Fabrication of SERS substrates containing dense “hot spots” by assembling star-shaped nanoparticles on superhydrophobic surfaces

Abstract

In this work, efficient SERS substrates containing dense hot spots were fabricated by assembling AuNS@Ag on SMCSL superhydrophobic platforms, based on an evaporation assembly technique. Scanning electron microscopy images and Raman images revealed that star-shaped nanoparticles were closely packed on to the SMCSL surfaces, giving rise to a high density of hot spots. The as-prepared AuNS@Ag/SMCSL substrates exhibited higher SERS enhancement than AuNPs/SMCSL substrates. Furthermore, the SERS substrates showed low detection limits to Nile Blue A (10⁻¹² M) with a high analytical enhancement factor of 6 × 10⁹, and excellent signal reproducibility (RSD ∼ 6.3%). Moreover, the results of simulated electric field distribution also proved that there was higher SERS enhancement of the SERS substrates based on the star-shaped particles. Additionally, ultrasensitive detection of OPD, 6-TG, and HGB demonstrated that the AuNS@Ag/SMCSL substrates possessed the capability of trace-level detection for realistic molecules.