3D Assembly Research Articles

Optical SERS sensor with dandelion flower-like Ag/ZnFe2O4 nanotubes on the Si pyramids for detecting trace dyes

It is difficult for metal-modified semiconductor nanotubes to obtain surface-enhanced Raman scattering (SERS) substrates through long-range ordered 3D assembly, which adversely affects both Raman signal enhancement and Raman signal uniformity. Here, ZnFe2O4 nanotubes with Ag nanoparticles modified on the inner and outer walls are induced to grow on the surface of the ordered Si pyramid by ZnO nanonedles as sacrificial templates. In this way, the composite nanotubes (Ag/ZnFe2O4) are assembled into dandelion flower-like 3D aggregates with a periodic arrangement of hexagonal close packing. This 3D ordered SERS substrate based on Ag/ZnFe2O4 nanotubes has excellent anti-reflective performance and carrier separation ability, which is conducive to the enhancement of Raman signal. When the SERS substrate is used as a sensor, it can achieve the single molecule (10-13M) detection level of Rhodamine 6G, the enhancement factor (EF) is 3.14 × 109, and the linear fit (R2) of quantitative analysis is as high as 0.998 from 10-13 to 10-4M. Meanwhile, the long-range ordered arrays on the SERS substrate can ensure the signal uniformity of sensor, which relative standard deviation (RSD) is as low as 3.37%. In addition, the photocatalytic self-cleaning capability of SERS substrate ensures that the sensor can be reused. Finally, the mechanism of the photogenerated carrier migration of Ag/ZnFe2O4 and its contribution to Raman signal enhancement were analyzed.

PhysFiT: Physical-aware 3D Shape Understanding for Finishing Incomplete Assembly

Understanding the part composition and structure of 3D shapes is crucial for a wide range of 3D applications, including 3D part assembly and 3D assembly completion. Compared to 3D part assembly, 3D assembly completion is more complicated which involves repairing broken or incomplete furniture that miss several parts with a toolkit. The primary challenge persists in how to reveal the potential part relations to infer the absent parts from multiple indistinguishable candidates with similar geometries, and complete for well-connected, structurally stable and aesthetically pleasing assemblies. This task necessitates not only specialized knowledge of part composition but, more importantly, an awareness of physical constraints, i.e. , connectivity, stability, and symmetry. Neglecting these constraints often results in assemblies that, although visually plausible, are impractical. To address this challenge, we propose PhysFiT, a physical-aware 3D shape understanding framework. This framework is built upon attention-based part relation modeling and incorporates connection modeling, simulation-free stability optimization and symmetric transformation consistency. We evaluate its efficacy on 3D part assembly and 3D assembly completion, a novel assembly task presented in this work. Extensive experiments demonstrate the effectiveness of PhysFiT in constructing geometrically sound and physically compliant assemblies.

Novel design and implementation of 3d packaged wideband bandpass filters

This study presents an innovative method for designing a 3D packaged wideband bandpass filter (BPF) by vertically integrating a high-pass filter (HPF) and a low-pass filter (LPF) using an air cavity and vertical interconnect accesses (VIAs). This integration enhances performance while significantly reducing system size. The fabricated BPF, constructed on multilayer substrates, achieves a passband from 2.175 to 4.2 GHz with less than 2.5 dB insertion loss and a return loss exceeding 10 dB. The design utilizes a partial substrate integrated suspended line (SISL) structure, enabling precise control over the equivalent dielectric constant and characteristic impedance to optimize insertion loss. The height of the air cavity, determined through theoretical analysis and S-parameter inversion, is critical for achieving optimal filter performance. The methodology allows for independent circuit designs on each layer, resulting in a 3D assembly. This refined approach makes it easier to produce compact bandpass and multi-band filters, simplifying circuit development and enabling scalable fabrication. This design is versatile across different frequency ranges, demonstrating significant practical and theoretical benefits.

