Fabrication Of Silver/Biomaterials Substrates And Study Of SERS Performance

Surface-enhanced Raman Scattering(SERS)is a kind of non-linear optical enhancement effect related to the metallic surface with nanoroughness and can reflect the unique vibration spectrum information of molecule,often being called“fingerprint" spectrum of molecule.Because of its advantages of high sensitivity,fast response and non-destructive analysis,it has become one of the most dynamic analytical tools in analytical chemistry,biosensing,food safety and environmental monitoring.In recent years,in order to promote the application and development of SERS technology in the fields of analysis and detection,the preparation of active substrates with low-cost and high SERS performance has drawn much attention of researchers.The purpose of this paper is to construct silver/biomaterials SERS substrates with different morphologies using natural biomaterials as scaffolds and with the help of the magnetron sputtering technology.Based on the surface plasmon resonance effect,the best SERS performance of the substrates can be achieved by tuning the“hot spots".The main research contents are as follows:(1)Silver was modified onto the dragonfly wings with periodic nanopillars by mag-netron sputtering technology.By optimizing the preparation conditions,high-intensity "hot spots" were formed between the adjacent nanopillars.With the help of surface plasmon reso-nance coupling effect,the optimal enhancement performance of the substrates was obtained.Meanwhile,the microstructures and SERS performance of the substrates were character-ized by scanning electron microscopy and Raman spectroscopy.Through three-dimensional finite-difference time-domain method,the local electric field distribution caused by high in-tensity "hot spots" was simulated.(2)Silver nanostructures were constructed and modified on the wings of Fulfora can-delaria with three-dimensional hierarchical reticular structure.Based on the dependence of SERS signals on the morphology of the substrates,we improved the effective "hot spot"density per unit laser illumination range on the silver/Fulfora candelaria wing substrates by optimizing the preparation parameters.By means of superposition of plasma resonance ef-fect on silver surface,effective local field enhancement could be provided to achieve a bet-ter enhancement performance than silver/dragonfly wing substrates.Meanwhile,the three-dimensional finite-difference time-domain simulation could vividly describe and analyze the local field enhancement effect caused by effective "hot spots" on the substrate surface.(3)The grating-like silver/moth wing SERS substrates were obtained by magnetron sputtering using the three-dimensional regular arrays of moth wings as the biological scaf-folds.By accurately adjusting sputtering parameters,the size,morphology,gap and rough-ness of silver nanoislands could meet the needs of grating-like arrays,so as to improve the quality and the density of "hot spots",and obtain the best SERS enhancement.To compen-sate for the negative effect of irregular morphology on SERS performance of silver/Fulfora candelaria wing substrates.Meanwhile,the enhancement effect of SERS caused by effective"hot spots" was characterized by experimental spectra and electric field distribution simula-tion.