Improved enzyme immobilization for enhanced bioelectrocatalytic activity of choline sensor

In this work, we report the development of a highly sensitive and stable choline sensor based on the synergetic effect of multi-walled carbon nanotubes and ZnO nanoparticles. This unique multi-layer structure provided a favorable microenvironment to maintain the bioactivity of choline oxidase, which led to a rapid amperometric response to choline. This nanomaterials-based choline sensor was highly sensitive and showed good stability over a relatively long-term storage (90 days). The sensor prepared by loading 1.0-unit choline oxidase showed a linear response range of 1.0 mu M to 0.8 mM, a sensitivity of 178 mu A mM(-1) cm(-2) and a detection limit of 0.3 mu M. The sensor prepared was used to detect choline in human blood plasma samples, and the obtained results were consistent with those of the HPLC-MS/MS assay.