A facile SERS strategy for quantitative analysis of trace glucose coupling glucose oxidase and nanosilver catalytic oxidation of tetramethylbenzidine.

Highly stable, SERS active and catalytic nanosilver sol (AgNP) was synthesized under the exposure of light wave, using AgNO3 as precursor and sodium citrate as reducer. Under the conditions of pH 7.0 NaH2PO4-Na2HPO4 buffer solution (PBS), the glucose can be catalyzed by glucose oxidase to produce H2O2 specifically. Based on the nanocatalyst and SERS substrate of AgNP, H2O2 can oxidize the 3,3',5,5'-tetramethylbenzidine (TMB) quickly to form a blue oxidation product (TMBox) that induced the AgNPs aggregation, which exhibited a strong SERS signal at 1606 cm-1. As the concentration of glucose increases, the TMBox molecular probes and AgNPs aggregation increase, and the intensity of SERS peak at 1606 cm-1 increase linearly. Thus, a new SERS strategy for quantitative analysis of 0.33-6.67 μmol/L glucose was developed, with a detection limit of 0.035 μmol/L, coupled the catalysis of nanosilver with glucose oxidase, and label-free molecular probe of TMBox.