A hybrid data-driven optimization and decision-making approach for a digital twin environment: Towards customizing production platforms

In the Industry 4.0 era, advanced technologies are transforming manufacturing processes and systems. Additionally, the increasing prevalence of big data and AI technologies have made decision-making using manufacturing data increasingly important. However, Small and Medium-sized Enterprises (SMEs) have encountered significant obstacles in adopting these technologies due to resource limitations and constraints. For SMEs, selecting an appropriate production strategy is challenging due to the complexity of manufacturing systems. As a response, this paper proposes a hybrid Simulation-Optimization with Multi-Criteria Decision-Making (SOMCDM) framework for SMEs to identify effective and customized production layouts. In the proposed approach, we model various production scenarios using a cellular manufacturing system. Surrogate models for different production layouts are created to basis functions using Multivariate Adaptive Regression Splines (MARS). Subsequently, the basis functions are used as fitness functions to identify optimal production parameters in a genetic algorithm. Then, optimized parameters are applied to production criteria and ranked using a multi-criteria decision-making technique. In a case study, the proposed framework is applied to select the best production platform among three scenarios for a company assembling complex products. The selected production platform improves overall manufacturing performance by 11.95% compared to the existing one. This study demonstrates the effectiveness of the proposed framework in identifying the best production platform for labor-intensive SMEs manufacturing high-mix, low-volume products using SOMCDM for a digital twin environment. The proposed framework is further detailed through a case study of a 3D printer assembly factory.

Exploring Polymorphism in Quinoline‐4‐Carbaldoxime: Experimental Validation and Computational Insights into Hydrogen Bonding and Structural Variations

AbstractThis study identifies and characterizes a second polymorph (Poly‐II) of quinoline‐4‐carbaldoxime (HQ), isolated from an acetone‐acetonitrile mixture. Poly‐II was compared to the previously known Poly‐I using PXRD, DSC, IR, and Raman spectroscopy. Poly‐I forms a 1D supramolecular assembly, whereas Poly‐II exhibits a 2D assembly with additional hydrogen bonds. Hirshfeld surface analysis reveals the presence of different non‐covalent interactions in Poly‐I and Poly‐II, and atom‐in‐molecule (AIM) analysis identifies their strength. AIM analysis, along with Espinosa's relation, was used to calculate the strength of O─H···N and C─H···N interactions in Poly‐I and Poly‐II. The values are −30.0 and −6.17 kJ/mol for Poly‐I, whereas the values for Poly‐II are −36.18 and −3.66 kJ/mol. The plane wave periodic DFT calculations determined the lattice energies of Poly‐I and Poly‐II to be −1.52 and −1.53 eV, respectively, indicating that both polymorphs have comparable stability. The crystal parameters of Poly‐I and Poly‐II obtained from theoretical simulations and the experiment are comparable, indicating the similar stability of Poly‐I and Poly‐II. Computational simulations confirmed experimental data, showing both polymorphs have similar stability and melting points despite different unit cell volumes.

Microsurgical Anatomy of the Common Tendinous Ring and Its Surgical Implications

BACKGROUND AND OBJECTIVES: The common tendinous ring (CTR), also known as the common annular tendon or annulus of Zinn, is a critical anatomic structure located at the convergence of the orbital apex, superior orbital fissure (SOF), optic canal, and the anterior aspect of the lateral sellar compartment. It plays a vital role in both neurosurgical and neuro-ophthalmological interventions. The aim of this study was to delineate the complex 3-dimensional (3D) topography of the CTR and explore its implications for surgical procedures. METHODS: Ten formalin-fixed skull base specimens from adult Chinese cadavers were meticulously dissected to investigate the morphology of the CTR, focusing particularly on its relationship with the 4 extraocular rectus tendons, the optic strut, the SOF, and the optic canal. Additional skull base specimens were subjected to 3D surface scanning, computed tomography, and histopathological examinations to deepen our understanding of the CTR's structural complexities. RESULTS: The CTR establishes a spatial, 3D tendinous assembly, encompassing 4 rectus tendons, 2 tendinous connections, and a singular common tendinous root. These components interlink to form a distinctive dual-ring configuration, featuring the optic foramen and the oculomotor foramen. The posterior part of the superior rectus tendon demarcates the common boundary between these 2 foramina. The oculomotor foramen itself serves as the central sector of the SOF. Precise incisions of the medial and lateral tendinous connections and fusions are essential for safely opening the CTR. CONCLUSION: The structural composition, interconnections, and dual-ring configuration of the CTR are crucial for precise and safe surgery of orbital apex and adjacent regions.

