Chiral perovskites have emerged as a significant class of materials showing promising optoelectronic and spintronic applications. Reports of chiral perovskite ferroelectrics, however, have been ...scarce. In this work, we have successfully synthesized homochiral lead–iodide perovskite ferroelectrics (R)‐N‐(1‐phenylethyl)ethane‐1,2‐diaminiumPbI4 and (S)‐N‐(1‐phenylethyl)ethane‐1,2‐diaminiumPbI4 by introducing a methyl group into the organic cation of the parent (N‐benzylethane‐1,2‐diaminium)PbI4. Vibrational circular dichroism spectra identify the chiral mirroring relationship. They both undergo 222F2‐type paraelectric–ferroelectric behavior at around 378 K coupled with clear ferroelastic domain “ON/OFF” switching. Besides, they exhibit an evident thermochromism with color change from orange–yellow to orange–red. To our knowledge, the discovery of integrated ferroelectricity, ferroelasticity, and reversible thermochromism in chiral perovskites is unprecedented.
2D homochiral lead‐iodide perovskites were constructed by the introduction of a chiral center. The perovskites exhibit coexisting ferroelectricity, ferroelasticity, and reversible thermochromism, offering great application prospects for next‐generation smart devices.
A high transition temperature (Tc) is essential for the practical application of ferroelectrics as electronic devices under extreme thermal conditions in the aerospace, automotive, and energy ...industries. In recent decades, the isotope effect and strain engineering are found to effectively modulate Tc; however, these strategies are limited to certain systems. Developing simple, universal, and practical methods to improve Tc has become an imminent challenge for expanding the applications of ferroelectrics. Here, by adopting a molecular design strategy involving H/F substitution on an organic–inorganic hybrid perovskite (1‐azabicyclo2.2.1heptane)CdCl3 at a Tc of 190 K, the successful synthesis of a multiaxial, ferroelectric hybrid perovskite (4‐fluoro‐1‐azabicyclo2.2.1heptane)CdCl3 is reported, which demonstrates a large spontaneous polarization of 11.2 µC cm−2 (greater than that of polyvinylidene difluoride) and a Tc of 419 K (greater than that of BaTiO3). This temperature enhancement (229 K) is the largest reported for molecular ferroelectrics, far exceeding the reported enhancements induced by the isotope effect and other techniques. This pioneering technique provides an effective and universal method for improving Tc in ferroelectrics and represents an important step toward the development of high‐performance ferroelectric technology.
From (1‐azabicyclo2.2.1heptane)CdCl3, a molecular design strategy of H/F substitution is applied to synthesize a multiaxial organic–inorganic hybrid perovskite ferroelectric (4‐fluoro‐1‐azabicyclo2.2.1heptane)CdCl3. The phase transition temperature is successfully increased from 190 to 419 K, which is a record enhancement of 229 K for molecular ferroelectrics, significantly outperforming those induced by the isotope effect and other techniques.
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Magnesium (Mg) and its alloys have become a research frontier in biodegradable materials owing to their superior biocompatibility and excellent biomechanical compatibility. However, ...their high degradation rate in the physiological environment should be well tackled prior to clinical applications. This review summarizes the latest progress in the development of polymeric coatings on biodegradable Mg alloys over the last decade, regarding preparation strategies for polylactic acid (PLA), poly (latic-co-glycolic) acid (PLGA), polycaprolactone (PCL), polydopamine (PDA), chitosan (CS), collagen (Col) and their composite, and their performance in terms of corrosion resistance and biocompatibility. Feasible perspectives and developing directions of next generation of polymeric coatings with respect to biomedical Mg alloys are briefly discussed.
