Abstract
Herein, a rapid and highly sensitive amperometric biosensor for the detection of α-ketoglutarate (α-KG) was constructed via an electrochemical approach, in which the glutamate dehydrogenase (GLUD) was modified on the surface of reduced graphene oxide-gold nanoparticle composite (rGO-Aunano composite). The rGO-Aunano composite was one-step electrodeposited onto glassy carbon electrode (GCE) surface and was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electrochemical techniques. In addition, the rGO-Aunano/GCE was also found to electrocatalyze the oxidation of β-nicotinamide adenine dinucleotide (NADH) at the peak potential of 0.3 V, which was negatively shifted compared with that at bare GCE or Aunano/GCE, illustrating better catalytic performance of rGO-Aunano. After the modification of GLUD, the GLUD/rGO-Aunano/GCE led to effective amperometric detection of α-KG through monitoring the NADH consumption and displayed a linear response in the range of 66.7 and 494.5 μM, with the detection limit of 9.2 μM. Moreover, the prepared GLUD/rGO-Aunano/GCE was further evaluated to be highly selective and used to test α-KG in human serum samples. The recovery and the RSD values were calculated in the range of 97.9–102.4% and 3.8–4.5%, respectively, showing a great prospect for its real application.
Highlights
Introduction αKetoglutarate (α-KG) is an important metabolic marker of early diagnosis of cancer and microbial fermentation monitoring and is a vital intermediate in the tricarboxylic acid cycle as well as a node to connect the carbonnitrogen metabolism in cells [1,2,3,4]
Several methods have been developed for the quantification of α-KG, such as electrochemical [8], gas chromatography-mass spectrometry (GCMS) [4], and high-performance liquid chromatography (HPLC) [5, 9]
Cyclic voltammetric (CV) was recorded during the electrodeposition of Gr oxide (GO) on glassy carbon electrode (GCE) (Figure 1(a)). ere is one anodic peak (I) and two cathodic peaks (II and III), corresponding to the redox pair of some oxygen-containing groups [30] and the irreversible electrochemical reduction of GO [31], respectively. e ongoing increase of the peak current with successive potential sweeps indicated that the rGO from GO dispersion was successfully deposited onto GCE
Summary
Ketoglutarate (α-KG) is an important metabolic marker of early diagnosis of cancer and microbial fermentation monitoring and is a vital intermediate in the tricarboxylic acid cycle as well as a node to connect the carbonnitrogen metabolism in cells [1,2,3,4]. Erefore, accurate and sensitive methods for the detection of α-KG are urgently required. Several methods have been developed for the quantification of α-KG, such as electrochemical [8], gas chromatography-mass spectrometry (GCMS) [4], and high-performance liquid chromatography (HPLC) [5, 9]. Wang and his coworkers have developed an electrochemical biosensor for rapid and sensitive detection of α-KG based on ruthenium-rhodium modified carbon fiber enzyme microelectrode [8]. A large overpotential was found at the microelectrode and the detection of α-KG was prone to suffer interference from other compounds
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