A Cobalt-Based Metal-Organic Framework Nanosheet as the Electrode for High-Performance Asymmetric Supercapacitor

Inspired by the significant advantages of the bottom-up synthesis whose structures and functionalities can be customized by the selection of molecular components, a 2D metal-organic framework (MOF) nanosheet Co-BTB-LB has been synthesized by a liquid-liquid interface-assisted method. The as-prepared Co-BTB-LB is identified by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX) and X-ray photoelectron spectroscopy (XPS), and the sheet-like structure is verified by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). Co-BTB-LB electrode exhibits an excellent capacity of 4969.3 F g-1 at 1 A g-1 and good cycling stability with 75% capacity retention after 1000 cycles. The asymmetric supercapacitor device with Co-BTB-LB as the positive electrode shows a maximum energy density of 150.2 Wh kg-1 at a power density of 1619.2 W kg-1 and good cycling stability with a capacitance retention of 97.1% after 10000 cycles. This represents a state-of-the-art performance reported for asymmetric supercapacitor device using electroactive bottom-up metal-complex nanosheet, which will clearly lead to a significant expansion of the applicability of this type of 2D nanomaterials.

Annulative π-Extension by Rh(III)-Catalyzed Ketone-Directed C-H Activation: Rapid Access to Pyrenes and Related PAHs

Annulative π-extension (APEX) reaction has become a powerful tool for the precise synthesis of well-defined polycyclic aromatic hydrocarbons (PAHs) such as nanographene, graphene, and other PAHs possessing unique structure. Herein, an APEX reaction has been realized at the masked bay-region for the efficient and rapid synthesis of valuable PAH, pyrene, bearing substitutions at the most challenging K-region. Rh(III)-catalyzed ketone-directed C-H activation at the peri-position of a naphthyl-derived ketone, alkyne-insertion, intramolecular nucleophilic attack at the carbonyl-group, dehydration, and aromatization steps occurred in one-pot to effectuate the protocol. Employing this strategy, a two-fold APEX reaction on enantiopure BINOL-derived ketones provided access to axially-chiral bipyrene derivatives. The detailed DFT study to support proposed mechanism, and synthesis of helical PAHs like dipyrenothiophene and dipyrenofuran are other highlights of the present study.

Plasmonic Color Printing via Bottom-Up Laser-Induced Photomodification Process

Plasmonic color printing has received significant attention owing to its advantages such as nonfading and nontoxic color expression, without necessitating the use of chemical dyes. Recently, color generation from laser-induced plasmonic nanostructures has been extensively explored because of its simplicity, cost-effectiveness, and large-scale processability. However, these methods usually utilize a top-down method that causes unexpected background colors. Here, we proposed a novel method of plasmonic color printing via a bottom-up type laser-induced photomodification process. In the proposed method, selective silver nanoparticles (Ag NPs) structure could be fabricated on a transparent substrate through a unique organometallic solution-based laser patterning process. A set of color palettes was formed on the basis of different processing parameters such as laser fluence, scanning speed, and baking time. This color change was verified by finite-difference time-domain (FDTD) simulations via monitoring the spectral peak shift of the localized surface plasmon resonance (LSPR) at Ag NPs. It was also confirmed that the colors can be fabricated at a relatively high scanning speed (≥10 mm/s) on a large substrate (>300 mm²). Since semitransparent color images can be patterned on various transparent substrates, this process will broaden the application range of laser-induced plasmonic color generation.

Preparation of oridonin nanocrystals and study of their endocytosis and transcytosis behaviours on MDCK polarized epithelial cells

Context: Oridonin (ORI) has obvious anticancer effects, but its solubility is poor. Nanocrystal (NC) is a novel nano-drug delivery system for increasing bioavailability for ORI. However, the endocytosis and transcytosis behaviours of oridonin nanocrystals (ORI-NCs) through epithelial membrane are still unclear.Objectives: ORI-NCs were prepared and characterized. The in vitro cytotoxicity and endocytosis and transcytosis process on Madin-Darby canine kidney (MDCK) monolayer were investigated.Materials and methods: Anti-solvent precipitation method was adopted in preparation of ORI-NCs. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were adopted to explore crystallography of ORI-NCs. Sulforhodamine B (SRB) method was used to test the inhibition effect on proliferation of MDCK cells. Quantitative analysis by HPLC was performed to study the endocytosis and transcytosis of ORI-NCs and ORI bulk drug, and the process was observed by confocal laser spectrum microscopy (CLSM) and flow cytometry.Results: The particle size of ORI-NCs was about 274 nm. The crystallography form of ORI was not changed after prepared into NCs. The dissolution rate of ORI-NCs was higher than pure ORI in 120 min. At higher concentrations (34, 84 and 135 μg/mL), ORI-NCs significantly reduced the cell viability compared with free ORI (p < 0.05, p < 0.01). ORI-NCs demonstrated higher endocytosis in MDCK cells than free ORI (p < 0.01). In the transport process, ORI-NC was taken up into cells in an intact form, and excreted out from basolateral membrane of polarized epithelial cells in an intact form. The internalization and transmembrane amount increased as a function of time.Conclusions: ORI-NCs transported through the MDCK monolayers in an intact form.

