An amperometric β-glucan biosensor based on the immobilization of bi-enzyme on Prussian blue–chitosan and gold nanoparticles–chitosan nanocomposite films

• Highly active nano-composite films were electrodeposited directly on the Au electrode.
• Nano-composite films display 3-D nature and uniform distribution.
• Bi-enzyme-based glucan biosensor was fabricated using biocompatible films.
• The synergy between nano-composites improved the performance of the biosensor.
• The fabricated biosensor exhibits a fast response to glucan.

A novel β-glucan biosensor was fabricated by immobilizing β-glucanase (β-G) with glucose oxidase (GOD) on nano-Prussian blue–chitosan (PB–CS) and gold nanoparticles–chitosan (AuNPs–CS) composites. Both the PB–CS and AuNPs_CS film were directly electrodeposited on the surface of gold electrode. The morphology of the AuNPs–CS/PB–CS nanocomposites was characterized by scanning electron microscope (SEM). The electrochemical behavior of the resulting sensor was investigated using cyclic voltammetry (CV) and amperometry. It was found that PB–CS nanocomposite exhibited an excellent electrocatalytic reduction towards hydrogen peroxide at a low applied potential window. The synergistic effect of AuNPs–CS/PB–CS nanocomposites could remarkably improve the performances of the biosensor. Under optimal conditions, the biosensor showed a wide linear range of 6.25–93.75 μM, with a correlation coefficient of 0.9991. The sensitivity at an applied potential of 0.0 V was 100 nA μM−1 cm−2, with a detection limit of 1.56 μM. The apparent Michaelis–Menten constant (Km) was found to be 1.0 mM, showed a high affinity of the immobilizing β-G for β-glucan. The biosensor displayed a rapid response (within 10 s) toward β-glucan, with a good selectivity and stability.