| Surface enhanced Raman spectroscopy has been a powerful technique that allows for highly sensitive detection of analytes with extremely low concentration since its discovery in the 1970 s.Due to its capability of label-free analysis,SERS has been applied to sensing of various analytes in different fields,such as,metabolites,disease markers,hazardous pollutants,illegal drugs,and explosives in biomedicine,food quality control,environmental monitoring,and security applications.The preparation of a high-efficiency SERS substrate has great practical significance in many fields and industries.The so-called high-efficiency SERS substrate needs at least the following characteristics:(1)Accurate detection,that is to say,it can make correct identification of detected products;(2)It is efficient and convenient,and can effectively identify the detected substances with very low content;(3)The production process is simple and the production cost is low.Low,the preparation of the substrate process is simple and convenient,does not have to spend a lot of time and materials,does not require very expensive precision instruments or materials.(4)The substrate stabilization signal has high reproducibility and good reproducibility,that is,the exposure to the substrate in the air for a relatively long period of time is relatively small.In the same case,the same signal is measured several times in the same manner.However,The typical material for SERS is noble metal,such as Au,Ag and Cu,and synthesis of the instrument or the operation process is relatively high,making it an efficient Raman substrate facing the following two difficulties::(1)Noble metal nanoparticles are prone to oxidation,which makes the substrate less stable(2)Raman enhancement of the substrate production methods are complex,made of the substrate costly?For the above difficulties,did a bit of research.(1)Aiming at the problem that the manufacturing method of the substrate iscomplex and the high cost of the substrate is produced,we demonstrate facile and low-cost fabrication of highly sensitive SERS substrates via galvanic replacement reaction by immersing Cu foils into an aqueous AgNO3 solution.Different morphologies of Ag nanostructures can be observed on the substrate surface by controlling the reaction time.The morphology-dependent SERS effect is tested.The experimental results show that this method is simple,the process is simple,and the raw materials used are very inexpensive and use less expensive large-scale or sophisticated instruments to exhibit a very high cost performance.Ag-Cu substrates are promising for various analytes fast,sensitive SERS detection.(2)In response to this problem,noble metal nanomaterials tend to be oxidized and their stability is poor.we investigate the GO-decorated Ag dendritic nanostructures on a copper substrate for SERS applications.Compared with the AgD/Cu substrate,the GO/AgD/Cu substrate shows much better performance in terms of sensitivity,signal-to-noise ratio,uniformity,and stability.This is due to the fact that graphene oxide itself is highly stable and has a high biocompatibility and its interaction with the Nano metal,which further enhances the effectiveness of the substrate.The minimum detected concentration from the GO/AgD/Cu substrate for R6 G can reach 10-11 M,which is one order of magnitude lower than that from AgD/Cu substrate.Experimental results also show that GO decoration can effectively prevent the oxidation of Ag dendrites and hence enable a long term stability of the SERS signal.The substrate has the advantages of accurate detection,high efficiency and convenience,simple manufacturing process,low production cost,simple and convenient preparation of the substrate,no need to consume a large amount of time and materials,high stability of substrate signal reproducibility,and good repeatability. |
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