Gold Nanoprism Research Articles

Gold nanoprism enhanced SERS aptasensor for simultaneous detection of thrombin and VEGF

Sensitive detection of disease-specific biomarkers with high accuracy is crucial for early diagnosis, therapeutic monitoring, and understanding underlying pathological mechanisms. Traditional methods, such as immunohistochemistry and enzyme-linked immunosorbent assays (ELISA), face limitations due to the complex and expensive production of antibodies. In this context, aptamers, short oligonucleotides with advantages like easy synthesis, low cost, high specificity, and stability, have emerged as promising alternatives for biomolecular sensing. In this study, we introduce a surface-enhanced Raman spectroscopy (SERS) aptasensor for the multiplexed detection of human α-thrombin and vascular endothelial growth factor (VEGF-165). By leveraging aptamer-based biorecognition elements, our approach capitalizes on the small gaps created by aptamers, generating intense electromagnetic hotspots that significantly amplify the SERS signal. This enables simultaneous detection of human α-thrombin and VEGF-165 with remarkable sensitivity (100 fM and 1 pM, respectively). Notably, we also employ a digital protocol for analyzing the obtained vibrational spectra, marking the first-time utilization of this method for such aptasensors and offering precise quantification even at ultralow concentration regimes. We envision the reported aptasensor provides a roadmap for developing superior aptamer-based spectroscopical tools for a wide range of applications in biology and medicine.

Insight into the photocatalytic and photothermal effect in plasmon-enhanced water oxidation property of AuTNP@MnOx core–shell nanoconstruct

The development of robust and efficient photocatalytic constructs for boosting the water oxidation reaction (WOR) is needed for establishing a sunlight-driven renewable energy infrastructure. Here, we synthesized plasmonic core–shell nanoconstructs consisting of triangular gold nanoprism (AuTNP) core with mixed manganese oxide (MnOx) shell for photoelectrocatalytic WOR. These constructs show electrocatalytic WOR with a low onset overpotential requirement of 270 mV at pH 10. Photoexcitation showed further enhancement of their catalytic activity resulting in ∼15% decrease of the onset overpotential requirement along with the generation of photocurrent density of up to 300 μA/cm2. We showed that such light-driven enhancement of AuTNP@MnOx dyad’s catalytic activity toward the WOR process includes contributions from both photocatalytic (hot carriers driven) and photothermal effects with photothermal effect playing the major role for wavelength between 532 and 808 nm. The contribution from the photocatalytic effect is appreciable only for high-energy excitations near the interband region, while the photothermal effect largely dominates for lower energy excitations near the LSPR wavelengths of the dyad.

Seed free synthesis of polyethylene glycol stabilized gold nanoprisms exploiting manganese metal at low pH.

Manganese powder with a suitable potential (, -1.19 V) has never been investigated for the reduction of Au3+ (, 1.00 V). In this study, we have utilized and low pH dependent for the polyethylene glycol stabilized gold nanoprism synthesis by reducing AuCl-4 in the presence of thiol terminated polyethylene glycol as the stabilizing agent. The synthetic methodology for gold nanoprisms has been optimized by pH and Cl- ion combination. Time dependent absorbance studies have been conducted to demonstrate the role of various reaction parameters such as the stabilizing agent, HCl concentration, temperature, and Mn metal. The synthesized gold nanoprism has been further utilized as a seed for nucleic acid and selected amino acid mediated edge and surface growth, respectively.

Ligand-mediated electron transport channels enhance photocatalytic activity of plasmonic nanoparticles.

Photoexcitation of noble metal nanoparticles creates surface plasmons which further decay to form energetic charge carriers. These charge carriers can initiate and/or accelerate various chemical processes at nanoparticle surfaces, although the efficiency of such processes remains low as a large fraction of these carriers recombine before they can reach the reaction sites. Thus efficient utilization of these charge carriers requires designing nanostructures that promote the separation of charges and their transport toward the reaction sites. Here we demonstrate that covalently bound surface-coating ligands with suitable orbital alignment can provide electron transport channels boosting hot electron extraction from a gold nanostructure leading to a huge enhancement in the rate of hydrogen evolution reaction (HER) under NIR excitation. A (p)Br-Ph-SH substituted gold nanoprism (AuTP) substrate produced ∼4500 fold more hydrogen compared to a pristine AuTP substrate under 808 nm excitation. Further experimental and theoretical studies on a series of substituted benzene-thiol bound AuTP substrates showed that the extent of the ligand-mediated HER enhancement depends not only on the polarity of the ligand but on the interfacial orbitals interactions.

