The unmediated choline sensor based on layered double hydroxides in hydrogen peroxide detection mode

In this work, we have developed a novel choline biosensor on the basis of immobilization of choline oxidase (ChOx) by the attractive materials layered double hydroxides (LDHs). Amperometric detection of choline was evaluated by holding the modified electrode at 0.5 V (vs. SCE). Due to the special properties of LDHs ([Zn₃-Al-Cl]), such as chemical inertness, high porosity, and swelling property, the [Zn₃-Al-Cl]/ChOx modified electrode exhibited an enhanced analytical performance. The biosensor provided a linear response to choline over a concentration range from 3.7 × 10⁻⁶ to 6.3 × 10⁻⁴ M with a low detection limit of 3 × 10⁻⁷ M based on S/N=3. The apparent Michaelis-Menten constant was calculated to be 1.38 mM. In addition, the interaction between ChOx and LDHs has also been investigated using FT-IR spectroscopy.