Triangular Nanostructures Research Articles

Spatially Controlled DNA Frameworks for Sensitive Detection and Specific Isolation of Tumor Cells.

High-affinity, specific, and sensitive probes are crucial for the specific recognition and identification of tumor cells from complex matrices. Multivalent binding is a powerful strategy, but the irrational spatial distribution of the functional moieties may reduce the probe performance. Here, we constructed a Janus DNA triangular prism nanostructure (3Zy1-JTP-3) for sensitive detection and specific isolation of tumor cells. Benefiting from spatial features of the triangular prism, the fluorescence intensity induced by 3Zy1-JTP-3 was almost 4 times that of the monovalent structure. Moreover, the DNA triangular prisms were connected to form hand-in-hand multivalent DNA triangular prism structures (Zy1-MTP), in which the fluorescence intensity and affinity were increased to 9-fold and 10-fold of 3Zy1-JTP-3, respectively. Furthermore, 3Zy1-JTP-3 and Zy1-MTP were combined with magnetic beads, and the latter showed higher capture efficiency (> 90%) in whole blood. This work provides a new strategy for the efficient capture of rare cells in complex biological samples.

Spatially Controlled DNA Frameworks for Sensitive Detection and Specific Isolation of Tumor Cells

High‐affinity, specific, and sensitive probes are crucial for the specific recognition and identification of tumor cells from complex matrices. Multivalent binding is a powerful strategy, but the irrational spatial distribution of the functional moieties may reduce the probe performance. Here, we constructed a Janus DNA triangular prism nanostructure (3Zy1‐JTP‐3) for sensitive detection and specific isolation of tumor cells. Benefiting from spatial features of the triangular prism, the fluorescence intensity induced by 3Zy1‐JTP‐3 was almost 4 times that of the monovalent structure. Moreover, the DNA triangular prisms were connected to form hand‐in‐hand multivalent DNA triangular prism structures (Zy1‐MTP), in which the fluorescence intensity and affinity were increased to 9‐fold and 10‐fold of 3Zy1‐JTP‐3, respectively. Furthermore, 3Zy1‐JTP‐3 and Zy1‐MTP were combined with magnetic beads, and the latter showed higher capture efficiency (> 90%) in whole blood. This work provides a new strategy for the efficient capture of rare cells in complex biological samples.

Welded Gold Nanoparticle Assemblies Defined Plasmonic Coupling.

Nanoparticle assemblies with interparticle ohmic contacts are crucial for nanodevice fabrication. Despite tremendous progress in DNA-programmable nanoparticle assemblies, seamlessly welding discrete components into welded continuous three-dimensional (3D) configurations remains challenging. Here, we introduce a single-stranded DNA-encoded strategy to customize welded metal nanostructures with tunable morphologies and plasmonic properties. We demonstrate the precise welding of gold nanoparticle assemblies into continuous metal nanostructures with interparticle ohmic contacts through chemical welding in solution. We find that the welded gold nanoparticle assemblies show a consistent morphology with welded efficiency over 90%, such as the rod-like, triangular, and tetrahedral metal nanostructures. Next, we show the versatility of this strategy by welding gold nanoparticle assemblies of varied sizes and shapes. Furthermore, the experiment and simulation show that the welded gold nanoparticle assemblies exhibit defined plasmonic coupling. This single-stranded DNA encoded welding system may provide a new route for accurately building functional plasmonic nanomaterials and devices.

Assembly of ligation chain reaction and DNA triangular prism for miRNA diagnostics

Controllable assembly of DNA nanostructure provides a powerful way for quantitative analysis of various targets including nucleic acid molecules. In this study, we have designed detachable DNA nanostructures at electrochemical sensing interface and constructed a ligation chain reaction (LCR) strategy for amplified detection of miRNA. A three-dimensional DNA triangular prism nanostructure is fabricated to provide suitable molecule recognition environment, which can be further regenerated for additional tests via convenient pH adjustment. Target triggered LCR is highly efficient and specific towards target miRNA. Under optimal experimental conditions, this approach enables ultrasensitive exploration in a wide linear range with a single-base resolution. Moreover, it shows excellent performances for the analysis of cell samples and clinical serum samples.

Nebulized Inhalation of Peptide-Modified DNA Origami To Alleviate Acute Lung Injury.

