Surface-enhanced Raman spectroscopy based on thioglycolic acid (TGA) functionalized silver-coated gold nanoparticles (Au@Ag-TGANPs) was developed for the facile screening of thiabendazole (TBZ) and ferbam (0.025–10 ppm) in liquid milk for the first time. Results showed that silver-coated gold nanoparticles (Au@AgNPs) with a core size of 32 nm and a shell thickness of 5 nm was successfully modified with 3 nm TGA. The sensitive Au@Ag-TGANPs could enhance TBZ and ferbam signals by factors of 6.4 × 10 4 and 9.8 × 10 4 , respectively, and achieved the detection of TBZ and ferbam with limits of detection of 0.12 and 0.003 ppm, R 2 of 0.988 and 0.9821, percent recoveries of 88–103% and of 87.2–103.5%, and relative standard deviations of 4.1–9.2% and 3.5–8.3%, respectively. The current simple and green method could thus be used to detect other unsafe chemicals in future studies.
Chuhong Zhu,Qiangsheng Zhao,Dexian Huo,Xiaoye Hu,Xiujuan Wang
We report a simple electrodeposition strategy to fabricate highly surface-roughened Au nanostructure arrays grown on a silicon wafer . Finite element method simulation reveals that lots of hot spots were generated around the tips of nanothorns and in the gaps between neighboring nanothorns by both plasmon coupling and ‘‘lightning-rod’’ effects. It was found that roughening the as-electrodeposited Au nanocones by a subsequent second-step electrodeposition induced a six times improvement in SERS intensity. The peak intensities of SERS spectra show a narrow distribution with a small relative standard deviation of 6.6%, confirming the high uniformity of the fabricated thorny Au nanostructure array SERS substrate. A high SERS sensitivity of the fabricated thorny Au nanostructure arrays was confirmed by a detectable concentration limit of 1 pM rhodamine 6G aqueous solutions. The SERS substrate also showed a high detection sensitivity toward ferbam with a limit of detection of about 2.40 nM. Calibration curves with a linear correlation of logarithmic SERS intensity with logarithmic concentration for R6G and 3,3′,4,4′-tetrachlorobiphenyl (PCB-77, a persistent organic pollutant) were achieved by using the fabricated rough gold nanoarrays, demonstrating a promising application in semi-quantitative or even quantitative detection. This work offered a facile but effective approach toward the rational designs of uniform, reproducible and sensitive SERS substrates for molecular detection.
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