Rapid synthesis of a highly active and uniform 3-dimensional SERS substrate for on-spot sensing of dopamine.

A rapid method is described for the preparation of a highly uniform and sensitive SERS substrate by an improved 'drop-and-dry' method. Gold nanobipyramids (Au NBPs) were prepared inside the nanoholes (nanowalls) of anodic aluminum oxide (AAO) templates with a typically 5-μm nanohole depth. The SERS substrate can be prepared by this method within 40 s and on large scale. The SERS signals obtained with this Au NBPs-AAO substrate is stronger by four-orders of magnitude compared to conventional a silicon wafer substrate. The SERS signal for dopamine (DA; measured at 1311 cm-1) is found to be enhanced by a factor of 2.2 × 108. The response to DA extends from 10 nM to 0.1 mM, and the limit of detection is 6.5 nM (at S/N = 3). The assay was applied to the determination of DA in spiked human serum. Graphical abstract Schematic presentation of a highly active and uniform 3-dimensional substrate composed of gold nanobipyramids and anodic aluminum oxide (Au NBP/AAO). It was used for on-spot sensing of dopamine.