Acute lung injury (ALI) is a severe inflammatory lung disease, with high mortality rates. Early intervention by reactive oxygen species (ROS) scavengers could reduce ROS accumulation, break the inflammation expansion chain in alveolar macrophages (AMs), and avoid irreversible damage to alveolar epithelial and endothelial cells. Here, we reported cell-penetrating R9 peptide-modified triangular DNA origami nanostructures (tDONs-R9) as a novel nebulizable drug that could reach the deep alveolar regions and exhibit an enhanced uptake preference of macrophages. tDONs-R9 suppressed the expression of pro-inflammatory cytokines and drove polarization toward the anti-inflammatory M2 phenotype in macrophages. In the LPS-induced ALI mouse model, treatment with nebulized tDONs-R9 alleviated the overwhelming ROS, pro-inflammatory cytokines, and neutrophil infiltration in the lungs. Our study demonstrates that tDONs-R9 has the potential for ALI treatment, and the programmable DNA origami nanostructures provide a new drug delivery platform for pulmonary disease treatment with high delivery efficiency and biosecurity.

DNA Nanostructures Treat Inflammatory Bowel Disease through ROS Scavenging and Gut Microbiota Modulation

AbstractInflammatory bowel disease (IBD) encompasses a collection of chronic inflammatory conditions impacting the gastrointestinal tract, with a discernible global rise in prevalence and severity. The overabundance of reactive oxygen species (ROS) in the intestinal environment leads disruption of local redox homeostasis, and perturbation of the gut microbiota, exacerbating IBD. Consequently, mitigating excess ROS and preserving gut microbiota homeostasis have emerged as effective approaches for IBD management. In this study, a triangular DNA origami nanostructure loaded with siRNA targeting tumor necrosis factor α (siTNF‐αtDON) is introduced for this purpose. This nanostructure demonstrates efficacy in eliminating ROS within cells closely associated with IBD, diminishing inflammation, and ameliorating disorders in gut microbiota, as evidenced in an IBD mouse model. Furthermore, this investigation demonstrates the effects of siTNF‐αtDON on related inflammatory signaling pathways, including NF‐κB, MAPK/ERK and Keap1/Nrf2. Collectively, this study offers insights into the potential utilization of DNA nanostructures as antioxidants and gut microbiota modulators, presenting promising avenues for the IBD treatment.

Quantum trapping and rotational self-alignment in triangular Casimir microcavities.

Casimir torque, a rotational motion driven by zero-point energy minimization, is a problem that attracts notable research interest. Recently, it has been realized using liquid crystal phases and natural anisotropic substrates. However, for natural materials, substantial torque occurs only at van der Waals distances of ~10 nm. Here, we use Casimir self-assembly with triangular gold nanostructures for rotational self-alignment at truly Casimir distances (100 to 200 nm separation). The interplay of repulsive electrostatic and attractive Casimir potentials forms a stable quantum trap, giving rise to a tunable Fabry-Pérot microcavity. This cavity self-aligns both laterally and rotationally to maximize area overlap between templated and floating flakes. The rotational self-alignment is sensitive to the equilibrium distance between the two triangles and their area, offering possibilities for active control via electrostatic screening manipulation. Our self-assembled Casimir microcavities present a versatile and tunable platform for nanophotonic, polaritonic, and optomechanical applications.

Effect of Size and Morphology of Different ZnO Nanostructures on the Performance of Dye-Sensitized Solar Cells

In this study, the influence of zinc oxide (ZnO) nanostructures with various morphologies on the performance of dye-sensitized solar cells (DSSCs) was investigated. Photo-electrodes were fabricated incorporating ZnO transport layers of distinct nanoscale morphologies—namely nanoparticles, microballs, spiky microballs, belts, and triangles—and their respective current–voltage characteristics were evaluated. It was observed that the DSSCs employing the triangular ZnO nanostructures, with a side length of approximately 30 nm, achieved the highest power conversion efficiency of 2.62%. This was closely followed by the DSSCs using spherical nanoparticles with an average diameter of approximately 20 nm, yielding an efficiency of 2.54%. In contrast, the efficiencies of DSSCs with microball and spiky microball ZnO nanostructures were significantly lower, measuring 0.31 and 1.79%, respectively. The reduction in efficiency for the microball-based DSSCs is attributed to the formation of micro-cracks within the thin film during the fabrication process. All DSSC configurations maintained a uniform active area of 4 mm². Remarkably, the highest fill factor of 59.88% was recorded for DSSCs utilizing the triangular ZnO morphology, with the spherical nanoparticles attaining a marginally lower fill factor of 59.38%. This investigation corroborates the hypothesis that reduced particle size in the transport layer correlates with enhanced DSSC performance, which is further amplified when the nanoparticles possess pointed geometries that induce strong electric fields due to elevated charge concentrations.

