamma-Fe2O3/PDA/GA were used to modified electrodes. Cyclic voltammetry (CV), square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS) were adopted to comparatively study their interfacial properties, their chelating abilities and their electrochemical responses to Cu2+ and Pb2+. (C) 2014 Elsevier Ltd. All rights reserved.