Preparation and application of a novel vanillin sensor based on biosynthesis of Au–Ag alloy nanoparticles

In this work, Au–Ag alloy nanoparticles were biosynthesized by yeast cells and applied to fabricate a sensitive electrochemical vanillin sensor. Fluorescence microscopic and transmission electron microscopic characterizations indicated that the Au–Ag alloy nanoparticles were mainly synthesized via an extracellular approach and generally existed in the form of irregular polygonal nanoparticles. Electrochemical investigations revealed that the vanillin sensor based on Au–Ag alloy nanoparticles modified glassy carbon electrode was able to enhance the electrochemical response of vanillin for at least five times. Under optimal working conditions, the oxidation peak current of vanillin at the sensor linearly increased with its concentration in the range of 0.2–50 μM with a low detection limit of 40 nM. This vanillin sensor was successfully applied to the determination of vanillin from vanilla bean and vanilla tea sample, suggesting that it may have practical applications in vanillin monitoring system.