Insight into the photocatalytic and photothermal effect in plasmon-enhanced water oxidation property of AuTNP@MnOx core-shell nanoconstruct

Development of robust and efficient photocatalytic constructs for boosting the water oxidation reaction (WOR) is needed for establishing a sunlight-driven renewable energy infrastructure. Here we synthesized plasmonic core-shell nanoconstructs consisting of triangular gold nanoprism (Au-TNP) core with mixed manganese oxide (MnOx) shell for photoelectrocatalytic WOR. These constructs show electrocatalytic WOR with low onset overpotential requirement of 270 mV at pH 10.5. Photoexcitation showed further enhancement of their catalytic activity resulting in ~15% decrease of the onset overpotential requirement along with the generation of photocurrent density of up to 300 µA/cm2. We showed that such light-driven enhancement of AuTNP@MnOx dyad's catalytic activity includes contributions from both photocatalytic (hot carriers driven) and photothermal effects with photothermal effect playing the major role for wavelength between 532 nm and 808 nm. The contribution from the photocatalytic effect is appreciable only for high-energy excitations near the interband region, while the photothermal effect largely dominates for lower energy excitations near the LSPR wavelengths of the dyad.

NIR-Driven Photocatalytic Hydrogen Production by Silane- and Tertiary Amine-Bound Plasmonic Gold Nanoprisms.

Near-infrared (NIR) photon-driven H2 production from water is regarded as one of the best routes for establishing a sustainable hydrogen-based energy economy. Here, we have developed a gold nanoprism-based photocatalytic assembly, rationally capped with an amine and a silane ligand pair, which exhibited an excellent H2 production rate (146 μL mg-1 h-1) in neutral water while achieving an absolute incident photon-to-hydrogen conversion efficiency of 0.53%. An array of spectroscopic and microscopic experiments unravel that the amine ligand scavenges the hot hole while the silane aids the H2 production via hydrolysis during the photocatalysis on the plasmon surface. This photocatalytic H2 production reactivity can be retained for multiple cycles following the replenishment of amine and silane. Hence, this photocatalytic assembly can set up the template for a large-scale NIR-driven H2 production unit.

Gold@Carbon Nitride Yolk and Core-Shell Nanohybrids.

Graphitic carbon nitride (g-C3N4) is a promising conjugated polymer with visible light responsiveness and numerous intriguing characteristics that make it highly beneficial for a myriad of potential applications. A novel design and universal approach for the fabrication of unique plasmonic g-C3N4 nanoscale hybrids, with well-controlled morphology, is presented. A single gold nanoprism is encapsulated within dense or hollow g-C3N4 spheres for the formation of Au@g-C3N4 core-shell and Au@g-C3N4 yolk-shell nanohybrids. Au nanoprisms were chosen duo to the strong (visible range) plasmon resonances and electromagnetic field hotspots formed at their sharp corners. The incorporation of Au nanoprisms into the g-C3N4 nanospheres results in a dramatic ∼threefold rise in the emission of plasmonic g-C3N4 yolk-shell nanohybrids and ∼3.6-fold enhancement of the photocurrent density obtained from the plasmonic g-C3N4 core-shell nanohybrids, when compared with the g-C3N4 hollow nanospheres. Hence, these hybrids can potentially benefit applications in the areas spanning from solar energy harvesting to biomedical imaging and theranostics.

Atomic structure of a seed-sized gold nanoprism

The growth of nanoparticles along one or two directions leads to anisotropic nanoparticles, but the nucleation (i.e., the formation of small seeds of specific shape) has long been elusive. Here, we show the total structure of a seed-sized Au56 nanoprism, in which the side Au{100} facets are surrounded by bridging thiolates, whereas the top/bottom {111} facets are capped by phosphine ligands at the corners and Br− at the center. The bromide has been proved to be the key to effectively stabilize the Au{111} to fulfill a complete face-centered-cubic core. In femtosecond electron dynamics analysis, the non-evolution of transient absorption spectra of Au56 is similar to that of larger-sized gold nanoclusters (n > 100), which is ascribed to the completeness of the prismatic Au56 core and an effective electron relaxation pathway created by the stronger Au-Au bonds inside. This work provides some insights for the understanding of plasmonic nanoprism formation.

