Hybrid Multilayered Plasmonic Nanostars for Coherent Random Lasing

Munkhbat, Battulga; Ziegler, Johannes; Pöhl, Hannes; Wörister, Christian; Sivun, Dmitry; Scharber, Markus C.; Klar, Thomas A.; Hrelescu, Calin

doi:10.1021/acs.jpcc.6b05737

Cited by 19 publications

(18 citation statements)

References 41 publications

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“…Importantly, their limited cytotoxicity 4 promises to enable their use in vitro and in vivo. However, despite the wealth of applied work 5,6,7 , very limited fundamental research has been carried out on these particles, both from the experimental and theoretical standpoints 8,9,10 . As a result, published research cannot be evaluated comparatively, and, therefore, implemented at the industrial scale for technologically relevant applications.…”

Section: Main Textmentioning

confidence: 99%

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Rational Design of Gold Nanostars with Tailorable Plasmonic Properties

Tsoulos

Atta²,

Lagos³

et al. 2018

Preprint

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<div>Gold nanostars display exceptional field enhancement properties and tunable resonant modes that can be leveraged to create effective imaging tags or phototherapeutic agents, or to design novel hot-electron based photocatalysts. From a fundamental standpoint, they represent important tunable platforms to study the dependence of hot carrier energy and dynamics on plasmon band intensity and position. Toward the realization of these platforms, holistic approaches taking into account both theory and experiments to study the fundamental behavior of these</div><div>particles are needed. Arguably, the intrinsic difficulties underlying this goal stem from the inability to rationally design and effectively synthesize nanoparticles that are sufficiently monodispersed to be employed for corroborations of the theoretical results without the need of single particle experiments. Herein, we report on our concerted computational and experimental effort to design, synthesize, and explain the origin and morphology-dependence of the plasmon modes of a novel gold nanostar system, with an approach that builds upon the well-known plasmon hybridization model. We have synthesized monodispersed samples of gold nanostars with finely tunable morphology employing seed-mediated colloidal protocols, and experimentally observed narrow and spectrally resolved harmonics of the primary surface plasmon resonance mode both at the single particle level (via electron energy loss spectroscopy) and in ensemble (by UV-Vis and ATR-FTIR spectroscopies). Computational results on complex anisotropic gold nanostructures are validated experimentally on samples prepared colloidally, underscoring their importance as ideal testbeds for the study of structure-property relationships in colloidal nanostructures of high structural complexity.</div>

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Section: Main Textmentioning

confidence: 99%

“…(6) (7) The absorption and scattering cross sections are defined by the energy rates absorbed and scattered by the nanostar volume and surface area, defined in Equations 8 and 9 respectively, and divided by the incident irradiance, given by Equation 10:…”

Section: )mentioning

confidence: 99%

Rational Design of Gold Nanostars with Tailorable Plasmonic Properties

Tsoulos

Atta²,

Lagos³

et al. 2018

Preprint

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“…Furthermore, in view of the potential use of nanostars as hot electron‐based photocatalysts, the possibility to isolate the tips from the remainder of the nanostar, thus enabling us to prove their role as source of hot electrons, could lead to interesting fundamental studies on the generation and fate of these hot carriers. While protocols exist to coat nanostars with silica, and silica coated nanostars have found wide range applicability, unfortunately, no established protocols exist to selectively coat the nanostar core while leaving the tips exposed. In addition, known protocols for silica etching would be too aggressive for the delicate nanostar morphology and would lead to tip reshaping …”

Section: Figurementioning

confidence: 99%

Highly Tunable Growth and Etching of Silica Shells on Surfactant‐Free Gold Nanostars

