title: Polymer-mediated formation and assembly of silver nanoparticles on silica nanospheres for sensitive surface-enhanced Raman scattering detection.
abstract: To impart a desired optical property to metal nanoparticles (NPs) suitable for surface-enhanced Raman scattering (SERS) applications, it is crucial to assemble them in two or three dimensions in addition to controlling their size and shape. Herein, we report a new strategy for the synthesis and direct assembly of Ag NPs on silica nanospheres (AgNPs-SiNS) in the presence of poly(ethylene glycol) (PEG) derivatives such as PEG-OH, bis(amino)-PEGs (DA-PEGs), and O,O'-bis(2-aminopropyl)PEG (DAP-PEG). They exhibited different effects on the formation of Ag NPs with variable sizes (10-40 nm) and density on the silica surface. As the molecular weight (MW) of DA-PEGs increased, the number of Ag NPs on the silica surface increased. In addition, DAP-PEG (MW of 2000), which has a 2-aminopropyl moiety at both ends, promoted the most effective formation and assembly of uniform-sized Ag NPs on a silica surface, as compared to the other PEG derivatives with the same molecular weight. Finally, we demonstrated that AgNPs-SiNS bearing 4-fluorobenzenethiol on its surface induced the strong SERS signal at the single-particle level, indicating that each hybrid particle has internal hot spots. This shows the potential of AgNPs-SiNS for SERS-based sensitive detection of target molecules.
authors.affiliation: Interdisciplinary Program in Nano-Science and Technology, Seoul National University , Seoul 151-747, Republic of Korea.
authors.forename: Homan
authors.initials: H
authors.lastname: Kang
authors.forename: Joonhyuk
authors.initials: J
authors.lastname: Yim
authors.forename: Sinyoung
authors.initials: S
authors.lastname: Jeong
authors.forename: Jin-Kyoung
authors.initials: JK
authors.lastname: Yang
authors.forename: San
authors.initials: S
authors.lastname: Kyeong
authors.forename: Su-Ji
authors.initials: SJ
authors.lastname: Jeon
authors.forename: Jaehi
authors.initials: J
authors.lastname: Kim
authors.forename: Khee Dong
authors.initials: KD
authors.lastname: Eom
authors.forename: Hyunmi
authors.initials: H
authors.lastname: Lee
authors.forename: Hye-In
authors.initials: HI
authors.lastname: Kim
authors.forename: Dae Hong
authors.initials: DH
authors.lastname: Jeong
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Yoon-Sik
authors.initials: YS
authors.lastname: Lee
mesh_terms: D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D010636:Phenols / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D010636:Phenols; D013438:Sulfhydryl Compounds; D012834:Silver; D011092:Polyethylene Glycols; D012822:Silicon Dioxide; C042983:thiophenol