Latest ArticlesInspired by the biosystems, the artificial smart membrane to control the mass transport and molecular conversion has attracted increasing attention in the fields of membrane separation, desalination, nanofiltration, healthcare and environmental remediation. However, the trade-off limitations in polymeric membranes greatly hinder the development of smart membranes with high permeability and manipulability. Recently, inspired by the unique physical/chemical properties of two-dimensional (2D) materials, 2D materials-based smart membranes (2DSMs) with the ability of intelligent regulation under different stimuli are highly suitable for membrane applications. According to the desired properties, the 2DSMs with abundant functional groups can be designed through chemical modification to change the original properties and obtain tunable interlayer spacings under different external conditions. In this review, we summarize the recent progress on artificial smart membranes based on 2D materials. The design concept and fabrication strategy of 2DSMs are first introduced. Following that, the developed 2DSMs are introduced and classified by the type of responsive stimuli, including pH, magnetic field, electric field, light and temperature. Then, the 2DSMs exhibiting unique performances as membrane separation, pressure sensors, blue energy harvesting, photoelectrochemical sensors and biomimetic devices are presented. Finally, the perspectives and challenges in the developments of 2DSMs are discussed
Pathogenic bacteria pose a global threat to public health and attract considerable attention in terms of food safety. Rapid and highly sensitive strategies for detecting pathogenic bacteria must be urgently developed to ensure food safety and public health. Microchips offer significant advantages for pathogenic bacterial detection in terms of speed and sensitivity compared with those of traditional techniques. Microfluidic devices, in particular, have attracted significant attention for the detection of pathogenic bacteria owing to their ease of operation, high throughput, cost-effectiveness, and high sensitivity. This review summarizes representative articles on the analysis of pathogenic bacteria using microchip-based systems. A detailed and comprehensive overview of microchip-based techniques for the detection of pathogenic bacteria is presented herein, and their advantages and disadvantages are discussed to compare their applications. The accomplishments and shortcomings of these microchips have been highlighted, and the direction of development and prospects of the analysis of pathogenic bacteria have been examined. The content of this review is anticipated to provide constructive suggestions for further development of highly effective and advanced microchip-based strategies for detecting pathogenic bacteria.
Biomass-derived dynamic covalent thermoset has been considered as a promising solution to the high dependence on fossil resources and the difficulty in recyclability after curing of conventional bisphenol A epoxy resins. However, the design and preparation of a dynamic covalent biobased epoxy thermoset with both comparable thermal and mechanical performances to bisphenol A epoxy resins and reprocessibility remains a significant challenge. Herein, based on imine chemistry, a novel Schiff base-containing dynamic covalent epoxy thermoset was facilely fabricated from biobased protocatechualdehyde and synthetic siloxane diamine. Due to the more reactive epoxides in the epoxy monomer than in bisphenol A epoxy oligomer, the thermoset exhibited a high cross-linking density, resulting in high thermal stability and glass transition temperature. The rigid aromatic Schiff base moieties endowed the thermoset with excellent mechanical properties: Thanks to the plasticization of the flexible siloxane, the thermoset displayed high impact strength. Meanwhile, owing to the high segmental mobility, the fast exchange of imine bonds was guaranteed; and the thermoset was able to be recycled through reprocessing. Taking these features, this work provided great potential for designing and preparing sustainable substitutes for bisphenol A epoxy resins in the high-performance applications.
Well-defined two-dimensional (2D) cobalt oxalate (CoC2O4·2H2O) nanosheets exhibit more excellent property than common bulk cobalt oxalate due to high specific surface areas and high-efficient transport of ion and electron. However, the delicate control of the 2D morphology of CoC2O4·2H2O during their synthesis remains challenging. Herein, 2D CoC2O4·2H2O nanosheets (M1), grown by straightforward chemical precipitation, can be tuned from three-dimensional (3D) structure during their synthesis with no templates or capping agents. This control is obtained by rationally changing the ratio of reactants with ethylene glycol as solvent. Moreover, Co3O4/CoC2O4 composites (M1-250) have been fabricated through low-temperature thermal treatment of the M1 precursor in air, which possess porous surfaces with the 2D morphology maintained. Benefiting from the porous surfaces, more redox-active sites and better electrical conductivity of Co3O4, the constructed M1-250//AC aqueous device manifest improved kinetics of the electrochemistry process with energy density of 27.9 Wh/kg at 550.7 W/kg and good cycling stability with sustaining 73.0 mAh/g after 5000 cycles.
