An Aptamer-Embedded Two-Dimensional DNA Nanoscale Material with the Property of Cells Recruitment

Stem cells possess exceptional proliferation and differentiation abilities, making them highly promising for targeted recruitment research in tissue engineering and other clinical applications. DNA is a naturally water-soluble, biocompatible, and highly editable material that is widely used in cell recruitment research. However, DNA nanomaterials face challenges, such as poor stability, complex synthesis processes, and demanding storage conditions, which limit their potential applications. In this study, we designed a highly stable DNA nanomaterial that embeds nucleic acid aptamers in the single strand region. This material has the ability to specifically bind, recruit, and capture human mesenchymal stem cells. The synthesis process involves rolling circle amplification and topological isomerization, and it can be stored for extended periods under varying temperatures and humidity conditions. This DNA material offers high specificity, ease of fabrication, simple preservation, and low cost, providing a novel approach to stem cell recruitment strategies.

Nanomeshes with Sub-10 nm Pores by Glycerol-Triggered 2D Assembly in Liquid Phases for Fast and Selective Membranes

Nanomeshes having ultrathin thicknesses and penetrating nanopores promise fast diffusion and precise selectivity and are highly desired in diffusion-involved processes such as separation. Herein, we report a liquid-phase two-dimensional (2D) assembly strategy to synthesize phenolic and carbonaceous nanomeshes with sub-10 nm pores and thicknesses. The synthesis is enabled simply by introducing glycerol in the thermopolymerization of resol/polyether micelles dispersed in ethanol. Experimental and simulation results reveal that glycerol's strong ability to form hydrogen bonds constrain the motion of the micelles, directing them to pack and merge exclusively in the lateral direction. Upon removal of polyether, we obtain phenolic nanomeshes with lateral sizes up to hundreds of micrometers, which can be further converted to carbonaceous nanomeshes. As a proof of concept, we use stacked phenolic and carbonaceous nanomeshes as separation membranes. They show superior permselectivity to nanosized solutes with permeance ∼2-110 times higher than that of other membranes.

Novel Stable DNA Nanoscale Material and Its Application on Specific Enrichment of DNA

DNA nanostructures are a new type of technology for constructing nanomaterials that has been developed in recent years. By relying on the complementary pairing of DNA molecules to form a double-stranded property, DNA molecules can construct a variety of nanoscale structures of 2D and 3D shapes. However, most of the previously reported DNA nanostructures rely solely on hydrogen bonds to maintain structural stability, resulting in DNA structures that can be maintained only at low temperature and in the presence of Mg²⁺, which greatly limits the application of DNA nanostructures. This study designed a DNA nanonetwork structure (nanonet) and changed its topological structure to DNA nanomesh by using DNA topoisomerase to make it thermally stable, while escaping the dependence on Mg²⁺, and the stability of the structure can be maintained in a nonsolution state. Moreover, the nanomesh also has a large amount of ssDNA (about 50%), providing active sites capable of exerting biological functions. Using the above characteristics, we prepared the nanomesh into a device capable of adsorbing specific DNA molecules, and used the device to enrich DNA. We also tried to mount antibodies using DNA probes. Preliminary results show that the DNA nanomesh also has the ability to enrich specific proteins.

Stretchable Transparent Conductors: from Micro/Macromechanics to Applications

Stretchable transparent conductors (STCs), generally consisting of conducting networks and stretchable transparent elastomers, can maintain stable conductivity and transparency even at large tensile strain, beyond the reach of rigid/flexible transparent conductors. They are essential components in stretchable/wearable electronics for using on irregular 3D conformable surfaces and have attracted tremendous attention in recent years. This review aims to provide systematical correlation of the conducting element-substrate interaction with the structural stability of conducting networks, as well as the properties and device applications of STCs. It starts with the micromechanics for stretching of conducting elements on substrates, including the mechanical mismatch, distribution/level of interfacial shear stress, and the deformation behavior of conducting elements on substrates. The macromechanics for stretching of conducting networks on substrates are then further illustrated from a more statistical point of view, namely sliding/preferred orientation of percolation networks, unfolding of buckled structures, and unit cell distortion/distributed rupture of nanomeshes. The structure-dependent properties as well as the state-of-the-art applications of STCs are summarized before ending with the conclusions and outlooks for STCs.

2D Single Crystal WSe2 and MoSe2 Nanomeshes with Quantifiable High Exposure of Layer Edges from 3D Mesoporous Silica Template

The design and fabrication of layered transition metal chalcogenides with high exposure of crystal layer edges is one of the key paths to achieve distinctive performances in their catalysis and electrochemistry applications. Two-dimensional WSe₂ and MoSe₂ nanomeshes with orderly arranged nanoholes were synthesized by using a mesoporous silica material KIT-6 with three-dimensional mesoporous structure as a hard template via a nanocasting strategy. Each piece of the nanomesh is a single crystal, and its c axis is always perpendicular to the nanomesh plane. The highly porous structure brings these nanomeshes extremely high exposure of layer edges, and the well-defined nanostructure provides an opportunity to quantitatively estimate the specific length of the crystal layer edges for the WSe₂ and MoSe₂ nanomeshes synthesized in this work, which are estimated to be 3.8 × 10¹⁰ and 6.0 × 10¹⁰ m g^-1, respectively. The formation of a 2D sheet-like nanomesh structure inside a 3D confined pore space should be attributed to the synergistic effect from the crystal self-limitation growth that is caused by their layered crystal structures and the space-limitation effect coming from the unique pore structure of the KIT-6 template. The catalytic activities of the nanomeshes in an electrocatalytic hydrogen evolution reaction were also investigated.

