Electrodeposition of alginate–MnO₂–C composite film on the carbon ionic liquid electrode for the direct electrochemistry and electrocatalysis of myoglobin

Since the direct electron transfer of myoglobin (Mb) is hardly realized on the bare electrode, the electrodeposition of the mixture of novel MnO₂–C composite microsphere, sodium alginate (SA) and Mb on the surface of the carbon ionic liquid electrode (CILE) was conducted to fabricate the modified electrode, denoted as Nafion/Mb–SA–MnO₂–C/CILE. The biological activity of Mb in the Mb–SA–MnO₂–C composite was confirmed by FTIR and UV–Vis absorption spectra. The fabricated Nafion/Mb–SA–MnO₂–C/CILE exhibited a fast electron transfer process with a pair of well-defined redox peaks attributed to the excellent electrochemical property of MnO₂–C composite microsphere and good biocompatibility of SA that could provide Mb suitable microenvironment to keep its biological activity and facilitate the electron transfer. Additionally, the modified electrode also exhibited a wider linear range and a low detection limit toward the electrocatalytic reduction in trichloroacetic acid with good stability, reproducibility and accurate detection for the real samples.