Use of seed-mediated growth of bimetallic nanorods as a knob for antioxidant assay

Seed-mediated growth has been proved to be a powerful means in the controlled synthesis of nanomaterials. In this work, using Au nanorods (AuNRs) as seeds, we successfully apply the principle of seed-mediated growth of bimetallic NRs in antioxidant assay. Specifically, evolution of the analytical probe from AuNRs to Au@Ag core-shell NRs is well regulated by seed-mediated growth, where trace amount of antioxidants play important roles in this process. Based on the localized surface plasmon resonance (LSPR) shift that directed by this evolution, a simple, reliable, highly sensitive and selective analytical method for antioxidant is developed. According to the linear relationship between LSPR peak shift and the concentration of antioxidant, the present method achieves a detectable range of 0.01-30 μM, with a limit of detection as low as 6.4 nM. Moreover, it has also been successfully applied in the detection of antioxidants in green tea. This work provides new insights into establishing sensitive sensing methods through precisely manipulating the evolution of analytical probe by seed-mediated growth.