Plasmon-enhanced nonlinear nanofocusing of gold nanoprisms driven via an ultrafast azimuthal vector beam.

We present the plasmon-enhanced nonlinear nanofocusing of a gold (Au) nanoprism array substrate (ANAS) driven via an ultrafast azimuthal vector beam (AVB). Theoretical calculations show that the electric-field intensity of the ANAS vertically excited via the femtosecond AVB is higher than that of LPB excitation. In this experiment, the second-order surface nonlinear optical response of the ANAS is adopted to examine the nonlinear plasmonic nanofocusing of the ANAS, and it was observed that the second harmonic (SH) intensity of the ANAS excited via the femtosecond AVB is ∼3.8 times higher than that of LPB excitation, revealing that the ANAS under AVB excitation has a better nonlinear plasmonic nanofocusing characteristic than that under LPB excitation. Furthermore, the GaSe nanosheets are transferred on the ANAS to examine the nonlinear plasmonic nanofocusing of the ANAS. The SH intensity of the GaSe nanosheets deposited on the ANAS via the femtosecond AVB excitation has been enhanced ∼4.7 times than that of LPB excitation, indicating that the ANAS via AVB excitation has better nonlinear plasmonic nanofocusing than that of LPB excitation. This method may be used as a nonlinear nanofocusing light source to increase the light-matter nonlinear interaction.

Modulation of LSPR spectra and enhanced RI-sensitivity through symmetry breaking in hollow gold nanoprism.

Optical responses of plasmonic nanostructures can be tailor-made by judiciously controlling their structural parameters. Here in this article, we describe how symmetry-breaking influences the optical properties of an anisotropic hollow nanostructure, a hollow gold nanoprism (HGN). We find that the introduction of structural asymmetry by shifting the cavity position alters the plasmon hybridization conditions, which, in turn, lifts the degeneracy of bonding plasmon modes and thereby causes mode splitting. The splitting between the nondegenerate bonding modes is directly correlated with the extent of the cavity offset. Interestingly, it is found that a reduced symmetry HGN having a cavity of any arbitrary size does not necessarily show such spectral modulation as a function of the cavity offset. Rather, there is a threshold value of (cavity diameter/edge length) ratio for observing this kind of optical behavior. Symmetry breaking not only leads to spectral modulation but also improves the refractive index (RI) sensitivity as well as the associated figure of merit of the HGN nanosensors tremendously. This comprehensive study develops a predictive understanding of the structure-specificity of the optical properties of HGNs and also suggest that sensible tailoring of the structural parameters can make HGNs as one of the most suitable candidates for RI sensing based applications.

Plasmonic Gold Nanoprism–Cobalt Molecular Complex Dyad Mimics Photosystem-II for Visible–NIR Illuminated Neutral Water Oxidation

Constructing an artificial assembly for efficient photocatalytic water splitting is key in the pursuit for a solar-driven renewable energy economy. Here, we have fabricated a covalently linked gold...

Tuning the linear and nonlinear optical properties of ordered plasmonic nanoarrays by morphological control with thermal annealing

The capability to tune the linear and nonlinear optical response of plasmonic nanoarrays is of great interest for the realization of solid-state plasmonic nanodevices with application in many different fields in nanophotonics. In the present work we demonstrated the possibility to tailor, in a controlled way, the morphological properties of gold nanoprism arrays fabricated by nanosphere lithography, by performing thermal annealing treatments in air, preserving their bidimensional ordered arrangement. This allows to engineer the linear optical properties of the samples, finely tuning the spectral position and amplitude of their surface plasmon resonance peak. Moreover, we demonstrated that the fine control of the nanostructures' morphology provides a way to get the continuous modulation of the nonlinear optical parameters (nonlinear refractive index and nonlinear absorption coefficient) of the nanoarray. The experimental findings have been supported by finite elements method electrodynamic simulations, which provided a very good agreement.

Dual-Targeted Gold Nanoprism for Recognition of Early Apoptosis, Dual-Model Imaging and Precise Cancer Photothermal Therapy.

