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Controlling the deposition and diffusion of adsorbed atoms (adatoms) on the surface of a solid material is vital for engineering the shape and function of nanocrystals. Here, we report the use of single-stranded DNA (oligo-adenine, oligo-A) to encode the wettability of gold seeds by homogeneous gold adatoms to synthesize highly tunable plasmonic nanostructures. We find that the oligo-A attachment transforms the nanocrystal growth mode from the classical Frank-van der Merwe to the Volmer-Weber island growth. Finely tuning the oligo-A density can continuously change the gold-gold contact angle (θ) from 35.1±3.6° to 125.3±8.0°. We further demonstrate the versatility of this strategy for engineering nanoparticles with different curvature and dimensions. With this unconventional growth mode, we synthesize a sub-nanometer plasmonic cavity with a geometrical singularity when θ90°. Superfocusing of light in this nanocavity produces a near-infrared intraparticle plasmonic coupling, which paves the way to surface engineering of single-particle plasmonic devices.

Super-resolution (SR) microscopy provides a revolutionary approach to study cells and animals by breaking the diffraction limit of optical imaging. However, the popularity of the super-resolution microscope in biological sciences remains to be impeded by the high cost of hardware and/or the complexity of software. Here, we present a conceptually different non-linear scanning switch-off microscopy (nSSM) that exploits the omnipresent switch-off effect of fluorophores to enable super-resolution imaging beyond the diffraction limit. We develop a theoretical model of nSSM and experimentally implement the nSSM scheme with an unmodified confocal microscope. We also release a free code for the automatic reconstruction of super-resolution images. By measuring the PSF of the imaged DNA origami nanostructure and mammalian cytoskeleton structures, we demonstrate an SR resolution of ~ 100 nm that excels the optical resolution limit by over two folds. We further show the generality of nSSM using a range of commercially available fluorescent dyes and proteins to realize SR imaging in various settings. This nSSM methodology may in principle empower any confocal microscope to implement SR imaging to promote biological research.

Properties of gold nanoparticles vary with their morphologies. Typically, the research on the properties and applications of the nonequilibrium intermediates generated by the morphological evolution of triangular gold nanoprisms is still incomplete. Herein, we employ thiol-DNA (HS-DNA) to protect the low-stability quasi-nanoprisms with different truncation degrees (R values). The presence of HS-DNA not only increases the stability of the quasi-nanoprisms in different microenvironments, but also facilitates us to investigate their intrinsic plasmonic properties related to morphology. Additionally, we serve quasi-nanoprisms loaded with HS-DNA as assembly modules and nanoplatforms for programmable self-assembly higher-order hybrid structures, as well as carriers for encoding and decoding of orthogonal barcode-like information, which opens new opportunities for developing novel building blocks for light manipulation at nanoscale.

Metallic nanocube ensembles exhibit tunable localized surface plasmon resonance to induce the light manipulation at the subwavelength scale. Nevertheless, precisely control anisotropic metallic nanocube ensembles with relative spatial directionality remains a challenge. Here, we report a DNA origami based nanoprinting (DOBNP) strategy to transfer the essential DNA strands with predefined sequences and positions to the surface of the gold nanocubes (AuNCs). These DNA strands ensured the specific linkages between AuNCs and gold nanoparticles (AuNPs) that generating the stereo-controlled AuNC-AuNP nanostructures (AANs) with controlled geometry and composition. By anchoring the single dye molecule in hot spot regions, the dramatic enhanced electromagnetic field aroused stronger surface enhanced Raman scattering (SERS) signal amplification. Our approach opens the opportunity for the fabrication of stereo-controlled metal nanostructures for designing highly sensitive photonic devices.

In this work, nitrogen-doped carbon quantum dots from poly(ethyleneimine) (PQDs) were synthesized by a low-cost and facile one-step hydrothermal method without other reagents. A quantum yield (QY) ...