Popping: A granular transition

In experiments conducted on a weakly confined 2D assembly of deformable cylinders subject ed to rapid in-plane shear loading, we have identified the key obstacle in achieving compaction. This obstacle involves a dynamic transition between mechanical instabilities, progressing from in-plane rearrangement to out-of-plane popping as the density increases. The popping effect reinforces the frictional constraints from the confining wall and restricts particle mobility, impeding the system from attaining greater compaction. We quantify this transition and demonstrate that interparticle friction contributes to smoothing the transition. Published by the American Physical Society 2024

Optimizing nickel-aluminium layered double hydroxides for supercapacitors: The role of 3D structural assembly

Nickel-aluminium layered double hydroxides (NiAl-LDHs) have emerged as promising electrode materials for supercapacitors (SCs) due to their inherently high specific surface area and theoretical specific capacitance, which are primarily attributed to the rapid pseudocapacitive response at the surface. However, NiAl-LDHs typically form agglomerated nanosheets, leading to a significant reduction in specific surface area, which is crucial for enhancing the number of active sites and improving the capacitive properties of the materials. To overcome this limitation, 2D nanostructures were assembled into 3D architectures by synthesizing NiAl-LDHs with distinct morphologies in a one-step hydrothermal process using an alkaline agent (NH4F). This approach resulted in the formation of 3D NiAl-LDH/HN4F structures, which exhibit a larger contact area and a greater number of redox-active sites. Consequently, the 3D NiAl-LDH/HN4F electrodes demonstrated a significantly higher specific surface area, leading to remarkable improvements in specific capacitance (1219 ± 30F g−1) and energy density (61 ± 1 Wh kg−1) compared to their 2D counterparts. This structural enhancement increases both the surface area and active site density while providing a new framework for designing high-performance LDH-based electrodes.

Self-Assembled Nanohelixes Driven by Host-Guest Interactions and Metal Coordination.

Helical nanostructures fabricated via the self-assembly of artificial motifs have been a captivating subject because of their structural aesthetics and multiple functionalities. Herein, we report the facile construction of a self-assembled nanohelix (NH) by leveraging an achiral aggregation-induced emission (AIE) luminogen (G) and pillar[5]arene (H), driven by host-guest interactions and metal coordination. Inspired by the "sergeants and soldiers" effect and "majority rule" principle, the host-guest complexation between G and H is employed to fixate the twisted conformation of G for the generation of "contortion sites", which further induced the emergence of helicity as the 1D assemblies are formed via Ag(I) coordination and hexagonally packed into nano-sized fibers. The strategy has proved feasible in both homogeneous and heterogeneous syntheses. Along with the formation of NH, boosted luminescence and enhanced productivity of reactive oxygen species (ROS) are afforded because of the efficient restriction on G, indicating the concurrent regulation of NH's morphology and photophysical properties by supramolecular assembly. In addition, NH also exhibits the capacity for bacteria imaging and photodynamic antibacterial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).

