Accurate SERS detection of malachite green in aquatic products on basis of graphene wrapped flexible sensor

• Published in: Analytica chimica acta 2018-10, Vol.1027, p.83-91
• Main Authors: Ouyang, Lei, Yao, Ling, Zhou, Taohong, Zhu, Lihua
• Format: Article
• Language: English
• Subjects: Accuracy; Accurate detection; Aquaculture; Aquaculture products; Bleaching; Fish; Flexible components; Flexible sensor; Graphene; Graphene wrapped Ag array; Graphite; Inspection; Leucomalachite green; Leukocytes; Malachite green; Organic chemistry; Pesticides; Raman spectra; Reproducibility; Scattering; Sensor arrays; Sensors; Surface chemistry; Surface enhanced Raman scattering
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2018.04.052

Malachite Green (MG) is a banned pesticide for aquaculture products. As a required inspection item, its fast and accurate determination before the products' accessing market is very important. Surface enhanced Raman scattering (SERS) is a promising tool for MG sensing, but it requires the overcoming of several problems such as fairly poor sensitivity and reproducibility, especially laser induced chemical conversion and photo-bleaching during SERS observation. By using a graphene wrapped Ag array based flexible membrane sensor, a modified SERS strategy was proposed for the sensitive and accurate detection of MG. The graphene layer functioned as an inert protector for impeding chemical transferring of the bioproduct Leucomalachite Green (LMG) to MG during the SERS detection, and as a heat transmitter for preventing laser induced photo-bleaching, which enables the separate detection of MG and LMG in fish extracts. The combination of the Ag array and the graphene cover also produced plentiful densely and uniformly distributed hot spots, leading to analytical enhancement factor up to 3.9 × 108 and excellent reproducibility (relative standard deviation low to 5.8% for 70 runs). The proposed method was easily used for MG detection with limit of detection (LOD) as low as 2.7 × 10−11 mol L−1. The flexibility of the sensor enable it have a merit for in-field fast detection of MG residues on the scale of a living fish through a surface extraction and paste transferring manner. The developed strategy was successfully applied in the analysis of real samples, showing good prospects for both the fast inspection and quantitative detection of MG. [Display omitted] •A new flexible SERS sensor was proposed for the sensitive and accurate detection of MG.•The sensor was fabricated by wrapping closely assembled Ag array with graphene layer.•The graphene impeded the chemical transferring between LMG to MG and the photo-bleaching effect.•Good sensitivity and accuracy was received for MG and LMG detection.•The developed strategy was successfully applied in the analysis of MG in real fish samples.