title: Competitive reaction pathway for site-selective conjugation of Raman dyes to hotspots on gold nanorods for greatly enhanced SERS performance.
abstract: Common methods to prepare SERS (surface-enhanced Raman scattering) probes rely on random conjugation of Raman dyes onto metal nanostructures, but most of the Raman dyes are not located at Raman-intense electromagnetic hotspots thus not contributing to SERS enhancement substantially. Herein, a competitive reaction between transverse gold overgrowth and dye conjugation is described to achieve site selective conjugation of Raman dyes to the hotspots (ends) on gold nanorods (GNRs). The preferential overgrowth on the nanorod side surface creates a barrier to prevent the Raman dyes from binding to the side surface except the ends of the GNRs, where the highest SERS enhancement factors are expected. The SERS enhancement observed from this special structure is dozens of times larger than that from conjugates synthesized by conventional methods. This simple and powerful strategy to prepare SERS probes can be extended to different anisotropic metal nanostructures with electromagnetic hotspots and has immense potential in in-depth SERS-based biological imaging and single-molecule detection.
authors.affiliation: Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, China; Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, HongKong, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Huang
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Wang
authors.forename: Weihong
authors.initials: W
authors.lastname: Jin
authors.forename: Penghui
authors.initials: P
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Han-Han
authors.initials: HH
authors.lastname: Xie
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Yu
authors.forename: Huaiyu
authors.initials: H
authors.lastname: Wang
authors.forename: Zhigao
authors.initials: Z
authors.lastname: Dai
authors.forename: Xiangheng
authors.initials: X
authors.lastname: Xiao
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu
mesh_terms: D016880:Anisotropy; D004396:Coloring Agents / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry; D060733:Electromagnetic Radiation; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology; D043942:Nanotubes / Q000737:chemistry*; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman; D020349:Surface Plasmon Resonance; D013499:Surface Properties
chemical_list: D004396:Coloring Agents; D003287:Contrast Media; D008670:Metals; D006046:Gold
keywords: gold nanorods; hot spots; overgrowth; plasmonic nanostructures; surface-enhanced raman scattering