Self‐Assembled Nanohelixes Driven by Host‐Guest Interactions and Metal Coordination

Helical nanostructures fabricated via the self‐assembly of artificial motifs have been a captivating subject because of their structural aesthetics and multiple functionalities. Herein, we report the facile construction of a self‐assembled nanohelix (NH) by leveraging an achiral aggregation‐induced emission (AIE) luminogen (G) and pillar[5]arene (H), driven by host‐guest interactions and metal coordination. Inspired by the “sergeants and soldiers” effect and “majority rule” principle, the host‐guest complexation between G and H is employed to fixate the twisted conformation of G for the generation of “contortion sites”, which further induced the emergence of helicity as the 1D assemblies are formed via Ag(I) coordination and hexagonally packed into nano‐sized fibers. The strategy has proved feasible in both homogeneous and heterogeneous syntheses. Along with the formation of NH, boosted luminescence and enhanced productivity of reactive oxygen species (ROS) are afforded because of the efficient restriction on G, indicating the concurrent regulation of NH's morphology and photophysical properties by supramolecular assembly. In addition, NH also exhibits the capacity for bacteria imaging and photodynamic antibacterial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).

Electron Transport over 2D Molecular Materials and Assemblies.

ConspectusTwo-dimensional (2D) molecular materials, in which the major interactions are confined in 2D planes with contrasted force fields acting in between the planes, have been key electronic functional materials since the past decade. Even without referring to the functionals of graphene-based systems, 2D electronic conjugated systems are expected to show extrawide dynamic ranges in electronic density of states (DOS) tuning, effective electron mass, electron mobility, and conductivity. A major advantage of 2D electronic systems is their compatibility with the ubiquitous electronic devices designed using planar structures, such as transistors and memories, which is associated with the utility of 2D active materials. The mobility of electrons in 2D systems is the key to their utility, and various conjugated molecular and 2D materials have been designed to optimize the mobility. This Account begins with an introduction for mobility assessment: using noncontact time-resolved microwave conductivity (TRMC) measurements as a technique to probe differential conductivity upon transient charge carrier injection into the materials. Electronic transport over 2D electronic materials such as graphenes, covalent organic frameworks (COFs), and metal-organic frameworks (MOFs) is discussed with a special emphasis on molecular building blocks, fine-tuning conducting species and linkages, topology of the framework, and controlling molecular doping. The superiority of β-ketoenamine-linked COF over imine-linked COF films in charge transport and dominant in-plane charge carrier mobility over out-of-plane mobility is also illustrated. Systematic molecular engineering of the building blocks of β-ketoenamine-linked COFs with varying degrees of donor-acceptor (D-A) conjugation, torsional angles, and reaction conditions resulted in the modulation of the efficiency of charge carrier generation/transport as well as exciton migration. The advantages of 2D systems are finally discussed in terms of the mobility interplaying with spatial arrangements of molecules as well as the substantial role of intermolecular interactions in stabilizing their condensed phases. The strong correlation between the dispersion of mobility and hierarchical intermolecular interactions sheds light on the way to overcome structural fluctuation on the optimization of charge transport in molecular electronic materials. The point of singularity in the dispersion at an intermolecular distance of d ∼ 0.3 nm is deduced from the overall mobility assessment in condensed phases of conjugated molecules, suggesting key roles of intermolecular electronic coupling: the new concept of electronic conjugation. Exceptional electronic coupling with relatively high charge carrier mobility was also observed, particularly in 2D spatial arrangements of chiral molecules in contrast to 3D analogues, where the reduction of gravitational density of the molecular condensates was impacting DOS: the Wallach's rule. 2D electronic systems are strong candidates for the violation of the long-lasting Wallach's rule in terms of DOS.

