Au Triangular Nanoprisms Research Articles

A sandwich-type electrochemical immunosensor prepared with graphyne-Au triangular nanoprisms and MoS2-AuPtCu hexagonal nanoframes for the detection of human growth/differentiation factor 15

Growth differentiation factor 15 (GDF-15) is an important biomarker for the early diagnosis and prognostic evaluation of cardiovascular disease (CVD). Monitoring the expression level of GDF-15 in serum can enable early diagnosis evaluation of CVDs. Therefore, the realization of high-sensitivity GDF-15 detection platforms is clinically significant. To detect GDF-15, we developed a sandwich-type electrochemical immunosensor based on hydrogen peroxide (H2O2) as a signal source. AuPtCu hexagonal metal nanoframes (AuPtCu HNFs) loaded onto molybdenum disulfide (MoS2) nanosheets (MoS2-AuPtCu HNF) as secondary antibody labels provided signal amplification. The hollow three-dimensional hexagonal-shaped structure of the AuPtCu nanoframe exposed abundant active sites and exhibited excellent catalytic properties. MoS2 nanosheets with flower-like structures and large specific surface areas can effectively load AuPtCu HNFs. The combination of AuPtCu HNFs and MoS2 nanosheets enhanced the catalytic activity toward H2O2 reduction and realized signal amplification. For the substrate material, two-dimensional Au triangular nanoprisms (Au TNPs) with two large surface planes were hybridized with graphyne (GDY) nanosheets. The obtained GDY-Au TNPs exhibited low catalytic activity and excellent electrical conductivity; therefore, they were used to load primary antibodies to effectively enhance the sensitivity. Under optimal conditions, the constructed immunosensor exhibited a wide detection range of 500 fg/mL to 50 ng/mL and low detection limit of 0.212 pg/mL. Moreover, the GDF-15 content in human serum was tested with satisfactory results. Therefore, the constructed immunosensor can sensitively and accurately detect GDF-15 for the early diagnosis of CVD.

The structure and plasmonic properties regulation of Au@Ag core-shell nanostructures with Au triangular nanoprisms as the core mediated by halide

The structure and plasmonic properties regulation of Au@Ag core-shell nanostructures with Au triangular nanoprisms as the core mediated by halide

Tuning the structure and plasmonic properties of Pt–Au triangular nanoprisms: From deposition to etching

Because of the strong electromagnetic field at the corners and more tunable surface plasmon resonance (SPR) bands in the visible and infrared regions, gold triangular nanoprisms can be applied to more fields. Compared with monometallic nanomaterials, polymetallic nanomaterials are composed of multiple metals and possess many special optical properties. Recently, structurally novel Pt-based polymetallic nanostructures have attracted much attention due to their superior catalytic performance. In this study, gold triangular nanoprisms were prepared by the seed growth method. By adjusting the amount of seeds, gold triangular nanoprisms of different sizes were formed. By changing the concentration of Cetyltrimethylammonium Bromide (CTAB) and Cetyltrimethylammonium chloride (CTAC), the purification process of gold triangular nanoprisms was adjusted to make gold triangular nanoprisms more uniform. The synthesis of Pt-Au triangular nanoprisms and the switching between etching and deposition dominated in the reaction is controlled by adjusting the volume of AgNO3, H2PtCl6, and the size of gold triangular nanoprisms. At relatively high H2PtCl6 concentrations, the etching process dominates; at lower H2PtCl6 concentrations, the etching process is restrained. Due to the good catalytic performance of Pt itself and the rough surface-induced Surface-Enhanced Raman Scattering (SERS) improvement of the nanoparticles, the application of Pt-Au triangular nanoprisms in the fields of catalysis and SERS is proposed.

Pd-Coated Au Triangular Nanoprisms as Catalysts for Hot-Carrier-Driven Photochemistry

Pd-Coated Au Triangular Nanoprisms as Catalysts for Hot-Carrier-Driven Photochemistry

Highly Efficient Photothermal Therapy with Cell-Penetrating Peptide-Modified Bumpy Au Triangular Nanoprisms using Low Laser Power and Low Probe Dose.

Photothermal therapy (PTT) exploits nanomaterials with optimal heat conversion and cellular penetration using near-infrared (NIR) laser irradiation. However, current PTT agents suffer from inefficient heat conversion, poor intracellular delivery, and a high dose of probes along with excessive laser irradiation, causing limited therapeutic outcomes. Here, bumpy Au triangular nanoprisms (BATrisms) are developed for increasing the surface area, improving cell penetration, shifting the absorption peak to the NIR region, and enhancing the photothermal conversion efficiency (∼86%). Further, leucine (L)- and lysine (K)-rich cell-penetrating peptides (LK peptides) were employed to largely improve their cellular uptake efficiency. Importantly, a significant in vivo therapeutic efficacy with LK-BATrisms was demonstrated in a triple-negative breast cancer xenograft mice model. A very small dose of LK-BATrism (2.5 μg Au) was enough to exert antitumor efficacy under very low laser power (808 nm, 0.25 W/cm2), causing minimal tissue damages while very efficiently killing cancer cells.

