TiO2 sol/graphene modified 3D porous Ni foam: A novel platform for enzymatic electrochemical biosensor

Abstract An integrated system based on nickel foam (Ni foam), titanium dioxide sol/graphene nanocomposite and lactate oxidase (LOx) has been successfully developed for the sensing of lactate. A TiO 2 /graphene nanocomposite was readily synthesized and coated on a 3D porous Ni foam electrode to develop a novel electrode in an electrochemical biosensor. The as-prepared nanocomposite and the modified Ni foam were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to verify the well intercalation of graphene within TiO 2 sol and successful coating of such nanocomposite on Ni foam surface, respectively. Comparing with an unmodified Ni foam, TiO 2 sol/graphene modified Ni foam offered a drastic increase in current response signal (a 28-fold) toward H 2 O 2 detection, suggesting a potential application of this system as a sensitive electrochemical sensor. Then, LOx was immobilized onto the modified electrode for lactate sensor via H 2 O 2 detection. Interestingly, the combination between graphene and TiO 2 sol enhanced both sensitivity and stability of this sensor. A wide linear range of 50 μM to 10 mM with a detection limit of 19 μM was obtained for lactate without interfering effect from ascorbic acid, dopamine, and glucose. This platform was sensitive enough for early diagnosis of severe sepsis and septic shock via the detection of concerned lactate level. Eventually, it was successfully applied to detection of lactate in a complex biological fluid.