Surface-enhanced Raman scattering (SERS) is a rapid and nondestructive spectroscopic method for trace detection. The enhancement based on both electromagnetic and chemical mechanism requires the molecules to be in close contact with the SERS-active material. Therefore, it is difficult to detect trace amounts of molecules in liquid directly. In this paper, graphene oxide (GO) and Ag nanoparticles (AgNPs) are uniformly modified on the inner wall of the capillary. GO can provide chemical enhancement by adsorbing the analyte onto its flat surface and producing efficient charge transfer resonance with the analyte. AgNPs can provide strong localized surface plasmon resonance for electromagnetic enhancement, while capillary can shorten the molecular enrichment time and provide long light–analyte interaction length. The synergism of GO, AgNPs, and capillary makes the optofluidic platform have the ability of ultrasensitive and real-time detection. The detection limit of Rhodamine 6G and thiram is as low as 10–12 and 10–10 M, respectively, and the enhancement factor is as high as 0.9 × 1010 and 108, which indicates that the SERS-active capillaries have great potentials in real-time ultratrace detection of water environment pollutants.

Microstructure fibers, integrating microfluidic channels and light guidance in one fiber, enable three-dimensional surface-enhanced Raman scattering (SERS) detection for large signal accumulation. However, the available fiber SERS probes are complicated to prepare and they are not reusable. In addition, light interacts with analytes in a form of an evanescent field, which is very weak. In this paper, we developed a SERS platform based on suspended-core photonic crystal fibers decorated with Ag/ZnO nanocomposites on the inner surface for direct, ultrasensitive, and reusable analyte detection. The unique configuration not only transfers a corelocalized field to the liquid interface to greatly enhance the light−analyte interaction but also facilitates charge transfer to further improve the SERS detection sensitivity and degradation efficiency. The detection limit of crystal violet solution is 10 −13 M, and the enhancement factor reaches 10 11 . The relative standard deviation is as low as 5.4%, ensuring the reproducibility of SERS detection. The probe has good photocatalytic performance and can degrade molecules under ultraviolet-light illumination within 20 min. This ultrasensitive and reusable SERS probe shows great application potential in rapid and in situ liquid detection.

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3-dimensional surface-enhanced Raman scattering (SERS) platforms greatly extend the interaction area and ensure the ability to directly detect trace amounts of molecules in liquids. Silver-coated capillary, with the ability of...