Multiwalled Carbon Nanotubes/Gold Nanoparticles Hybrid Electrodes for Enzyme-Free Electrochemical Glucose Sensor

We followed a facile strategy to fabricate glucose sensors using mildly oxidized multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs) and thiol acids including mercaptoacetic acid (MAA), mercaptopropionic acid (MPA), and mercaptosuccinic acid (MSA). The thiol acids separately bonded to MWCNTs anchored AuNPs of average diameter 14 nm, and yielded three different nanohybrids; MWCNTs-MAA-AuNPs, MWCNTs-MPA-AuNPs and MWCNTs-MSA-AuNPs. The nanohybrids after coating onto glassy carbon (GC) electrode resulted into enzyme free glucose sensors (GC-MWCNTs-MAA-AuNPs, GC-MWCNTs-MPA-AuNPs and GC-MWCNTs-MSA-AuNPs). Their electrocatalytic glucose sensing ability was examined through cyclic voltammetry and amperometry. GC-MWCNTs-MSA-AuNPs electrode showed high stability and activity in the electrocatalytic oxidation of glucose compared to other two sensors. It also showed a wide range of response for glucose concentration from 0.12 to 4.0 μM, and low detection limit of 0.036 μM (S/N = 3). The optimum rate of applied potential was 0.8 V/s, which proves the effective sensing of glucose. The selective sensing of glucose in the presence of H₂O₂, uric acid and blood cancer drug (imatinib mesylate) was verified through amperometry. The electrode can be a new addition to glucose sensors and bioanalytical techniques.