Co3O4-CuCoO2 Nanomesh: An Interface-Enhanced Substrate that Simultaneously Promotes CO Adsorption and O2 Activation in H2 Purification

Nanomaterials are widely used as redox-type reaction catalysts, while reactant adsorption and O₂ activation are hardly to be promoted simultaneously, restricting their applications in many important catalytic fields such as preferential CO oxidation (CO-PROX) in H₂-rich stream. In this work, an interface-enhanced Co₃O₄-CuCoO₂ nanomesh was initially synthesized by a hydrothermal process using aluminum powder as a sacrificial agent. This nanomesh is systematically characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, Raman spectroscopy, X-ray absorption near-edge spectroscopy, hydrogen temperature-programmed reduction, and oxygen temperature-programmed desorption. It is demonstrated that the nanomesh possesses high-density nanopores, enabling a large number of CO adsorption sites exposed to the surface. Meanwhile, electron transfer from O^2- to Co³⁺/Co²⁺ and the weakened bonding strength of Co-O bond at surfaces promoted the oxygen activation and redox ability of Co₃O₄. When tested as a catalyst for CO-PROX, this nanomesh with an optimized pore structure and a surface electronic structure, exhibits a strikingly high catalytic oxidation activity at low temperatures as well as a broader operation temperature window (i.e., CO conversion >99.0%, 100-200 °C) in the CO selective oxidation reaction. The present finding should be highly useful in promoting the quest for better CO-PROX catalysts, a hot topic for proton exchange membrane fuel cells and automotive vehicles.

Synthesis of Gold Nanoparticle-Embedded Silver Cubic Mesh Nanostructures Using AgCl Nanocubes for Plasmonic Photocatalysis

A novel room-temperature aqueous synthesis for gold nanoparticle-embedded silver cubic mesh nanostructures using AgCl templates via a template-assisted coreduction method is developed. The cubic AgCl templates are coreduced in the presence of AuCl₄^- and Ag⁺ , resulting in the reduction of AuCl₄^- into gold nanoparticles on the outer region of AgCl templates, followed by the reduction of AgCl and Ag⁺ into silver cubic mesh nanostructures. Removal of the template clearly demonstrates the delicately designed silver mesh nanostructures embedded with gold nanoparticles. The synthetic mechanism, structural properties, and surface functionalization are spectroscopically investigated. The plasmonic photocatalysis of the cubic mesh nanostructures for the degradation of organic pollutants and removal of highly toxic metal ions is investigated; the photocatalytic activity of the cubic mesh nanostructures is superior to those of conventional TiO₂ catalysts and they are catalytically functional even in natural water, owing to their high surface area and excellent chemical stability. The synthetic development presented in this study can be exploited for the highly elaborate, yet, facile design of nanomaterials with outstanding properties.

Transparent Electrophysiology Microelectrodes and Interconnects from Metal Nanomesh

Mapping biocurrents at both microsecond and single-cell resolution requires the combination of optical imaging with innovative electrophysiological sensing techniques. Here, we present transparent electrophysiology electrodes and interconnects made of gold (Au) nanomesh on flexible substrates to achieve such measurements. Compared to previously demonstrated indium tin oxide (ITO) and graphene electrodes, the ones from Au nanomesh possess superior properties including low electrical impedance, high transparency, good cell viability, and superb flexibility. Specifically, we demonstrated a 15 nm thick Au nanomesh electrode with 8.14 Ω·cm² normalized impedance, >65% average transmittance over a 300-1100 nm window, and stability up to 300 bending cycles. Systematic sheet resistance measurements, electrochemical impedance studies, optical characterization, mechanical bending tests, and cell studies highlight the capabilities of the Au nanomesh as a transparent electrophysiology electrode and interconnect material. Together, these results demonstrate applicability of using nanomesh under biological conditions and broad applications in biology and medicine.

Selective Plasma Etching of Polymeric Substrates for Advanced Applications

In today’s nanoworld, there is a strong need to manipulate and process materials on an atom-by-atom scale with new tools such as reactive plasma, which in some states enables high selectivity of interaction between plasma species and materials. These interactions first involve preferential interactions with precise bonds in materials and later cause etching. This typically occurs based on material stability, which leads to preferential etching of one material over other. This process is especially interesting for polymeric substrates with increasing complexity and a “zoo” of bonds, which are used in numerous applications. In this comprehensive summary, we encompass the complete selective etching of polymers and polymer matrix micro-/nanocomposites with plasma and unravel the mechanisms behind the scenes, which ultimately leads to the enhancement of surface properties and device performance.

