A reliable upconversion (UC) material assembled from Au@Ag (UC@SiO2@Au@Ag), as the substrate, was firstly employed to detect hexamethylenetetramine (HMT) in bean vermicelli by surface enhanced Raman spectroscopy (SERS). In this substrate, UC can convert near-infrared (NIR) light into visible light to promote localized surface plasmon resonance (LSPR) of noble metal nanoparticles to enhance the SERS signal. According to optimized synthesis conditions, the SERS substrate was obtained and evaluated. The substrate shows uniformity with RSD of 7.05% and 7.37% for the Raman vibrations at ∼780 cm−1 and ∼1043 cm−1 respectively, and sensitivity with detection limits of 1 mg L−1 for HMT. Based on the better sensitivity of this method, the artificially positive samples have been detected.
