Facile In-Situ photocatalytic reduction of AuNPs on multilayer Core-Shell Fe3O4@SiO2@PDA magnetic nanostructures and their SERS application

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 302; p. 123101
• Main Authors: Wu, Panfeng, Sun, Xiaoping, Hao, Nana, Wang, Li, Huang, Jian, Tang, Jianjiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.12.2023
• Subjects: Core-shell; Multilayer; Nanostructures; Photocatalytic; SERS; Photocatalytic; Nanostructures; Multilayer; SERS; Core-shell
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.123101

[Display omitted] •Novel multilayer core–shell magnetic SERS substrate was synthesized.•High-density gold nanoparticles were modified and loaded by photocatalysis.•Magnetic nanostructures SERS substrates with higher sensitivity and specificity.•Practicality and reliability were confirmed by detecting melamine. Surface-enhanced Raman scattering (SERS) is a promising analytical technique for the rapid, sensitive, and repeatable detection in various SERS application fields. Herein, a new type of potential magnetically recyclable SERS substrate was designed and rapidly synthesized via a facile three-step template method. First, the magnetic ferroferric oxide (Fe3O4) cores were prepared by a convenient solvothermal approach, and coated with a thin layer of silica by a sol–gel process in order to improve their stability in complicated environments. Next, the negatively charged polydopamine (PDA)/K6[SiW11VIVO40]·7H2O (PDA/SiW11V) outer shell was assembled upon the magnetic Fe3O4@SiO2 core–shell nanoparticles via a layer-by-layer sequential adsorption process using the stickiness of PDA. The SiW11V multilayer shell can be used as the subsequent photocatalytic reduction precursors for the in-situ loading of high-density gold nanoparticles (AuNPs), without any other organic additives. The AuNPs decorated multilayer core–shell Fe3O4@SiO2@PDA magnetic nanostructures were employed as a potential magnetically recyclable SERS substrate, and showed excellent SERS performance. Using crystal violet (CV) as a model target, the as-fabricated AuNPs modified multilayer core–shell Fe3O4@SiO2@PDA magnetic nanostructures SERS substrates exhibited significant enhancement, and pushed the detection limit down to 10-12 M. Aside from the ultrahigh sensitivity, these SERS substrates also possess an excellent reproducibility (relative standard deviation (RSD) ∼ 8.3%), long-term stability (75 days), and unique chemical stability capability in different organic solvents and different environments with pH ≤ 10. Furthermore, a real-life application is also performed by the detection of melamine in spiked milk solution using the as-prepared magnetic nanostructures SERS-active substrates (limit of detection (LOD), 10-8 M). These results highlight that the rational design and controllable synthesis of multifunctional magnetic SERS substrates is a promising strategy in many different application fields such as biosensing, photoelectrocatalysis, and medical diagnosis.