3D microgel with extensively adjustable stiffness and homogeneous microstructure for metastasis analysis of solid tumor

3D microgels with various mechanical properties have been important platforms tumor metastasis analysis, and widely adjustable stiffness is crucial for deeper researches. Herein, by mixing biodegradable polylactic acid (PLA) nanofibers in the modified alginate with different concentrations of Ca²⁺, we significantly enhance the stiffness range of microgels while retaining the pore size, which provides bionic microenvironment for tumor analysis. As a proof of concept, we simulated the mechanical characteristics of breast tumors by encapsulating cells in 3D microgels with diverse stiffness, and analyzed cellular behaviors of two typical breast cancer cell lines: MCF-7 and SUM-159. Results showed that with the addition of 2.0% (w/v) PLA short nanofibers, the Young's modulus of modified alginate increased more than three-fold. Besides preserving high survival and proliferation rates, both cells also displayed stronger migration ability in soft microgel spheres, where RT-qPCR analysis revealed the underlying changes at the genetic level. This systematic study demonstrated our method is powerful for creating widely adjustable 3D mechanical microenvironment, and the results of cellular behavior analysis shows its promising application prospects in tumorigenesis and progression.     

Synergistic Pd/Cu-catalyzed regio- and stereoselective cascade Heck cyclization/borylation/cross-coupling

A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes, B₂Pin₂ and alkene-tethered aryl halides is reported. This reaction proceeds under mild conditions and shows broad substrate scope, providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity. This transformation features the catalytic generation of β-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings. An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenylboronate moiety.     

Basics of optical force

Light possesses momentum, and hence, force is exerted on materials if they absorb and/or scatter light. Laser techniques that use optical forces are currently attracting considerable attention. Optical manipulation for trapping, transporting small particles, and measuring the interparticle force is a representative technique. In addition, photoinduced force microscopy is a promising scanning type of microscopy using optical force. Optical force techniques have recently been used in various fields of research, such as molecular bioscience, organic photochemistry, materials engineering, and molecular fluid dynamics. In these techniques, several types of optical forces such as scattering, absorption, and gradient forces play their respective roles. In this article, we summarize the basics of optical forces and present their elementary expressions for using simplified models of light and matter systems. This will help the readers of this Special Issue to understand how different types of forces are distinguished in the basic expressions used for analyzing the optical force phenomena that appear depending on the light geometry and matter systems. After observing simplified cases of scattering and absorption forces, we introduce general formulae for the optical force and then discuss how different components appear in particular cases of laser geometry and materials.     

A Robust Metal-Organic Framework with Scalable Synthesis and Optimal Adsorption and Desorption for Energy-Efficient Ethylene Purification

Adsorptive separation is an energy-efficient alternative, but its advancement has been hindered by the challenge of industrially potential adsorbents development. Herein, a novel ultra-microporous metal-organic framework ZU-901 is designed that satisfies the basic criteria raised by ethylene/ethane (C₂H₄/C₂H₆) pressure swing adsorption (PSA). ZU-901 exhibits an “S” shaped C₂H₄ curve with high sorbent selection parameter (65) and could be mildly regenerated. Through green aqueous-phase synthesis, ZU-901 is easily scalable with 99 % yield, and it is stable in water, acid, basic solutions and cycling breakthrough experiments. Polymer-grade C₂H₄ (99.51 %) could be obtained via a simulating two-bed PSA process, and the corresponding energy consumption is only 1/10 of that of simulating cryogenic distillation. Our work has demonstrated the great potential of pore engineering in designing porous materials with desired adsorption and desorption behavior to implement an efficient PSA process.     

Ambient Preparation of Benzoxazine-based Phenolic Resins Enables Long-term Sustainable Photosynthesis of Hydrogen Peroxide

Rational design of polymer structures at the molecular level promotes the iteration of high-performance photocatalyst for sustainable photocatalytic hydrogen peroxide (H₂O₂) production from oxygen and water, which also lays the basis for revealing the reaction mechanism. Here we report a benzoxazine-based m-aminophenol-formaldehyde resin (APFac) polymerized at ambient conditions, exhibiting superior H₂O₂ yield and long-term stability to most polymeric photocatalysts. Benzoxazine structure was identified as the crucial photocatalytic active segment in APFac. Favorable adsorption of oxygen/intermediates on benzoxazine structure and commendable product selectivity accelerated the reaction kinetically in stepwise single-electron oxygen reduction reaction. The proposed benzoxazine-based phenolic resin provides the possibility of production in batches and industrial application, and sheds light on the de novo design and analysis of metal-free polymeric photocatalysts.     

Host–Guest Doping in Flexible Organic Crystals for Room-Temperature Phosphorescence

Organic single crystals (OSCs) with excellent flexibility and unique optical properties are of great importance due to their broad applicability in optical/optoelectronic devices and sensors. Nevertheless, fabricating flexible OSCs with room-temperature phosphorescence (RTP) remains a great challenge. Herein, we propose a host–guest doping strategy to achieve both RTP and flexibility of OSCs. The single-stranded crystal is highly bendable upon external force application and can immediately return to its original straight shape after removal of the stress, impressively emitting bright deep-red phosphorescence. The theoretical and experimental results demonstrate that the bright RTP arises from Förster resonance energy transfer (FRET) from the triphenylene molecules to the dopants. This strategy is both conceptually and synthetically simple and offers a universal approach for the preparation of flexible OSCs with RTP.     

