Investigation On The Effect Of Substrate Morphology And Structure On Surface-enhanced Fluorescence

Surface enhanced fluorescence(SEF)refers to the phenomenon that when the fluorescent molecules are surrounded by noble metal nanostructures such as Au and Ag,the fluorescence intensity of the molecules is greatly increased compared with the free state.As a non-destructive testing technology with fast response and good selectivity,it is widely used in the fields of environmental monitoring,life system,food safety and so on.Compared with traditional fluorescence spectroscopy,SEF technology can significantly improve the fluorescence intensity by utilizing different microstructures of the substrate.The morphology and structure of the substrate are still important factors affecting SEF effect which has become one of the focus of researchers.In this paper,SEF substrates with rough micromorphology,simple synthesis steps and stable properties were prepared by sputtering noble metal nanoparticles on the surface of natural biomaterials,at the same time,the optical properties and application value of SEF substrates were tested.The details are as follows:(1)The growth situation of Ag NPs on different morphologies of biological substrates was studied.Wheat leaves(WL)with hemispherical convex structure and razor clam(RC)with coral-like structure were selected as experimental materials.Ag NPs were deposited on the experimental materials by magnetron sputtering method,which is easy to operate and has little damage to the material.The morphology of SEF substrate was optimized by adjusting magnetron sputtering time.The growth morphology of the substrate was observed by scanning electron microscope(SEM),and the changes of micro-morphology and size between different substrates were compared.At the same time,the element composition of the substrate was analyzed by X-ray diffraction spectrometer.(2)The SEF performance of Ag@WL substrate are analyzed,and its detection of toxic substance crystal violet(CV)was explored.Rhodamine B(RB)fluorescent molecule was used as fluorescent probe to screen the optimal substrate,and Rhodamine 6G(R6G)fluorescent molecule was used to verify the experimental results to increase the accuracy of the experimental.The optical properties of the substrate were observed by UV-Vis spectrum and fluorescence spectrum,and the optimal fluorescence enhancement effect of the substrate was screened.At the same time,the hot spot and electromagnetic field spatial distribution of the substrate were analyzed by using finite difference time domain(FDTD)method.Finally,the stability and reproducibility of the optimal substrate were analyzed and applied to the actual detection of CV.(3)The SEF performance analysis of Ag@RC substrate is studied and its application value is explored.The microstructure of RC was coral-like at nano-scale.A series of isoplasmon resonance SEF substrates were obtained by adjusting the magnetron sputtering time.The SEM was used to analyze the morphology of the substrate,and fluorescence spectrometer was used to screen the substrate with the optimal SEF performance.At the same time,the electromagnetic field distribution of the optimal substrate was simulated,and the enhancement of fluorescence signal was analyzed from the mechanism.Finally,the reproducibility,stability,reusability and application value of the substrate were studied.