DNA origami can provide programmed information to guide the self‐assembly of gold nanospheres (Au NSs) into higher‐order supracolloids. Molecularly precise and truly 2D/3D integration of Au NSs is ...possible using DNA origami‐enabled assembly, and the resulting assemblies have potential applications in plasmonics and metamaterials. However, the relatively small size (<60 nm) and randomly faceted Au NSs that have been used thus far in DNA origami‐enabled assembly have limited their nanophotonic applications. Here, the robust self‐assembly of the 60–100 nm roundest Au NSs into metamolecular assemblies using 3D DNA origami is described. These Au NSs are successfully conjugated with DNA oligonucleotides and are therefore stable at high salt concentrations even without backfilling using organic ligands. The roundest Au NSs are successfully assembled into supracolloidal metamolecules and chains via 3D DNA origami. These plasmonic metamolecules and chains display strong electric and unnatural magnetic resonances that can be deterministically controlled.
3D DNA origami‐enabled robust self‐assembly of relatively large, roundest gold nanospheres into various plasmonic assemblies ranging from supracolloidal ring clusters to oligomeric chains is reported. The plasmonic assemblies generate strong electric and unnatural magnetic resonances due to their high structural fidelity.
The scaling down of meta‐atoms or metamolecules (collectively denoted as metaunits) is a long‐lasting issue from the time when the concept of metamaterials was first suggested. According to the ...effective medium theory, which is the foundational concept of metamaterials, the structural sizes of meta‐units should be much smaller than the working wavelengths (e.g., << 1/5 wavelength). At relatively low frequency regimes (e.g., microwave and terahertz), the conventional monolithic lithography can readily address the materialization of metamaterials. However, it is still challenging to fabricate optical metamaterials (metamaterials working at optical frequencies such as the visible and near‐infrared regimes) through the lithographic approaches. This serves as the rationale for using colloidal self‐assembly as a strategy for the realization of optical metamaterials. Colloidal self‐assembly can address various critical issues associated with the materialization of optical metamaterials, such as achieving nanogaps over a large area, increasing true 3D structural complexities, and cost‐effective processing, which all are difficult to attain through monolithic lithography. Nevertheless, colloidal self‐assembly is still a toolset underutilized by optical engineers. Here, the design principle of the colloidally self‐assembled optical metamaterials exhibiting unnatural refractions, the practical challenge of relevant experiments, and the future opportunities are critically reviewed.
The colloidal self‐assembly of optical metamaterials has come to the fore along with recent advances in synthetic strategies of colloids, self‐assembly routes for clusters and superlattices, and effective medium theory for analyzing colloidal assemblies. In particular, unnatural optical refractions such as extremely high and negative refractive indices could be available with colloidal self‐assembly.
Nanoscale manipulation of magnetic fields has been a long‐term pursuit in plasmonics and metamaterials, as it can enable a range of appealing optical properties, such as high‐sensitivity circular ...dichroism, directional scattering, and low‐refractive‐index materials. Inspired by the natural magnetism of aromatic molecules, the cyclic ring cluster of plasmonic nanoparticles (NPs) has been suggested as a promising architecture with induced unnatural magnetism, especially at visible frequencies. However, it remains challenging to assemble plasmonic NPs into complex networks exhibiting strong visible magnetism. Here, a DNA‐origami‐based strategy is introduced to realize molecular self‐assembly of NPs forming complex magnetic architectures, exhibiting emergent properties including anti‐ferromagnetism, purely magnetic‐based Fano resonances, and magnetic surface plasmon polaritons. The basic building block, a gold NP (AuNP) ring consisting of six AuNP seeds, is arranged on a DNA origami frame with nanometer precision. The subsequent hierarchical assembly of the AuNP rings leads to the formation of higher‐order networks of clusters and polymeric chains. Strong emergent plasmonic properties are induced by in situ growth of silver upon the AuNP seeds. This work may facilitate the development of a tunable and scalable DNA‐based strategy for the assembly of optical magnetic circuitry, as well as plasmonic metamaterials with high fidelity.
DNA origami is used to program an assembly of nanoparticles into magnetic architectures exhibiting resonant coupling and propagation of magnetic plasmons at visible frequencies, including antiferromagnetism, a purely magnetic‐based Fano resonance, and magnetic surface plasmon polaritons.