2019

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Herein, we report an efficient method to coat gold nanostars with a silica shell of variable thickness and then tunably etch it by using a mild silica etching reagent, NaBH 4 . This method generates a novel type of nanostar coating in which silica only covers the core, leaving the tips variably exposed.Gold nanostars are a subtype of colloidal nanomaterial that consists of a central core from which multiple sharp branches protrude. [1][2][3][4] They exhibit intense and tunable localized surface plasmon resonances (LSPRs) in the near-infrared (NIR), that have been leveraged in biological applications, especially for multimodal imaging and photothermal therapy. [5][6][7][8] Owing to their resonances in the NIR and intense near-field enhancements, nanostars can afford intense imaging response and photothermal heating without substantial tissue damage, which is important in view of clinical implementations. To better understand how to best leverage these particles, it is first necessary to characterize their physical and optical properties, and to do so quantitatively, while also trying to design predictive tools that could aid us in tuning their synthesis to achieve the desired behavior. As a first step toward this goal, we have recently implemented an experimental-computational approach to calculate the extinction coefficient of gold nanostars employing finite element (FEM) calculations, obtaining very similar results to what achieved by Hamad-Schifferli and co-workers, who employed discrete dipole approximation (DDA) calculations. [9][10] The evaluation of extinction coefficients for plasmonic nanoparticles is the gateway to quantification and real life applicability; nonetheless, it is extremely complex for nanoparticles of complex morphology such as nanostars, and often not practical. Therefore, we hypothesized that by going back to the drawing board, and cleverly designing SiO 2 coating protocols, which would leave only the nanostar spikes exposed from the silica shell, we could still leverage the intense near-field enhancements at the tips while having to deal with a much more simplified morphology. Moreover, the partial silica coating would increase colloidal stability and biocompatibility, leading to improved applicability in vitro. As we previously observed, [11] the optical properties of tunable silica shells can be reflected in the overall dielectric function of the core-shell colloid, leading to surface-enhanced Raman scattering (SERS) enhancement factors that depend both on the extent of tip exposure and the thickness of the silica shell, providing SERS tags of variable brightness. Furthermore, in view of the potential use of nanostars as hot electron-based photocatalysts, [12][13] the possibility to isolate the tips from the remainder of the nanostar, thus enabling us to prove their role as source of hot electrons, could lead to interesting fundamental studies on the generation and fate of these hot carriers. While protocols exist to coat nanostars with silica, and silica coated nanostars have found wi...

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“…Hrelescu. et al reported that hybrid multilayered plasmonic nanostars can reduce the pumping threshold for random lasing [ 20 ]. Follow-up demonstrations have motivated researchers to study localized surface plasmon resonance random multimode lasers in polymer thin films doped with gain dye and silver nanoparticles [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Large-Area Biocompatible Random Laser for Wearable Applications

Guo

et al. 2021

Nanomaterials

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Recently, wearable sensor technology has drawn attention to many health-related appliances due to its varied existing optical, electrical, and mechanical applications. Similarly, we have designed a simple and cheap lift-off fabrication technique for the realization of large-area biocompatible random lasers to customize wearable sensors. A large-area random microcavity comprises a matrix element polymethyl methacrylate (PMMA) in which rhodamine B (RhB, which acts as a gain medium) and gold nanorods (Au NRs, which offer plasmonic feedback) are incorporated via a spin-coating technique. In regards to the respective random lasing device residing on a heterogenous film (area > 100 cm2), upon optical excitation, coherent random lasing with a narrow linewidth (~0.4 nm) at a low threshold (~23 μJ/cm2 per pulse) was successfully attained. Here, we maneuvered the mechanical flexibility of the device to modify the spacing between the feedback agents (Au NRs), which tuned the average wavelength from 612.6 to 624 nm under bending while being a recoverable process. Moreover, the flexible film can potentially be used on human skin such as the finger to serve as a motion and relative-humidity sensor. This work demonstrates a designable and simple method to fabricate a large-area biocompatible random laser for wearable sensing.

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Hybrid Multilayered Plasmonic Nanostars for Coherent Random Lasing

Cited by 19 publications

References 41 publications

Rational Design of Gold Nanostars with Tailorable Plasmonic Properties

Rational Design of Gold Nanostars with Tailorable Plasmonic Properties

Highly Tunable Growth and Etching of Silica Shells on Surfactant‐Free Gold Nanostars

Large-Area Biocompatible Random Laser for Wearable Applications

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