Potentiometric glucose biosensor based on core–shell Fe3O4–enzyme–polypyrrole nanoparticles

• Core–shell Fe3O4–GOD–Ppy nanoparticles with excellent magnetism and conductivity were synthesized.
• Fe3O4–GOD–Ppy nanoparticles were modified onto MGCE through magnetism immobilization.
• A novel potentiometric biosensor with high activity and stability was developed.
• The constructed biosensor exhibited excellent performance for glucose determination.

Core–shell Fe3O4–enzyme–polypyrrole (Ppy) nanoparticles with excellent magnetism and conductivity were successfully prepared via the surface modification and enzyme self-encapsulation within Ppy. A novel potentiometric glucose biosensor has been constructed by effectively attaching the proposed Fe3O4–enzyme–Ppy nanoparticles to the surface of the magnetic glassy carbon electrode (MGCE). The optimum biosensing conditions could be provided with polymerization time of pyrrole for 6 h and 0.42 mg immobilization amount of Fe3O4–enzyme–Ppy nanoparticles on MGCE. The performance of the developed glucose biosensor was evaluated and the results indicated that a sensitive glucose biosensor could be fabricated. The obtained glucose biosensor presents shorter response time (6 s), wider linear range (0.5 μM to 34 mM), lower limit of detection (LOD, 0.3 μM), high-selectivity monitoring of glucose and good stability (with about 98.1% of the initial response signal retained after 20 days). The analytical application of the glucose biosensor confirms the feasibility of glucose detection in serum sample.