Visual detection of glucose using triangular silver nanoplates and gold nanoparticles

A sensitive spectrophotometric detection of glucose based on triangular silver nanoplates (Ag TNPs) coupled with gold nanoparticles (Au NPs) was carried out. Relying on the glucose oxidase (GOD) mimetics of small Au NPs, glucose was catalytically oxidized in the presence of oxygen. The product of H2O2 then induced the etching of Ag TNPs from triangular to round, which led to blue-shifting of the peak wavelength and a decrease of the absorbance. The color changes of the solution could be used for visual detection (from dark blue to light pink) of glucose by the naked eye. The blue-shift of the peak wavelength was linear proportional to the glucose concentration in the range from 0.5 to 20 μM with a detection limit of 0.3 μM. The high sensitivity of the method is due to the highly reactive tips and strong tip sharpness of Ag TNPs. Moreover, the effect of L-cysteine (Cys) assembled on metal nanomaterials was investigated in the system.