Tunable Dimensions Research Articles

Nanocarbon Materials: Synthesis of Newly Discovered Carbon Nanoframes and Hollow Carbon Nanocubes

AbstractNanocarbons are emerging at the forefront of nanoscience, and a wide variety of nanocarbons with unique structures have appeared over the past two decades. Currently, many carbon nanostructures have not been synthesized in the field of nanocarbons. The focus of this work is to present a new ideology and report two carbon nanostructures that have never been reported before. Inspired by the phenomenon of crystal growth, a new concept of thought is proposed. In brief, the diversity of crystal structures is utilized to enable surfactants to replicate their framework structures to create carbon nanomaterials with novel structures. In this work, carbon nanoframes (CNFEs) and hollow carbon nanocubes (HCNBs) synthesized by the 3‐(N,N‐dimethyldodecylammonio) propanesulfonate (SB3‐12)@NaCl self‐assembly strategy are used as proof of the ideology concept. It is shown that the prepared CNFEs have tunable dimensions (320–565 nm) and specific optical properties (fluorescence). The obtained HCNBs are 575 ± 20 nm in size and have fluorescent properties. It is found that changes in the concentration of SB3‐12 are a key driver of size changes, especially morphological evolution. It is believed that the ideology of this work provides a new entry point for the synthesis of carbon nanomaterials.

Photocatalytically self-cleaning graphene oxide nanofiltration membranes reinforced with bismuth oxybromide for high-performance water purification

Graphene oxide (GO) membranes have emerged as promising candidates for water purification applications, owing to their unique physicochemical attributes. Nevertheless, the trade-off between permeability and selectivity, coupled with their vulnerability to membrane fouling, poses significant challenges to their widespread industrial deployment. In this study, we introduce an innovative in-situ growth and layer-by-layer assembly technique for fabricating multilayer GO membranes reinforced with bismuth oxybromide (BiOBr) on commonly employed Nylon substrates. This method allows for the creation of two-dimensional lamellar membranes capable of photocatalytic self-cleaning and tunable nanochannel dimensions. The synthesized GO/BiOBr composite membranes exhibit remarkable water permeance rates (approximately 493.9 LMH/bar) and high molecular rejection efficiency (>99 % for Victoria Blue B and Congo Red dyes). Notably, these membranes showcase an enhanced photocatalytic self-cleaning performance upon exposure to visible light. Our work provides a viable route for the fabrication of functionalized GO-based nanofiltration membranes with BiOBr inclusions, offering a synergistic combination of high water permeability, modifiable nanochannels, and effective self-cleaning capabilities through photocatalysis.

Nanopipette dynamic microscopy unveils nano coffee ring

Liquid-phase electron microscopy (LP-EM) imaging has revolutionized our understanding of nanosynthesis and assembly. However, the current closed geometry limits its application for open systems. The ubiquitous physical process of the coffee-ring phenomenon that underpins materials and engineering science remains elusive at the nanoscale due to the lack of experimental tools. We introduce a quartz nanopipette liquid cell with a tunable dimension that requires only standard microscopes. Depending on the imaging condition, the open geometry of the nanopipette allows the imaging of evaporation-induced pattern formation, but it can also function as an ordinary closed-geometry liquid cell where evaporation is negligible despite the nano opening. The nano coffee-ring phenomenon was observed by tracking individual nanoparticles in an evaporating nanodroplet created from a thin liquid film by interfacial instability. Nanoflows drive the assembly and disruption of a ring pattern with the absence of particle-particle correlations. With surface effects, nanoflows override thermal fluctuations at tens of nanometers, in which nanoparticles displayed a "drunken man trajectory" and performed work at a value much smaller than kBT.

Fabrication of Crescent Shaped Microparticles for Particle Templated Droplet Formation.