Photothermal therapy as novel strategy to convert near-infrared (NIR) light into heat for treatment cancers has attracted great attention and been widely studied. However, side effects and low efficiency remain the main challenge of precise cancer photothermal therapy.Methods: In this study, we have successfully fabricated and characterized the dual-targeted gold nanoprisms, whereby bare gold nanoprisms (Au NPR) were conjugated to a phenanthroline derivatives-functionalized tetraphenylethene (TPE) and further stabilized with target peptide aptamers via Au-S bonds (Au-Apt-TPE). Then, the remaining nitrogen atoms of the Au-Apt-TPE could effectively chelate with Zn2+ ions (Au-Apt-TPE@Zn) for monitoring early stage apoptotic cells.Results: The as-synthesized Au-Apt-TPE@Zn exhibited good monodispersity, size stability and consistent spectral characteristics. TPE synthesized here showed aggregation-induced emission (AIE) characteristics, and zinc conjunction (TPE@Zn) endowed Au-Apt-TPE@Zn with the cell membrane-targeted ability to selectively recognize the membranes of early stage apoptotic cells but not respond to healthy cells, which provided valuable diagnosis information on therapeutic efficacy. Au-Apt-TPE@Zn achieved specifically nuclear-targeted ability by surface decoration of AS1411 DNA aptamer. Au-Apt-TPE@Zn under NIR irradiation showed effective photothermal therapy against SGC-7901 human gastric carcinoma cells growth in vitro by inducing apoptosis through triggering reactive oxygen species (ROS) overproduction and regulating multiple signal crosstalk. In vivo studies revealed that Au-Apt-TPE@Zn under NIR irradiation showed deep penetration and dual-model imaging application (cancer-targeted fluorescence imaging and light-up photoacoustic imaging). Au-Apt-TPE@Zn under NIR irradiation also displayed strong photothermal therapy against gastric carcinoma xenograft growth in vivo by induction of apoptosis. Importantly, analysis of histopathology, hematotoxicity and immunocytotoxicity indicated that Au-Apt-TPE@Zn had less side effect and high biocompatibility.Conclusions: Our findings validated the design of using Au nanoprism with AIE materials and dual-targeted decoration could be an effective strategy in recognition of early apoptosis, dual-model imaging and precise cancer photothermal therapy.

Enhanced direct electron transfer of glucose oxidase based on gold nanoprism and its application in biosensing

Gold nanoprism (AuNP) was used for immobilization of glucose oxidase (GOD), and the direct electrochemistry of GOD–AuNP–chitosan modified GCE and glucose biosensing were studied. Transmission electron microscopy, UV–vis spectroscopy and electrochemical impendence spectroscopy were employed to confirm the morphology and film modification changes of the prepared biosensor. Results showed that the AuNP can provide a favorable and biocompatible microenvironment for facilitating the direct electron transfer between proteins and electrode surface. It was found that the special structure of gold nanoprism exhibited enhanced performances in direct electron transfer of GOD and glucose sensing. The adsorbed GOD displayed an apparent electron transfer rate constant (ks) of 24.92s−1. The constructed biosensor exhibited a good response to glucose with linear range from 0.05 to 1.2mM (R2=0.9975), low detection limit of 0.01mM and high sensitivity of 11.83μAmM−1cm−2. The proposed biosensor offers an alternative method for the determination of glucose in real samples and has potential applications in the fabrication of other biosensors with redox proteins.

T 1-Weighted MR/CT dual-modality imaging-guided photothermal therapy using gadolinium-functionalized triangular gold nanoprism

Triangular gold nanoprism decorated with gadopentetic acid (TGP–PEG–Gd) for PTT guided by T1-weighted MR/CT dual-modality imaging.

Hollow Gold Nanoprism as Highly Efficient “Single” Nanotransducer for Surface-Enhanced Raman Scattering Applications

In this Article, we report the optical properties of anisotropic hollow nanostructure, hollow gold nanoprism (HGN, an equilateral triangular gold nanoprism with a circular cavity) and its application as a highly active “nonaggregated” surface-enhanced Raman scattering (SERS) substrate. Small colloidal HGNs are prepared using sacrificial galvanic replacement method. Our study reveals that HGNs are highly stable nanostructure in solution and robust against salt or ligand induced aggregation. We find that the LSPR spectra of the HGNs can be tuned by controlling their aspect ratios. Excellent SERS were detected from the J-aggregates of pseudoisocyanine dye, adsorbed on the HGN surface. Interestingly, strong SERS is obtained without the need of any aggregation of the nanoparticles. Numerical simulations reveal that a single HGN can not only harvest large local electromagnetic fields but also offer large sensing volume due to efficient plasmon hybridization, due to the presence of the cavity. This large sensing...

Gold nanoprism-nanorod face off: comparing the heating efficiency, cellular internalization and thermoablation capacity.

