The seeded-synthesis of core–shell Au dumbbells with inbuilt Raman molecules and their SERS performance

Abstract

Core-shell Au dumbbells with inbuilt Raman molecules were synthesized by a seeded reduction method using core–shell Au nanorod (NR)@PSPAA nanoparticles as the seed. Most of the NRs finally maintained two secondary growth caps on the ends, showing a dumbbell-like shape. The lengths of the NRs were from 350 to 450 nm and the diameters of the caps were about 95 ± 20 nm. Due to the existence of “hot spots” around their caps, where the inbuilt Raman molecule 2-naphthalenethiol (2NT) also presents, the Au dumbbells exhibited significant SERS activity with an enhancement ratio of about 2, compared with AuNR@PSPAA. The Au dumbbells also showed excellent stability with a decrease ratio of 34.6% for SERS intensity after one month attributed to the encapsulation of 2NT by the PSPAA shell. The relative standard deviations of SERS peaks at 1066, 1382, and 1624 cm⁻¹ were 5.64%, 6.05%, and 6.80%, which indicates good homogeneity of the Au dumbbells. Therefore, such Au dumbbells may have great practical applications in reproducible quantitative SERS-based detection of chemical and biological pollutants.