A wavelength-modulated localized surface plasmon resonance (LSPR) optical fiber sensor for sensitive detection of mercury(II) ion by gold nanoparticles-DNA conjugates

Publication date: 30 August 2018
Source:Biosensors and Bioelectronics, Volume 114
Author(s): Shuo Jia, Chao Bian, Jizhou Sun, Jianhua Tong, Shanhong Xia
The study presented herein investigated an easy preparation, high performance, wavelength-modulated LSPR optical fiber chemosensor coated by gold nanospheres(AuNS) for Hg²⁺ detection based on thymine-Hg²⁺-thymine base pair mismatches and the coupled plasmonic resonance effect.Utilizing electrostatic self-assembly method, the high density and dispersivity monolayer AuNS coated LSPR fiber sensor had the near field refractive index sensitivity up to 2016 nm/RIU. The single-strand probe DNA served as a binding element for free AuNS labelled-target DNA conjugates was attached to the monolayer AuNS by Au-S bond. In the present of Hg²⁺, the coupled plasmonic resonance band between monolayer AuNS and free AuNS was produced by thymine-Hg²⁺-thymine structure and leaded to red-shift of LSPR peak. Under the optimal conditions, the enlarged red-shift in peak of LSPR spectroscopy was linearly with the concentration of Hg²⁺ in the range from 1.0 × 10⁻⁹ to 5.0 × 10⁻⁸ M with the coefficient of 0.976. The limit of detection was 0.7 nM(S/N = 3). The specificity of the sensor was proved high by evaluating the response to other heavy metal ions. The proposed fiber sensor provided a label-free, miniature, low-cost approach for the Hg²⁺ detection and had potential in real environmental evaluations.



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