Fabrication of a new ECL biosensor for choline by encapsulating choline oxidase into titanate nanotubes and Nafion composite film

A simple strategy for encapsulating choline oxidase (ChOD) into the titanate nanotubes (TNTs) and Nafion composite film for choline sensing was proposed. Hydrogen peroxide, as the product of the redox enzymatic reaction, could enhance the ECL of luminol. Therefore, the substrates of corresponding redox enzymes could be detected indirectly through the determination of hydrogen peroxide in the luminol ECL system. Through this approach, it was found that ChOD could be fixed firmly into the TNTs contained composite film. TNTs would not only offer excellent photocatalytic activity toward luminol-H2O2 ECL system, but also provide a shelter for the biomolecules, such as redox enzyme to retain its bioactivity.