Direct electrochemistry of myoglobin on TiO2 and alginate composite modified carbon ionic liquid electrode via the electrodeposition method

In this work, electrodeposition of the mixture of myoglobin (Mb), sodium alginate (SA), and TiO 2 nanoparticles on the carbon ionic liquid electrode (CILE) was performed to fabricate the modified electrode which was abbreviated as Nafion/Mb-SA-TiO 2 /CILE. FT-IR and UV-vis absorption spectra confirmed that Mb could retain its native structure after being immobilized in the SA-TiO 2 composite film. The electrochemical characterization of Nafion/Mb-SA-TiO 2 /CILE revealed that a pair of symmetric redox peaks appeared in the cyclic voltammograms, indicating that direct electron transfer of Mb was realized on the modified electrode. The good biocompatibility of SA, the good electrocatalytic capability of TiO 2 nanoparticles, and their synergistic effects were beneficial to the electron transfer between Mb and CILE. The electrochemical parameters of the electron transfer number ( n ), the charge transfer coefficient ( α ), and the electron transfer rate constant ( k s ) were calculated as 1.032, 0.402, and 0.511 s −1 , respectively. The modified electrode exhibited good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) and displayed wide linear range from 5.3 to 114.2 mmol/L and low detection limit as 0.152 mmol/L (3 σ ). The apparent Michaelis-Menten constant K M app was 32.3 mmol/L. The proposed electrode with good stability and reproducibility had the potential application in the third-generation electrochemical biosensors.