Facile and sensitive glucose sandwich assay using in situ-generated Raman reporters.

A facile and sensitive glucose sandwich assay using surface-enhanced Raman scattering (SERS) has been developed through the use of the self-assembled p-mercaptophenylboronic acid (PMBA) monolayer on a smooth gold-coated slide and the SERS tags of Ag nanoparticles (AgNPs) modified with p-aminothiophenol (PATP) and PMBA. The photocoupling product 4,4'-dimercaptoazobenzene (DMAB), generated in situ from PATP on the AgNP surface during the SERS measurement, possessed considerably intense characteristic SERS peaks and acted as the actual Raman reporter, which improved the sensitivity of glucose detection devoid of interference of other biomolecules. The facile sandwich assay showed a high selectivity of glucose over fructose and galactose. This facile, sensitive, and selective SERS-based glucose sandwich assay can be developed into a diagnostic tool for determination of glucose levels.