| Surface-Enhanced Raman Spectroscopy exhibits advantages including high sensitivity,label-free,fast detection in several seconds,and the stability of SERS signal,which has been applied in many fields.But the reproducibility based on the intensity of SERS signal is the most important challenge to limit the development of SERS.A new biomolecule detection method for SERS based on the frequency shifts phenomenon was proposed by Malini Olivo.The frequency shifts phenomenon is due to the existence of outer pressure to cause the compressions of covalent bonds of molecule.Owing to this consideration,the enhancement factors from the substrate,the effective number of molecule in “hot spots” and the measurement conditions coming from the optical systems have no or much small influence to the reproducibility of the frequency shifts phenomenon.For these reasons,we hope that we can improve the reproducibility of the SERS technology to detect molecules.We have investigated the universal properties of the frequency shifts phenomenon including the Gaussian distribution of the center peak of C-S bonds in 4-ATP,the red shifts of Raman shifts of the center peak of C-S bonds in 4-ATP caused by outer pressures.In the process to fabricate the proper substrate applied in the frequency shifts phenomenon,we also found that the flexible components and variable factors from the gold nanoshell substrate make it not suitable for the study of frequency shifts phenomenon.The hollow nanoring,fabricated by the combination of ion beam sputtering system and ion beam etching system,has a good enhancement factors and also makes its hot spots region on the top of substrate that can sense the changes of outer pressures sensitively.At last,we use this kind of substrate to make an initial test of biological macromolecules of hCG antigen that can realize the nanogram level even piquegram detection.But the establishment of more detailed detection method requires further study in future. |
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