20 research outputs found
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 ā¼1 nm Ag<sub>25</sub> 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 ā¼1 nm Ag<sub>25</sub> nanoclusters by PATP in the form of [Ag<sub>25</sub>(PATP)<sub><i>n</i></sub>]<sup><i>n</i>+</sup> (<i>n</i> < 12), which were then further electrostatically or covalently interconnected by PATP to form the repeated unit cells of [Ag<sub>25</sub>(PATP)<sub><i>n</i>ā1</sub>]<sup>(<i>n</i>ā1)+</sup>āPATPā[Ag<sub>25</sub>(PATP)<sub><i>n</i>ā1</sub>]<sup>(<i>n</i>ā1)+</sup> (abbreviated as Ag<sub>25</sub>āPATPāAg<sub>25</sub>). Second, these Ag<sub>25</sub>āPATPāAg<sub>25</sub> complexes were employed as building blocks to construct lamellar AgNLs under the directions of the strong dipoleādipole interaction and the ĻāĻ 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 āmolecular junctionsā 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<sub>p</sub>)
efficiently dominates the genomic RNA encapsidation to determine the
length of assembled TMV nanotubes, whereas the incorporated <i>Escherichia coli-</i>expressed cp (cp<sub>ec</sub>) 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 proteināRNA and proteināprotein
interfacial interactions
Selective in Situ Assembly of Viral Protein onto DNA Origami
Engineering hybrid proteināDNA
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 origamiāprotein
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 proteināDNA
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<sub><i>x</i></sub>Se<sub>1ā<i>x</i></sub>)<sub>2</sub> 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 CuSbĀ(S<sub><i>x</i></sub>Se<sub>1ā<i>x</i></sub>)<sub>2</sub> nanosheets
in a facile one-pot reaction with yield >3 g. The molar ratio of
S/(S
+ Se) in CuSbĀ(S<sub><i>x</i></sub>Se<sub>1ā<i>x</i></sub>)<sub>2</sub> 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 CuSbĀ(S<sub><i>x</i></sub>Se<sub>1ā<i>x</i></sub>)<sub>2</sub> 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 metalāhistidine 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 Ni<sup>2+</sup>āNTA chelates,
so that the protein nanocage can controllably assemble onto the AuNPs
via the HistagāNi<sup>2+</sup> 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 CopperāAntimony Sulfide Nanocrystals
Ternary copperāantimony 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 CuSbS<sub>2</sub> nanosheets
(NSs), trigonal-pyramidal Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub> NCs, and rhombic Cu<sub>3</sub>SbS<sub>3</sub> NSs, by cothermodecomposition
of copper diethyldithiocarbamate trihydrate (CuĀ(Ddtc)<sub>2</sub>)
and antimony diethyldithiocarbamate trihydrate (SbĀ(Ddtc)<sub>3</sub>). The direct and indirect band gaps of the obtained CAS NCs were
systematically studied by performing KubelkaāMunk transformations
of their solid-state diffuse reflectance spectra