Dendritic Ag@Cu bimetallic interface for enhanced electrochemical responses on glucose and hydrogen peroxide

Dendritic Ag@Cu core-shell bimetallic nano-composite in low-cost was prepared at room temperature by a mild single-step solution method, and was further investigated by various characterization methods like Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscope (AFM). The biosensors using dendritic Ag@Cu and ionic liquid (IL) as an electrochemical interface immobilizing glucose oxidase (GOx)/hemoglobin (Hb) were subsequently constructed for rapid detection of glucose/hydrogen peroxide (H2O2). The measurement results showed that the Ag@Cu significantly enhanced the electrochemical responses of GOx/Hb which remained their good bioactivity and high catalytic activity for glucose and H2O2. The developed biosensor has linear range of glucose concentration from 5 to 3000 μM with a detection limit of 3 μM and a linear range of H2O2 concentration from 0.5 to 50 μM with a detection limit of 0.3 μM (S/N = 3), respectively. Especially for H2O2, catalytic effect of the biosensor was better, whose detection limit was reduced by an order of magnitude. The enhanced performance of the biosensors can be attributed to the unique structure of dendritic Ag@Cu core-shell, whose Cu shell can immobilize GOx/Hb via dendritic spines as well as retain its bioactivity, while the synergetic effect of Cu shell, Ag cores and IL can facilitate the transfer of electron between GOx/Hb and electrode, prevent from the denaturation and leakage of GOx/Hb.