Crescent-shaped hydrogel microparticles are shown to template uniform volume aqueous droplets upon simple mixing with aqueous and oil media for various bioassays. This emerging "lab on a particle" technique requires hydrogel particles with tunable material properties and dimensions. The crescent shape of the particles is attained by aqueous two-phase separation of polymers followed by photopolymerization of the curable precursor. In this work, the phase separation of poly(ethylene glycol) diacrylate (PEGDA, Mw 700) and dextran (Mw 40000) for tunable manufacturing of crescent-shaped particles is investigated. The particles' morphology is precisely tuned by following a phase diagram, varying the UV intensity, and adjusting the flow rates of various streams. The fabricated particles with variable dimensionsencapsulate uniform aqueous droplets upon mixing with an oil phase. The particles are fluorescently labeled with red and blue emitting dyes at variable concentrations to produce six color-coded particles. The blue fluorescent dye shows a moderate response to the pH change. The fluorescently labeled particles are able to tolerate an extremely acidic solution (pH 1) but disintegrate within an extremely basic solution (pH 14). The particle-templated droplets are able to effectively retain the disintegrating particle and the fluorescent signal at pH 14.

Reactive Vapor-Phase Inhibitors for Area-Selective Depositions at Tunable Critical Dimensions.

Area-selective depositions (ASD) take advantage of the chemical contrast between material surfaces in device fabrication, where a film can be selectively grown by chemical vapor deposition on metal versus a dielectric, for instance, and can provide a path to nontraditional device architectures as well as the potential to improve existing device fabrication schemes. While ASD can be accessed through a variety of methods, the incorporation of reactive moieties in inhibitors presents several advantages, such as increasing thermal stability and limiting precursor diffusion into the blocking layer. Alkyne-terminated small molecule inhibitors (SMIs)─propargyl, dipropargyl, and tripropargylamine─were evaluated as metal-selective inhibitors. Modeling these SMIs provided insight into the binding mechanism, influence of sterics, and complex polymer network formed from the reaction between inhibitors consisting of alkene, aromatic, and network branchpoints. While a significant contrast in the binding of the SMIs on copper versus a dielectric was observed, residual amounts were detected on the dielectric surfaces, leading to variable ALD growth rates dependent on pattern-critical dimensions. This behavior can be controlled and utilized to direct film growth on patterns only above a critical threshold dimension; below this threshold, both the dielectric and metal features are protected. This method provides another design parameter for ASD processes and may extend its application to broader-ranging device fabrication schemes.

Cation-π interactions enabled water-stable perovskite X-ray flat mini-panel imager

Sensitive and stable perovskite X-ray detectors are attractive in low-dosage medical examinations. The high sensitivity, tunable chemical compositions, electronic dimensions, and low-cost raw materials make perovskites promising next-generation semiconductors. However, their ionic nature brings serious concerns about their chemical and water stability, limiting their applications in well-established technologies like crystal polishing, micro-processing, photolithography, etc. Herein we report a one-dimensional tryptamine lead iodide perovskite, which is stable in water for several months as the strong cation-π interactions between organic cations. The one-dimensional and two-dimensional tryptamine lead iodide perovskite tablets are switchable through thermal-annealing or water-soaking treatments to relax microstrains. The water-stable and microstrain-free one-dimensional perovskite tablets yield a large sensitivity of 2.5 × 106 μC Gyair−1 cm−2 with the lowest detectable dose rate of 5 nGyair s−1. Microelectrode arrays are realized by surface photolithography to construct high-performance X-ray flat mini-panels with good X-ray imaging capability, and a record spatial resolution of 17.2 lp mm−1 is demonstrated.

Fabricating mesoscale polymer ribbons with tunable mechanical properties via evaporative deposition and dewetting.

