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A new protein biosensing strategy based on a graphene tube (GT)‐modified electrode was developed in this article. GT as a fixed material and signal amplifier was loaded on the carbon ionic liquid electrode (CILE) surface, which could provide a suitable environment for myoglobin (Mb) immobilization and promote electron transfer between Mb and the electrode. Fourier‐transform infrared spectroscopy (FT‐IR) of Mb before and after mixing with GT was checked and showed that the native structure of Mb was maintained. The direct electrochemistry of Mb was investigated with a pair of obtained well‐defined and quasireversible redox peaks. The modified electrode (Nafion/Mb/GT/CILE) also showed excellent electrocatalytic activity for the reduction of trichloroacetic acid (TCA) and NaNO2, which could be utilized to determine the concentrations of TCA and NaNO2 with wide detection range and low detection limit. The biosensor was further applied to the detection of a real sample and obtained satisfactory experimental results. [ABSTRACT FROM AUTHOR]

Direct electrochemistry and electrocatalysis of myoglobin (Mb) on a gold nanorod (AuNR)‐decorated carbon ionic liquid electrode (CILE) were studied in this article. The fabricated Nafion/Mb/AuNRs/CILE was used as an electrochemical biosensor for determining trichloroacetic acid (TCA) and sodium nitrite (NaNO2). AuNRs exhibited high metal conductivity, and acted as the bridge between electrochemical active centers of Mb and the substrate electrode with the electron transfer rate accelerated. Electrochemical performances of Nafion/Mb/AuNRs/CILE were checked in pH 3.0 phosphate buffer solution with the electrochemical parameters calculated. Low detection limits and wide linear ranges were obtained in electrocatalytic investigations of different catalytic substrates including TCA and NaNO2, which exhibited potential applications in actual sample detection. [ABSTRACT FROM AUTHOR]

In this paper, a WS2 nanosheet was modified on the surface of a carbon ionic liquid electrode (CILE), and horseradish peroxidase (HRP) was further fixed on the electrode with a Nafion film. Direct electrochemistry and bioelectrocatalysis of HRP incorporated on the modified electrode were investigated in detail. On Nafion/HRP/WS2/CILE, a pair of well‐defined quasi‐reversible redox peaks appeared on the cyclic voltammogram, indicating that the presence of the WS2 nanosheet on the electrode surface could provide a specific interface with large surface area for HRP and its direct electron transfer rate was greatly enhanced. The formal potential (E0) obtained was –0.179 V, which was the typical feature of heme Fe(III)/Fe(II) in HRP. The electron transfer coefficient (α) and the heterogeneous electron transfer rate constant (ks) of HRP were calculated as 0.44 and 1.01 s–1, respectively. This HRP‐modified electrode showed excellent electrocatalytic activity for the reduction of trichloroacetic acid and NaNO2 with a wide linear range and low detection limit. Real samples were detected by this proposed method, indicating the successful fabrication of a new third‐generation electrochemical enzyme sensor utilizing the WS2 nanosheet. [ABSTRACT FROM AUTHOR]

Abstract A facile and effective approach was developed for the preparation of mesoporous Fe-NC by pyrolyzing the mixture of FeCl 2 , urea, (NH 4) 2 MoO 7 , phthalic anhydride and SBA-15, during which the in-situ formation of iron phthalocyanine is confirmed. The obtained catalyst exhibits high catalytic activity towards ORR, whose half-wave potential can be 53 mV more positive than that of commercial Pt/C catalyst. Besides, the catalyst also exhibits high selectivity of four electron path, along with excellent stability and methanol tolerance in alkaline media. Based on the characterization results, we suggest, the higher surface areas, highly porous structures induced by SBA-15 addition, as well as high graphitic N content should be the proper origins for its outstanding catalytic performance. Highlights • A facil, rational and effective method was developed for ORR catalyst. • Iron phthalocyanine was in-situ formed. • The catalyst has high surface areas and predominant mesopores. • The electrocatalyst showed excellent ORR performance in alkaline media. [ABSTRACT FROM AUTHOR]

In this paper cobalt oxide (Co 3 O 4) nanoparticles were mixed with polyacrylonitrile to prepare Co 3 O 4 doped carbon nanofiber (CNF) composite by electrospinning and carbonization, which was further used to modify on carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on Co 3 O 4 –CNF/CILE surface with Nafion acted as the protective film to fabricate an electrochemical biosensor (Nafion/Hb/Co 3 O 4 –CNF/CILE). Electrochemical behavior of Hb on the electrode was investigated with a pair of quasi-reversible redox peak appeared on cyclic voltammogram and electrochemical parameters were calculated. Moreover, this biosensor had good analytical capabilities for electrocatalytic reduction of different substrates including trichloroacetic acid, potassium bromate and sodium nitrite with wider detection range from 40.0 to 260.0 mmol L−1, 0.1 to 48.0 mmol L−1 and 1.0 to 12.0 mmol L−1 by cyclic voltammetry, respectively. The proposed method showed excellent anti-interferences ability with good selectivity and was successful used for quantitative detection of real samples, which displayed the potential applications to develop into a new analytical device. Image 1 • A cobalt oxide nanoparticle doped carbon nanofiber composite was synthesized for the design of electrochemical biosensor. • Direct electrochemical behaviors of hemoglobin were realized. • Electrocatalytic reduction to various substrates were investigated. [ABSTRACT FROM AUTHOR]

Carbon ionic liquid electrode (CILE) was used as the basic electrode, which was coated with nano-diamond (ND), myoglobin (Mb) and Nafion in sequence to construct a bioelectrochemical sensor (Nafion/Mb/ND/CILE). ND had the advantages of large specific surface area and useful electrochemical properties. Spectral analysis indicated that Mb was not denatured or inactivated after mixed with ND. Electrochemical behaviors of Mb on the modified electrode were checked by cyclic voltammetry with a pair of symmetric and quasi-reversible redox peaks exhibited, which proved the acceleration effect of ND to electron transfer of Mb. This Mb sensor displayed excellent electrocatalytic properties to the reduction of various substrates such as sodium nitrite, trichloroacetic acid and hydrogen peroxide with the detection range from 0.02 to 6.60 mmol/L, 1.1 to 30.0 mmol/L and 0.3 to 19.0 mmol/L, respectively. Real sample was detected by this sensor with satisfactory result. Therefore, ND showed potential application to construct third-generation electrochemical biosensor. Unlabelled Image • Electrochemical biosensor was designed with nanodiamond and myoglobin as modifiers. • Direct electrochemical behaviors of myoglobin were realized. • Electrocatalytic reduction to various substrates was investigated. [ABSTRACT FROM AUTHOR]