Triangular pyramid nanostructure enhanced photothermal utilization of noble metal nanoparticles

The triangular pyramid nanostructure (TPN) raises a perfect prerequisite for the aggregation of surface plasmon resonances (SPRs). However, the application of TPN in thermoplasmonics has not yet been developed. The aim of this study is to explore the development potential of TPNs for enhanced noble metal photothermal applications. We investigated the optical absorption properties, photothermal conversion efficiency, and photothermal response under continuous wave irradiation of TPNs based on Ag and Au nanomaterials. The results show that TPN helps to enhance the SPR excitation of Ag and Au in the near-infrared. TPN based on noble metal nanomaterials shows good light absorption capacity and photothermal response. The photothermal conversion efficiencies of the TPN nanoparticle suspensions increased by 56.95% (Ag) and 49.57% (Au), respectively, compared to the same volume of noble metal nanospheres. This work is intended to researchers better understand the development potential of TPN in thermoplasmonics applications.

Enhancement of absorption by incorporating aluminum triangular nanostructures into perovskite

Enhancement of absorption by incorporating aluminum triangular nanostructures into perovskite

Effect of surface structure on fluid flow and heat transfer in cold and hot wall nanochannels

Nanochannels consisting of hot and cold walls with periodic rectangular and triangular nanostructures were simulated by molecular dynamics in this paper, the periodic size dimensionless parameters φ was defined to describe the dimension of nanostructures on the wall. The results show that the addition of nanostructures leads to the variation of mass density distribution of fluid near the wall. A hot wall with nanostructures can promote the appearance of a fluid high-potential area near it. The discrepant attraction for fluid from the wall caused by the different wall conditions leads to different flow characteristics in nanochannels. Fluid velocity growth rate near the hot wall is 10.5% higher than that near the cold wall. Average velocity of the fluid near the hot wall is 5.1% higher than that of fluid near the cold wall. A wall with rectangular nanostructures at φ = 0.28 shows minimum flow resistance among rough hot walls, while a wall with triangular nanostructures at φ = 0.14 has minimum flow resistance among rough cold walls. Heat is transferred from the hot wall to the cold wall through fluid flow. Wall conditions impact the heat transfer situation of fluid in flow boundary by changing the fluid mass density contribution. The addition of nanostructures and decrease of nanostructures size is beneficial for heat transfer while unfavorable for fluid flow, convective heat transfer was influenced by their combination. For a wall with 300 K, the addition of rectangular nanostructures at φ = 0.07 has the best convective heat transfer performance. For a wall with 200 K temperature, increasing triangular nanostructures at φ = 0.14 on the wall can reach the best convective heat transfer capacity. This paper can provide a theoretical foundation for the optimization of nanochannels to achieve best convective heat transfer ability.

High-performance plasmonic metasurface sensor by triangular nano-structures

The increasing need to sense different materials has caused sensors and efforts to improve their performance to receive a lot of attention in the optics field. In this report, we present a high-performance plasmonic metasurface sensor by the DGTD method that includes a two-dimensional periodic lattice of nano-triangles on a glass film and a TiN mirror. The TiN prevents light transmission from the resonators, causing a deeper reflection dip. Two resonances are observed, which offer a maximum sensitivity of about 417 nm/RIU and 735 nm/RIU, correspondingly. In this structure, augmenting the nano-triangles enhances hot spots, improving spectral response and sensitivity. Moreover, the structure maintains an almost unchanged spectral response for small angles. Overall, this sensor can be suitable for various applications such as biosensing.

Energy-efficient resistive switching synaptic devices based on patterned Ag nanotriangles with tunable gaps fabricated using plasma-assisted nanosphere lithography.

