Microfiber-directed reversible assembly of Au nanoparticles for SERS detection of pollutants

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Abstract
Surface-enhanced Raman scattering (SERS) spectroscopy has attracted tremendous interest as a highly sensitive label-free tool to detect pollutants in aqueous environments. However, the high cost and poor reusability of conventional SERS substrates restrict their further applications in rapid and reproducible pollutant detection. Here, we report a reliable optical manipulation method to achieve rapid photothermal self-assembly of Au nanoparticles (AuNPs) in water within 30 s by a tapered optical fiber, which is utilized for highly sensitive SERS substrate preparation. The results show that the SERS substrate achieves low detection limits of 10−9 mol/L with an enhancement factor (EF) of 106 for chemical pollutants solutions, including thiram, pyrene, and rhodamine 6G. The SERS enhancement effect based on assembled AuNPs was more than 20 times that based on a gold colloid solution. As a result, the smart reversible assembly of AuNPs exhibits switchable plasmonic coupling for tuning SERS activity, which is promising for the application of SERS-based sensors and environmental pollutant detection.
Funding Information
  • National Natural Science Foundation of China (11964032, 11874157)
  • Science and Technology Program of Guangzhou (2019050001)
  • Science and Technology Planning Project of Guangdong Province (2019A1515011014)
  • Key Project of Education Department of Guangdong Province (2018KZDXM025)
  • Guangdong Provincial Key Laboratory of Optical Information Materials and Technology (2017B030301007)
  • National Center for International Research on Green Optoelectronics
  • 111 Project
  • Open Fund of Guangdong Provincial Key Laboratory of Information Photonics Technology of Guangdong University of Technology (GKPT20-12)

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