High performance liquid chromatography-mass spectrometry is one of the most commonly used strategies for lipid analysis. The development of versatile chromatographic stationary phases to meet the increasing demands for separation of complex lipids is very important. Styrene-maleic acid (SMA) copolymer is an amphiphilic polymer, which has been proven to have the ability to solubilize lipid molecules of various structures. In this study, styrene-maleic anhydride copolymer coated silica was first prepared by the thiol-ene click reaction. With l-cysteine hydrochloride or dodecanol as the post-modification reagents, Sil-SMA-amino acid and Sil-SMA-dodecanol stationary phase materials were further successfully fabricated via nucleophilic ring-opening reaction. The Fourier-transform infrared, thermogravimetric analysis, and elemental analysis results confirmed the two stationary phase materials were successfully prepared. Furthermore, both the Sil-SMA-dodecanol column and the Sil-SMA-amino acid column possessed reversed-phase/hydrophilic interaction/ion exchange mixed-mode retention mechanisms. The column efficiency of the Sil-SMA-derivatives columns reached 77,300 N/m. Based on the mixed-mode retention characteristics, the Sil-SMA-derivatives columns achieved both the lipid classes and species separation via a single column. The Sil-SMA-amino acid column was further successfully used to separate lipid extract from gastric cancer cell membrane. All these results demonstrated that the SMA-based stationary phase materials have a good potential for use in lipid separation.
Sophoralines A-C, three novel [2 + 2] cycloaddition dimers of matrine-based alkaloids with an unprecedented 6/6/6/6/4/6/6/6/6 nonacyclic skeleton containing 11 stereogenic centers, were isolated from Sophora alopecuroides. Their structures were determined by spectroscopic methods, and the absolute configurations were further determined by single-crystal X-ray diffraction analysis for 1 and quantum chemical calculations of electronic circular dichroism (ECD) spectra for 2 and 3. Moreover, 1 exhibited excellent hepatoprotective activities in acetaminophen-induced liver injury in vitro and in vivo.
The cellular response to the complex extracellular microenvironment is highly dynamic in time and type of extracellular matrix. Accurately reconstructing this process and analyzing the changes in receptor conformation on the cell membrane surface and intracellular or intercellular signaling has been a major challenge in analytical chemistry and biophysical methodology. In this paper, a time-coded multi-concentration microfluidic chemical waveform generator was developed for the dynamic signaling probing with single-cell array of high temporal resolution, high throughput, and multi-concentration combination stimulation. Based on innovative microchannel structure, sophisticated external control methods and multiplexing technology, the system not only allowed for temporally sequential permutations of the four concentrations of stimuli (time code), but also generated pulsed and continuous waveforms at different frequencies in a highly controllable manner. Furthermore, the single-cell trap array was set up to efficiently capture cells in suspension, dramatically increasing throughput and reducing experiment preparation time. The maximum frequency of the platform was 1 Hz, and one cell could be stimulated at multiple frequencies. To show the ability of the system to investigate rapid biochemical events in high throughput, pulse stimulation and continuous stimulation of different frequencies and different time codes, combined with four concentrations of histamine (HA), were generated for probing G protein-coupled receptor (GPCR) signaling in HeLa cells. Then, statistical analysis was performed for the mean peak height and mean peak area of the cellular response. We believe that the time-coded multi-concentration microfluidic chemical waveform generator will provide a novel strategy for analytical chemistry, biophysics, cell signaling, and individualized medicine applications.
Concentration gradient and fluid shear stress (FSS) for cell microenvironment were investigated through microfluidic technology. The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploited to design the microfluidic chip, and the FSS distribution on the cell model with varying micro-channels (triangular, conical, and elliptical). The diffusion with the incompressible laminar flow model by solving the time-dependent diffusion–convection equation was applied to simulate the gradient profiles of concentration in the micro-channels. For the study of single cell in-depth, the FSS was investigated by the usage of polystyrene particles and the concentration diffusion distribution was studied by the usage of different colors of dyes. A successful agreement between model simulations and experimental data was obtained. Finally, based on the established method, the communication between individual cells was envisaged and modeled. The developed method provides valuable insights and allows to continuously improve the design of microfluidic devices for the study of single cell, the occurrence and development of tumors, and therapeutic applications.
The urgent need for immediate personal protection against chemical warfare agents (CWAs) spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices. Herein, as a new concept for CWA decontamination catalyst design, sub-nanoscale, catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures. The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt% and therefore, demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA, soman (GD) (t1/2 = 5.0 min) and CWA simulant, methyl paraoxon (DMNP) (t1/2 = 8.9 min). Meanwhile, due to the covalent nature of cross-linkages and the high flexibility of polymer strands, the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO2 and O2, enabling their extended applications in the field of collective/personal protective materials with body comfort.
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