The increases in refractive indices (n) of materials are crucial for transformative optical technologies. With the progress of monolithic lithography, large advances have been achieved with several ...semiconductors, including silicon, germanium, and gallium arsenide, which generally provide higher n of ∼4.0 compared to those of other elements. Nevertheless, above this upper limit of naturally available n, the range of light–matter interactions could be unprecedentedly expanded, which in turn enriches the possible applications. Here, we present a soft self-assembly of polyhedral Au colloids as a promising method to achieve unnaturally high n values. The interfacial assembly of Au nanocubes provides n of 6.4 at the resonant wavelength (near-infrared) and 4.5 in the off-resonant regimes (mid-infrared), which have not been previously reached. The soft self-assembly of polyhedral Au colloids can be a versatile and highly effective route for the fabrication of optical metamaterials with unnaturally high n values.
The authors develop a mechanically robust silver nanowires (AgNWs) electrode platform for use in flexible and stretchable triboelectric nanogenerators (TENGs). The embedding of an AgNWs network into ...a photocurable or thermocurable polymeric matrix dramatically enhances the mechanical robustness of the flexible and stretchable TENG electrodes while maintaining a highly efficient triboelectric performance. The AgNWs/polymeric matrix electrode is fabricated in four steps: (i) the AgNWs networks are formed on a hydrophobic glass substrate; (ii) a laminating photocurable or thermocurable prepolymer film is applied to the developed AgNWs network; (iii) the polymeric matrix is crosslinked by UV exposure or thermal treatment; and (iv) the AgNWs‐embedded polymeric matrix is delaminated from the glass substrate. The AgNWs‐embedded polymeric matrix electrodes with four different sheet resistances, controlled by varying the AgNWs network deposition density, are deployed in TENG devices. The authors find that the potential difference between the two contact surfaces of the AgNWs network‐embedded polymer matrix electrodes and the nylon (or perfluoroalkoxy alkane) governs the output triboelectric performances of the devices, rather than the sheet resistance. Both Kelvin probe force microscopy and numerical simulations strongly support these observations.
A mechanically robust silver nanowires (AgNWs) electrode platform for use in flexible and stretchable triboelectric nanogenerators (TENGs) is developed. The embedding of an AgNWs network into a photocurable or thermocurable polymeric matrix dramatically enhances the mechanical robustness of the flexible and stretchable TENG electrodes while maintaining a highly efficient triboelectric performance.
Van der Waals Colloidal Crystals Cho, YongDeok; Park, Sung Hun; Kwon, Min ...
Advanced materials (Weinheim),
06/2024, Letnik:
36, Številka:
23
Journal Article
Recenzirano
A general guiding principle for colloidal crystallization is to tame the attractive enthalpy such that it slightly overwhelms the repulsive interaction. As‐synthesized colloids are generally designed ...to retain a strong repulsive potential for the high stability of suspensions, encoding appropriate attractive potentials into colloids has been key to their crystallization. Despite the myriad of interparticle attractions for colloidal crystallization, the van der Waals (vdW) force remains unexplored. Here, it is shown that the implementation of gold cores into silica colloids and the resulting vdW force can reconfigure the pair potential well depth to the optimal range between −1 and −4 kBT at tens of nanometer‐scale colloidal distances. As such, colloidal crystals with a distinct liquid gap can be formed, which is evidenced by photonic bandgap‐based diffractive colorization.
The van der Waals (vdW) force has been regarded as a versatile and universal potential. Nevertheless, whether vdW force can be used as an attractive potential for the crystallization of colloids remains to be proven. Here, it is shown that the implementation of gold cores into silica colloids can reconfigure vdW force to optimal range in terms of colloidal crystallizations.
We describe a DNA base pair (bp) stacking driven 3D crystallization of 70–80 nm gold nanospheres (Au NSs) into a large-area, face-centered-cubic (FCC) lattice. Although great advances have been ...achieved over the past decade, DNA nanoparticle (NP) crystallization has relied solely on the base complementary binding. This limits the accessible crystal size particularly for the larger and heavier Au NPs (>50 nm). In this work, we argue that the use of DNA bp-stacking (so-called blunt-end stacking) instead of complementary binding can widen the scope of controlled interparticle interactions used to assemble larger Au colloids into a larger-area crystal. Through the optimization of the melting transition, relatively large Au NSs (e.g., 75 nm) with nearly ideal roundness can be crystallized into FCC crystals with the area of up to approximately 1400 μm2. A strong metallodielectric stopband is experimentally observed in the visible range, confirming the high quality of our self-assembled Au colloidal crystals.
