| The Surface-Enhanced Raman Scattering（SERS）effect refers to the phenomenon that the Raman signal of the analyte is greatly enhanced when the analyte is adsorbed or close to the rough metal surface.SERS can amplify the Raman signal of the analyte by several orders of magnitude.The nanoparticles in the highly reflective metal liquidlike films（MeLLFs）are closely arranged to form high-density Raman hot spots,which can be used as a SERS active substrate.The liquid-liquid interface self-assembly method with the characteristics of simple preparation process,simple operation and easy realization,is a common way to prepare MeLLFs.The hot spots formed by MeLLFs can directly contact the analyte to produce high SERS signals,but it will inevitably lead to competitive adsorption,especially for biological system samples with complex components.In addition,the presence of organic phases in MeLLFs tends to denature biomolecules（such as proteins,nucleic acids,etc.）,resulting in poor biocompatibility and limitations in cell imaging.In this paper,MeLLFs are formed by self-assembly at the liquid-liquid interface and fixed on the surface of the polymer membrane in situ to realize the separation of the water phase and the oil phase.A solid SERS substrate with a new polymer-MeLLFs was prepared.MeLLFs provide the substrate with high SERS activity,and combine the properties of different polymers to provide the substrate with properties such as resistance to protein macromolecule interference and flexibility.In addition,due to the removal of the organic phase,the prepared SERS active material has good biocompatibility and broad application prospects in the field of biological sample detection and cell imaging.The work is carried out through the following two aspects:1.SERS substrate based on highly reflective metal liquid-like films wrapped hydrogels for direct determination of small molecule in proteinA polyacrylamide hydrogel（PAAG）SERS substrate coated with a metal liquid film was prepared by the liquid-liquid interface self-assembly method.MeLLFs provide high-density SERS active hot spots,and PAAG has anti-fouling properties that can shield the SERS signal of protein macromolecules.The calculated enhancement factor was 8.0 x 106,and the LOD was 76.8pM（S/N=3）,indicating that the prepared MeLLFs@PAAG substrate has good SERS activity.Use MeLLFs@PAAG SERS substrate to detect the small molecule Adriamycin（DOX）in high-concentration protein human serum albumin（HSA）.The binding rate of DOX and HSA was calculated to be 70%.The experimental results prove that the prepared new substrate has the function of shielding macromolecular proteins,making it a promising candidate for the detection of complex biological sample systems.2.Flexible SERS substrate with polycaprolactone as template for label-free detection of cancer cellsThe liquid-liquid interface self-assembly method was also used to prepare a SERS substrate with polycaprolactone（PCL）as the substrate to fix MeLLFs.The separation of the organic phase makes the MeLLFs/PCL substrate have good biocompatibility,which is conducive to the SERS detection of biological systems.In addition,the PCL supporting MeLLFs makes the substrate flexible,which is more flexible than other rigid solid substrates.R6G was used as the analyte to characterize the performance of the substrate.The calculated enhancement factor was 1.3 x 105,and the LOD was 16.3 nM（S/N=3）,indicating that the prepared MeLLFs@PAAG substrate has good SERS activity.We added MeLLFs/PCL substrate to the interface of FC40/medium system and inoculated HCT-116 cells.We found that the cells successfully grew on the substrate,proving that the existence of the substrate does not affect the viability of the cells.More importantly,the MeLLFs/PCL substrate provides strong SERS activity for the detection of HCT-116 cells,and at the same time provides a good application prospect for the label-free SERS detection of cancer cells. |
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