A high-yield, one-step synthesis of surfactant-free gold nanostars and numerical study for single-molecule SERS application

Chatterjee, Sharmistha; Ringane, A. B.; Arya, Akash; Das, Gour Mohan; Dantham, Venkata Ramanaiah; Laha, Ranjit; Hussian, Shymaa K.

doi:10.1007/s11051-016-3557-0

Cited by 23 publications

(15 citation statements)

References 27 publications

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“…Here, we report a simple, one-step surfactant-free wet chemistry method for synthesizing Au nanostructures with high stability and yield. This improves on our previously reported AuNS synthesis method [46], where the stability was poor and the control of the nanostar synthesis parameters was not possible. Synthesis as well as optical and electron spectroscopy characterization of these highly stable nanoparticles (stability > 5 months in aqueous solution) indicate that these nanoparticles have remarkable plasmonic features.…”

Section: Introductionsupporting

confidence: 69%

Heterodimeric Plasmonic Nanogaps for Biosensing

et al. 2018

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We report the study of heterodimeric plasmonic nanogaps created between gold nanostar (AuNS) tips and gold nanospheres. The selective binding is realized by properly functionalizing the two nanostructures; in particular, the hot electrons injected at the nanostar tips trigger a regio-specific chemical link with the functionalized nanospheres. AuNSs were synthesized in a simple, one-step, surfactant-free, high-yield wet-chemistry method. The high aspect ratio of the sharp nanostar tip collects and concentrates intense electromagnetic fields in ultrasmall surfaces with small curvature radius. The extremities of these surface tips become plasmonic hot spots, allowing significant intensity enhancement of local fields and hot-electron injection. Electron energy-loss spectroscopy (EELS) was performed to spatially map local plasmonic modes of the nanostar. The presence of different kinds of modes at different position of these nanostars makes them one of the most efficient, unique, and smart plasmonic antennas. These modes are harnessed to mediate the formation of heterodimers (nanostar-nanosphere) through hot-electron-induced chemical modification of the tip. For an AuNS-nanosphere heterodimeric gap, the intensity enhancement factor in the hot-spot region was determined to be 106, which is an order of magnitude greater than the single nanostar tip. The intense local electric field within the nanogap results in ultra-high sensitivity for the presence of bioanalytes captured in that region. In case of a single BSA molecule (66.5 KDa), the sensitivity was evaluated to be about 1940 nm/RIU for a single AuNS, but was 5800 nm/RIU for the AuNS-nanosphere heterodimer. This indicates that this heterodimeric nanostructure can be used as an ultrasensitive plasmonic biosensor to detect single protein molecules or nucleic acid fragments of lower molecular weight with high specificity.

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Section: Introductionsupporting

confidence: 69%

Heterodimeric Plasmonic Nanogaps for Biosensing

et al. 2018

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“…Anisotropic gold nanoparticles synthesized via seed [1, 2] and seedless [3] as well as surfactant [4, 5] and surfactant-free [6, 7] synthetic methods yield shape and size tunable optical properties [8, 9] that are widely used for chemical [10], biological [11, 12], and medical sensing [13] applications. Gold nanostars exhibit large surface energies and small positive and negative curvature features relative to spheres and larger structures, thus flocculation and restructuring over time are likely.…”

Section: Introductionmentioning

confidence: 99%

How to accurately predict solution-phase gold nanostar stability

Phan

Haes

2018

Anal Bioanal Chem

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Unwanted nanoparticle aggregation and/or agglomeration may occur when anisotropic nanoparticles are dispersed in various solvents and matrices. While extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory has been successfully applied to predict nanoparticle stability in solution, this model fails to accurately predict the physical stability of anisotropic nanostructures; thus limiting its applicability in practice. Herein, DLVO theory was used to accurately predict gold nanostar stability in solution by investigating how the choice of the nanostar dimension considered in calculations influences the calculated attractive and repulsive interactions between nanostructures. The use of the average radius of curvature of the nanostar tips instead of the average radius as the nanostar dimension of interest increases the accuracy with which experimentally observed nanoparticle behavior can be modeled theoretically. This prediction was validated by measuring time-dependent localized surface plasmon resonance (LSPR) spectra of gold nanostars suspended in solutions with different ionic strengths. Minimum energy barriers calculated from collision theory as a function of nanoparticle concentration were utilized to make kinetic predictions. All in all, these studies suggest that choosing the appropriate gold nanostar dimension is crucial to fully understanding and accurately predicting the stability of anisotropic nanostructures such as gold nanostars; i.e., whether the nanostructures remain stable and can be used reproducibly, or whether they aggregate and exhibit inconsistent results. Thus, the present work provides a deeper understanding of internanoparticle interactions in solution and is expected to lead to more consistent and efficient analytical and bioanalytical applications of these important materials in the future. Graphical abstract ᅟ.

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“…The SERS enhancement due to chemisorption were found to be negligible in both our present cases, as there was neither a red-shift nor a blue-shift of analyte vibration peaks. [8] Thus, the observed tremendous SERS enhancement was clearly attributed to increased photonic density of states in case of Au nanostellates. Moreover, as revealed from the diffraction studies, larger crystallite domain extended along high energy facets drastically affect the plasmon dephasing and hence boost the characteristic electromagnetic enhancement effects.…”

Section: Sers Capabilities Of Nanospheres and Nanostellatesmentioning

confidence: 95%

Pertinent Shape Effects of Gold Nanospheres and Nanostellates

Verma¹,

Newmai²,

Kedia³

et al. 2017

IOSR JAP

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Modulating optical resonances in plasmonic resonators were easily achieved by virtue of their constituent composition, size as well as shape. Such confinement of electric field in the nano-regime enhances extraordinarily the light-matter interaction, further enabling wide range of applications in nanophotonics, SERS etc. Herein, we compare and contrast the surface plasmon modes of Au nanospheres and nanostellates, the visibly distinct morphologies of which not only correlates exceptionally well with their structure-property functional relationships, but also articulate their respective growth mechanisms in a rather meticulous manner. Higher amplification of analyte Raman signals visibly demonstrates the increased number of hot-spots with reference to their surface morphology and roughness.

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A high-yield, one-step synthesis of surfactant-free gold nanostars and numerical study for single-molecule SERS application

Cited by 23 publications

References 27 publications

Heterodimeric Plasmonic Nanogaps for Biosensing

Heterodimeric Plasmonic Nanogaps for Biosensing

How to accurately predict solution-phase gold nanostar stability

Pertinent Shape Effects of Gold Nanospheres and Nanostellates

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