Plasmonic polymers consisting of metallic nanoparticles (NPs) are able to squeeze light into the deep-subwavelength space and transfer along a highly confined nanoscale path in long range. DNA ...nanotechnology, particularly benefiting from the molecular programmability of DNA origami, has provided otherwise nearly impossible platforms for constructing plasmonic nanoparticle polymers with designer configurations and nanoscale gaps. Here, we design and assemble a DNA origami hashtag tile that is able to polymerize into one-dimensional chains with high rigidity. The DNA origami hashtag chains are used as frames to enable robust, versatile, and precise arrangement of metallic NPs into micrometer-long chiral and magnetic plasmonic polymers, which are capable of efficiently transporting plasmonic angular momentum and magnetic surface plasmonic polaritons at the deep-subwavelength scale. Our work provides a molecular platform for the fabrication of long, straight, and structurally complex nanoparticle polymers with emerging plasmonic properties that are appealing to a variety of fields.
All‐dielectric nanoparticles (NPs) with high (>3.0) or moderate (1.7–3.0) refractive indices have become fundamental to meta‐optics, as they enable low‐loss, low‐heating, and quenching‐free ...magnetodielectric Mie resonances, which are difficult to achieve by use of plasmonic counterparts. However, a scalable and versatile synthetic route for such magnetodielectric NPs retaining high uniformity, roundness, and robustness has remained elusive. Thus, soft self‐assembly still represents an underutilized method in the optical engineer's toolset, which in turn limits the accessible range of meta‐optics. Herein, a gram‐scale and versatile synthesis of dielectric colloidal Mie resonators is presented, in which selenous acid precursors are converted into highly uniform, crystalline colloids by a low demand reaction. These crystalline selenium (c‐Se) colloids enable strong electric and magnetic resonances due to their moderate refractive index (2.8–3.2 at optical frequencies), while simultaneously satisfying the requirements of high uniformity, roundness, and robustness. Even with these exotic properties, c‐Se colloids are successfully self‐assembled into various all‐dielectric meta‐optics systems including (i) metafluids exhibiting directional scattering, (ii) metamolecules with nanogap‐dielectric resonances, and (iii) metacrystals with magnetodielectric bandgaps. The design space of all‐dielectric meta‐optics will be greatly expanded by utilizing soft self‐assembly of c‐Se colloids.
Highly uniform, robust, and scalable high‐index selenium colloids are successfully synthesized under mild conditions. With explicit demonstration of selenium colloids self‐assembled into various platforms including metafluids, metamolecules, and metacrystals, selenium colloids are proven to serve as general building block for “soft” meta‐optics.
Quantitative determination and in situ monitoring of molecular chirality at extremely low concentrations is still challenging with simple optics because of the molecular-scale mismatch with the ...incident light wavelength. Advances in spectroscopy
and nanophotonics have successfully lowered the detection limit in enantioselective sensing, as it can bring the microscopic chiral characteristics of molecules into the macroscopic scale
or squeeze the chiral light into the subwavelength scale
. Conventional nanophotonic approaches depend mainly on the optical helicity density
by localized resonances within an individual structure, such as localized surface plasmon resonances (LSPRs)
or dielectric Mie resonances
. These approaches use the local chiral hotspots in the immediate vicinity of the structure, whereas the handedness of these hotspots varies spatially. As such, these localized resonance modes tend to be error-prone to the stochasticity of the target molecular orientations, vibrations and local concentrations
. Here we identified enantioselective characteristics of collective resonances (CRs)
arising from assembled 2D crystals of isotropic, 432-symmetric chiral gold nanoparticles (helicoids)
. The CRs exhibit a strong and uniform chiral near field over a large volume above the 2D crystal plane, resulting from the collectively spinning, optically induced dipoles at each helicoid. Thus, energy redistribution by molecular back action on the chiral near field shifts the CRs in opposite directions, depending on the handedness of the analyte, maximizing the modulation of the collective circular dichroism (CD).