Synthetic replication of the precise mesoscale control found in natural systems poses substantial experimental challenges due to the need for manipulation across multiple length scales (from nano- to millimeter). We address this challenge by using a 'flow coating' method to fabricate polymer ribbons with precisely tunable dimensions and mechanical properties. Overcoming barriers that previously limited the achievable range of properties with this method, we eliminate the need for substrate patterning and post-processing etching to facilitate the production of high aspect ratio, filament-like ribbons across a range of polymers-from glassy polystyrene to elastomeric poly(butadiene), as well as poly(butadiene-block-styrene). Our method uniquely enables the preservation of chemical fidelity, composition, and dimensions of these ribbons, leveraging polymers with elastic moduli from GPa to tens of MPa to achieve multi-scale features. We demonstrate the role of the elastocapillary length (γ/E) in determining morphological outcomes, revealing the increase in curvature with lower elastic modulus. This finding underscores the intricate relationship among surface tension, elastic modulus, and resultant structural form, enabling control over the morphology of mesoscale ribbons. The soft (MPa) polybutadiene-based ribbons exemplify our method's utility, offering structures with significant extensibility, resilience, and ease of handling, thus expanding the potential for future applications. This work advances our understanding of the fundamental principles governing mesoscale structure formation and unlocks new possibilities for designing soft materials with tailored properties, mirroring the complexity and functionality observed in nature.

In situ biosynthesis of bacterial cellulose hydrogel spheroids with tunable dimensions

Bacterial cellulose (BC) hydrogel spheroid plays a significant role in diverse fields due to its spatial 3D structure and properties. In the present work, a series of BC spheroids with controllable size and shape was obtained via an in situ biosynthesis. Crucial factors for fabricating BC spheroid including inoculum concentration of 1.35 × 103 CFU/mL, shaking speeds at 100 r/min, and 48–96 h incubation time during the biosynthetic process, were comprehensively established. An operable mechanism model for tuning the size of BC spheroids from 0.4 to 5.0 mm was proposed with a fresh feeding medium strategy of dynamic culture. The resulting BC spheroids exhibit an interactive 3D network of nanofibers, a crystallinity index of 72.3 %, a specific surface area of 91.2 m2/g, and good cytocompatibility. This study reinforces the understanding of BC spheroid formation and explores new horizons for the design of BC spheroids-derived functional matrix materials for medical care.

Patterning of Protein-Sequestered Liquid-Crystal Droplets Using Acoustic Wave Trapping.

Development of spatially organized structures and understanding their role in controlling kinetics of multistep chemical reactions are essential for the successful design of efficient systems and devices. While studies that showcase different types of methodologies for the spatial organization of various colloidal systems are known, design and development of well-defined hierarchical assemblies of liquid-crystal (LC) droplets and subsequent demonstration of biological reactions using such assemblies still remain elusive. Here, we show reversible and reconfigurable one-dimensional (1D) assemblies of protein-bioconjugate-sequestered monodisperse LC droplets by combining microfluidics with noninvasive acoustic wave trapping technology. Tunable spatial geometries and lattice dimensions can be achieved in an aqueous medium comprising ≈19 or 62 μm LC droplets. Different assemblies of a mixed population of larger and smaller droplets sequestered with glucose oxidase (GOx) and horseradish peroxidase (HRP), respectively, exhibit spatially localized enzyme kinetics with higher initial rates of reaction compared with GOx/HRP cascades implemented in the absence of an acoustic field. This can be attributed to the direct substrate transfer/channeling between the two complementary enzymes in close proximity. Therefore, our study provides an initial step toward the fabrication of LC-based devices for biosensing applications.

Tunable Zeolitic Imidazolate Framework-8 Nanoparticles for Biomedical Applications.

Zeolite imidazole framework-8 (ZIF-8) is the most prestigious one among zeolitic imidazolate framework (ZIF) with tunable dimensions and unique morphological features. Utilizing its synthetic adjustability and structural regularity, ZIF-8 exhibits enhanced flexibility, allowing for a wide range of functionalities, such as loading of nanoparticle components while preserving biomolecules activity. Extensive efforts are made from investigating synthesis techniques to develop novel applications over decades. In this review, the development and recent progress of various synthesis approaches are briefly summarized. In addition, its interesting properties such as adjustable porosity, excellent thermal, and chemical stabilities are introduced. Further, five representative biomedical applications are highlighted based on above physicochemical properties. Finally, the remaining challenges and offered insights into the future outlook are also discussed. This review aims to understand the co-relationships between structures and biomedical functionalities, offering the opportunity to construct attractive materials with promising characteristics.

