Abstract
A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources.
Highlights
Malachite green (MG) is a popular cationic triphenylmethane dye and has widely been used in the silk, dye, leather and textile industry[1]
These results proved that nanosilver layer has been successfully grown on the surface of magnetic particles
Scanning electron microscopy (SEM) image showed that the as-prepared magnetic particles were spherical with a mean diameter of 645 ± 40 nm (Fig. 1d)
Summary
In this case, the LOD was determined to be 2 × 10−15 mol/L by using 3σ /S calculation parameter (average standard deviation of measurements (σ ) and the slope of the dose-response (S) fitting curve). The SERS signal intensity of magnetic particles washed by HCl solution is very low, indicating the complete removal of the MG adsorbed on magnetic particles (Fig. 5). The silver-coated magnetic particles could be readily regenerated as SERS substrate using low pH acid to perform multiple sensing events, which makes it the defined protocol a low-cost technique In additional, this proposed method was successfully employed to determine MG in several spiked environmental samples without obvious matrix effect. We only demonstrated the detection of MG, we envisioned that the demonstrated strategy had great potential in the ultrasensitive analysis and effective removal of other dyes and small molecules, which satisfied the high demand for ensuring the safety of water sources
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