Nanomesh-Type Graphene Superlattice on Au(111) Substrate

The adherence of graphene to various crystalline substrates often leads to a periodic out-of-plane modulation of its atomic structure due to the lattice mismatch. While, in principle, convex (protrusion) and concave (depression) superlattice geometries are nearly equivalent, convex superlattices have predominantly been observed for graphene on various metal surfaces. Here we report the STM observation of a graphene superlattice with concave (nanomesh) morphology on Au(111). DFT and molecular dynamics simulations confirm the nanomesh nature of the graphene superlattice on Au(111) and also reveal its potential origin as a surface reconstruction, consisting of the imprinting of the nanomesh morphology into the Au(111) surface. This unusual surface reconstruction can be attributed to the particularly large mobility of the Au atoms on Au(111) surfaces and most probably plays an important role in stabilizing the concave graphene superlattice. We report the simultaneous observation of both convex and concave graphene superlattices on herringbone reconstructed Au(111) excluding the contrast inversion as the origin of the observed concave morphology. The observed graphene nanomesh superlattice can provide an intriguing nanoscale template for self-assembled structures and nanoparticles that cannot be stabilized on other surfaces.

Fabricating Hexagonal Al-Doped LiCoO2 Nanomeshes Based on Crystal-Mismatch Strategy for Ultrafast Lithium Storage

In the designed synthesis, low crystal-mismatch strategy has been applied in the synthesis of ion-doped LiCoO2 materials, and a good success of single crystal property has been achieved between the precursor and the final sample for the first time. The hexagonal LiCo0.8Al0.26O2 (LCAO) nanomesh possesses several advantages in morphology and crystal structure, including mesoporous structure, single crystal, atomic even distribution, high exposing surface area as (100) or their equivalent planes, and shortened Li ions diffusion distance. All the merits are beneficial to the application in Li-ion batteries (LIBs) cathode, for example, accelerating Li ions diffusion rate, improving the Li ions shuttle between the LCAO nanomesh and electrolyte, and reducing the Li ions capacitive behavior during Li intercalation. Hence, our research adopts Al-contained precursor with morphology of hexagonal nanoplates to fabricate designed Al-doped LiCoO2 nanomeshes and greatly improves the cathode performance in LIBs.

Monolithic carbon structures including suspended single nanowires and nanomeshes as a sensor platform

With the development of nanomaterial-based nanodevices, it became inevitable to develop cost-effective and simple nanofabrication technologies enabling the formation of nanomaterial assembly in a controllable manner. Herein, we present suspended monolithic carbon single nanowires and nanomeshes bridging two bulk carbon posts, fabricated in a designed manner using two successive UV exposure steps and a single pyrolysis step. The pyrolysis step is accompanied with a significant volume reduction, resulting in the shrinkage of micro-sized photoresist structures into nanoscale carbon structures. Even with the significant elongation of the suspended carbon nanowire induced by the volume reduction of the bulk carbon posts, the resultant tensional stress along the nanowire is not significant but grows along the wire thickness; this tensional stress gradient and the bent supports of the bridge-like carbon nanowire enhance structural robustness and alleviate the stiction problem that suspended nanostructures frequently experience. The feasibility of the suspended carbon nanostructures as a sensor platform was demonstrated by testing its electrochemical behavior, conductivity-temperature relationship, and hydrogen gas sensing capability.

Graphene nanomesh promises extremely efficient in vivo photothermal therapy

Reduced graphene oxide nanomesh (rGONM), as one of the recent structures of graphene with a surprisingly strong near-infrared (NIR) absorption, is used for achieving ultraefficient photothermal therapy. First, by using TiO2 nanoparticles, graphene oxide nanoplatelets (GONPs) are transformed into GONMs through photocatalytic degradation. Then rGONMs functionalized by polyethylene glycol (PEG), arginine-glycine-aspartic acid (RGD)-based peptide, and cyanine 7 (Cy7) are utilized for in vivo tumor targeting and fluorescence imaging of human glioblastoma U87MG tumors having αν β3 integrin receptors, in mouse models. The rGONM-PEG suspension (1 μg mL(-1) ) exhibits about 4.2- and 22.4-fold higher NIR absorption at 808 nm than rGONP-PEG and graphene oxide (GO) with lateral dimensions of ≈60 nm and ≈2 μm. In vivo fluorescence imaging demonstrates high selective tumor uptake of rGONM-PEG-Cy7-RGD in mice bearing U87MG cells. The excellent NIR absorbance and tumor targeting of rGONM-PEG-Cy7-RGD results in an ultraefficient photothermal therapy (100% tumor elimination 48 h after intravenous injection of an ultralow concentration (10 μg mL(-1) ) of rGONM-PEG-Cy7-RGD followed by irradiation with an ultralow laser power (0.1 W cm(-2) ) for 7 min), whereas the corresponding rGO- and rGONP-based composites do not present remarkable treatments under the same conditions. All the mice treated by rGONM-PEG-Cy7-RGD survived over 100 days, whereas the mice treated by other usual rGO-based composites were dead before 38 days. The results introduce rGONM as one of the most promising nanomaterials in developing highly desired ultraefficient photothermal therapy.