It is very vital to construct the dense hot spots for the strong surface-enhanced Raman scattering (SERS) signals. We take full advantage of the MoS edge-active sites induced from annealing the Ag film on the surface of the MoS. Furthermore, the composite structure of Au-Ag bi-metal nanoparticles (NPs)/MoS hybrid with pyramid structure is obtained by the in situ grown AuNPs around AgNPs, which serves the optimal SERS performance (enhancement factor is ~9.67 × 10) in experiment. Due to the introduction of AuNPs with the simple method, the denser hot spots contribute greatly to the stronger local electric field, which is also confirmed by the finite-different time-domain (FDTD) simulation. Therefore, the ultralow limit of detection (the LOD of 10 and 10 M respectively for the resonant R6G and non-resonant CV), quantitative detection and excellent reproducibility are achieved by the proposed SERS substrate. For practical application, the melamine molecule is detected with the LOD of 10 M using the proposed SERS substrate that has the potential to be a food security sensor.
An Au film/graphene D-shaped plastic optical fiber (D-POF) functionalized with dopaminebinding aptamer (DBA) was proposed to achieve a sensitive and specific detection of the small molecule dopamine. The surface plasmon resonance sensor combines the virtues of a D-shaped fiber, the transfer of graphene via gold film, and the amplification of the refractive index with the conformational transformation of DBA. The sensitivity of the Au film/graphene D-POF sensor (1539 nm/RIU) is higher than that without graphene in ethanol solution. The dopamine concentrations of 10 −10 M to 10 −6 M were measured. And the decoration of DBA onto graphene for dopamine detection with a good linearity was verified in experiments. The proposed sensor possesses high sensitivity and specificity, which will provide good application prospects for the development of biosensing in disease treatment.
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