Spontaneous hierarchical surface engineering of minerals through coupled dissolution‐precipitation chemistry

AbstractPeculiar hierarchical microstructures in creatures inspire modern material design with distinct functionalities. Creatures can effortlessly construct sophisticated yet long‐range ordered microstructure across bio‐membrane through ion secretion and precipitation. However, microstructure biomimicry in current technology generally requires elaborate, point‐by‐point fabrication. Herein, a spontaneous yet controllable strategy is developed to achieve surface microstructure engineering through a natural surface phenomenon similar to ion secretion‐precipitation, that is, coupled dissolution‐precipitation. A series of hierarchical microstructures on mineral surfaces in fluids with tunable morphology, orientation, dimension, and spatial distribution are achieved by simply controlling initial dissolution and fluid chemistry. In seawater, long‐range ordered film of vertically aligned brucite flakes forms through interfacial dissolution, nucleation, and confinement‐induced orientation of flakes with vertically grown {110} plane, on the edge of which, fusiform aragonite epitaxially precipitates. With negligible initial surface dissolution, prismatic aragonite epitaxially grows on a calcite polyhedron‐packed surface. By tuning fluid chemistry, closely packed calcite polyhedron and loosely packed calcite micro‐pillars are engineered through rapid and retarded precipitation, respectively. Surprisingly, the spontaneously grown microstructures resemble those deliberately created by human or found in nature, and tremendously modulate surface functionality. These findings open new possibilities for facile and customizable engineering of microstructural surfaces, hierarchical heterostructures, and biomimetic materials.

Multilevel Monte Carlo FEM for elliptic PDEs with Besov random tree priors

We develop a multilevel Monte Carlo (MLMC)-FEM algorithm for linear, elliptic diffusion problems in polytopal domain D⊂Rd\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal {D}}\\subset {\\mathbb {R}}^d$$\\end{document}, with Besov-tree random coefficients. This is to say that the logarithms of the diffusion coefficients are sampled from so-called Besov-tree priors, which have recently been proposed to model data for fractal phenomena in science and engineering. Numerical analysis of the fully discrete FEM for the elliptic PDE includes quadrature approximation and must account for (a) nonuniform pathwise upper and lower coefficient bounds, and for (b) low path-regularity of the Besov-tree coefficients. Admissible non-parametric random coefficients correspond to random functions exhibiting singularities on random fractals with tunable fractal dimension, but involve no a-priori specification of the fractal geometry of singular supports of sample paths. Optimal complexity and convergence rate estimates for quantities of interest and for their second moments are proved. A convergence analysis for MLMC-FEM is performed which yields choices of the algorithmic steering parameters for efficient implementation. A complexity (“error vs work”) analysis of the MLMC-FEM approximations is provided.

Cobalt-based conjugated coordination polymers with tunable dimensions for electrochemical sensing of p-nitrophenol

Using planar π-conjugated 2,5-diamino-1,4-benzenedithiol as organic ligand, Co-based conjugated coordination polymers (CoCCPs) with different morphology were prepared through controlling the injection rate of Co2+. When the injection rate decreases from 1.00 to 0.25 mL min−1, the obtained CoCCPs change from 2D nanosheets to quasi-1D nanorods. It is found that the different-shaped CoCCPs exhibit varying electrochemical sensing performance. The prepared CoCCPs-1 with quasi-1D nanowires and porous network structure possesses larger active area, faster electron transfer and higher accumulation ability. Moreover, the CoCCPs-1 is more active for the oxidation of p-nitrophenol (PNP), and greatly enhances its oxidation signal. Based on the morphology-tuned sensing performance of CoCCPs, a highly-sensitive electrochemical sensor has been developed for PNP, with detection limit of 0.00986 μM (9.86 nM). It was used in the analysis of wastewater samples, and the results is validated by other instrumental method.