Electrochemical immunosensor based on MoS2 NFs/Au@AgPt YNCs as signal amplification label for sensitive detection of CEA

Medically, the dynamic change of carcinoembryonic antigen (CEA) concentration has been an important indicator for monitoring and diagnosing tumors. The sensitive and early detection of CEA plays a momentous role in the prevention and diagnosis of cancer and the evaluation of treatment efficiency. In this work, a sensitive sandwich-type electrochemical immunosensor was fabricated for the quantitative detection of CEA. The trimetallic yolk-shell Au@AgPt nanocubes (Au@AgPt YNCs) loaded on amino-functionalized MoS2 nanoflowers (MoS2 NFs/Au@AgPt YNCs) were used as the labels to conjugate with secondary antibodies. The Au@AgPt YNCs with internal space and permeable shell improved catalytic active surface area. The nanosheet-based MoS2 NFs with good catalytic activity were used as carriers to load Au@AgPt YNCs effectively. Due to the biphasic synergistic catalysis, MoS2 NFs/Au@AgPt YNCs catalyzed the reduction of H2O2 effectually to amplify the current signal. Besides, Au triangular nanoprisms (Au TNPs) were used as substrate material to increase the effective contact areas with the surface of electrode and accelerate the interface electron transfer. Under the optimal conditions, a broad linear range from 10 fg mL−1 to 100 ng mL−1 with low detection limit of 3.09 fg mL−1 (S/N = 3) for detecting CEA was obtained. Moreover, the detection results of the human serum samples were satisfactory, indicating the fabricated immunosensor had potential application values in the early clinical analysis.

Photocurrent Enhancements of TiO2-Based Nanocomposites with Gold Nanostructures/Reduced Graphene Oxide on Nanobranched Substrate

In this work, we studied three-dimensional (3D) highly branched TiO2 nanorod (b-NR) arrays decorated with plasmonic Au triangular nanoprisms (TNPs) and reduced graphene oxide (rGO) sheets for photo...

Wavelength-dependent nonlinear absorption and ultrafast dynamics process of Au triangular nanoprisms.

The nonlinear absorption and ultrafast dynamics process of Au triangular nanoprisms were investigated by using broadband (ranging from 550 to 700 nm) nanosecond Z-scan measurements and femtosecond time-resolved transient absorption spectrum, respectively. We found that Au triangular nanoprisms exhibit saturation absorption (SA) at low excitation intensities. With the increase of incident intensity, a switch from SA to reverse saturation absorption (RSA) occurs. Photo-dynamics process was found to be a double-exponential energy relaxation with a fast and a slow decay component. Interestingly, when probe wavelength is away from the plasma resonance peak, the decay of relaxation also shows the modulation due to the vibration mode of the coherent excitation.

Anisotropic Ag2S–Au Triangular Nanoprisms with Desired Configuration for Plasmonic Photocatalytic Hydrogen Generation in Visible/Near‐Infrared Region

AbstractAnisotropic Ag2S‐edged Au‐triangular nanoprisms (TNPs) are constructed by controlling preferential overgrowth of Ag2S as plasmonic photocatalysts for hydrogen generation. Under visible and near‐infrared light irradiation, Ag2S‐edged Au‐TNPs exhibit almost fourfold higher efficiency (796 µmol h−1 g−1) than those of Ag2S‐covered Au‐TNPs (216 µmol h−1 g−1) and pure Au‐TNPs in hydrogen generation. A single‐particle photoluminescence study demonstrates that the plasmon‐induced hot electrons transfer from Au‐TNPs to Ag2S for hydrogen generation. Finite‐difference‐time‐domain simulations verify that the corners/edges of Au‐TNPs are high‐curvature sites with maximum electric field distributions facilitating hot electron generation and transfer. Therefore, Ag2S‐edged Au‐TNPs are efficient plasmonic photocatalyst with the desired configurations for charge separation boosting hydrogen generation.

Pt-Au Triangular Nanoprisms with Strong Dipole Plasmon Resonance for Hydrogen Generation Studied by Single-Particle Spectroscopy.

Three anisotropic Pt-covered, Pt-edged, and Pt-tipped Au triangular nanoprisms (TNPs) were prepared by controlling the overgrowth of Pt as photocatalysts for H2 generation. With strong electric field and more interface for the hot electrons transfer, the H2 generation rate of Pt-edged Au TNPs was 3 and 5 times higher than those of Pt-tipped and Pt-covered Au TNPs. Single-particle photoluminescence (PL) spectra and finite-difference-time-domain (FDTD) simulations demonstrated that dipole surface plasmon resonance (DSPR) of Au TNPs enhanced the hot electrons transfer from Au to Pt leading to H2 generation. SPR bands of Au TNPs depending on the size play an important role on the photocatalytic activity of Pt-edged Au TNPs.

