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

• Ni–Pd/core–shell nanoparticles were synthesized.
• Nanoparticles were immobilized onto electrodes through thermal polymerization.
• The modified sensor exhibited excellent stability and sensitivity for glutamate detection.
• The biosensor exhibited remarkable electrocatalytic activity toward glutamate.
• The sensor successfully detected glutamate in tomato soup samples.

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 μM, S/N = 3), high sensitivity (4.768 μA μM−1 cm−2), and a wide, useful linear range (0.1–500 μM). 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.

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