Recent Advances on Porous Siliceous Materials Derived from Waste.

In recent years, significant efforts have been made in view of a transition from a linear to a circular economy, where the value of products, materials, resources, and waste is maintained as long as possible in the economy. The re-utilization of industrial and agricultural waste into value-added products, such as nanostructured siliceous materials, has become a challenging topic as an effective strategy in waste management and a sustainable model aimed to limit the use of landfill, conserve natural resources, and reduce the use of harmful substances. In light of these considerations, nanoporous silica has attracted attention in various applications owing to the tunable pore dimensions, high specific surface areas, tailorable structure, and facile post-functionalization. In this review, recent progress on the synthesis of siliceous materials from different types of waste is presented, analyzing the factors influencing the size and morphology of the final product, alongside different synthetic methods used to impart specific porosity. Applications in the fields of wastewater/gas treatment and catalysis are discussed, focusing on process feasibility in large-scale productions.

Chiral and helical states in selective-area epitaxial heterostructure

The quasi-1D chiral edge states in a quantum anomalous Hall insulator are dissipationless, while the 2D helical surface states in a topological insulator are insensitive to spin-independent scatterings due to the topological protection. Both serve as essential ingredients for topological electronics. Here, we integrate these states into a single device using selective area epitaxy based on the molecular beam epitaxy technique. The chiral edge state comes from the quantum anomalous Hall insulator Cr:(Bi,Sb)2Te3, while the helical surface state comes from the intrinsic topological insulator (Bi,Sb)2Te3 which only interfaces with a partial edge of the former, forming a selective-area heterostructure. At the heterointerface, the chiral state in Cr:(Bi,Sb)2Te3 is allowed to be scattered into (Bi,Sb)2Te3 so that the incoming current will be redistributed according to the coordination between the chirality and helicity. Our device enables the collaboration between chiral and helical states for low-dissipative transport with tunable current dimension.

Functionalization of electrospun nanofiber for biomedical application

AbstractFor centuries, nanofibers have been fabricated by converting polymeric materials into nanofibers with tunable mixtures, dimensions, pore structure, and interface properties. Nanofibers include many benefits for transporting drug substances with various biomedical applications. Electrospun nanofibers with customizable geometries and release properties are readily formed due to advances in nanotechnology. The structural characteristics of the electrospun nanofibers/nano yarns are tremendous owing to their large surface‐to‐volume ratio, interconnected pores, lightweight and permeability, which helps in their wide applications in the health care, energy and environmental aspects of research. The present review focuses on the recent advances in electrospun nanofibers for biomedical applications. Further, this review will examine nanofiber uses in therapeutic delivery and tissue engineering. Additionally, the potential biomedical applications of nanofibers in wound healing and cancer research are reviewed.

Controllable Crystallization of Two-Dimensional Bi Nanocrystals with Morphology-Boosted CO2 Electroreduction in Wide pH Environments.

Two-dimensional low-melting-point (LMP) metal nanocrystals are attracting increasing attention with broad and irreplaceable applications due to their unique surface and topological structures. However, the chemical synthesis, especially the fine control over the nucleation (reduction) and growth (crystallization), of such LMP metal nanocrystals remains elusive as limited by the challenges of low standard redox potential, low melting point, poor crystalline symmetry, etc. Here, a controllable reduction-melting-crystallization (RMC) protocol to synthesize free-standing and surfactant-free bismuth nanocrystals with tunable dimensions, morphologies, and surface structures is presented. Especially, ultrathin bismuth nanosheets with flat or jagged surfaces/edges can be prepared with high selectivity. The jagged bismuth nanosheets, with abundant surface steps and defects, exhibit boosted electrocatalytic CO2 reduction performances in acidic, neutral, and alkaline aqueous solutions, achieving the maximum selectivity of near unity at the current density of 210mA cm-2 for formate evolution under ambient conditions. This work creates the RMC pathway for the synthesis of free-standing two-dimensional LMP metal nanomaterials and may find broader applicability in more interdisciplinary applications.