An Aseptic One-Shot Bottom-Up Method To Produce Progesterone Nanocrystals: Controlled Size and Improved Bioavailability

Progesterone (PG) is an essential sex hormone with a variety of important biological functions, but its insolubility leads to low bioavailability of most water-based formulations. What is more, the commercial oil-based formulations often cause severe side effects after long-term injection due to poor tissue absorption of oil. Herein, we report an aseptic bottom-up method utilizing emulsion freeze-drying technology that produces size-controllable, highly bioavailable, and water-based PG nanocrystal injection. The key factors that can determine the features of nanocrystals were investigated, including solvents, water-to-oil ratio, drug concentrations, type of surfactants, temperature in freeze-drying process, and lyoprotectants. Mechanisms of crystal growth formation process for PG nanocrystals were also analyzed theoretically. The prepared water-based PG nanocrystal suspension injection (PG/NSI) not only showed quick dissolution behaviors but also had significantly improved bioavailability in vivo. Therefore, this method can effectively control the size of nanocrystals, enhance bioavailability of insoluble drugs, and produce aseptic water-based nanocrystals that can be directly used for injection. Moreover, this method can also be used to prepare nanocrystals with the desired size under aseptic conditions for other poorly water-soluble drugs.

A Hybrid Strategy to Construct Multistage Adaptive Tests

How to effectively construct multistage adaptive test (MST) panels is a topic that has spurred recent advances. The most commonly used approaches for MST assembly use one of two strategies: bottom-up and top-down. The bottom-up approach splits the whole test into several modules, and each module is built first, then all modules are compiled to obtain the whole test, while the top-down approach follows the opposite direction. Both methods have their pros and cons, and sometimes neither is convenient for practitioners. This study provides an innovative hybrid strategy to build optimal MST panels efficiently most of the time. Empirical data and results by using this strategy will be provided.

Single-Carbon-Nanotube Manipulations and Devices Based on Macroscale Anthracene Flakes

Because of the outstanding mechanical and electrical properties of carbon nanotubes (CNTs), a CNT-based torsion pendulum is demonstrated to show great potential in nano-electromechanical systems. It is also expected to achieve various manipulations for further characterization and increase device sensitivity using ultrlong CNTs and macroscale moving parts. However, the reported top-down method limits the CNT performance and device size by introducing inevitable contamination and destruction, which greatly hinders the development of single-molecule devices. Here, a bottom-up method is introduced to fabricate heterostructures of anthracene flakes (AFs) and suspended CNTs, providing a nondamaging CNT mechanical measurement before further applications, especially for the twisting behavior, and providing a controllable and clean transfer method to fabricate CNT-based electrical devices under ambient conditions. Based on the unique geometry of CNT/AF heterostructures, various complex manipulations of single-CNT devices are conducted to investigate CNT mechanical properties and prompt novel applications of similar structures in nanotechnology. The AF-decorated CNTs show high Young's modulus (≈1 TPa) and tensile strength (≈100 GPa), and can be considered as the finest and strongest torsional springs. CNT-based torsion balance enables to measure fN-level forces and the torsional spring constant is two orders of magnitude lower than previously reported values.

Template-Free Bottom-Up Method for Fabricating Diblock Copolymer Patchy Particles

Patchy particles are one of most important building blocks for hierarchical structures because of the discrete patches on their surface. We have demonstrated a convenient, simple, and scalable bottom-up method for fabricating diblock copolymer patchy particles through both experiments and dissipative particle dynamics (DPD) simulations. The experimental method simply involves reducing the solvent quality of the diblock copolymer solution by the slow addition of a nonsolvent. Specifically, the fabrication of diblock copolymer patchy particles begins with a crew-cut soft-core micelle, where the micelle core is significantly swelled by the solvent. With water addition at an extremely slow rate, the crew-cut soft-core micelles first form a larger crew-cut micelle. With further water addition, the corona-forming blocks of the crew-cut micelles begin to aggregate and eventually form well-defined patches. Both experiments and DPD simulations indicate that the number of patches has a very strong dependence on the diblock copolymer composition-the particle has more patches on the surface with a lower volume fraction of patch-forming blocks. Furthermore, particles with more patches have a greater ability to assemble, and particles with fewer patches have a greater ability to merge once assembled.

Facile Fabrication of N-Doped Graphene as Efficient Electrocatalyst for Oxygen Reduction Reaction

A facile bottom-up method is reported here for the fabrication of N-doped graphene for oxygen reduction. It consists of a two-step calcination strategy and uses α-hydroxy acids (AHAs) as carbon source and melamine as nitrogen source. Three different AHAs, malic acid, tartaric acid, and citric acid, were chosen as the carbon sources. The prepared N-doped graphenes have a typical thin layered structure with a large specific surface area. It was found that the N content in the obtained N-doped graphenes varies from 4.12 to 8.11 at. % depending on the AHAs used. All of the samples showed high performance in oxygen reduction reaction (ORR). The N-doped graphene prepared from citric acid demonstrated the highest electrocatalytic activity, which is comparable to the commercial Pt/C and exhibited good durability, attributing to the high pyridinic N content in the composite.