Highly efficient biosensors by using well-ordered ZnO/ZnS core/shell nanotube arrays

We have studied the fabrication of highly efficient glucose sensors using well-ordered heterogeneous ZnO/ZnS core/shell nanotube arrays (CSNAs). The modified electrodes exhibit a superior electrochemical response towards ferrocyanide/ferricyanide and in glucose sensing. Further, the fabricated glucose biosensor exhibited good performance over an acceptable linear range from 2.39 x 10(-5) to 2.66 x 10(-4) mM, with a sensitivity of 188.34 mAmM(-1) cm(-2), which is higher than that of the ZnO nanotube array counterpart. A low limit of detection was realized (24 mu M), which is good compared with electrodes based on conventional structures. In addition, the enhanced direct electrochemistry of glucose oxidase indicates the fast electron transfer of ZnO/ZnS CSNA electrodes, with a heterogeneous electron transfer rate constant (Ks) of 1.69 s(-1). The fast electron transfer is attributed to the high conductivity of the modified electrodes. The presented ZnS shell can facilitate the construction of future sensors and enhance the ZnO surface in a biological environment.