Research ArticleNANOMATERIALS

Controlled growth and shape-directed self-assembly of gold nanoarrows

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Science Advances  27 Oct 2017:
Vol. 3, no. 10, e1701183
DOI: 10.1126/sciadv.1701183
  • Fig. 1 Schematics of synthesis and self-assembly of GNAs.

    (A) Controlled growth of GNA under kinetic control coupled with selective surface passivation. (B) GNA consisting of two pyramidal heads and a four-wing shaft. (C) Self-assembly process of GNAs through bulk solvent evaporation. Note that the pink arrow denotes the moving direction of the three-phase contact line, and the black arrows indicate the evaporation of solvent. (D) Self-assembled GNA SCs with varied packing and interlocking states.

  • Fig. 2 Characterization of representative GNAs.

    (A to C) SEM (A and B) and TEM (C) images of GNAs. (D and E) TEM images of single GNAs lying on the (110) plane (D) and the (100) plane (E). Insets show the schematic illustrations. (F and G) HRTEM images of framed areas in (D) and (E), respectively.

  • Fig. 3 Morphology evolution and absorption spectra of GNAs.

    (A) Schematic illustration of the overgrowth of GNRs into GNAs. Structural parameters, including length (L) and width (D) of GNA, spacing between two pyramid heads (l), and width of crossed laminas (d), are shown in the side view. (B and C) TEM images of GNAs with aspect ratios (L/D) of 2.3 (B) and 1.7 (C). (D) Structural parameters of GNAs plotted as a function of the concentration of HAuCl4 for the GNA growth. (E) Absorption spectra of GNAs with different aspect ratios. Inset shows the photograph of the solutions containing GNAs. Note that the red and blue arrows indicate the red shift and blue shift of two plasmonic absorption peaks, respectively. a.u., arbitrary unit.

  • Fig. 4 2D SCs assembled by GNAs.

    SEM images (A1, A2, B1, B2, C1, C2, D1, D2, E1, and E2) and geometric models (A3, A4, B3, B4, C3, C4, D3, D4, E3, and E4) of Net-I (A1 to A4), Net-II (B1 to B4), Zipper (C1 to C4), Weave-I (D1 to D4), and Weave-II (E1 to E4) SCs. Insets show the corresponding FFT patterns. The red rhomboids in (A3) represent the unit cell of Net-I SCs with lattice parameters of a and θ, and the black dashed lines denote the glide planes. Two Net-I SCs with the limiting conformations are also shown in (A3). Facets lying against the facets of neighboring GNAs are painted in saffron in (A4), (B4), (C4), (D4), and (E4).

  • Fig. 5 3D SCs assembled by GNAs.

    SEM images (A1, A2, B1, B2, B3, C1, and C2) and geometric models (A3, A4, B4, C3, and C4) of Net-III (A1 to B4) and Weave-III (C1 to C4) SCs. Insets show the corresponding FFT patterns. Facets lying against the facets of neighboring GNAs are painted in saffron in (A4), (B4), and (C4).

  • Fig. 6 Simulated modeling of electric field distributions for GNA SCs.

    Simulated patterns of the normalized electric field distributions (left) and geometric models (right) of Net-I (A), Net-II (B), Zipper (C), Weave-I (D), Weave-II (E), and bilayer Weave-III (F) SCs at an incident wavelength of 633 nm. Note that the GNAs on the top and bottom layers in (F) are presented in different colors.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/10/e1701183/DC1

    Supplementary Materials and Methods

    fig. S1. Characterization of GNRs used as the seeds for the growth of GNAs.

    fig. S2. Time-dependent morphology evolution of GNAs.

    fig. S3. Characterizations of Au nanocrystals synthesized with different AgNO3 concentrations.

    fig. S4. Characterizations of Au nanocrystals synthesized with different CTAC concentrations.

    fig. S5. X-ray photoelectron spectroscopy elemental analysis of Ag, Cl, and Au on GNAs.

    fig. S6. Scheme of the possible mechanism of GNR overgrowth under different kinetic conditions.

    fig. S7. TEM images and the statistics of the structural parameters of various GNAs.

    fig. S8. Schematic illustration of self-assembly of GNAs into SCs by bulk solution evaporation.

    fig. S9. TEM characterization of the nanogap sizes between GNAs in Net-I SCs.

