Highly sensitive glucose biosensor based on Au–Ni coaxial nanorod array having high aspect ratio

• We report a highly sensitive glucose biosensor based on an Au–Ni coaxial nanorod array.
• The biosensor could operate in a linear range of 27.5 μM–27.5 mM with a detection limit of 5.5 μM and a very high sensitivity of 769.6 μA mM−1 cm−2.
• The proposed nanorod array electrode demonstrated good selectivity.
• Long-term stability was examined through successive detections over a period of 30 days.

An effective glucose biosensor requires a sufficient amount of GOx immobilizing on the electrode surface. An electrode of a 3D nanorod array, having a larger surface-to-volume ratio than a 2D nanostructure, can accommodate more GOx molecules to immobilize onto the surface of the nanorods. In this study, a highly sensitive Au–Ni coaxial nanorod array electrode fabricated through the integration of nano electroforming and immersion gold (IG) method for glucose detection was developed. The average diameter of the as-synthesized Ni nanorods and that of the Au–Ni nanorods were estimated to be 150 and 250 nm, respectively; both had a height of 30 μm. The aspect ratio was 120. Compared to that of a flat Au electrode, the effective sensing area was enhanced by 79.8 folds. Actual glucose detections demonstrated that the proposed Au–Ni coaxial nanorod array electrode could operate in a linear range of 27.5 μM–27.5 mM with a detection limit of 5.5 μM and a very high sensitivity of 769.6 μA mM−1 cm−2. Good selectivity of the proposed sensing device was verified by sequential injections of uric acid (UA) and ascorbic acid (AA). Long-term stability was examined through successive detections over a period of 30 days.