Surface enhanced Raman scattering improvement of gold triangular nanoprisms by a gold reflective underlayer for chemical sensing

We report on an improvement way of the SERS signal of Au triangular nanoprisms for a highly sensitive detection of chemical molecules. This improvement is obtained by a simple addition of a gold reflective layer under Au nanoprisms. Using the same Au triangular nanoprisms obtained by nanosphere lithography, we studied experimentally the thickness effect of this gold underlayer on the SERS intensity of the triangular nanoprisms. We demonstrated that this SERS intensity increased with the thickness of the gold reflective underlayer, and this is due to the increment of the Au underlayer reflectivity. Thus, we showed that the metallic reflective underlayer has an important key for SERS enhancement. Indeed, enhancement factors of 108 were found for the most important thickness of the gold underlayer.

Controlling the LSPR properties of Au triangular nanoprisms and nanoboxes by geometrical parameter: a numerical investigation

We have simulated the extinction spectra of Au triangular nanoprisms and nanoboxes by finite difference time domain method. It is found that the refractive index sensitivity increases linearly and near exponentially as the aspect ratio of nanoprisms increases and wall thickness of nanoboxes decreases, respectively. A sensing figure of merit (FOM) calculation shows that there is an optimum wall thickness for each edge length and height of the box, which makes them to be promising candidates for effective sensing applications. We have also shown that the higher FOM in triangular nanoboxes compared to the cubic nanoboxes and other solid structure is inherent in the shape of nanoparticles.

Ultrafast Third-Order Optical Nonlinearity in Au Triangular Nanoprism with Strong Dipole and Quadrupole Plasmon Resonance

Au triangular nanoprisms have been prepared by the wet chemical method. By using absorption measurements and finite difference time domain (FDTD) calculations, the dipole and quadrupole plasmon resonances of Au triangular nanoprisms are investigated experimentally and theoretically. Calculations show that large electric fields are confined at the tips of the Au prisms, leading to large third-order optical nonlinearities. The Z-scan measurements show a third-order optical susceptibility of about 1.25 × 10–11 esu at 1240 nm, which is 19 times larger than that at 800 nm. The ultrafast light response time is about 482 fs measured by optical Kerr effect technique at 800 nm. The distinct third-order optical nonlinearities and the ultrafast response time enable the Au triangular prisms to be a good candidate for future all-optical switches and ultrafast optical information manipulators.

Dipole plasmon resonance induced large third-order optical nonlinearity of Au triangular nanoprism in infrared region

Au triangular nanoprisms with strong dipole plasmon absorption peak at 1240 nm were prepared by wet chemical methods. Both numerical calculations and experiments were carried out to investigate the optical properties of the samples. Finite difference time domain (FDTD) and Local Density of States (LDOS) calculations demonstrate that strong electric field enhancement and large LDOS can be obtained at tip areas of the Au triangular nanoprisms. Z scan techniques were used to characterize the nonlinear absorption, nonlinear refraction, as well as one- and two-photon figures of merit (W and T, respectively) of the sample. The results show that maximum nonlinear refractive index can be obtained around the resonance absorption wavelength of 1240 nm, detuning the wavelength from the absorption peak will lead to the decrease of the nonlinear refractive index n(2), while the nonlinear absorption coefficient β doesn't change much with the wavelength. This large wavelength dependence of n(2) and small change of β enable the sample to satisfy the all-optical switching demand of W> 1 and T< 1 easily in a large wavelength range of 1200-1300 nm. These significant nonlinear properties of the sample imply that Au triangular nanoprism is a good candidate for future optical switches in infrared optical communication wavelength region.

Controlling Orientational Order in 1-D Assemblies of Multivalent Triangular Prisms.

Multivalent nanostructures are becoming an increasingly important player in the self-assembly of supramolecular lattices. Understanding the role that shape plays in the coordination of the assemblies is crucial for the functional response of the material. We develop a simple design rule for the assembly of multivalent Au triangular nanoprisms into 1-D ordered arrays based on both the length of the valent DNA and the aspect ratio of the prism. Using MD simulations, we describe an order parameter that captures the short-range order of the assembly controlled by the design parameters. The order parameter shows that even short chains (N = 4) of prisms have a high degree of orientational order that transitions to no orientational order when the DNA length is similar to the prism length. Unlike isotropic polyvalent assemblies, we find that the highly oriented chains of prisms lose orientational order in discrete steps during melting as the prisms in the arrays dissociate.

Selective Excitation of Plasmon Resonances of Single Au Triangles by Polarization-Dependent Light Excitation

The plasmonic properties of single Au triangular nanoprisms are investigated using photoemission electron microscopy with particular emphasis on polarization dependence. Two localized surface plasmon resonances (LSPRs) are studied, namely, the in-plane dipolar and quadrupolar plasmon excitations. Experimental maps of the near-field spatial distribution upon polarization and wavelength of the exciting field are interpreted in the framework of a group theory description and finite difference time domain simulations. This work demonstrates the selective excitations, by lifting of degeneracy, of the different LSPR eigenmodes at the single object level and opens ways for the active control of the angular radiation patterns of optical nanoantennas. This approach is general and applies to any nano-object, whatever its initial shape symmetry.