    fig. S10. Net-I SCs with the two limiting conformations.

    fig. S11. Unit cells of GNA SCs.

    fig. S12. SEM images of Net-III SCs with specific shapes.

    fig. S13. Representative SCs formed by GNAs with different aspect ratios (L/D).

    fig. S14. Area fractions of SCs assembled from GNAs with different aspect ratios.

    fig. S15. SEM images of the assembled structures under different humidity conditions.

    fig. S16. Simulated electric field distribution and extinction spectra of typical GNAs.

    fig. S17. Simulated patterns of the normalized electric field distribution of Net-I SCs.

    fig. S18. Simulated absorption, scattering, and extinction spectra of three SCs and simulated electric field and surface charge distribution of Zipper SCs.

    fig. S19. Simulated scattering spectra of Net-I and Zipper SCs with the polarizations of the incident light along 0° and 90°.

    fig. S20. SERS detection of 4-aminothiophenol on Net-I SCs assembled on Si/Au substrate using an incident laser of 633 nm.

    fig. S21. SERS measurements conducted on Net-I and Zipper SCs.

    table S1. Concentrations of HAuCl4 and AA in the growth solution of GNAs with various aspect ratios.

    table S2. Cell parameters and packing efficiencies of the various SCs shown in fig. S11.

    note S1. Discussion on simulated absorption, scattering, and extinction spectra of GNA SCs.

    note S2. Discussion on polarization-dependent scattering of GNA SCs.

    note S3. Discussion on SERS performance of GNA SCs.

    movie S1. Rotation of two GNAs around the z and x axes showing the geometric models.

    movie S2. Locking and unlocking process of two GNAs with a concave geometry.

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • fig. S1. Characterization of GNRs used as the seeds for the growth of GNAs.
    • fig. S2. Time-dependent morphology evolution of GNAs.
    • fig. S3. Characterizations of Au nanocrystals synthesized with different AgNO3 concentrations.
    • fig. S4. Characterizations of Au nanocrystals synthesized with different CTAC concentrations.
    • fig. S5. X-ray photoelectron spectroscopy elemental analysis of Ag, Cl, and Au on GNAs.
    • fig. S6. Scheme of the possible mechanism of GNR overgrowth under different kinetic conditions.
    • fig. S7. TEM images and the statistics of the structural parameters of various GNAs.
    • fig. S8. Schematic illustration of self-assembly of GNAs into SCs by bulk solution evaporation.
    • fig. S9. TEM characterization of the nanogap sizes between GNAs in Net-I SCs.
    • fig. S10. Net-I SCs with the two limiting conformations.
    • fig. S11. Unit cells of GNA SCs.
    • fig. S12. SEM images of Net-III SCs with specific shapes.
    • fig. S13. Representative SCs formed by GNAs with different aspect ratios (L/D).
    • fig. S14. Area fractions of SCs assembled from GNAs with different aspect ratios.
    • fig. S15. SEM images of the assembled structures under different humidity conditions.
    • fig. S16. Simulated electric field distribution and extinction spectra of typical GNAs.
    • fig. S17. Simulated patterns of the normalized electric field distribution of Net-I SCs.
    • fig. S18. Simulated absorption, scattering, and extinction spectra of three SCs and simulated electric field and surface charge distribution of Zipper SCs.
    • fig. S19. Simulated scattering spectra of Net-I and Zipper SCs with the polarizations of the incident light along 0° and 90°.
    • fig. S20. SERS detection of 4-aminothiophenol on Net-I SCs assembled on Si/Au substrate using an incident laser of 633 nm.
    • fig. S21. SERS measurements conducted on Net-I and Zipper SCs.
    • table S1. Concentrations of HAuCl4 and AA in the growth solution of GNAs with various aspect ratios.
    • table S2. Cell parameters and packing efficiencies of the various SCs shown in fig. S11.
    • note S1. Discussion on simulated absorption, scattering, and extinction spectra of GNA SCs.
    • note S2. Discussion on polarization-dependent scattering of GNA SCs.
    • note S3. Discussion on SERS performance of GNA SCs.
    • Legends for movies S1 and S2

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.avi format). Rotation of two GNAs around the z and x axes showing the geometric models.
    • movie S2 (.avi format). Locking and unlocking process of two GNAs with a concave geometry.

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