Highly selective and efficient Pb2+ capture using PO4-loaded 3D-NiFe layer double hydroxides derived from MIL-88A

Lead (Pb) contamination in water requires improved decontamination technologies. The addition of phosphate to precipitate Pb2+ is a widely used method for remediating Pb in soil and water, though it has certain limitations. This study focuses on novel 3D mesoporous layered double hydroxide (LDH) sorbents functionalized with phosphate anions for Pb2+ removal from contaminated waters. Our innovative strategy involves converting a sacrificial template metal-organic frameworks (MOFs) structure (MIL-88A(Fe)) into NixFe LDH, followed by an anion exchange reaction with phosphate anions. This process preserves the 3D microrod architecture of MIL-88A and prevents deleterious LDH particle aggregation. The synthesis results in stable microrod crystals, 1–2 μm long, composed of 3D assemblies of NixFe-PO4 LDH nanoplatelets with a specific surface area exceeding 110 m2/g. The novel LDH materials display fast adsorption kinetics (pseudo-second order model) and remarkably high Pb2+ removal performances (Langmuir isotherm model) with a capacity of 538 mg/g, surpassing other reported adsorbents. LDH-PO4 exhibits high selectivity for Pb2+ over competing ions like Ni2+ and Cd2+ (selectivity order is: Pb2+ > Ni2+ > Cd2+). Removal of Pb2+ from NixFeLDH/88A-PO4 involves various mechanisms, including surface complexation and surface precipitation of lead phosphate or lead hydroxide phases as revealed by structural characterization techniques.

Distribution and propagation of stress and strain in cube honeycombs as trabecular bone substitutes: Finite element model analysis

For designing trabecular (Tb) bone substitutes suffering from osteoporosis, finite element model (FEM) simulations were conducted on honeycombs (HCs) of 8 × 8 × 1 (2D) and 8 × 8 × 8 (3D) assemblies of cube cellular units consisting of 0.9 mm long Nylon® 66 (PA, Young's modulus E: 2.83 GPa) and polyethylene (PE, E: 1.1 GPa) right square prisms. Osteoporotic damage to the Tb bone was simulated by removing the inner vertical struts (pillars; the number of removed pillars: Δn ≤ 300) and by thinning the strut (thickness, d: 0.4–0.1 mm), while the six facade lattices were kept flawless. Uniform and uniaxial compressive loads on the HCs induced elastic deformation of the struts. The pillars held almost all the load, while the horizontal struts (beams) shared little. E for PA 3D HCs of all d smoothly decreased with Δn. PA 3D HCs of 0.2 mm struts deserved to be the substitutes for Tb bone, while PE 3D HCs of 0.05 mm struts were only for the Tb bone of the poorest bone quality. For the PA 3D HCs, the maximum von Mises stress (σM) first rapidly increased with Δn and showed a break at Δñ50, then gradually approached the yield stress of PA (50 MPa). Moreover, small portions of the stress were transferred from the façade pillars to the adjacent inner beams, especially those near the lost-pillar sites, denoted as X defects. The floor beams of thinner struts associated with the X-defects were lifted, and similar lifting effects in smaller amounts were propagated to the other floors. The 3DHCs of the thicker struts showed no such flexural deformations. The concept of force percolation through the remaining struts was proposed to interpret those mechanical behaviors of the HCs.

Controlling Protein Assembly with Superchaotropic Nano-Ions.

In living systems, protein assemblies have essential functions, serving as structural supports, transport highways for molecular cargo, and containers of genetic material. The construction of protein assemblies, which involves control over space and time, remains a significant challenge in biotechnology. Here, we show that anionic boron clusters, 3,3'-commo-bis[closo-1,2-dicarba-3-cobaltadodecaborane] (COSAN-), and halogenated closo-dodecarboranes (B12X122-, X = Η, Cl or I), described as super-chaotropic nano-ions, induce the formation of 2D assemblies of model proteins, myoglobin, carbonic anhydrase, and trypsin inhibitor. We found that the nano-ion concentration reversibly controls the size of the protein assemblies. Furthermore, the secondary structures of the proteins are only slightly affected by assembly formation. For myoglobin, the formation of these assemblies even prevents temperature denaturation, highlighting a preservation effect of nano-ions. Our study reveals that inorganic boron-based nano-ions act as a reversible molecular glue for proteins, providing a potential starting point for the further development of controlled protein assemblies.

