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The extensive use of pesticides such as methyl parathion (MP) and carbendazim (CBM) has posed serious risks to human health due to their high toxicity, coexistence, and persistence in the environment. Therefore, it is very urgent to develop a multipesticide detection platform to realize the simultaneous detection of many kinds of pesticides. Here, nanoporous gold (NPG) with unique structural and functional properties was selected as a recognition element to construct an electrochemical sensor. This is the first time that NPG, as an active electrocatalyst, achieved the simultaneous electrochemical detection of MP and CBM, with a large peak potential separation of 0.70 V. For the detection of MP and CBM, good linear responses were observed in large concentration ranges of 0.5–150 μΜ for MP and 3.0–120 μΜ for CBM, with high sensitivities of 186.53 μA mM−1 cm−2 for MP and 484.51 μA mM−1 cm−2 for CBM, as well as low detection limits of 0.02 μM for MP and 0.24 μM for CBM. Additionally, the NPG/GCE electrode presented strong specificity, selectivity, and anti-interference capability in the simultaneous detection of MP and CBM. The environmental water sample analysis was also achieved with satisfactory results, which made the NPG/GCE electrode a reliable method for the simultaneous electrochemical detection of MP and CBM. [ABSTRACT FROM AUTHOR]

Abstract A highly sensitive whole cell based electrochemical biosensor was developed for catechol detection in this study. The carE gene of Sphingobium yanoikuyae XLDN2–5 encoding catechol 2,3-dioxygenase (C23O), a key enzyme in the biodegradation of aromatic compound, was cloned and over-expressed in Escherichia coli BL21 (E. coli BL21). Compared to Sphingobium yanoikuyae XLDN2–5, the recombinant E. coli BL21 over-expressed C23O exhibited higher catalytic activity towards catechol. Moreover, the whole cells provided a better environment for C23O to maintain its catalytic activity and stability compared with crude enzyme. The distinctive features of the recombinant E. coli BL21 over-expressed C23O made it an ideal bio-recognition element for the fabrication of a microbial biosensor. Additionally, nanoporous gold (NPG) with unique properties of structure and function was selected as a support to immobilized the recombinant E. coli BL21 over-expressed C23O. Based on the synergistic effect of C23O and NPG, the E. coli BL21-C23O/NPG/GCE bioelectrode showed a good linear response for catechol detection ranging from 1 μM to 500 μM with a high sensitivity of 332.24 μA mM−1 cm−2 and a low detection limit of 0.24 μM. Besides, the E. coli BL21-C23O/NPG/GCE bioelectrode exhibited strong anti-interference and good stability. For the detection of catechol in wastewater samples, the concentrations detected by the E. coli BL21-C23O/NPG/GCE bioelectrode were in good agreement with the standard concentrations that added in the wastewater samples, which make the E. coli BL21-C23O/NPG/GCE bioelectrode an ideal tool for reliable catechol detection. Highlights • The carE gene encoding catechol 2,3-dioxygenase (C23O) was cloned and over-expressed in E. coli BL21. • A sensitive microbial biosensor was constructed based on the recombinant E. coli BL21-C23O cells for catechol detection. • The resulting microbial biosensor exhibited good performance for catechol detection. [ABSTRACT FROM AUTHOR]