Correction to In Situ Determination of Colloidal Gold Concentrations with UV–Vis Spectroscopy: Limitations and Perspectives

Hendel, Thomas; Wuithschick, Maria; Kettemann, Frieder; Birnbaum, Alexander; Rademann, Klaus; Polte, Jörg

doi:10.1021/acs.analchem.5b01602

Cited by 4 publications

(5 citation statements)

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“…To investigate the additional gain in SERS enhancement, as predicted by the electromagnetic simulations, we used 4-nitrothiophenol (NTP), a nonresonant Raman marker with high binding affinity to the gold surface. Since our main objective was to compare the SERS efficiency of the prepared superstructures in a close-to-application scenario, we adjusted all dispersions to the same gold concentration (Au 0 , 0.25 mM), as determined spectroscopically . Without NTP, the unlabeled particles show weak signals that can be assigned to the surface chemistry of the building blocks (Table S3).…”

Section: Results and Discussionmentioning

confidence: 99%

“…Since our main objective was to compare the SERS efficiency of the prepared superstructures in a close-to-application scenario, we adjusted all dispersions to the same gold concentration (Au 0 , 0.25 mM), as determined spectroscopically. 41 Without NTP, the unlabeled particles show weak signals that can be assigned to the surface chemistry of the building blocks (Table S3). 25 However, these background signals are significantly less intense than the ones of the aromatic marker NTP.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Colloidal Superstructures with Triangular Cores: Size Effects on SERS Efficiency

et al. 2020

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The design of colloidal nanostructures as surface-enhanced Raman scattering (SERS) substrates requires control over both structural and optical characteristics. A widespread expectation is that the SERS efficiency depends crucially on whether the plasmonic excitation matches the exciting laser wavelength. However, also the balance between radiative (scattering) and non-radiative (absorbing) properties plays a major role, regarding both the efficiency of near field enhancement and the experimentally observed signal intensity. We present a study of the influence of mode-excitation matching and extinction characteristics for core/satellite superstructures, comprising gold nanotriangles decorated with small gold nanospheres. The variation of the core size and aspect ratio allowed tuning the main coupled mode between 700 and 800 nm, from off-resonant through resonant at 785 nm, as well as tuning extinction contributions, from dominantly absorbing to dominantly scattering. We observed additional gains of 1-2 orders of magnitude in signal enhancement, which were correlated to core size and diffuse optical properties. Our findings indicate a competition between SERS enhancement and increased scattering losses in larger assemblies. Thus, a balance of optical parameters is required for efficient SERS and the development of assemblies as advanced sensing devices.

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Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Colloidal Superstructures with Triangular Cores: Size Effects on SERS Efficiency

et al. 2020

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“…in which we use the extinction at 400 nm as a close estimation of the Au 0 content in the sample medium. 51 The small spherical NPs (red) show the highest heating efficiency (Fig. 5b), above 90%.…”

Section: Plasmonic Heating Efficiencymentioning

confidence: 94%

SERS and plasmonic heating efficiency from anisotropic core/satellite superstructures

et al. 2019

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“…Solid samples were mounted on a custom-made holder (Ultimaker 3; Ultimaker B.V.) that allowed measurements along the gradient with a spot size of 2 × 5 mm 2 in millimeter steps. The extinction at the wavelength of 400 nm (interband transitions), which is assumed to have a size-independent absorption coefficient, − was used to normalize the UV/vis/NIR spectra and to calculate the molar concentration of Au 0 in the NP dispersions. The molar concentration of Au 0 and the size of the nanoparticles obtained from TEM images enabled the calculation of the particle concentration (number of AuNPs per volume).…”

Section: Methodsmentioning

confidence: 99%

Plasmonic Gradient Arrays for Rapid Screening of Surface-Enhanced Raman Scattering Efficiency: Particle Libraries of Gold Nanostars

2021

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The efficiency of signal enhancement for surface-enhanced Raman scattering (SERS) spectroscopy is a crucial parameter for the design and development of nanoparticle-based sensing applications. However, screening SERS capabilities of anisotropic nanoparticles by iterative synthesis is time consuming, and their prediction still suffers from the complex nonlinear relationships of morphological and electromagnetic properties. We present an approach to use a macroscopic gradient array of substrate-supported nanoparticles for rapid screening of their SERS efficiencies. The gradient represents a “plasmonic library” of colloids synthesized by two-step post-modification of a monolayer of randomly close-packed gold nanospheres covered with poly(N-isopropylacrylamide) shells. A first chemical overgrowth process yields a continuous gradient of seed particles, with diameters ranging between 10 and 60 nm. Subsequently, the seeds are further grown into nanostars (NSs) with spiky tips, which improve their SERS-enhancing capabilities. Raman mapping along the gradient provides rapid and reliable quantification of the specific SERS efficiencies for the whole library, as well as correlation of their optical and structural properties. By ensuring that the number and density of particles in the Raman excitation volume remain constant, the most appropriate synthetic conditions for efficient SERS can be readily identified on a single screening. As a proof of application, we screened the SERS performance of a library of NSs and applied the selected best candidates for the detection of the bacterial biomarker pyocyanin. This bacterial quorum sensing signaling molecule was quantitatively detected within a linear dynamic range between 10–7 and 10–5 M, suitable for clinical applications.

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Correction to In Situ Determination of Colloidal Gold Concentrations with UV–Vis Spectroscopy: Limitations and Perspectives

Cited by 4 publications

References 0 publications

Colloidal Superstructures with Triangular Cores: Size Effects on SERS Efficiency

Colloidal Superstructures with Triangular Cores: Size Effects on SERS Efficiency

SERS and plasmonic heating efficiency from anisotropic core/satellite superstructures

Plasmonic Gradient Arrays for Rapid Screening of Surface-Enhanced Raman Scattering Efficiency: Particle Libraries of Gold Nanostars

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