Morphology evolution of supramolecular aggregates from C3-symmetric peptide amphiphiles

During the aging of supramolecular systems, new stable materials with different morphologies, molecular packing, and hierarchical organization may form from the initial assembly. Understanding the mechanisms and pathways accompanying age-related changes may allow for the controlled synthesis of multiple materials from a single molecule in a nature-inspired manner. Herein, we demonstrate the multi-stage evolution of a single solution of C3-symmetric peptide amphiphile containing diphenylalanine fragment and benzyl-1,3,5-tricarboxamide core. Transmission electron microscopy reveals the rapid formation of 20–40 nm wide nanoribbons in an aqueous solution within 60 s after preparation. The lateral edges of nanoribbons contain solvent-exposed aromatic residues that tend to merge via an unconventional edge-to-edge zipping mechanism, leading to the nanoribbon’s growth in width. After reaching a critical width and flexibility, “sticky edges” on the same nanoribbon may merge via a self-zipping mechanism, forming rigid nanotubes. Eventually, mechanical perturbations cause buckling and fracture of nanotubes into shorter nanotubes via flexural or tensile failure. This work reports new evolution pathways in soft 2D assemblies and introduces solution ageing as a promising method to control morphology of peptide amphiphiles.

Controlling Protein Assembly with Superchaotropic Nano‐Ions.

In living systems, protein assemblies have essential functions, serving as structural supports, transport highways for molecular cargo, and containers of genetic material. The construction of protein assemblies, which involves control over space and time, remains a significant challenge in biotechnology. Here, we show that anionic boron clusters, 3,3’‐commo‐bis[closo‐1,2‐dicarba‐3‐cobaltadodecaborane] (COSAN‐), and halogenated closo‐dodecarboranes (B12X122‐, X = Η, Cl or I), described as super‐chaotropic nano‐ions, induce the formation of 2D assemblies of model proteins, myoglobin, carbonic anhydrase, and trypsin inhibitor. We found that the nano‐ion concentration reversibly controls the size of the protein assemblies. Furthermore, the secondary structures of the proteins are only slightly affected by assembly formation. For myoglobin, the formation of these assemblies even prevents temperature denaturation, highlighting a preservation effect of nano‐ions. Our study reveals that inorganic boron‐based nano‐ions act as a reversible molecular glue for proteins, providing a potential starting point for the further development of controlled protein assemblies.

Use of 3D foot and ankle puzzle enhances student understanding of the skeletal anatomy in the early years of medical school

Purpose3D visualization is an important part of learning anatomy with cadavers generally used to effectuate this. However, high cost, ethical considerations, and limited accessibility can often limit the suitability of cadavers as teaching tools. Anatomical 3D printed models offer an alternative tool for teaching gross anatomy due to their low cost and accessibility. This study aims to investigate if combing gamification with 3D printed models can enhance the learning experience and be effective for teaching anatomy.Methods3D printed models of the bones of the foot and ankle were generated, and 267 first-year medical students from 2 consecutive cohorts worked in groups to put it together as a puzzle. Participants completed a questionnaire regarding perceptions of 3D models and their knowledge of foot anatomy, before and after the session and were asked to provide comments.ResultsAnalysis of the responses showed a significant increase in the confidence of the learners in their anatomy knowledge and an increased appreciation of the role that 3D models have in enhancing the learning experience. After the session, there were many comments saying how enjoyable and engaging 3D models were.ConclusionThrough the puzzle element of the session, the students were challenged mentally to work out the anatomical features of the foot and ankle. The combined elements of the puzzle and the features of the 3D model assembly made the activity fun and conducive to active learning. The possibility of having fun was not something the students had considered before the session.

