Pt electrodes have been modified with electrospun titanium dioxide (TiO 2 ) nanofibers with controllable densities for electrochemical detection. The TiO 2 nanofiber/Pt electrodes show excellent electrocatalytic activity to electro-oxidation of hydrogen peroxide and the response current density to an addition of hydrogen peroxide is 30% higher than that for a Pt electrode. Glucose oxidase (GOx) molecules have been effectively immobilized on the surface of the TiO 2 nanofibers and the resulted chitosan/GOx/TiO 2 nanofiber/Pt electrodes with a optimum density of nanofibers exhibit excellent glucose bioelectrocatalytic performance including good amperometric current response (9.25 μA cm −2 mM −1 ), short response time (10 s) and low detection limit (0.01 mM). We have found that the nanofibers modified on the Pt electrode improved the sensitivity of the enzyme electrode to glucose for 2.7 times and extended the detection limit by one order of magnitude in comparison with flat Pt electrodes. It is expected that electrodes modified with electrospun TiO 2 nanofibers will find more promising applications in high performance electrochemical biosensors.
In this work, a label-free electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA). Flower-like Ag/MoS 2 /rGO nanocomposites were employed as the signal amplification platform of the designed immunosensor for the first time. Due to the synergistic effect between molybdenum disulfide (MoS 2 ), reduced graphene oxide (rGO) and Ag nanoparticles (NPs), Ag/MoS 2 /rGO nanocomposites could provide a high sensitivity for the label-free electrochemical immunosensor. The detection mechanism was based on the monitoring of the electrocatalytic current response change towards the reduction of hydrogen peroxide (H 2 O 2 ) when immunoreaction occurred on the surface of the electrode modified with Ag/MoS 2 /rGO nanocomposites. Using amperometric i-t curve to record the electrocatalytic process, the proposed immunosensor achieved an ultrasensitive and specific detection of CEA with a low detection limit of 1.6 fg/mL. Under optimal conditions, the fabricated immunosensor exhibited acceptable reproducibility, selectivity and excellent stability. This designed immunosensor could provide an effective method in the clinical diagnosis of other tumor markers.
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