Understanding how the geometrical property of chirality is transferred into the physical properties of chiral materials is becoming increasingly important in various research fields, including ...plasmonics. Advances in DNA nanotechnology, especially DNA origami techniques, have enabled routine fabrication of complex chiral plasmonic assemblies. However, most of the work undertaken to date has involved plasmonic enantiomers. The concept of multiple chiral centers in stereochemistry provides simple guidelines for generating multiple chiral configurations beyond enantiomers. In this issue of ACS Nano, Wang et al. report DNA origami-based assembly and characterization of reconfigurable plasmonic chiral stereoisomers with up to three chiral centers. In this Perspective, we explore the implication of these results for further development of functional chiral plasmonic systems.
DNA nanotechnology offers a versatile toolbox for precise spatial and temporal manipulation of matter on the nanoscale. However, rendering DNA‐based systems responsive to light has remained ...challenging. Herein, we describe the remote manipulation of native (non‐photoresponsive) chiral plasmonic molecules (CPMs) using light. Our strategy is based on the use of a photoresponsive medium comprising a merocyanine‐based photoacid. Upon exposure to visible light, the medium decreases its pH, inducing the formation of DNA triplex links, leading to a spatial reconfiguration of the CPMs. The process can be reversed simply by turning the light off and it can be repeated for multiple cycles. The degree of the overall chirality change in an ensemble of CPMs depends on the CPM fraction undergoing reconfiguration, which, remarkably, depends on and can be tuned by the intensity of incident light. Such a dynamic, remotely controlled system could aid in further advancing DNA‐based devices and nanomaterials.
The spatial configuration and optical properties of non‐photoresponsive DNA‐origami‐based plasmonic assemblies can be controlled with light using a photoresponsive medium. Upon exposure to visible light, the medium's pH decreases, inducing the formation of DNA triplex links in the plasmonic assemblies, leading to their spatial reconfiguration, which can be reversed by turning the light off.
Accurate and reliable biosensing is crucial for environmental monitoring, food safety, and diagnostics. Spatially reconfigurable DNA origami nanostructures are excellent candidates for the generation ...of custom sensing probes. Here we present a nanoscale biosensing device that combines the accuracy and precision of the DNA origami nanofabrication technique, unique optical responses of chiral plasmonic assemblies, and high affinity and selectivity of aptamers. This combination enables selective and sensitive detection of targets even in strongly absorbing fluids. We expect that the presented sensing scheme can be adapted to a wide range of analytes and tailored to specific needs.
Orientational control of anisotropic plasmonic nanoparticles is an attractive proposition to generate dynamic plasmonic responses. Particularly, the use of light as a stimulus to modulate the ...orientation is extremely useful owing to its spatiotemporal operative ability. This work showcases a light‐mediated approach to tune the orientational features of gold nanorods in DNA‐engineered hydrogel materials. The strategy relies on the use of visible‐light‐induced photothermal effects to cause deformation of the hydrogel matrix, resulting in temperature‐controlled polarization‐dependent optical responses whose anisotropy features are highly adaptive to the nature of DNA crosslinks. The visible‐light‐mediated approach showcased here can open novel avenues to create dynamic light‐responsive materials with reconfigurable plasmonic responses.
A DNA‐engineered hydrogel matrix for light‐adaptive plasmonic responses is presented. When irradiated with visible light, the hydrogel undergoes deformation induced by photothermal effects. This results in temperature‐controlled polarization‐dependent optical responses of gold nanorods that are adaptive to the DNA crosslinks and light intensity.
Reliable characterization of binding affinities is crucial for selected aptamers. However, the limited repertoire of universal approaches to obtain the dissociation constant (K D) values often ...hinders the further development of aptamer-based applications. Herein, we present a competitive hybridization-based strategy to characterize aptamers using DNA origami-based chiral plasmonic assemblies as optical reporters. We incorporated aptamers and partial complementary strands blocking different regions of the aptamers into the reporters and measured the kinetic behaviors of the target binding to gain insights on aptamers’ functional domains. We introduced a reference analyte and developed a thermodynamic model to obtain a relative dissociation constant of an aptamer–target pair. With this approach, we characterized RNA and DNA aptamers binding to small molecules with low and high affinities.
One-dimensional (1D) metal-coated Pd structures are efficient catalysts for the ethanol electro-oxidation and promising strategy for minimizing the Pd-loading toward commercialization of direct ...ethanol fuel cells (DEFCs). Herein, the decorated and core-shell architectures of a novel Pd coating on Ag nanowires (PdAg-NWs) are controllable by a two-step polyol method based on the galvanic replacement reaction. The integration of uniform shell with a low Pd concentration and partial hollow structure onto 1D PdAg-NWs exhibits the highest efficiency for ethanol oxidation reaction (EOR) in alkaline solution. In comparison with Pd nanoparticles (PdNPs/C), the PdAgNWs/C performes 11 times superior EOR activity, and the onset potential shifts 80 mV negatively. The presence of Ag in PdAg-NWs enhances the absorption capacity of ethanol molecules and hydroxyl ions on the active sites, and improves the catalyst tolerance to CO-like intermediates, making them a potential anodic catalyst for DEFCs.
