Spontaneous Self-Assembly of Silver Nanoparticles into Lamellar Structured Silver Nanoleaves

Uniform lamellar silver nanoleaves (AgNLs) were spontaneously assembled from 4 nm silver nanoparticles (AgNPs) with <i>p</i>-aminothiophenol (PATP) as mediator under mild shaking at room temperature. The compositions of the AgNLs were verified to be ∼1 nm Ag₂₅ nanoclusters and PATP molecules in quinonoid model. The underlying assembly mechanism was systematically investigated and a two-step reaction process was proposed. First, the 4 nm AgNPs were quickly etched to ∼1 nm Ag₂₅ nanoclusters by PATP in the form of [Ag₂₅(PATP)_<i>n</i>]^<i>n</i>+ (<i>n</i> < 12), which were then further electrostatically or covalently interconnected by PATP to form the repeated unit cells of [Ag₂₅(PATP)_<i>n</i>−1]^{(<i>n</i>−1)+}–PATP–[Ag₂₅(PATP)_<i>n</i>−1]^{(<i>n</i>−1)+} (abbreviated as Ag₂₅–PATP–Ag₂₅). Second, these Ag₂₅–PATP–Ag₂₅ complexes were employed as building blocks to construct lamellar AgNLs under the directions of the strong dipole–dipole interaction and the π–π stacking force between the neighboring benzene rings of PATP. Different reaction parameters including the types and concentrations of ligands, solvents, reaction temperature, ionic strength, and pH, <i>etc</i>., were carefully studied to confirm this mechanism. Finally, the preliminary investigations of the applications for AgNLs as “molecular junctions” and SERS properties were demonstrated. We expect that this convenient and simple method can be in principle extended to other systems, or even mixture system with different types of NPs, and will provide an important avenue for designing metamaterials and exploring their physicochemical properties

Coassembly of Tobacco Mosaic Virus Coat Proteins into Nanotubes with Uniform Length and Improved Physical Stability

Using tobacco mosaic virus coat proteins (TMVcp) from both sources of the plant and bacterial expression systems as building blocks, we demonstrate here a coassembly strategy of TMV nanotubes in the presence of RNA. Specifically, plant-expressed cp (cp_p) efficiently dominates the genomic RNA encapsidation to determine the length of assembled TMV nanotubes, whereas the incorporated <i>Escherichia coli-</i>expressed cp (cp_ec) improves the physical stability of TMV nanotubes by introducing disulfide bonds between the interfaces of subunits. We expect this coassembly strategy can be expanded to other virus nanomaterials to obtain desired properties based on rationally designed protein–RNA and protein–protein interfacial interactions

Selective in Situ Assembly of Viral Protein onto DNA Origami

Engineering hybrid protein–DNA assemblies in a controlled manner has attracted particular attention, for their potential applications in biomedicine and nanotechnology due to their intricate folding properties and important physiological roles. Although DNA origami has served as a powerful platform for spatially arranging functional molecules, <i>in situ</i> assembly of proteins onto DNA origami is still challenging, especially in a precisely controlled and facile manner. Here, we demonstrate <i>in situ</i> assembly of tobacco mosaic virus (TMV) coat proteins onto DNA origami to generate programmable assembly of hybrid DNA origami–protein nanoarchitectures. The protein nanotubes of controlled length are precisely anchored on the DNA origami at selected locations using TMV genome-mimicking RNA strands. This study opens a new route to the organization of protein and DNA into sophisticated protein–DNA nanoarchitectures by harnessing the viral encapsidation mechanism and the programmability of DNA origami

Origin of the Plasmonic Chirality of Gold Nanorod Trimers Templated by DNA Origami

Templated by DNA origami, plasmonic gold nanorods (AuNRs) could be assembled into complex nanostructures with strong chiroptical activities. However, it is still not clear how the plasmonic chirality of a complex nanostructure matters with its daughter structural components. Here, we rationally design and fabricate a series of AuNR trimers and their daughter AuNR dimers. Strikingly, we corroborate by circular dichroism spectroscopy that the plasmonic chirality of asymmetrical AuNR trimers is a nearly perfect summation of the chiroptical response of all their constituent dimeric components. Our results provide fundamental insight into the origin of the plasmonic chirality of complex nanostructures

Large-Scale Synthesis of Single Crystalline CuSb(S_<i>x</i>Se_1–<i>x</i>)₂ Nanosheets with Tunable Composition

Alloying nanocrystals with multicomponent has been an effective way to tune the band gap of semiconductor nanocrystals, which promises their wide applications in optoelectronics, photovoltaics, etc. However, colloidal synthesis of homogeneous phase multicomponent nanocrystals in a large scale remains great challenge. Here, we declare the successful preparation of single-crystalline quaternary CuSb­(S_<i>x</i>Se_1–<i>x</i>)₂ nanosheets in a facile one-pot reaction with yield >3 g. The molar ratio of S/(S + Se) in CuSb­(S_<i>x</i>Se_1–<i>x</i>)₂ could be easily tuned from 1.5% to 13.7% by increasing the reaction temperature which enhances the reactivity of S source in the reaction, and accordingly, the band gap of the obtained CuSb­(S_<i>x</i>Se_1–<i>x</i>)₂ varies from 0.9 to 1.1 eV

Self-Assembly of Protein Crystals with Different Crystal Structures Using Tobacco Mosaic Virus Coat Protein as a Building Block

