| Indian scientists discovered a technique that can be used effectively to reflect the analysis of molecular structural features information on the test, this was the origin of Raman scattering effect. However, the study found that after scattering observations obtained through its signal strength is very weak, and this disadvantage limited the application of the actual detection analysis for quite a long time. In contrast, with the use of surface-enhanced Raman scattering analysis of the analyte molecules, the effect of the molecular signals can often reach106times to normal Raman, which is benefit from the roughed surface of the metal substrate. And it is detected non-destructive and efficient treatment excellent performance in the test, making surface-enhanced Raman scattering come into play in many fields of science.In recent years, the researchers’emphasis is on the preparation of an effective Raman active substrate, and they found that the highly efficient and stable substrate plays a vital role for the molecular detection. It often requires a certain roughness to the substrate, and the roughness of the law ordered structure is more conducive to enhancing molecular signals during Raman testing. On the other hand, in nature, the researchers of biologists found that a variety of plants and animals due to the result of a long through natural selection, and gradually evolved to the various excellent features to better adapt to the changes in the natural environment. And these features’ surface is not only closely related to the constituent components, but also has a certain degree of contact with the microstructure in the surface. For example, some scientists found cicada wing surface is covered with a uniform and orderly papilla structure through the scanning electron microscope. The structural characteristics of the surface due to their relative performance are closely linked, research in bio-mimetic materials has attracted much attention.In view of this, base on the uniform structure on the surface of cicada wings which exactly meets the Raman active substrate roughness characteristics, and coupled with its super-hydrophobic properties of the surface which is able to concentrate molecules during the test. Therefore, in this paper, we intend to use the natural green cicada wings biological material to be prepared a Raman substrate. The aim is to simplify the current manufacturing process and preparation for the Raman substrate, and to further improve detection limit in the test. There by establishing a new green, simple and inexpensive Raman substrate. We verified the performance of our substrate through a series of methods. Meanwhile, the applicability and the enhancement mechanism of our substrate have also been discussion in this paper. So in this paper, five parts can be found as following:First, according to the periodical3D nanostructures on the surfaces of the cicada wings and its ability of the super-hydrophobic, the Ag NP-modified cicada wings (Ag/cicada wing) were prepared as a SERS substrate, since it might emerge much higher SERS effect and achieve trace detection to target molecules. Ag NPs were deposited onto the surfaces of cicada wings by chemical deposition. Field emission scanning electron microscopy (FE-SEM)(JEOL JSM-6700F), X-ray diffractometer (XRD)(RigakuUltima Ⅲ) and X-ray photoelectron spectroscopy (XPS)(ESCALAB MK Ⅱ) were used to illustrate the surface information of cicada wing with or without Ag NPs, respectively. The contact angles (CAs) were measured with an OCA20machine (Data Physics, Germany).Second, the SERS performances of Ag/cicada wing substrate were demonstrated using R6G as the probe molecule. The signal reproducibility and uniformity of this active SERS substrate were also demonstrated by R6G moleculer for practical SERS applications.Third, the3D finite-difference time-domain (3D-FDTD) simulation was introduced, which as a well-known theoretical simulation method could be more clearly to show electromagnetic source of Raman signal amplification at the surfaces of noble metal NPs.Forth, the thiram with different concentrations for10-3-10-7M was detected by Ag NP/cicada wing. The potential candidate was discussed for rapid and quantitative detection of trace organic molecules or even single molecules.Lastly, for the excellent performance of our substrate, not only the adenosine triphosphate (ATP) and adenosine diphosphate (ADP) were test by this substrate, but also two kinds of bacteria of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were test to illustrate the bioassays applicability of Ag/cicada wing substrate. |
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