An application of Au-Ag alloy nanoparticles to glucose detection in the liquid phase was reported in this paper. The excellent biological compatibility of gold and silver has attracted attention to their use in glucose sensors. Alloy nanoparticles exhibit different electronic and optical properties from those of single metal nanoparticles. Although Au-Ag alloy nanoparticles can be synthesized using thermal liquid-phase reduction, precise temperature control is required for the synthesis. To overcome this issue, Au-Ag alloy nanoparticles were synthesized using a non-thermal liquid-phase reduction with a mixture of citric acid and tannic acid aqueous solution as the reducing agent in this study. The synthesized Au-Ag alloy nanoparticles exhibit a mean diameter of 9.1 nm and a coefficient of variation of 0.24, as determined by TEM image analysis. Additionally, a glucose detection test was conducted using the absorption spectra of a mixture of the synthesized Au-Ag alloy nanoparticles and a glucose aqueous solution. The glucose sensitivity was calculated based on the relation between the peak absorbance reduction and glucose concentration. The measured absorption spectra confirmed that the peak wavelength of Au-Ag alloy nanoparticles decreased with increasing glucose concentration, and the glucose sensitivity showed 0.107 /M for the Au-Ag alloy nanoparticles and 0.068 /M for the Au nanoparticles. These results found that the Au-Ag alloy nanoparticles exhibited 1.6 times higher sensitivity compared to the Au nanoparticles.
