Integrated accurate extraction and fast detection of analyte: Capillarity-Based SERS substrate using in effluent monitoring

In order to realize integration of directional extraction and Raman detection for analytes in effluent, a capillarity-based surface-enhanced Raman spectroscopy (SERS) structure of CuO@Ag nanocapillaries (NCs) has been designed and prepared in this paper. Benefitting from the capillaries formed inside the CuO@Ag NC, probe molecules can be spontaneously transferred and concentrated from the CuO@Ag NC bottom to the top. Further processed with infrared irradiation, the CuO@Ag NC changes from amphiphilic state to hydrophobic-oleophilic state, which can accurately extract molecules that dissolved in oil-phase liquid from the mixed oil/water solution. Numerical simulations by finite-difference time domain method illustrate theoretically that the CuO@Ag NC top is also the position where the strongest electric flied located in this structure, demonstrating the integration feasibility of high-efficient extraction, enrichment and detection in one structure. Experimentally, the enhancement factor and relative standard deviation for R6G molecule of this structure are 1.67 x 10(11) and 15.7% respectively, with other Raman properties also showing remarkable performance. In the simulated wastewater detection test, this structure realizes the fast recognition of trace Sudan I dyes (10(-7) M) in the mixed hexane/water solution composed of both target analyte Sudan I and interferent molecule rhodamine 6G, indicating its promising prospect using in effluent monitoring.

Automated summary

A capillarity-based surface-enhanced Raman spectroscopy (SERS) structure of CuO@Ag nanocapillaries has been designed to integrate directional extraction and Raman detection for analytes in effluent. The structure shows promising prospect in effluent monitoring with fast recognition of trace dyes and high efficient extraction and detection.