Efficient concentration of trace analyte with ordered hotspot construction for a robust and sensitive SERS platform

Surface enhanced Raman scattering (SERS) enabled trace molecules detection has important application prospects. By structuring/modifying the surface of SERS substrate, molecules in highly-diluted solution can be concentrated into localized active area for highly sensitive detection. However, subject to the difficulty of fabrication process, it remains challenging to balance hot-spots construction and concentration capacity to molecules simultaneously. Therefore, preparing SERS substrate with dense ordered hot-spots and efficient concentration capacity is of great significance for highly sensitive detection. Herein, we propose the Ag and fluoroalkyl modified hierarchical armour substrate (Ag/F-HA), which has a double-layer stacking design to combine analyte concentration with hotspot construction. The micro armour structure fabricated by femtosecond-laser processing to serve as a superhydrophobic and low-adhesive surface to concentrate molecules, while anodic aluminum oxide (AAO) template creates nanopillars array serving as dense and ordered hot spots. Under the synergy action of hot-spots and molecule concentration, Ag/F-HA achieves the detection limit down to 10−7 M of Doxorubicin (DOX) molecules with a relative standard deviation (RSD) of 7.69%. Additionally, Ag/F-HA exhibits the excellent robustness to resist external disturbance such as liquid splash or abrasion. Based on our strategy, the SERS substrates with directional analyte concentration are further explored by patterning microcone array with a defect. This work opens a way to the realistic implementation of SERS in diverse scenarios.