title: Silver overlayer-modified surface-enhanced Raman scattering-active gold substrates for potential applications in trace detection of biochemical species.
abstract: Because Ag and Au nanoparticles (NPs) possess well-defined localized surface plasmon resonance (LSPR) they are popularly employed in the studies of surface-enhanced Raman scattering (SERS). As shown in the literature and in our previous studies, the advantage of SERS-active Ag NPs is their higher SERS enhancement over Au NPs. On the other hand, the disadvantage of SERS-active Ag NPs compared to Au NPs is their serious decay of SERS enhancement in ambient laboratory air. In this work, we develop a new strategy for preparing highly SERS-active Ag NPs deposited on a roughened Au substrate. This strategy is derived from the modification of electrochemical underpotential deposition (UPD) of metals. The coverage of Ag NPs on the roughened Au substrate can be as high as 0.95. Experimental results indicate that the SERS of Rhodamine 6G (R6G) observed on this developed substrate exhibits a higher intensity by ca. 50-fold of magnitude, as compared with that of R6G observed on the substrate without the deposition of Ag NPs. The limit of detection (LOD) for R6G measured on this substrate is markedly reduced to 2×10(-15)M. Moreover, aging of SERS effect observed on this developed substrate is significantly depressed, as compared with that observed on a generally prepared SERS-active Ag substrate. These aging tests were performed in an atmosphere of 50% relative humidity (RH) and 20% (v/v) O2 at 30°C for 60 day. Also, the developed SERS-active substrate enables it practically applicable in the trace detection of monosodium urate (MSU)-containing solution in gouty arthritis without a further purification process.
authors: Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan; School of Dentistry, College of Oral Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan; Research Center for Biomedical Devices, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan.
authors: Keng-Liang
authors: KL
authors: Ou
authors: General Education Center, Vanung University, No. 1, Van Nung Road, Chung-Li City, Taiwan.
authors: Ting-Chu
authors: TC
authors: Hsu
authors: Department of Biochemistry, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan; Biomedical Mass Imaging Research Center, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan. Electronic address: liuyc@tmu.edu.tw.
authors: Yu-Chuan
authors: YC
authors: Liu
authors: Department of Materials Science and Engineering, Vanung University, No. 1, Van Nung Road, Chung-Li City, Taiwan.
authors: Kuang-Hsuan
authors: KH
authors: Yang
authors: School of Dentistry, College of Oral Medicine, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 11031, Taiwan.
authors: Hui-Yen
authors: HY
authors: Tsai
mesh_terms: D002623:Chemistry Techniques, Analytical; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D012235:Rhodamines / Q000032:analysis; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D012235:Rhodamines; C026188:rhodamine 6G; D012834:Silver; D006046:Gold
keywords: Coverage; Monosodium urate; Stability; Surface-enhanced Raman scattering; Underpotential deposition