One-pot electrografting preparation of bifunctionalized carbon nanotubes for sensitive electrochemical immunosensing

Carbon nanomaterials such as multiwalled carbon nanotubes (MWCNT) have received intense interest in the field of electrochemical biosensing due to their unique electrical, optical, thermal, and mechanical properties. In general, biomolecule conjugation and attachment of an electrochemical probe are two key elements for preparing an electrochemical sensor. The above tasks are often achieved by a step-by-step reaction due to different reaction conditions. However, because of the low reactivity of MWCNT, it is challenging to precisely control the amount of the two modifiers on the MWCNT surface with sequential reactions. Herein, we report a one-pot electrografting procedure based on free-radical polymerization to attach both an electrochemical probe and a biomolecular coupling agent on MWCNT in a highly controlled manner. The ratio of the two modifiers was facilely regulated to balance the electrochemical signal intensity and the biomolecule conjugation, which played an important role in enhancing sensor performance. By taking alpha-fetoprotein (AFP) as a model analyte, the immunosensor based on bifunctionalized MWCNT showed a wide linear range from 10 ng·mL−1 to 50 μg·mL−1, which could greatly meet the actual requirement for liver cancer diagnosis. This work provides a new avenue for the construction of electrochemical biosensors with enhanced signal amplification for the fields of biosensing and clinical diagnosis. •An immunosensor was designed with one-pot electropolymerized bifunctionalized MWCNT.•Both probes and bio- coupling agents were attached to MWCNT with a controlled manner.•The modified MWCNT provided fast electron transfer and abundant sites for biomolecules.