Selective and sensitive SERS sensor for detection of Hg²⁺ in environmental water base on rhodamine-bonded and amino group functionalized SiO₂-coated Au–Ag core–shell nanorods

Abstract

Here, we designed a new type of SERS sensor with high selectivity and sensitivity for the determination of Hg 2+ at picomolar concentrations based on hydrolysis reactions. The Rhodamine 6G-derived Schiff base bonded and amino group functionalized SiO 2 -coated Au-Ag core-shell nanorods (Au@Ag@SiO 2 -NH 2 -R6G, NR-Rs), which show extraordinary enhancement factors (EF) and good stability, were employed as the SERS substrate of the sensor. The tunable ability of the chemical bonding of the substrate generates appropriate probe molecules bound to the surface of the nanorods (NRs) and improves the selectivity and sensitivity of the SERS sensor dramatically. The limit of detection (LOD) of Hg 2+ obtained using the present SERS sensor was 0.33 pmol L À1 . Furthermore, the proposed substrate has pH-responsive ability.The present sensor is suitable for the on-site determination of pH and Hg 2+ by combining with a portable Raman spectrometer.

Rapid detection of mercury contamination in water by surface enhanced Raman spectroscopy

“…10,11 Many examples of SERS detection of Hg(II) in water were demonstrated recently in literature. [12][13][14] In these examples various approaches were adopted for the metal ion detection, such as the use of Raman reporters or the utilisation of the thymidine-Hg(II)-thymidine coordination chemistry. 10 Generally, metal ions are known to have small Raman scattering cross-section with no vibrational modes making their direct detection by SERS difficult.…”

A tunable nanopore sensor for the detection of metal ions using translocation velocity and biphasic pulses

“…Such materials can include carbon nanotubes, 1,2 nanorods 3 and nanoparticles of copper 4 , gold, 5 magnetic, 6 and silica. 7 These systems can be designed to produce a signal upon binding to the metal ion or integrated into detection platforms such as atomic adsorption, [8][9][10][11] electrochemical assays, 1,12,13 fluorescence 4,14 and colorimetric sensors 15,16 .…”

Shell‐Isolated Nanoparticle‐Enhanced Raman and Fluorescence Spectroscopies: Synthesis and Applications

“…Functionalized shells can be prepared by coating special polymer shell on plasmonic nanoparticles or decorating the SiO 2 with molecules or ions. The detection of trinitrotoluene, heavy metal ion (Hg 2+ ), pesticide residues, and many other kinds of target analytes in food or biological samples can be realized using this strategy . Xie and co‐workers synthesized an iodide modified Au@SiO 2 nanoparticles and tried to specify pesticide residues in biologic fluid.…”

“…Xie and co‐workers synthesized an iodide modified Au@SiO 2 nanoparticles and tried to specify pesticide residues in biologic fluid. [70b] When the Au@SiO 2 nanoparticle surface was decorated with iodide, the modified SHINs could effectively attract analysts through electrostatic attraction. Through this method, a rapid detection of paraquat was realized with a portable Raman spectrometer, giving a limit of detection (LOD) of 1 µg L −1 .…”

“…Yang and co‐workers coated the Au nanoparticles with poly‐(2‐aminothiophenol) shell retaining amino group on the surface. [70c] TNT molecules could be selectively captured by forming Meisenheimer complexes with the polymer shell. By adjusting the molar ratio of sodium dodecylsulfate to 2‐aminothiophenol, the polymer shell thickness could be tuned to 2 nm to achieve a higher sensitivity.…”