Engineering epitaxy and condensation: Fabrication of Ge nanolayers, mechanism and applications

Superior properties for complex photonic integrated circuits can be obtained by materials other than silicon but compatible with established silicon electronics, e.g., germanium. In this work, we demonstrate the integration with silicon of fully relaxed germanium-on-insulator nanolayers enabled by micro-holes patterning. The heterosystems are fabricated thanks to the combination of epitaxy, electron beam lithography, and condensation. High resolution transmission electron microscopy and geometrical phase analyses show that for holes patterning with periodicities lower than 1 µm, the germanium nanolayers are fully relaxed and free of extended defects, while having numerous defects for larger periodicities and unpatterned settings. The experimental results are discussed with the aid of calculations of the stress for coherent epitaxial silicon–germanium layer with finite size effects and phase-field simulations accounting for the morphological evolution of the germanium crystals. The fabrication method presented here enables the growth of thick monocrystalline germanium-on-insulator layers, with great potential for optoelectronic devices with tunable dimensions and high quality. Also, these systems are suitable for high-speed germanium-on-Si photodetectors with enhanced quantum efficiency resulting from light manipulation by the array of holes. This innovative system, which is expected to operate at the visible and near-infrared range of wavelengths, has huge potential for cutting-edge applications where photodetectors and bipolar transistors are integrated into the same wafer e.g. facial recognition and LIDAR.

Controlled on-chip fabrication of large-scale perovskite single crystal arrays for high-performance laser and photodetector integration

Metal halide perovskites possess intriguing optoelectronic properties, however, the lack of precise control of on-chip fabrication of the large-scale perovskite single crystal arrays restricts its application in integrated devices. Here, we report a space confinement and antisolvent-assisted crystallization method for the homogeneous perovskite single crystal arrays spanning 100 square centimeter areas. This method enables precise control over the crystal arrays, including different array shapes and resolutions with less than 10%-pixel position variation, tunable pixel dimensions from 2 to 8 μm as well as the in-plane rotation of each pixel. The crystal pixel could serve as a high-quality whispering gallery mode (WGM) microcavity with a quality factor of 2915 and a threshold of 4.14 μJ cm−2. Through directly on-chip fabrication on the patterned electrodes, a vertical structured photodetector array is demonstrated with stable photoswitching behavior and the capability to image the input patterns, indicating the potential application in the integrated systems of this method.

Tunable nanochannel resistive pulse sensing device using a novel multi-module self-assembly

Nanochannel-based resistive pulse sensing (nano-RPS) system is widely used for the high-sensitive measurement and characterization of nanoscale biological particles and biomolecules due to its high surface to volume ratio. However, the geometric dimensions and surface properties of nanochannel are usually fixed, which limit the detections within particular ranges or types of nanoparticles. In order to improve the flexibility of nano-RPS system, it is of great significance to develop nanochannels with tunable dimensions and surface properties. In this work, we proposed a novel multi-module self-assembly (MS) strategy which allows to shrink the geometric dimensions and tune surface properties of the nanochannels simultaneously. The MS-tuned nano-RPS device exhibits an enhanced signal-to-noise ratio (SNR) for nanoparticle detections after shrunk the geometric dimensions by MS strategy. Meanwhile, by tuning the surface charge, an enhanced resolution for viral particles detection was achieved with the MS-tuned nano-RPS devices by analyzing the variation of pulse width due the tuned surface charge. The proposed MS strategy is versatile for various types of surface materials and can be potentially applied for nanoscale surface reconfiguration in various nanofluidic devices.