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•Novel PdAg core-shell nanowires with a low Pd-loading were synthesized.•Controllable configuration of Pd layer by temperature and PVP concentration.•Adjustable particle size of Pd by reaction time and Pd/Ag molar ratio.•Efficient bifunctional electrocatalyst for direct ethanol fuel cells in alkaline media.
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•Pd-coated Ni nanowires (PdNi-NWs/C) with a low Pd:Ni molar ratio were first time prepared.•A unique Pd coating with a high catalytic efficiency was achieved by controllable ...synthesized conditions.•PdNi-NWs/C showed superior catalytic ability in EOR and CO-tolerance compared to palladium nanoparticles (PdNPs/C).•Remarkable improvement in electro-catalytic activity for EOR derived from the addition of Ni and 1D core-shell structure.
The major hindrance for a successful commercialization of direct ethanol fuel cells (DEFCs) is the sluggish ethanol oxidation reaction (EOR) and the rapid poisoning of anodic catalysts by by-products. In this work, a high-performance PdNi nanowire (PdNi-NWs) catalyst was prepared via a two-step process in polyol medium based on the galvanic replacement reaction. By carefully screening parameters for a uniform deposition of Pd layers on Ni nanowires, the PdNi-NWs electrode exhibits a significant enhancement of both catalytic activity and durability for the EOR in alkaline media, which may be ascribed to the electronic structure modification and bifunctional electrocatalytic mechanism with hydroxyl and ethanol bindings on Ni and Pd, respectively. Moreover, these nanowire structures are efficient electron and mass transfer and enriched with abundant active sites by oxygen-rich compounds of Ni. The highest electrocatalytic performance has achieved with a low Pd:Ni molar ratio of 18:100, which reaches 9.3 times superior mass activity and the EOR onset potential shifts 50 mV negatively compared with Pd nanoparticles (PdNPs). These results highlight the active role of PdNi-NWs catalysts in DEFCs.
The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic nanostructures. The high spatial precision of a DNA ...origami-templated assembly allows controlling the coupling between plasmonic resonances of individual particles and enables tailoring optical properties of the constructed nanostructures. Recently, chiral plasmonic systems attracted a lot of attention due to the strong correlation between the spatial configuration of plasmonic assemblies and their optical responses (e.g., circular dichroism CD). In this protocol, we describe the whole workflow for the generation of DNA origami-based chiral assemblies of gold nanorods (AuNRs). The protocol includes a detailed description of the design principles and experimental procedures for the fabrication of DNA origami templates, the synthesis of AuNRs, and the assembly of origami-AuNR structures. In addition, the characterization of structures using transmission electron microscopy (TEM) and CD spectroscopy is included. The described protocol is not limited to chiral configurations and can be adapted for the construction of various plasmonic architectures.
Surface-enhanced Raman scattering (SERS) and fluorescence microscopy are a widely used biological and chemical characterization techniques. However, the peak overlapping in multiplexed experiments ...and rapid photobleaching of fluorescent organic dyes is still the limitations. When compared to Ag nanocubes (NCs), higher SERS sensitivities can be obtained with thin shelled silica Ag@SiO2 NCs, in contrast metal-enhanced photoluminescence (MEPL) is only found with NCs that have thicker silica shells. A ‘dual functionality’ represented by the simultaneous strengthening of SERS and MEPL signals can be achieved by mixing Ag@SiO2 NCs, with a silica shell thickness of ~1.5nm and ~4.4nm. This approach allows both the Ag@SiO2 NCs SERS and MEPL sensitivities to be maintained at ~90% after 12weeks of storage. Based on the distinguished detection of creatinine and flavin adenine dinucleotide in the mixture, the integration of SERS and MEPL together on a stable single plasmonic nanoparticle platform offers an opportunity to enhance both biomarker detection sensitivity and specificity.
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•Various thicknesses of silica shell were coated on Ag nanocubes.•SERS and MEPL effects can be adjusted by controlling SiO2 thickness on Ag.•Bifunctional SERS-MEPL was achieved based on a combination of Ag@SiO2 nanocubes.•The stability and sensitivity of SERS-MEPL remained ~90% after 12-week storage.•The label-free SERS-MEPL identification of creatinine and FAD was evaluated.
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