title: Hierarchically assembled NiCo@SiO2@Ag magnetic core-shell microspheres as highly efficient and recyclable 3D SERS substrates.
abstract: The hierarchically nanosheet-assembled NiCo@SiO2@Ag (NSA) core-shell microspheres have been synthesized by a layer-by-layer procedure at ambient temperature. The mean particle size of NSA microspheres is about 1.7 μm, which is made up of some nanosheets with an average thickness of ∼20 nm. The outer silver shell surface structures can be controlled well by adjusting the concentration of Ag(+) ions and the reaction times. The obtained NSA 3D micro/nanostructures show a structure enhanced SERS performance, which can be attributed to the special nanoscale configuration with wedge-shaped surface architecture. We find that NSA microspheres with nanosheet-assembled shell structure exhibit the highest enhancement efficiency and high SERS sensitivity to p-ATP and MBA molecules. We show that the detection limits for both p-ATP and MBA of the optimized NSA microsphere substrates can approach 10(-7) M. And the relative standard deviation of the Raman peak maximum is ∼13%, which indicates good uniformity of the substrate. In addition, the magnetic NSA microspheres with high saturation magnetization show a quick magnetic response, good recoverability and recyclability. Therefore, such NSA microspheres may have great practical potential applications in rapid and reproducible trace detection of chemical, biological and environment pollutants with a simple portable Raman instrument.
authors.affiliation: Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, 230031, P. R. China. awzhao@iim.ac.cn.
authors.forename: Maofeng
authors.initials: M
authors.lastname: Zhang
authors.forename: Aiwu
authors.initials: A
authors.lastname: Zhao
authors.forename: Dapeng
authors.initials: D
authors.lastname: Wang
authors.forename: Henghui
authors.initials: H
authors.lastname: Sun
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry; D008280:Magnetics; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008863:Microspheres; D009532:Nickel / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D004785:Environmental Pollutants; D058185:Magnetite Nanoparticles; C062136:nickel copper alloy; D012834:Silver; D012822:Silicon Dioxide; D003300:Copper; D009532:Nickel; D000255:Adenosine Triphosphate