Approaches to the Synthesis and Characterization of Spherical and Anisotropic Silver Nanomaterials

Ledwith, Deirdre M.; Aherne, Damian; Kelly, John M.

doi:10.1002/9783527610419.ntls0125

Cited by 3 publications

(5 citation statements)

References 157 publications

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“…Highly anisotropic silver nanoparticles such as nanoprisms have received considerable attention because of their ability to easily tune the in-plane dipole LSPR across the entire visible spectrum and into the NIR , but also because of the superior optical properties of silver compared to other noble metals such as gold . Despite these advantages, unprotected silver nanoparticles are unstable under physiological conditions because of a catalytic oxidation (etching) of the surface in the presence of chloride and other anions. , This etching process can have drastic consequences such as the etching of triangular silver nanoprisms to discs or, at higher concentrations of chloride, the etching to very small spherical nanoparticles of a few nanometres in diameter .…”

Section: Introductionmentioning

confidence: 99%

“…29,30 In addition, the development of biosensors that are based on a change in the local refractive index upon the selective binding of an analyte has also become very promising. 1,31 Highly anisotropic silver nanoparticles 32 such as nanoprisms have received considerable attention because of their ability to easily tune the in-plane dipole LSPR across the entire visible spectrum and into the NIR 33,34 but also because of the superior optical properties of silver compared to other noble metals such as gold. 35 Despite these advantages, unprotected silver nanoparticles are unstable under physiological conditions because of a catalytic oxidation (etching) of the surface in the presence of chloride and other anions.…”

Section: Introductionmentioning

confidence: 99%

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Etching-Resistant Silver Nanoprisms by Epitaxial Deposition of a Protecting Layer of Gold at the Edges

Aherne¹,

Charles²,

Fournet

et al. 2009

Langmuir

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The protection of silver nanoprisms against etching by the epitaxial deposition of a thin layer of gold in solution has been investigated. It has been found that at low Au/Ag ratios (approximately 0.08 to 0.17) a thin layer of gold is deposited on the edges of the nanoprisms as expected, but without the structural damage typically associated with galvanic replacement. Furthermore, this layer of gold provides robust protection against etching of the nanoprisms by chloride and is strong evidence that etching by chloride is face-selective and does not take place at the flat {111} faces of the nanoprisms. Additionally, the deposition of a protecting layer of gold results in only a small red shift in the position of the main plasmon resonance. We have investigated the sensitivity of the localized surface plasmon resonance (LSPR) to changes in the bulk refractive index of the solution and find that the gold-protected silver nanoprisms are promising candidates for the development of new refractive index-based biosensors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Etching-Resistant Silver Nanoprisms by Epitaxial Deposition of a Protecting Layer of Gold at the Edges

Aherne¹,

Charles²,

Fournet

et al. 2009

Langmuir

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“…Such highly anisotropic silver nanoplates have received considerable interest due the ability to tune their in-plane dipole LSPR across the visible spectrum and into the NIR. 31 It is postulated that silver nanoparticles are advantageous over other noble metal nanoparticles within visible wavelengths as their LSPR energy is removed from interband transitions (3.8 eV ϳ 327 nm). 32 This results in a narrow LSPR fwhm which exhibits a much stronger shift with increasing local dielectric constant than is the case of gold or copper at these wavelengths.…”

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confidence: 99%

“…Solution phase triangular silver nanoplates (TSNP) are herein examined as tunable LSPR sensors with excellent potential for versatile and highly responsive biosensing. Such highly anisotropic silver nanoplates have received considerable interest due the ability to tune their in-plane dipole LSPR across the visible spectrum and into the NIR . It is postulated that silver nanoparticles are advantageous over other noble metal nanoparticles within visible wavelengths as their LSPR energy is removed from interband transitions (3.8 eV ∼ 327 nm) .…”