The development of synaptic devices featuring metallic nanostructures with brain-analog hierarchical architecture, capable of mimicking cognitive functionalities, has emerged as a focal point in neuromorphic computing. However, existing challenges, such as inconsistent and unpredictable switching, high voltage requirements, unguided filament formation, and detailed fabrication processes, have impeded technological progress in the domain. The present study addresses some of these challenges by leveraging periodic nanostructures of Ag fabricated via plasma-assisted nanosphere lithography (NSL). The triangular nanostructures with a preferred orientation offer enhanced localized electric fields, facilitating low voltage electromigration at the sharp edges to guide predictive filament formation. A thorough investigation into gap control between the nanostructures through oxygen plasma treatment enables the attainment of an optimized low switching voltage of 0.86 V and retention at an ultra-low current compliance of 100 nA. The optimized device consumes low power, typically in the fJ range, akin to biological neurons. Furthermore, the device showcases intriguing synaptic characteristics, including controlled transition from short- to long-term potentiation, associative learning, etc., projecting its potential in perceptive learning, memory formation, and brain-inspired computing. COMSOL Multiphysics simulation, supported by ex situ electron microscopic imaging, confirms the controlled and predictable filament formation facilitated by electric field enhancement across the strategic nanostructures. Thus, the work highlights the potential of NSL-based cost-effective fabrication techniques for realizing efficient and biomimetic synaptic devices for neuromorphic computing applications.

Synthesis of Plasmonically Active Titanium Nitride Using a Metallic Alloy Buffer Layer Strategy.

Titanium nitride (TiN) has emerged as a highly promising alternative to traditional plasmonic materials. This study focuses on the inclusion of a Cr90Ru10 buffer layer between the substrate and thin TiN film, which enables the use of cost-effective, amorphous technical substrates while preserving high film quality. We report best-in-class TiN thin films fabricated on fused silica wafers, achieving a maximum plasmonic figure of merit, -ϵ'/ϵ″, of approximately 2.8, even at a modest wafer temperature of around 300 °C. Furthermore, we delve into the characterization of TiN thin film quality and fabricated TiN triangular nanostructures, employing attenuated total reflectance and cathodoluminescence techniques to highlight their potential applications in surface plasmonics.

Enhanced THz Radiation from Spatially Inhomogeneous Fields

Nonlinear terahertz (THz) radiation from gas media usually relies on the asymmetric laser-induced current produced by ultra-intense two-color laser fields with a specific phase delay. Here a new scheme is proposed and theoretically investigated, in which the radiation is generated by spatially inhomogeneous fields induced by relatively low-intensity monochromatic lasers and an array of single triangular metallic nanostructures. Our simulations are based on the classical photocurrent model and the time-dependent Schrödinger equations separately. It is found that the collective motion of the ionized electrons can be efficiently controlled by the inhomogeneous field, resulting in strong residual currents. The intensity of the THz radiation could be enhanced by about two orders of magnitude by increasing the spatial inhomogeneity of the field.

Quasi-Resonant Tunneling States in Triangular Double-Barrier Nanostructures

The quasi-resonant tunneling energies and lifetimes of symmetrical triangular double-barrier nanostructures fabricated from GaAs-Aly Ga1-yAs were investigated. The complex energy approach is used to calculate the resonant tunneling energy and its associated lifetime. The results show that decreasing the well width and increasing the aluminum concentration within the barrier material enhances the quasi-resonant tunneling energies for a fixed barrier thickness. Furthermore, increasing both the aluminum concentration and the barrier thickness results in longer resonant tunneling lifetimes. The current study's findings show that resonant tunneling energies and lifetimes closely match available data in the literature.

Replica symmetry breaking in a colloidal plasmonic random laser with gold-coated triangular silver nanostructures.

Plasmonic random lasers have drawn significant attention recently due to their versatility, low threshold, and the possibility of achieving tunable and coherent/incoherent outputs. However, in this Letter, the phenomenon of replica symmetry breaking is reported in intensity fluctuations of a rarely used colloidal plasmonic random laser (RL) illumination. Triangular nanosilver scatter particles produced incoherent RL action when used in a dimethylformamide (DMF) environment in a Rhodamine-6G gain medium. The use of gold-coated triangular nanosilver as the scatterer in place of triangular nanosilver offered a dual contribution of scattering and lower photo-reabsorption, which caused a reduction in the lasing threshold energy of 39% compared to that obtained with the latter. Further, due to its long-term photostability and chemical properties, a phase transition from the photonic paramagnetic to the glassy phase is observed experimentally in the RL system used. Interestingly, the transition occurs at approximately the lasing threshold value, which is a consequence of stronger correlation of modal behaviors at high input pump energies.

