Controlled stepwise-synthesis of core–shell Au@MIL-100 (Fe) nanoparticles for sensitive surface-enhanced Raman scattering detection

Abstract

A novel porous Au@MIL-100 (Fe) core–shell structure in which a Au nanoparticle (AuNP) core is coated with a controllable uniform metal–organic framework shell has been fabricated by using a facile step-by-step procedure. The as-synthesized Au@MIL-100 (Fe) takes advantage of the high adsorption capability of the MIL-100 (Fe) shell and the localized surface plasmon resonance properties of the AuNP core, and was used as a hybrid surface enhanced Raman scattering (SERS) substrate. We discussed the fabrication, physical characterization, and SERS activity of our novel substrate, and found that this new substrate had controllable shell thickness, high stability and good SERS activity. The potential practical application of the novel SERS substrate was firstly evaluated by quantitative analysis of malachite green in aquaculture water. The method showed good linearity between 3.0 × 10⁻⁸–1.0 × 10⁻⁶ mol L⁻¹ for malachite green with a correlation coefficient of 0.9945. The limit of detection (LOD) was 8.0 × 10⁻⁹ mol L⁻¹. Then the applicability of Au@MIL-100 (Fe) as the SERS substrate for in situ detection of malachite green on the fish body indicated its great potential as a rapid and on-site detection analytical strategy. In addition, the preliminary investigation also shows that the Au@MIL-100 (Fe) has SERS activity toward carbon disulfide which would be a new strategy for SERS-based gas sensors.