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Environmental pollution caused by sulfide compounds has become a major problem for public health. Hence, there is an urgent need to explore a sensitive, selective, and simple sulfide detection method for environmental monitoring and protection. Here, a novel microbial biosensor was developed using recombinant Escherichia coli BL21 ( E. coli BL21) expressing sulfide:quinone oxidoreductase (SQR) for sulfide detection. As an important enzyme involved in the initial step of sulfide metabolism, SQR oxidizes sulfides to polysulfides and transfers electrons to the electron transport chain. Nanoporous gold (NPG) with its unique properties was selected for recombinant E. coli BL21 cells immobilization, and then glassy carbon electrode (GCE) was modified by the resulting E. coli /NPG biocomposites to construct an E. coli /NPG/GCE bioelectrode. Due to the catalytic oxidation properties of NPG for sulfide, the electrochemical reaction of the E. coli /NPG/GCE bioelectrode is attributed to the co-catalysis of SQR and NPG. For sulfide detection, the E. coli /NPG/GCE bioelectrode showed a good linear response ranging from 50 μM to 5 mM, with a high sensitivity of 18.35 μA mM −1 cm −2 and a low detection limit of 2.55 μM. The anti-interference ability of the E. coli /NPG/GCE bioelectrode is better than that of enzyme-based inhibitive biosensors. Further, the E. coli /NPG/GCE bioelectrode was successfully applied to the detection of sulfide in wastewater. These unique properties potentially make the E. coli /NPG/GCE bioelectrode an excellent choice for reliable sulfide detection. [ABSTRACT FROM AUTHOR]

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]