This work compares the synthesis, heating capability, cellular internalization and thermoablation capacity of two different types of anisotropic gold nanoparticles: gold nanorods (NRs) and nanoprisms (NPrs). Both particles possess surface plasmon resonance absorption bands in the near-IR, and their heating efficiency upon irradiation with a continuous near-IR laser (1064 nm) was evaluated. The cellular internalization, location and toxicity of these PEG-stabilized NPrs and NRs were then assessed in the Vero cell line by transmission electron microscopy and inductively coupled plasma mass spectrometry analysis, and their ability to induce cell death upon laser irradiation was then evaluated and compared. Although both nanoparticles are highly efficient photothermal converters, NRs possessed a more efficient heating capability, yet the in vitro thermoablation studies clearly demonstrated that NPrs were more effective at inducing cell death through photothermal ablation due to their greater cellular internalization.

Plasmon Hybridization Mediated Structure-Specific Refractive Index Sensitivity of Hollow Gold Nanoprism in the Vis-NIR Region

The refractive index sensitivity of plasmonic nanoantennas depends on the plasmon field strength and its distribution (sensing volume). As a result, the sensitivity factors can be larger for hollow nanoparticles than for solid ones of comparable dimensions due to their larger sensing volume and the strong local electric fields resulting from the plasmon hybridization between the external and internal surfaces. The plasmonic field strength of a hollow nanostructure is further enhanced when it has anisotropic shape. In the present paper, the plasmon resonances along with the associated local electric fields and the RI sensitivity factors of an anisotropic hollow nanostructure, namely, hollow gold nanoprism (HGN, an equilateral triangular gold nanoprism with a circular cavity) of different cavity size and thickness have been determined by finite-difference time-domain simulation. The dependence of the RI sensitivity factors on the prism thickness, the size, and the position of the cavity, and shape defects s...

Multimodal Nonlinear Optical Imaging of Live Cells Using Plasmon-Coupled DNA-Mediated Gold Nanoprism Assembly.

Multiphoton excitation microscopy techniques are the emerging nonlinear optical (NLO) imaging methods to watch the biological world due its ability to penetrate deep into living tissues. Driven by the need to develop multimodal NLO imaging probe, current article reports the design of DNA-mediated gold nanoprisms assembly based optical antennas to enhance multiphoton imaging capability in biological II window. Reported experimental data show a unique way to enhance second harmonic generation (SHG) and two-photon fluorescence (TPF) properties by several orders of magnitudes via plasmon coupled organization into gold nanoprism assembly structures. Experimental and theoretical modeling data using finite difference time domain (FDTD) simulations indicate that huge enhancement of SHG and TPF properties are mainly due to the electric quadrupole contribution and electric field enhancement. Using 1100 nm biological II window light, reported results demonstrated that antibody conjugated assembly structures are capable of exhibiting highly selective and very bright multimodal SHG and TPF imaging of human Hep G2 liver cancer cells.

Synthesis and Conversion of Gold Nanosphere into Nanoprism Platform using Laurencia papillosa: A Novel Natural Method

This is the first report on a rapid green synthesis of gold nanoparticles (GNPs) using red algae (Laurencia papillosa). The green synthesis of eco-friendly nanoparticles is of a great interest in Nanoscience for biomedical applications and specifically for clinical diagnostic applications. GNPs especially nanoprism represents a new advanced tool to study cell function and useful in optoelectronics, in developing a drug delivery system to control plant virus diseases and in nanomedicine. Conventional physical and chemical methods have been developed for the synthesis of metal nanoparticles, but these methods are expensive and require the use of toxic and aggressive chemicals. In this paper it is demonstrated that a rapid, low coast and ecofriendly method for synthesis of gold nanosphere and its conversion into gold nanoprism has been developed. The method involves using water solvent extract of Laurencia papillosa as a reducing agent. Nanoscopy analysis revealed that the nanoprism and other different morphologies were obtained just by varying the concentration molarity of tetrachloauric acid (HAuCl4), keeping the concentration of pure algal extract (PAE) constant. The best concentration of AuCl4 was 5 mM and best concentration of the red algae extract was at 0.05 g/ml. The functional groups responsible for conversion of nanospheres into nanoprism were NH and OH groups found in the contents of the red algae extract. The as-synthesized gold nanoprisms were characterized by several physicochemical techniques. The nanoprisms are single crystalline, whose basal plates surface are atomically flat