Greater SERS Activity of Ligand-Stabilized Gold Nanostars with Sharp Branches

Meng, Xianghua; Dyer, Jacqueline E.; Huo, Yifeng; Jiang, Chaoyang

doi:10.1021/acs.langmuir.0c00079

Cited by 51 publications

(40 citation statements)

References 63 publications

(91 reference statements)

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“…Gold nanostars (AuNSs) are of special interest because morphological modifications, such as number of tips and their length, can be used to tune the position of the band of localized surface plasmon resonance [19,20] to place it within a biological window [21,22]. In addition, strong electric field enhancements due to the presence of multiple sharp tips of AuNSs transform them into high-performance detection materials for surface-enhanced Raman scattering (SERS) [23,24] and surface-enhanced fluorescence (SEF) [25,26]. Properly designed AuNSs can be applied for drug delivery and/or photothermal therapy in the treatment of diseases [16,18] and can be combined with diagnostic mechanisms for surface enhancement in imaging or detection [15,22,26].…”

Section: Introductionmentioning

confidence: 99%

Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring

et al. 2021

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Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic β-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV–VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 ± 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection.

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Section: Introductionmentioning

confidence: 99%

Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring

et al. 2021

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“…We attribute these spectral changes to variations in gold nanostar morphology and their resulting plasmonic properties near the excitation wavelength. Because an increase in radius of curvature of the tips of the nanostar branches [11] as well as a decrease in nanostar concentration should cause SERS intensities to decrease, [49] the observed systematic and reproducible increase in SERS magnitude likely depends on branch morphology (i.e., length and aspect ratio) and as a result improved plasmonic properties for SERS enhancement. Namely, as branch aspect ratio (and length) increases, electromagnetic enhancement associated with the bonding (i.e., bright) plasmonic mode becomes more favorable, and plasmonic contributions arising from branch-branch coupling are promoted, thereby increasing the overall SERS signal observed for uranyl through dark plasmon mode [20,36,50] excitation.…”

Section: Sers Detection Of Uranyl Using Tunable Gold Nanostarsmentioning

confidence: 99%

“…The lightning rod or antenna effect associated with anisotropic nanostructures such as gold nanostars makes these materials ideal for substrates in surface‐enhanced Raman scattering (SERS). Previously, it was shown that cubes, [ 1 ] triangles, [ 2,3 ] rods, [ 4–8 ] tetrapods, [ 9 ] and spiked nanostructures (i.e., nanostars) [ 8,10–12 ] are superior substrates for SERS because of the large electromagnetic fields that arise at the near‐field of structural features with small radii of curvature. Gold nanostars, for instance, were previously shown to exhibit large electromagnetic fields near the sharp tips at the ends of their branches.…”

Section: Introductionmentioning

confidence: 99%

Tuning gold nanostar morphology for the SERS detection of uranyl

Harder

Wijenayaka

Phan

et al. 2020

J Raman Spectroscopy

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The impact of tunable morphologies and plasmonic properties of gold nanostars is evaluated for the surface‐enhanced Raman scattering (SERS) detection of uranyl. To do so, gold nanostars are synthesized with varying concentrations of the Good's buffer reagent, 2‐[4‐(2‐hydroxyethyl)‐1‐piperazinyl]propanesulfonic acid (EPPS). EPPS plays three roles including as a reducing agent for nanostar nucleation and growth, as a nanostar‐stabilizing agent for solution phase stability, and as a coordinating ligand for the capture of uranyl. The resulting nanostructures exhibit localized surface plasmon resonance (LSPR) spectra that contain two visible and one near‐infrared plasmonic modes. All three optical features arise from synergistic coupling between the nanostar core and branches. The tunability of these optical resonances is correlated with nanostar morphology through careful transmission electron microscopy (TEM) analysis. As the EPPS concentration used during synthesis increases, both the length and aspect ratio of the branches increase. This causes the two lower energy extinction features to grow in magnitude and become ideal for the SERS detection of uranyl. Finally, uranyl binds to the gold nanostar surface directly and via sulfonate coordination. Changes in the uranyl signal are directly correlated to the plasmonic properties associated with the nanostar branches. Overall, this work highlights the synergistic importance of nanostar morphology and plasmonic properties for the SERS detection of small molecules.

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“…We found that Au NSs have a higher SERS enhancement as compared to normal gold nanoparticles. 41 These Au NSs with the modification of proper capping agent can be suspended in aqueous media and behaved as colloidal SERS substrates. 41,42 Recently, there are also reports on the use of encoded Au NSs for various applications such as cell discrimination.…”

Section: Introductionmentioning

confidence: 99%

“…41 These Au NSs with the modification of proper capping agent can be suspended in aqueous media and behaved as colloidal SERS substrates. 41,42 Recently, there are also reports on the use of encoded Au NSs for various applications such as cell discrimination. 15,16 However, some of the preparation methods are rather complicated.…”

Section: Introductionmentioning

confidence: 99%