In this work, a typical cylinder-shaped tobacco mosaic virus coat protein (TMVCP) is employed as an anisotropic building block to assemble into triclinic and hexagonal close-packed (HCP) protein crystals by introducing cysteine residues at the 1 and 3 sites and four histidine residues at the C-terminal, respectively. The engineered functional groups of cysteine and histidine in the TMVCP and the self-assembly conditions determine the thermodynamics and kinetics in the self-assembly process for forming different crystal structures. The results show that the TMVCPs are thermodynamically driven to form triclinic crystals due to the formation of disulfide bonds between neighboring TMVCPs. On the other hand, the self-assembly of HCP crystals is kinetically directed by the strong metal–histidine chelation. This work not only greatly expands TMVCP for fabricating promising nanomaterials but also represents an approach to adjusting the protein crystal structures by tuning the thermodynamics and kinetics during crystallization

Modular Assembly of Plasmonic Nanoparticles Assisted by DNA Origami

Arraying noble metal nanoparticles with nanoscale features is an important way to develop plasmonic devices with novel optical properties such as plasmonic chiral metamolecules, optical waveguides, and so forth. Along with top-down methods of fabricating plasmonic nanostructures, solution-based self-assembly provides an alternative approach. There are mainly two routes to organizing metal nanoparticles via self-assembly. One is directly linking nanoparticles through linker molecules, and the other is using nanoparticles to decorate a preformed template. We combine these two routes and herein report a strategy for the DNA origami-assisted modular assembly of gold nanoparticles into homogeneous and heterogeneous plasmonic nanostructures. For each module, we designed W-shaped DNA origami with two troughs as two domains. One domain is used to host a gold nanoparticle, and the other domain is designed to capture another gold nanoparticle hosted on a different module. By simply tuning the sequences of capture DNA strands on each module, gold nanoparticles including spherical and rod-shaped gold nanoparticles (denoted as AuNPs and AuNRs) could be well organized in a predefined manner to form versatile plasmonic nanostructures. Since the interparticle distances could be precisely controlled at the nanoscale, we also studied the plasma coupling among the assembled plasmonic nanostructures. This modular assembly strategy represents a simple yet general and effective design principle for DNA-assembled plasmonic nanostructures

Controlled Self-Assembly of Proteins into Discrete Nanoarchitectures Templated by Gold Nanoparticles via Monovalent Interfacial Engineering

Designed rational assembly of proteins promises novel properties and functionalities as well as new insights into the nature of life. <i>De novo</i> design of artificial protein nanostructures has been achieved using protein subunits or peptides as building blocks. However, controlled assembly of protein nanostructures into higher-order discrete nanoarchitectures, rather than infinite arrays or aggregates, remains a challenge due to the complex or symmetric surface chemistry of protein nanostructures. Here we develop a facile strategy to control the hierarchical assembly of protein nanocages into discrete nanoarchitectures with gold nanoparticles (AuNPs) as scaffolds via rationally designing their interfacial interaction. The protein nanocage is monofunctionalized with a polyhistidine tag (Histag) on the external surface through a mixed assembly strategy, while AuNPs are modified with Ni²⁺−NTA chelates, so that the protein nanocage can controllably assemble onto the AuNPs via the Histag−Ni²⁺ affinity. Discrete protein nanoarchitectures with tunable composition can be generated by stoichiometric control over the ratio of protein nanocage to AuNP or change of AuNP size. The methodology described here is extendable to other protein nanostructures and chemically synthesized nanomaterials, and can be borrowed by synthetic biology for biomacromolecule manipulation

Disulfide Bond: Dramatically Enhanced Assembly Capability and Structural Stability of Tobacco Mosaic Virus Nanorods

Tobacco mosaic virus (TMV) is a classical viral nanoarchitecture that has been extensively employed as a promising template for the fabrication of novel nanomaterials and nanostructures. Despite being an ideal source, the Escherichia coli-derived TMV nanorod is suffering from tenuous assembly capability and stability. Inspired by the disulfide bond widely employed in biosystems, here we rationally introduce a cysteine into TMV coat protein (TMV-CP) to enable disulfide bond formation between adjacent subunits, thereby radically altering the behaviors of original noncovalent assembling system of wild type TMV-CP. The dramatically enhanced self-assembly capability and stability of the engineered TMV nanorods are observed and the essential roles of disulfide bonds are verified, illustrating a promising strategy to obtain desired genetic-modified nanorods that are inaccessible in plants. We expect this work will benefit the development of TMV-based nanotechnology and encourage the utilization of disulfide bonds in other biomacromolecules for improved properties as nanoscaffolds

Selective Synthesis of Ternary Copper–Antimony Sulfide Nanocrystals

Ternary copper–antimony sulfide nanocrystals (CAS NCs) have attracted increasing attention in photovoltaics and photoelectric nanodevices due to their tunable band gaps in the near-IR regime. Although much progress in the synthesis of CAS NCs has been achieved, the selective synthesis of CAS NCs with controllable morphologies and compositions is preliminary: in particular, a facile method is still in demand. In this work, we have successfully selectively synthesized high-quality CAS NCs with diverse morphologies, compositions, and band gaps, including rectangular CuSbS₂ nanosheets (NSs), trigonal-pyramidal Cu₁₂Sb₄S₁₃ NCs, and rhombic Cu₃SbS₃ NSs, by cothermodecomposition of copper diethyldithiocarbamate trihydrate (Cu­(Ddtc)₂) and antimony diethyldithiocarbamate trihydrate (Sb­(Ddtc)₃). The direct and indirect band gaps of the obtained CAS NCs were systematically studied by performing Kubelka–Munk transformations of their solid-state diffuse reflectance spectra