title: Three-dimensional reduced-symmetry of colloidal plasmonic nanoparticles.
abstract: Owing to their novel optical properties, three-dimensional plasmonic nanostructures with reduced symmetry such as a nanocrescent and a nanocup have attracted considerable current interest in biophotonic imaging and sensing. However, their practical applications have been still limited since the colloidal synthesis of such structures that allows, in principle, for in vivo application and large-scale production has not been explored yet. To date, these structures have been fabricated only on two-dimensional substrates using micro/nanofabrication techniques. Here we demonstrate an innovative way of breaking symmetry of colloidal plasmonic nanoparticles. Our strategy exploits the direct overgrowth of Au on a hybrid colloidal dimer consisting of Au and polystyrene (PS) nanoparticles without the self-nucleation of Au in an aqueous solution. Upon the overgrowth reaction, the steric crowding of PS leads to morphological evolution of the Au part in the dimer ranging from half-shell, nanocrescent to nanoshell associated with the appearance of the second plasmon absorption band in near IR. Surface-enhanced Raman scattering signal is obtained directly from the symmetry-broken nanoparticles solution as an example showing the viability of the present approach. We believe our concept represents an important step toward a wide range of biophotonic applications for optical nanoplasmonics such as targeting, sensing/imaging, gene delivery, and optical gene regulations.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, 121-742, Korea.
authors.forename: Eunhye
authors.initials: E
authors.lastname: Jeong
authors.forename: Kihoon
authors.initials: K
authors.lastname: Kim
authors.forename: Inhee
authors.initials: I
authors.lastname: Choi
authors.forename: Sunil
authors.initials: S
authors.lastname: Jeong
authors.forename: Younggeun
authors.initials: Y
authors.lastname: Park
authors.forename: Hyunjoo
authors.initials: H
authors.lastname: Lee
authors.forename: Soo Hong
authors.initials: SH
authors.lastname: Kim
authors.forename: Luke P
authors.initials: LP
authors.lastname: Lee
authors.forename: Yeonho
authors.initials: Y
authors.lastname: Choi
authors.forename: Taewook
authors.initials: T
authors.lastname: Kang
mesh_terms: D003102:Colloids; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles
chemical_list: D003102:Colloids