Highly Aligned Cellulose/Polypyrrole Composite Nanofibers via Electrospinning and In Situ Polymerization for Anisotropic Flexible Strain Sensor.

Flexible strain sensors have recently attracted great attention due to their promising applications in human motion detection, healthcare monitoring, human-machine interfaces, and so forth. However, traditional uniaxial strain sensors can only detect strain in a single direction. Herein, an anisotropic flexible strain sensor is fabricated based on conductive and highly aligned cellulose composite nanofibers, via facile electrospinning cellulose acetate, deacetylation, and in situ polymerization of pyrrole, to detect complex multidimensional strains. Benefiting from the unique well-ordered structure of conductive composite nanofibers, the obtained strain sensor shows extraordinary anisotropic sensing performance with a sensitivity of 0.73 and 0.01 for the tensile applied perpendicular and parallel to the nanofiber alignment, respectively. The sensor also exhibits outstanding durability (2000 cycles) due to the strong hydrogen bonding between cellulose nanofibers and polypyrrole. Moreover, the flexible strain sensors exhibit promising potentials for application in motion detection, as demonstrated by the detection of various joint movements in the human body.

Heat-Resistant, Robust, and Hydrophilic Separators Based on Regenerated Cellulose for Advanced Supercapacitors.

Separators in supercapacitors (SCs) typically suffer from defects of low mechanical property, limited ion transport, and electrolyte wettability, and poor thermal stability, impeding the development of SCs. Herein, high-performance regenerated cellulose (RC) based separators are designed that are fabricated by effective hydrolytic etching of inorganic CaCO3 nanoparticles from a filled RC membrane. The as-prepared RC separator displays excellent comprehensive performances such as higher tensile strength (75.83 MPa) and thermal stability (200 °C), which is superior to commercial polypropylene-based separator (Celgard 2500) and sufficient to maintain their structural integrity even at temperatures in excess of 200 °C. Benefiting from its hydrophilicity, high porosity, and outstanding electrolyte uptake rate (208.5%), the RC separator exhibits rapid transport and permeability of ions, which is 2.5× higher than that of the commercial nonwoven polypropylene separator (NKK -MPF30AC-100) validated by electrochemical tests in the 1.0 m Na2 SO4 electrolyte. Results show that porous RC separator with unique advantages of superior electrolyte wettability, mechanical robustness, and high thermal stability, is a promising separator for SCs with high-performance and safety.

Janus Biopolymer Sponge with Porous Structure Based on Water Hyacinth Petiole for Efficient Solar Steam Generation.

Solar-driven steam generation for desalination is a facile, sustainable, and energy-saving approach to produce clean freshwater. However, the complicated fabrication process, high cost, potential environmental impact, and salt crystallization of conventional evaporators limit their large-scale application. Herein, we present a sustainable Janus evaporator based on a biopolymer sponge from the water hyacinth petiole (WHP) for high-performance solar steam generation. The freeze-dried WHP maintained its original porous structure and aligned channels well, and therefore holds the capability for rapid water transport due to strong capillary action. The WHP coated with carbon nanotubes/ethyl cellulose paste on its surface (WHP-C) gains a good photothermal property, thus achieving an efficient solar steam generation with a rate of 1.50 kg m-2 h-1 under 1 sun irradiation. Moreover, the WHP-C after hydrophobic modification by fluorocarbon (WHP-CH) is endowed with high water repellency and exhibits good salt resistance during long-term solar desalination. Additionally, we demonstrate that a stable wet surface that enables efficient water supply and vapor escape is also significant to the successive desalination of a solar evaporator. Our work provides new insights into the high-value utilization of biomass waste, i.e., water hyacinth, and the development of sustainable interfacial solar evaporators for the environmentally friendly production of freshwater.

Smart Responsive Azo-Copolymer with Photoliquefaction for Switchable Adhesive Application.

The development and utilization of switchable adhesives are considered to be an essential target to solve the problems of their separation and recycling in some specific service environments, such as the preparation or repair process of electronic devices. Intelligent materials with controllable phase transition are utilized to fabricate switchable adhesives because of the significantly diverse adhesion strengths in different phase states. Photoresponsive azobenzene and its derivatives usually possess different melting temperatures (Tm) or/and glass transition temperatures (Tg) of the cis-trans isomers, which are beneficial to making the photoinduced solid-liquid phase transition for switchable adhesive application possible. Here, a novel three-component azo-copolymer (PNIM-Azo) with fast and reversible photoinduced solid-liquid phase transition has been designed and synthesized. PNIM-Azo possesses reversible bonding/debonding processes, resulting from the different adhesion strengths between trans-configuration PNIM-Azo in the solid state and cis-configuration in the liquid state. Moreover, by incorporating commercialized 2-methoxyethyl acrylate and N-isopropylacrylamide with O and N heteroatoms into the copolymer, the trans-configuration PNIM-Azo possesses the highest adhesion strength (∼11 MPa between two glass substrates) among all of the reported azobenzene-based switchable adhesives, which could be attributed to the increase in the entanglement effect because of the H-bond in the polymer chains formed by introducing heteroatoms. Our synthesized PNIM-Azo copolymer provides an alternative for designing and developing switchable adhesives with high adhesion strength for some electronic production processes.

