Alignment of Rod-Shaped Gold Particles by Electric Fields

Zande, B. M. I. van der; Koper, Ger J. M.; Lekkerkerker, H.N.W.

doi:10.1021/jp984737a

Cited by 164 publications

(128 citation statements)

References 26 publications

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“…The collective oscillation of the conduction band electrons in noble metal nanoparticles gives rise to very large scattering and absorption cross-sections (23). In addition to the high photostability (22), lack of photoblinking (24), and excellent biocompatibility (25), the polarization of the absorbed scattered light can be tuned readily through the shape of the nanoparticles allowing for orientational imaging (26). One of the best studied metallic nanoparticles with an anisotropic shape are Au NRs that have longitudinal and transverse SP modes polarized parallel to the long and short axes of the NRs, respectively (27).…”

mentioning

confidence: 99%

Plasmonic nanorod absorbers as orientation sensors

Chang¹,

Ha²,

Slaughter³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

268

288

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Nanoparticles are actively exploited as biological imaging probes. Of particular interest are gold nanoparticles because of their nonblinking and nonbleaching absorption and scattering properties that arise from the excitation of surface plasmons. Nanoparticles with anisotropic shapes furthermore provide information about the probe orientation and its environment. Here we show how the orientation of single gold nanorods (25 × 73 nm) can be determined from both the transverse and longitudinal surface plasmon resonance by using polarization-sensitive photothermal imaging. By measuring the orientation of the same nanorods separately using scanning electron microscopy, we verified the high accuracy of this plasmon-absorption-based technique. However, care had to be taken when exciting the transverse plasmon absorption using a large numerical aperture objective as out-of-plane plasmon oscillations were also excited then. For the size regime studied here, being able to establish the nanorod orientation from the transverse mode is unique to photothermal imaging and almost impossible with conventional dark-field scattering spectroscopy. This is important because the transverse surface plasmon resonance is mostly insensitive to the medium refractive index and nanorod aspect ratio allowing nanorods of any length to be used as orientation sensors without changing the laser frequency.gold nanorod | surface plasmon | single-particle spectroscopy | photothermal imaging O ptical probes for biological imaging should yield large photon count rates with little background noise due to autofluorescence or scattering, have a high photostability and good biocompatibility, and cause only minimal interference (1-5). A high degree of polarization anisotropy is also desirable because it gives access to the orientation of the probe, and thereby provides important information about the conformation and dynamics of the biological system (1-3, 5). The surface plasmon (SP) absorption of individual metallic nanoparticles recorded by high-sensitivity photothermal imaging presents an excellent step toward the realization of optimized optical probes with the aforementioned properties (6, 7). Here we show that, by tuning the shape of gold nanoparticles and hence the anisotropy of the SP oscillation, the orientation of single gold nanorods (Au NRs) can be determined very accurately based on the SP absorption. We found excellent agreement for NR orientations determined using SEM compared to polarization-sensitive photothermal imaging of the longitudinal SP mode. Furthermore, our studies show that the transverse SP mode along the smaller NR dimension also yields accurate NR orientations if a low N.A. objective was used. This cannot be accomplished using conventional dark-field scattering spectroscopy (8, 9). In addition, because the transverse SP resonance is insensitive to the NR aspect ratio (10), the orientations of NRs with different lengths in environments with varying local refractive indices can be measured using only one laser frequency.Singl...

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mentioning

confidence: 99%

Plasmonic nanorod absorbers as orientation sensors

Chang¹,

Ha²,

Slaughter³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

268

288

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“…[11] Other researchers have shown that orientation can be induced in both conductive and dielectric rod-shaped particles dispersed in a suitable solvent. [22,23] We chose to investigate electric-field-induced orientation of molecular-sieve crystals dispersed in solvents to develop a technique to deposit the crystals as a film with controlled crystal orientation. Fibrous aluminum phosphate number five (AlPO 4 -5) molecular-sieve crystals were synthesized following previously described procedures.…”

Section: Methodsmentioning

confidence: 99%

Electric‐Field‐Driven Assembly of Oriented Molecular‐Sieve Films

Lin

Yates²,

Petkoska

et al. 2004

Advanced Materials

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“…26 In 1997, van der Zande et al achieved electrochemical deposition of gold in mesoporous silica pores. 27,28 In this study, a hard template, a stiff porous layer on an electrode, regulated the shapes of nanoparticles and enabled the electrochemical deposition of uniform rod-shaped nanoparticles. The nanorods could be dispersed in an aqueous solution, showing two remarkable SP bands originating from the anisotropic shapes.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Gold-based Nanoparticles: Preparation, Properties, and Applications

2016

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Among the several types of nanoparticles in existence, anisotropic gold-based nanoparticles demonstrate special advantages because of their unique properties. Gold nanoparticles can be prepared and modified with a wide range of functional materials including polymers, surfactants, ligands, dendrimers, drugs, DNA, RNA, proteins, peptides, and oligonucleotides. Hence, they are a promising vehicle for bioimaging, drug delivery, and other therapies. This review mainly addresses the properties, preparation, and applications of anisotropic gold nanoparticles in biomedical applications and targeted drug delivery.

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Alignment of Rod-Shaped Gold Particles by Electric Fields

Cited by 164 publications

References 26 publications

Plasmonic nanorod absorbers as orientation sensors

Plasmonic nanorod absorbers as orientation sensors

Electric‐Field‐Driven Assembly of Oriented Molecular‐Sieve Films

Anisotropic Gold-based Nanoparticles: Preparation, Properties, and Applications

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