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confidence: 99%

Versatile Solution Phase Triangular Silver Nanoplates for Highly Sensitive Plasmon Resonance Sensing

et al. 2009

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Solution phase triangular silver nanoplates (TSNP) with versatile tunability throughout the visible-NIR wavelengths are presented as highly sensitive localized surface plasmon refractive index sensors. A range of 20 TSNP solutions with edge lengths ranging from 11 to 200 nm and aspect ratios from 2 to 13 have been studied comprehensively using AFM, TEM, and UV-vis-NIR spectroscopy. Studies of the localized surface plasmon resonance (LSPR) peak's sensitivity to refractive index changes are performed using a simple sucrose concentration method whereby the surrounding refractive index can solely be changed without variation in any other parameter. The dependence of the TSNP localized surface plasmon resonance (LSPR) peak wavelength lambda(max) and its bulk refractive index sensitivity on the nanoplate's structure is determined. LSPR sensitivities are observed to increase linearly with lambda(max) up to 800 nm, with the values lying within the upper limit theoretically predicted for optimal sensitivity, notwithstanding any diminution due to ensemble averaging. A nonlinear increase in sensitivity is apparent at wavelengths within the NIR region with values reaching 1096 nm.RIU(-1) at lambda(max) 1093 nm. Theoretical studies performed using a simple aspect ratio dependent approximation method and discrete dipole approximation methods confirm the dependence of the LSPR bulk refractive index sensitivity upon the TSNP aspect ratio measured experimentally. These studies highlight the importance of this key parameter in acquiring such high sensitivities and promote these TSNP sols for sensing applications at appropriate wavelengths for biological samples.

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“…The LSPR consists of the collective oscillation of the metal's conduction electrons along the nanostructure's surface upon excitation by an external electromagnetic field. Control of electromagnetic scattering, absorption and extinction properties enables noble metallic nanostructure functionalities to be optically tuned across spectral wavelengths [7,8], for their exploitation in different nanoscale applications [9][10][11]. Specific parameters, such as nanostructure size [12], shape [13], dielectric constant [14][15][16] and the dielectric constant of the surrounding medium [17], strongly influence the nanostructure's LSPR and hence the applicability of the nanostructure in the various applications.…”

Section: Introductionmentioning

confidence: 99%

Scaling of Surface Plasmon Resonances in Triangular Silver Nanoplate Sols for Enhanced Refractive Index Sensing

Charles¹,

Gara²,

Aherne³

et al. 2011

Plasmonics

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The plasmonic spectra of solution phase ensembles of triangular silver nanoplates have been analysed in order to examine the fundamental properties underlying their size-dependent enhanced refractive index sensitivities. Linewidth studies highlight variations in the response of these solution phase nanostructures to those previously reported for single immobilized triangular nanostructures. The observation of insignificant broadening of the resonance linewidth for larger edge length nanoplates highlights minimal contribution of radiative damping processes at these dimensions. Comparative single nanoplate studies using discrete dipole approximations were performed to analyse the dephasing processes contributing to these reduced linewidths and to determine the key parameters defining the underlying plasmonic response. These single nanoplate approximations highlight the dominance of absorption processes over radiative processes and demonstrate that this dominance can be attributed to the platelet nature/geometry of the nanoplates. These calculations indicate that the higher aspect ratio allows for the maintenance of coherent plasmon oscillations as the edge length of the triangular platelet increases within the sols. Thickness studies verify that this reduction in radiation damping is due to high aspect ratio and can act to confine electromagnetic fields at the nanoplate surface, thereby increasing near-field enhancement and hence the resultant plasmonic refractive index sensitivity.

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Approaches to the Synthesis and Characterization of Spherical and Anisotropic Silver Nanomaterials

Cited by 3 publications

References 157 publications

Etching-Resistant Silver Nanoprisms by Epitaxial Deposition of a Protecting Layer of Gold at the Edges

Etching-Resistant Silver Nanoprisms by Epitaxial Deposition of a Protecting Layer of Gold at the Edges

Versatile Solution Phase Triangular Silver Nanoplates for Highly Sensitive Plasmon Resonance Sensing

Scaling of Surface Plasmon Resonances in Triangular Silver Nanoplate Sols for Enhanced Refractive Index Sensing

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