Immobilization of Ni-Pd/core-shell nanoparticles through thermal polymerization of acrylamide on glassy carbon electrode for highly stable and sensitive glutamate detection

The preparation of a persistently stable and sensitive biosensor is highly important for practical applications. To improve the stability and sensitivity of glutamate sensors, an electrode modified with glutamate dehydrogenase (GDH)/Ni-Pd/core-shell nanoparticles was developed using the thermal polymerization of acrylamide (AM) to immobilize the synthesized Ni-Pd/core-shell nanoparticles onto a glassy carbon electrode (GCE). The modified electrode was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Electrochemical data showed that the prepared biosensor had remarkably enhanced electrocatalytic activity toward glutamate. Moreover, superior reproducibility and excellent stability were observed (relative average deviation was 2.96% after continuous use of the same sensor for 60 times, and current responses remained at 94.85% of the initial value after 60 d). The sensor also demonstrated highly sensitive amperometric detection of glutamate with a low limit of detection (0.052 mu M, S/N - 3), high sensitivity (4.768 mu A mu M-1 cm(-2)), and a wide, useful linear range (0.1-500 mu M). No interference from potential interfering species such as L-cysteine, ascorbic acid, and L-aspartate were noted. The determination of glutamate levels in actual samples achieved good recovery percentages. (C) 2015 Elsevier B.V. All rights reserved.