Synthesis of Anisotropic Concave Gold Nanocuboids with Distinctive Plasmonic Properties

Abstract

Gold nanoparticles have attracted considerable attention owing to their appealing plasmonic properties that have found applications in sensing, imaging, and energy harvesting. In the present article, we report the synthesis of anisotropic concave Au nanocuboids using a seeded growth method controlled by a seed concentration. Unlike conventional nonconcave counterparts which typically present two fundamental plasmonic modes (transverse and longitudinal modes), our experimental measurements and theoretical analysis show that the anisotropic concave Au nanocuboid has three plasmonic resonances. Theoretical calculations based on a finite element method confirm that the third resonance is a transverse "edge" mode, which is enhanced by the sharpened edges of the concave surfaces. This third resonance is found to be separated from the conventional broad transverse mode band. Because of the separation of the resonance mode, the quality-factor of the original transverse mode shows nearly a 3-fold enhancement.

Concave gold nanoparticle-based highly sensitive electrochemical IgG immunobiosensor for the detection of antibody–antigen interactions

“…42 7.5 mL of a growth solution containing a mixture of 2.5 Â 10 À4 M HAuCl 4 and 0.01 M CTAB solutions were added to ve 20 mL conical asks. 42 7.5 mL of a growth solution containing a mixture of 2.5 Â 10 À4 M HAuCl 4 and 0.01 M CTAB solutions were added to ve 20 mL conical asks.…”

“…48 As the concentration of the AuNR seeds plays an essential role in the control of nanoparticle growth, we have optimized various seed concentrations ranging from 5 Â C 0 to 0.2 Â C 0 (C 0 represents the concentration of the AuNR seed stock solution) to obtain concave nanoparticles, and the resultant products are designated as AuNP-5C 0 , AuNP-2C 0 , AuNP-C 0 , AuNP-0.5C 0 , and AuNP-0.2C 0 . 42 When the seed concentration is reduced to 2 Â C 0 , the grown AuNPs begin to exhibit facets with irregular trapezoidal and triangular structures on the surface. [49][50][51] Such higher seed concentrations normally lead to the isotropic overgrowth of Au seeds, resulting in the formation of a rod-like nanostructure with at surfaces.…”

“…42 It is known that the higher seed concentration of 5 Â C 0 has been frequently used for AuNP synthesis. 42 The concave nanocuboids can be obtained in a moderate seed concentration between 0.5 Â C 0 and to 1 Â C 0 (Fig. 42 When the seed concentration is reduced to 2 Â C 0 , the grown AuNPs begin to exhibit facets with irregular trapezoidal and triangular structures on the surface.…”

“…32,33 Therefore, nanomaterials can facilitate electron transfer or act as an electrocatalyst for the oxidation reaction with antibodies, and are important and necessary modications on electrodes. 42 It is very important to mention that the CAuNCs are not common nanostructures, and generally possess high-index facets {720}, which exhibit much higher chemical activities 40,41,43 and superior electrocatalytic performance compared with conventional AuNPs enclosed by low-index facets such as {111}, {100}, and {110}. This enables tuning of the plasmon resonance from the visible to near-IR spectral regions.…”

Intertwining Roles of Silver Ions, Surfactants, and Reducing Agents in Gold Nanorod Overgrowth: Pathway Switch between Silver Underpotential Deposition and Gold–Silver Codeposition

“…We also found that the transverse plasmon mode of DBLNRs split into two peaks, which is a spectral signature of NRs with surface indentations. 63 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 12…”