Ultraviolet (UV) light has long been known to damage nucleic acids. In this work, a DNA origami radiometer has been developed for measuring UV exposure by monitoring the morphological evolution of DNA origami nanostructures. Unlike linear DNA strands that tend to be degraded into small segments upon UV exposure, the structural complexity and interstrand connectivity of DNA origami remarkably alter the pathway of UV-induced DNA damage. A general pathway of expansion, distortion, and final disintegration is observed for DNA origami regardless of their shape and size; however the deformation kinetics is positively correlated with the number of nicks in the nanostructure. This structural continuity-dependent deformation can be translated into a DNA-based radiometer for measuring UV dose in the environment.

Nobel metal nanoparticles with tunable morphologies are highly desirable due to their unique electronic, magnetic, optical, and/or catalytic features. Here we report the use of multilayered graphdyine (GD) as a substrate for the reductant-free, room-temperature synthesis of single-crystal Au nanostructures with tunable morphology. We find that the GD template rich in sp-carbon atoms possesses high affinity with Au atoms on the {111} facets, and that the intrinsic reductivity of GD facilitates the rapid growth of Au nanoplates. The introduction of single-stranded DNA strands further results in the synthesis of Au nanostructures with decreased anisotropy, i.e., polygons and flower-like nanoparticles. The DNA-guided tunable Au growth arises from the strong adsorption of DNA on the GD template that alters the uniformity of the interface, which provides a direct route to synthesize Au nanostructures with tailorable morphology and photonic properties., We report the use of multilayered graphdyine (GD) as a substrate for surfactant-free, room-temperature synthesis of Au nanostructures with tunable morphology.

The future photonic age largely depends on our ability to manipulate optical waves in confined systems. Particularly, understanding the behavior of a plasmonic charge density wave (p-CDW) in optical resonators is vital for engineering 2D plasmonic devices. In this study, the standing p-CDW on the surface of a gold triangle resonator is examined through diffraction limited all-optical far field power loss microscopy. The scattering light map captured by this microscopy, named plasmonic Chladni figure, is directly proportional to the entire in-plane photonic local density of state. The theoretical model of the plasmonic Chladni figure proposed in this study is related to the 2D standing p-CDW node pattern, which is similar to the mechanical Chladni, but follows a special node selection rule. Investigating the plasmonic Chladni phenomenon provides an in-depth understanding of fundamental plasmonic physics and plasmonic chemistry and presents various possibilities for plasmonic application, such as 2D dimensi...

Three dimensional scaffolded DNA origami with inorganic nanoparticles has been used to create tailored multidimensional nanostructures. However, the image contrast of DNA is poorer than those of the heavy nanoparticles in conventional transmission electron microscopy at high defocus so that the biological and non-biological components in 3D scaffolds cannot be simultaneously resolved using tomography of samples in a native state. We demonstrate the use of electron ptychography to recover high contrast phase information from all components in a DNA origami scaffold without staining. We further quantitatively evaluate the enhancement of contrast in comparison with conventional transmission electron microscopy. In addition, We show that for ptychography post-reconstruction focusing simplifies the workflow and reduces electron dose and beam damage.

In this work, nitrogen-doped carbon quantum dots from poly(ethyleneimine) (PQDs) were synthesized by a low-cost and facile one-step hydrothermal method without other reagents. A quantum yield (QY) of up to 23.2% with maximum emission at 460 nm under an excitation wavelength of 340 nm was ascribed to the high nitrogen doping (20.59%). The PQDs selectively form a blue complex with Cu

