Abstract: Au-Ag bimetallic plasmonic nanostructures were successfully prepared by introducing silver into the nano gap of the gold nanoparticles（AuNPs） dimer based on the silver ion soldering method and the seed-mediated growth method. Due to the etching effect of H2O2 on the silver conductive junction which was formed by enzymatic oxidation of glucose, the charge transfer plasmon (CTP) would have a good response to glucose. Based on this, it could be applied to the detection of glucose. The relationship between glucose concentration and the intensity, wavelength of CTP peak，and surface enhanced Raman spectroscopy (SERS) intensity, as well as the selectivity of the sensor were investigated. The experimental results show that the method has high sensitivity and good selectivity towards glucose. Two linear relationships were identified between the CTP peak intensity change value and the glucose concentration in the range of 0.5～4 μmol/L and 4～10 μmol/L, respectively, with a limit of detection (3σ rule) reaching 0.2 μmol/L. The naked-eye detection of glucose can reach the micromolar level. The SERS also exhibited a linear response toward glucose, within the concentration range of 1～10 μmol/L.

Key words: plasmonic nanostructure, charge transfer plasmon, optical sensing, glucose