Design and synthesis of chromone-nitrogen mustard derivatives and evaluation of anti-breast cancer activity.

Chromone has emerged as one of the most important synthetic scaffolds for antitumor activity, which promotes the development of candidate drugs with better activity. In this study, a series of nitrogen mustard derivatives of chromone were designed and synthesised, in order to discover promising anti-breast tumour candidates. Almost all target derivatives showed antiproliferative activity against MCF-7 and MDA-MB-231 cell lines. In particular, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed the most potent antiproliferative activity with IC50 values of 1.83 and 1.90 µM, respectively, and it also exhibited certain selectivity between tumour cells and normal cells. Further mechanism exploration against MDA-MB-231 cells showed that it possibly induced G2/M phase arrest and apoptosis by generating intracellular ROS and activating DNA damage. In addition, it also inhibited MDA-MB-231 cells metastasis, invasion and adhesion. Overall, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed potent antitumor activities and relatively low side effects, and deserved further investigation.

Hydrogen sulfide releasing oridonin derivatives induce apoptosis through extrinsic and intrinsic pathways.

Hydrogen sulfide (H2S) has been recognized as the third endogenous signaling gasotransmitter following nitric oxide (NO) and carbon monoxide (CO), and exhibits antiproliferative activity against several cancer cells. In order to stably and controllably release H2S, H2S donating compound (ADT-OH) was used in the present study and 18H2S releasing natural ent-kaurane diterpenoid oridonin derivatives were designed and synthesized. Most derivatives showed more potent antiproliferative activities than oridonin against HepG2 and K562 cell lines, while they were lack of sensitivity to HCT-116 and B16 cells. In particular, 12b showed the most potent antiproliferative activities against HepG2, HCT-116 and K562 cells with IC50 values of 2.57, 5.81 and 0.95 µM, respectively. Through cell cycle analysis, 12b caused cell cycle arrest at S phase in K562 cells and G1 phase in HepG2 cells. In Hoechst 33258 staining assay, cell shrinkage and fragmentation of cell nuclei indicated apoptotic morphological changes. Considering the decline of mitochondrial membrane potential and changes in the levels of apoptosis-related proteins, 12b was shown to induce apoptosis through extrinsic and intrinsic apoptosis pathways.

Marine-Derived Natural Lead Compound Disulfide-Linked Dimer Psammaplin A: Biological Activity and Structural Modification.

Marine natural products are considered to be valuable resources that are furnished with diverse chemical structures and various bioactivities. To date, there are seven compounds derived from marine natural products which have been approved as therapeutic drugs by the U.S. Food and Drug Administration. Numerous bromotyrosine derivatives have been isolated as a type of marine natural products. Among them, psammaplin A, including the oxime groups and carbon-sulfur bonds, was the first identified symmetrical bromotyrosine-derived disulfide dimer. It has been found to have a broad bioactive spectrum, especially in terms of antimicrobial and antiproliferative activities. The highest potential indole-derived psammaplin A derivative, UVI5008, is used as an epigenetic modulator with multiple enzyme inhibitory activities. Inspired by these reasons, psammaplin A has gradually become a research focus for pharmacologists and chemists. To the best of our knowledge, there is no systematic review about the biological activity and structural modification of psammaplin A. In this review, the pharmacological effects, total synthesis, and synthesized derivatives of psammaplin A are summarized.

Bioactive Natural Spirolactone-Type 6,7-seco-ent-Kaurane Diterpenoids and Synthetic Derivatives.

Diterpenoids are widely distributed natural products and have caused considerable interest because of their unique skeletons and antibacterial and antitumor activities and so on. In light of recent discoveries, ent-kaurane diterpenoids, which exhibit a wide variety of biological activities, such as anticancer and anti-inflammatory activities, pose enormous potential to serve as a promising candidate for drug development. Among them, spirolactone-type 6,7-seco-ent-kaurane diterpenoids, with interesting molecular skeleton, complex oxidation patterns, and bond formation, exhibit attractive activities. Furthermore, spirolactone-type diterpenoids have many modifiable sites, which allows for linking to various substituents, suitable for further medicinal study. Hence, some structurally modified derivatives with improved cytotoxicity activities are also achieved. In this review, natural bioactive spirolactone-type diterpenoids and their synthetic derivatives were summarized.