A key issue for redox reactions in plasmon-induced photocatalysis, particularly for water oxidation, is the concentration of surface-accumulating charges (electrons or holes) at a reaction site for artificial photosynthesis. However, where plasmonic charge accumulated at a catalyst's surface, and how to improve local charge density at active sites, remains unknown because it is difficult to identify the exact spatial location and local density of the plasmon-induced charge, particularly with regard to holes. Herein, we show that at the single particle level, plasmon-coupling-induced holes can be greatly accumulated at the plasmonic Au nanoparticle dimer/TiO2 interface in the nanogap region, as directly evidenced by the locally enhanced surface photovoltage. Such an accumulation of plasmonic holes can significantly accelerate the water oxidation reaction (multi-holes involved) at the interfacial reaction site, with nearly one order of magnitude enhancement in photocatalytic activities compared to those of highly dispersed Au nanoparticles on TiO2. Combining Kelvin probe force microscopy and theoretical simulation, we further clarified that the local accumulated hole density is proportional to the square of the local near-field enhancement. Our findings advance the understanding of how charges spatially distribute in plasmonic systems and the specific role that local charge density at reaction sites plays in plasmonic photocatalysis., Plasmon coupled nanostructure severing as light-harvesting centers was demonstrated to generate a high density of holes at catalytic sites, which significantly accelerate photocatalytic water oxidation reaction.

Core-shell plasmonic metal nanoparticles with interior nanogaps are superior nanostructures owing to their large signal enhancement for Surface enhanced Raman spectroscopy (SERS). Herein, we incorporated Terminal deoxynucleotidyl transferase (TdT)-catalyzed DNA in the preparation of core-shell nanostructures for the detection of Escherichia coli O157:H7 (E. coli O157:H7) cells. The elongated products-homo-nucleotides-composed of long single DNA strands (hn-D) are used not only to induce tunable-size nanogaps but also as Raman reporters with consistent and uniform signal enhancement. Using this synthetic process of hn-D-embedded core-shell nanoparticles (hn-DENPs), we found that the length of hn-D strands affects the size of the nanogap. In addition, performances of the specific Raman imaging of E. coli O157:H7, high detection sensitivity of 2 CFU/mL, and the recovery of 98.1%–105.2% measured in the real food samples, make hn-DENP a biosensor that will be widely used in biological detection.

DNA nanostructures are promising drug carriers with their intrinsic biocompatibility, uniformity and versatility. However, rapid serum disintegration leads to low bioavailability at targeted sites following systemic administration, hindering their biomedical applications. Here we demonstrate transdermal delivery of framework nucleic acids (FNAs) through topical applications. By designing FNAs with distinct shapes and sizes, we interrogate their penetration on mice and human skin explant. Skin histology reveals size-dependent penetration, with FNAs ≤75 nm effectively reaching dermis layer. 17 nm-tetrahedral FNAs show greatest penetration to 350 µm from skin periphery. Importantly, structural integrity is maintained during the skin penetration. Employing a mouse melanoma model, topical application of doxorubicin-loaded FNAs accommodates ≥2-fold improvement in drug accumulation and tumor inhibition relative to topically-applied free doxorubicin, or doxorubicin loaded in liposomes and polymeric nanoparticles. Programmable penetration with minimal systemic biodistribution underlines FNA potential as localized transdermal drug delivery carriers., DNA nanostructures hold great promise for drug delivery, but systemic administration is problematic. Here, the authors demonstrate that framework nucleic acids (FNAs) improve drug accumulation in tumours in topical application and that penetration depth is controllable through adjusting FNA size.

Plasmonic nanostructures supporting strong spatially confined field enhancement are developed to probe single-molecule SERS., Tailored metal nanoclusters have been actively developed to manipulate light at the subwavelength scale for nanophotonic applications. Nevertheless, precise arrangement of molecules in a hot spot with fixed numbers and positions remains challenging. Here, we show that DNA origami metamolecules with Fano resonances (DMFR) can precisely localize single dye molecules and produce quantified surface-enhanced Raman scattering (SERS) responses. To enable tailored plasmonic permutations, we develop a general and programmable method for anchoring a set of large gold nanoparticles (L-AuNPs) on prescribed n-tuple docking sites of super-origami DNA frameworks. A tetrameric nanocluster with four spatially organized 80-nm L-AuNPs exhibits peak-and-dip Fano characteristics. The drastic enhancement at the wavelength of the Fano minimum allows the collection of prominent SERS spectrum for even a single dye molecule. We expect that DMFR provides physical insights into single-molecule SERS and opens new opportunities for developing plasmonic nanodevices for ultrasensitive sensing, nanocircuits, and nanophotonic lasers.