Nature-inspired biogenic synthesis of silver nanoparticles for antibacterial applications

In recent decades, nanotechnology has been empowered as a new and developing interdisciplinary region of science and innovation that coordinates material science and biology. Nanoscience and nanotechnology open up new streets of examination that are helpful in synthesizing novel nanomaterials with remarkable applications. Among different metal nanomaterials, silver nanoparticles (AgNPs) attracted the attention of researchers due to their versatile antibacterial characteristics and biological properties. Biogenically synthesizing AgNPs from plants and microorganisms seems to be a highly promising alternative for developing a technology that is both environmentally benign and fast. Plants and microorganisms' ability to synthesize AgNPs has mostly remained untapped, and the lack of investigation is due to the vast variety of plants and microorganisms. This review aims to describe the current progress in various synthetic techniques for AgNPs and their potential for antibacterial applications. It discusses biogenic synthetic approaches, the role of various metabolites in the growth processes of AgNPs with antibacterial implications, bactericidal mechanisms, and the influence of operational parameters on AgNPs synthesis. Furthermore, the present status, critical challenges, and future outlook of AgNPs will be explored, which will definitely affect their present and future scenarios. We believe that by focusing readers' attention on nature-inspired, biogenically synthesized AgNPs and their bactericidal applications, this review will enable them to formulate a new perspective.     

Comparative Study on Different Expression Hosts for Alkaline Phytase Engineered in <Emphasis Type="Italic">Escherichia coli</Emphasis>

The application of alkaline phytase as a feed additive is restricted by the poor specific activity. Escherichia coli is a frequently used host for directed evolution of proteins including alkaline phytase towards improved activity. However, it is not suitable for production of food-grade products due to potential pathogenicity. To combine the advantages of different expression systems, mutants of the alkaline phytase originated from Bacillus subtilis 168 (phy168) were first generated via directed evolution in E. coli and then transformed to food-grade hosts B. subtilis and Pichia pastoris for secretory expression. In order to investigate the suitability of different expression systems, the phy168 mutants expressed in different hosts were characterized and compared in terms of specific activity, pH profile, pH stability, temperature profile, and thermostability. The specific activity of B. subtilis-expressed D24G/K70R/K111E/N121S mutant at pH 7.0 and 60 °C was 30.4 U/mg, obviously higher than those in P. pastoris (22.7 U/mg) and E. coli (19.7 U/mg). Moreover, after 10 min incubation at 80 °C, the B. subtilis-expressed D24G/K70R/K111E/N121S retained about 70 % of the activity at pH 7.0 and 37 °C, whereas the values were only about 25 and 50 % when expressed in P. pastoris and E. coli, respectively. These results suggested B. subtilis as an appropriate host for expression of phy168 mutants and that the strategy of creating mutants in one host and expressing them in another might be a new solution to industrial production of proteins with desired properties.     

Open‐Pore Two‐Dimensional MFI Zeolite Nanosheets for the Fabrication of Hydrocarbon‐Isomer‐Selective Membranes on Porous Polymer Supports

Two‐dimensional zeolite nanosheets that do not contain any organic structure‐directing agents were prepared from a multilamellar MFI (ML‐MFI) zeolite. ML‐MFI was first exfoliated by melt compounding and then detemplated by treatment with a mixture of H₂SO₄ and H₂O₂ (piranha solution). The obtained OSDA‐free MFI nanosheets disperse well in water and can be used for coating applications. Deposits made on porous polybenzimidazole (PBI) supports by simple filtration of these suspensions exhibit an n‐butane/isobutane selectivity of 5.4, with an n‐butane permeance of 3.5×10^?7 mol m^?2 s^?1 Pa^?1 (ca. 1000 GPU).     

The SOC in cells’ living expectations of Conway’s Game of Life and its extended version

In self-organized systems such as Conway’s Game of Life (CGL). Wikipedia, Conway’s game of the life, https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life., though whether the single cell will survive or die seems unpredictable, the log–log distribution of all cells living frequency satisfies the 1/f linear law, thus meets the Self-organized Criticality(SOC) rule, which not only proves that CGL is a self-organized system, but more significantly, that the chance of living for each cell is spatial heterogeneous, and is statistical fractal.After carried out CGL, the specified iterative period which begins with a random initial condition and ends when it reaches the homeostasis, add up all the states which the living cells are marked by 1s, and the dead are marked by 0s. The resulted sum picture consisting of cells having its gray level representing the living times during the iterative process. By plotting the gray level distribution of the sum picture on log–log scale, the graph indicates the spatial living expectations distributions. Then we find the curve of the graph satisfies the Self-organized Criticality(SOC) rule, showing its linear feature in the intermediate zone, which also has name of 1/f feature.To examine its universality, we designed a more complicated self-organized cellular automata with each cell having five possible states thus the rule table becomes more complicated. As expected, the consequence shows the similar feature, and the linear feature is even more obvious when the similar experiments are carried out.To conclude, it is a new discovery of SOC from a new perspective. And with the self-organized systems expanding to other different rule tables, this feature may still be satisfied.More further, considering the natural self-organized systems of living creatures, the spatial living expectations of different phenotypes may satisfy the 1/f law, too. Though we regard this as an inspirational orientation, the supposition needs more designed experiments to prove.