Patent conversion of a novel closed chest drainage device

Closed chest drainage is typically necessary following Lobar and Sublobar resections to evacuate gases and fluids from the thoracic cavity, eliminate residual pleural space for lung expansion, and maintain negative pressure. Currently, three conventional closed chest drainage systems are commonly employed: single-chamber, double-chamber, and triple-chamber systems; each system has its own advantages and disadvantages. Despite the emergence of digital drainage systems in recent years, their high cost hinders their widespread adoption. Based on this premise, our research team has achieved a patent for a micro air pump-integrated chest closed drainage bottle, which has been further developed into a novel device integrating a three-chamber system with negative pressure control and power supply capabilities. This device enables patients undergoing perioperative lung procedures to ambulate freely while simultaneously receiving chest suction therapy—a concept that theoretically promotes rapid postoperative recovery. Moreover, this device offers economic benefits and holds potential for clinical implementation (particularly in economically underdeveloped regions). In this article, we modified the thoracic closed drainage device based on our patent and presented this novel thoracic closed drainage device after 3D printing and assembly.

3D Printed Swordfish‐Like Wireless Millirobot

Inspired by the efficient swimming capabilities of swordfish, a novel wireless soft swordfish‐like robot with programmable magnetization has been developed, integrating direct‐ink‐writing (DIW) 3D printing and assembly technology. This 20 mm long robot features a streamlined form and magnetically programmable movements, enabling biomimetic locomotion patterns such as straight‐line swimming and turning swimming. The robot includes a silicone‐based torso (body, abdomen, and pectoral fin) and a crescent‐shaped tail fin made from a magnetically programmable polymer embedded with neodymium‐iron‐boron (NdFeB) particles. The tail fin, fabricated by multi‐material alternating printing to achieve a gradient magnetism distribution, is controlled by an external magnetic field to mimic the rapid oscillation of a swordfish's tail, achieving a swimming speed of 0.51 BL/ s. The tail fin's asymmetric oscillation amplitudes, adjusted by magnetic field control, allow the robot to transition seamlessly from high‐speed straight swimming to agile turning. The robot can perform tracking swimming along specific planned paths, such as “C” and “Z” shaped trajectories. Potential applications include environmental monitoring and targeted drug release. The multi‐material 3D printing technology enhances the robot's efficiency and sensitivity in simulating natural biological movements, extending to the design and development of various flexible devices and soft robots.

Formation of Linear Plasmonic Heterotrimers Using Nanoparticle Docking to DNA Origami Cages.

The fabrication of complex assemblies with interesting collective properties from plasmonic nanoparticles (NPs) is often challenging. While DNA-directed self-assembly has emerged as one of the most promising approaches to forming such complex assemblies, the resulting structures tend to have large variability in gap sizes and shapes, as the DNA strands used to organize these particles are flexible, and the polydispersity of the NPs leads to variability in these critical structural features. Here, we use a new strategy termed docking to DNA origami cages (D-DOC) to organize spherical NPs into a linear heterotrimer with a precisely defined geometrical arrangement. Instead of binding NPs to the exterior of the DNA templates, D-DOC binds the NPs to either the interior or the opening of a 3D cage, which significantly reduces the variability of critical structural features by incorporating multiple diametrically arranged capture strands to tether NPs. Additionally, such a spatial arrangement of the capture strand can work synergistically with shape complementarity to achieve tighter confinement. To assemble NPs via D-DOC, we developed a multistep assembly process that first encapsulates an NP inside a cage and then binds two other NPs to the openings. Microscopic characterization shows low variability in the bond angles and gap sizes. Both UV-vis absorption and surface-enhanced Raman scattering (SERS) measurements showed strong plasmonic coupling that aligned with predictions by electrodynamic simulations, further confirming the precision of the assembly. These results suggest D-DOC could open new opportunities in biomolecular sensing, SERS and fluorescence spectroscopies, and energy harvesting through the self-assembly of NPs into more complex 3D assemblies.