Theory of the collective behavior of two-dimensional periodic ensembles of dipole-coupled magnetic nanoparticles

The magnetic behavior of two-dimensional (2D) periodic ensembles of dipole-coupled nanoparticles (NPs) is investigated theoretically by considering all possible structural organizations in 2D Bravais lattices, namely, square, triangular, rectangular, rhombic, and oblique lattices. The different interaction-energy landscapes (ELs) are characterized by determining the local minima that define the stable and metastable magnetic configurations as well as the transition states connecting them. The topology of the resulting ergodic ensemble of stationary states is analyzed from both local and energy perspectives by calculating the corresponding kinetic networks and disconnectivity graphs. For all lattices, the magnetic orders of the ground-state and low-lying metastable configurations are identified, including the elementary relaxation processes between them. A remarkable profound dependence of the collective magnetic behavior on the structural arrangement of the NPs is revealed. Square and triangular nanostructures are extremely good structure seekers, showing starlike kinetic networks and disconnectivity graphs with palm-tree form. Their continuously degenerate ground states are throughout-reaching hubs connected to nearly all excited magnetic configurations over a single first-order saddle point. Rhombic ensembles have double-funnel ELs in which the time-inversion-related ground states play the role of hubs with exceedingly high connectivity densities. These systems need to undergo very few elementary transitions with small downward energy barriers to relax from any configuration towards one of the ground states. However, the energy barriers between the two funnels are quite large and, furthermore, they increase as the number of particles in the unit cell is increased. Therefore, ergodicity breaking is expected in the thermodynamic limit. Finally, the rectangular and oblique lattices show contrasting ground-state orders, the former consists of an antiferromagnetic alternation of head-to-tail chains of spins while the latter is ferromagnetic. Nevertheless, the ELs of these nanostructures are qualitatively very similar. In both cases, all excited magnetic configurations consist of independent flipping of the chains of spins that are formed along the direction of the shorter Bravais vector. The whole energy spectrum of metastable magnetic configurations can thus be mapped to a one-dimensional Ising model. As a result, the kinetic network of stationary points is latticelike and the disconnectivity graphs have a willow-tree form. In conclusion, the collective magnetic behaviors of nanostructures having different point-group symmetries are contrasted and related by varying the parameters of the lattices that interpolate between them.

Electrochemical Aptasensing of SARS-CoV-2 Based on Triangular Prism DNA Nanostructures and Dumbbell Hybridization Chain Reaction.

Development of convenient, accurate, and sensitive methods for rapid screening of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection is highly desired. In this study, we have developed a facile electrochemical aptasensor for the detection of the SARS-CoV-2 S1 protein amplified by dumbbell hybridization chain reaction (DHCR). A triangular prism DNA (TPDNA) nanostructure is first assembled and modified at the electrode interface. Due to the multiple thiol anchors, the immobilization is quite stable. The TPDNA nanostructure also provides an excellent scaffold for better molecular recognition efficiency on the top single-strand region (DHP0). The aptamer sequence toward the SARS-CoV-2 S1 protein is previously localized by partial hybridization with DHP0. In the presence of the target protein, the aptamer sequence is displaced and DHP0 is exposed. After further introduction of the fuel stands of DHCR, compressed DNA linear assembly occurs, and the product can be stacked on the TPDNA nanostructure for the enrichment of electrochemical species. This electrochemical method successfully detects the target protein in clinical samples, which provides a simple, robust, and accurate platform with great potential utility.

Morphological and optical characterizations of different ZnO nanostructures grown by mist-CVD

In this study, the effects of growth temperatures, post-growth treatment, and substrate cleaning recipes on structural, morphological, luminescence, and growth kinetics of ZnO nanostructures grown by mist Chemical Vapor Deposition method (mist-CVD) on SiO2/Si substrates are investigated. The grown ZnO nanostructures have polycrystalline wurtzite (wz) hexagonal crystal structure according to X-ray Diffraction (XRD) measurements. However, the lower growth temperature is found to lead to the formation of ZnO nanostructures oriented in the [0002] direction. From Atomic Force Microscope (AFM) measurements, it is seen that the Root Mean Square (RMS) values decrease with decreasing growth temperature. In addition, it is shown that the surface covering is tightly dependent on decreasing growth temperature of the ZnO nanostructures. The hexagonal and triangular pyramid-like ZnO nanostructures are grown on the surface according to the Scanning Electron Microscope (SEM) measurements. The wurtzite type of crystallization is also demonstrated by confocal Raman measurements. The characteristic vibration modes related to Zn and O motion in the lattice are found to be ∼435 cm−1 and ∼100 cm−1, respectively. The luminescence properties are studied by low-temperature (10 K) Photoluminescence (PL) measurements. The spectra are dominated by the transition related to the donor-bound exciton (DBE) with a peak position typically observed at ∼369 nm (3.362 eV) in hexagonal ZnO structures. Defect-related transitions are observed to be strongly correlated with growth temperature and post-growth treatment.