One-step method to prepare coccinellaseptempunctate-like silver nanoparticles for high sensitivity SERS detection

The surface morphology of metal particles can be adjusted by the annealing process to enhance the activity of Raman substrate and achieve an ultra-low concentration detection limitation. In this study, a surface-enhanced Raman scattering (SERS) substrate of coccinellaseptempunctate-like silver nanospheres coated with a silver nanoisland structure (Ag NI@Ag NSs) was prepared using a simple annealing process. Numerous silver nanospheres were dispersed on the surface of the silver nanoislands, which exhibited a single crystal plane (111) orientation. The SERS substrate had an enhancement factor of 108 for Rhodamine B (Rh B) and was highly sensitive to phosphoethanolamine (PETA). The SERS response toward PETA showed excellent correlation during the range of 5 × 10−7 - 1 × 10−5 mol/L with the detection limitation as low as 5 × 10−7 mol/L, and the correlation coefficient is 0.9918. The simulated high-pressure test showed that the SERS response could be still observed at 1100 m sub ocean pressure even with a PETA concentration of 1 mM. The test results of selectivity, reproducibility, and accuracy indicated that the Ag NI@Ag NS sensor possessed potential applications in the deep-sea analytical and other related fields.