Facile detection of glucose in human serum employing silver-ion-guided surface-enhanced Raman spectroscopy signal amplification.

A facile surface-enhanced Raman scattering (SERS) sensor based on a silver-ion-mediated amplification effect was designed for the determination of glucose concentration. In this approach, 4-aminothiophenol (4-ATP) molecules assembled on the surface of a gold wafer (Au wafer@4-ATP) act not only as Raman tags but also as linkage agents. Silver nanoparticles marked with cysteamine (AgNP@cys) were used as the SERS enhancement components because they could be bound to the Au wafer@4-ATP in the presence of silver ions through the formation of N → Ag+ ← N coordination compounds. Here, the Ag+ ions were obtained by using glucose oxidase to catalyze the oxidation of glucose, producing hydrogen peroxide (H2 O2 ) to etch the AgNPs. Therefore, we recorded the SERS intensity of 4-ATP to determine the concentration of glucose in a phosphate buffer as low as 0.1 mM and further achieved a lowest detection of 0.5 mM glucose in human serum. These results show that the proposed approach has strong potential for practical applications.