| Surface-enhanced Raman Scattering (SERS), which has advantages of high sensitivity, simple sample preparation, facile process, sample flexibility and non-invasive detection, shows great application potential in fields of biochemical analysis, imaging, food & environmental engineering, criminal investigation, archaeology and so on. Fabrication of SERS substrates is a crucial step thus it has become one of the most important issues in SERS study. Due to its unique optical property and periodic micro-nanostructures, photonic crystal (PhC) has become one of the non-neglect materials for fabrication of SERS substrates. In this dissertation, several kinds of SERS substrates based on photonic crystal have been fabricated and their SERS performance has also been investigated. The enhancement was evaluated by both experiments and numerical simulations. Photonic crystal effects on SERS substrates were also illustrated. The detailed work is as follow:(1) Two approaches toward fabricating SERS substrates were proposed based on three kinds of butterflies. The first one is the carbonization process. By carbonization, fluorescence signal of the butterfly wing was removed. Morphology of the butterfly before and after carbonization were observed. Feasibility of butterfly wing used for SERS was verified. The second is the fabrication butterfly wing-gold nanoparticle compound. This approach is a simple, reproducible, inexpensive and green method utilizing the redox chemistry of butterfly wings and the whole natural structure of the butterfly wing was fully taken advantage of. By morphology observation and chemical component characterization, it is shown that micro/nanostructures of the butterfly wing have not been destroyed. Besides, the amine of the organic component is coordinated with gold nanoparticles and the gold nanoparticles formed the ridge contours. Results shown that SERS substrate based on Morpho menelaus has the best SERS performance in all the four substrates.(2) Plasmonic staining of an inverse opal PhC structure composed of po lyacryl amide (PAM) hydrogel was exploited for multiplexed protein detection. Three kinds of plasmonic staining of inverse opal PhC beads were designed, fabricated and characterized. Time of plasmonic staining, reflection peak of PhC beads and wavelength of lasers were optimized to get the maximum near-field intensity. Band structure and near field distribution were illustrated. It is found that hydrogel PhC beads with reflection peak at 650 nm gave rise to the best SERS performance in terms of Raman intensity, RSD and SNR when the exciting laser was 532 nm. Hydrogel PhC supported one order of extra enhancement to the LSPR effect of silver nanoparticles.(3) An inexpensive and rapid approach was reported to fabricate the plasmonic gold micro-cage (PMC), which encapsulates inverse opal gold nanoshells. Two types of PMC structures, the "Closed"-PMC and the "Open"-PMC, were fabricated by tuning the existence of gold nanocluster on silica photonic crystal beads (PCBs) as the templates. Both two types of PMCs exhibited strong near field inside the cage and can be used as a sample vessel for surface enhanced Raman (SERS) detection. It is shown that "Open"-PMC is 16 times and 4 times electrical field and SERS intensity than that of "Closed"-PMC in simulations and experiments, respectively. To analvze the sensing performance of the "Open"-PMC, we employ the "Open"-PMC as SERS substrates for probing R6G molecules. The results showed that as low as 10-12 M R6G can be detected and an experimental SERS enhancement factor of 4.46 ×106 was obtained. These PMCs offers the potential of realizing the trace analyte analysis. |
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