Facile detection of glucose in human serum employing silver-ion-guided surface-enhanced Raman spectroscopy signal amplificationElectronic supplementary information (ESI) available: Additional information including TEM, UV-vis characterization of the Ag NPs, and SERS measurements from the sensor. See DOI: 10.1039/c7an00604g

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 (H 2 O 2 ) 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. Schematic of facile detection of glucose in human serum employing silver-ion-guided surface-enhanced Raman spectroscopy signal amplification.