Magnesium (Mg) and its alloys have become a research frontier in biodegradable materials owing to their superior biocompatibility and suitable biomechanical compatibility. However, the principal drawback of Mg-based implants is their poor corrosion resistance in physiological environments. Hence, it is vital to mitigate the degradation/corrosion behavior of Mg alloys for safe biomedical deployments. This review summarizes the latest progress in development of polymeric coatings on biomedical Mg alloys regarding preparation strategy, corrosion resistance and biocompatibility, including polylactic acid (PLA), poly (latic-co-glycolic) acid (PLGA), polycaprolactone (PCL), chitosan (CS), polydopamine (PDA), collagen (Col) and their composite. In addition, functionalized polymer coatings with Mg alloys exhibits a promising prospect owing to their ability of degradation along with biocompatibility, self-healing, drug-delivery and osteoinduction.
Here, we report the hypoxia-responsive ionizable liposomes to deliver small interference RNA (siRNA) anticancer drugs, which can selectively enhance cellular uptake of the siRNA under hypoxic and ...low-pH conditions to cure glioma. For this purpose, malate dehydrogenase lipid molecules were synthesized, which contain nitroimidazole groups that impart hypoxia sensitivity and specificity as hydrophobic tails, and tertiary amines as hydrophilic head groups. These malate dehydrogenase molecules, together with DSPE-PEG2000 and cholesterol, were self-assembled into O'
,O
-(3-(dimethylamino)propane-1,2-diyl) 16-bis(2-(2-methyl-5-nitro-1
-imidazol-1-yl)ethyl) di(hexadecanedioate) liposomes (MLP) to encapsulate siRNA through electrostatic interaction. Our study showed that the MLP could deliver polo-like kinase 1 siRNA (siPLK1) into glioma cells and effectively enhance the cellular uptake of MLP/siPLK1 because of increased positive charges induced by hypoxia and low pH. Moreover, MLP/siPLK1 was shown to be very effective in inhibiting the growth of glioma cells both in vitro and in vivo. Therefore, the MLP is a promising siRNA delivery system for tumor therapy.
Organic radical ferroics such as TEMPO have attracted widespread interest. However, the relatively low Curie temperature of 287 K and melting point of 311 K severely hinder its application potential. ...Despite extensive interest, high‐temperature radical ferroics have not yet been found. Here, taking advantage of chemical design and supramolecular radical chemistry, we designed two high‐temperature organic supramolecular radical ferroics (NH3‐TEMPO)(18crown‐6)(ReO4) (1) and (NH3‐TEMPO)(18crown‐6)(ClO4) (2), which can retain ferroelectricity up to 413 K and 450 K, respectively. To our knowledge, they are both the first supramolecular radical ferroics and unprecedented high‐temperature radical ferroics, where the supramolecular component is vital for the stabilization of the radical and extending the working temperature window. Both also have paramagnetism, non‐interacting spin moments, and excellent piezoelectric and electrostrictive behaviors comparable to that of LiNbO3.
The first supramolecular radical ferroics show paramagnetism, non‐interacting spin moments, excellent piezoelectric and electrostrictive behaviors, as well as high‐temperature ferroelectricity.
The suprachiasmatic nucleus (SCN) drives circadian clock coherence through intercellular coupling, which is resistant to environmental perturbations. We report that primary cilia are required for ...intercellular coupling among SCN neurons to maintain the robustness of the internal clock in mice. Cilia in neuromedin S-producing (NMS) neurons exhibit pronounced circadian rhythmicity in abundance and length. Genetic ablation of ciliogenesis in NMS neurons enabled a rapid phase shift of the internal clock under jet-lag conditions. The circadian rhythms of individual neurons in cilia-deficient SCN slices lost their coherence after external perturbations. Rhythmic cilia changes drive oscillations of Sonic Hedgehog (Shh) signaling and clock gene expression. Inactivation of Shh signaling in NMS neurons phenocopied the effects of cilia ablation. Thus, cilia-Shh signaling in the SCN aids intercellular coupling.
As particles carry quantified energy, photon radiation enables orbital transitions of energy levels, leading to changes in the spin state of electrons. The resulting switchable structural bistability ...may bring a new paradigm for manipulating ferroelectric polarization. However, the studies on molecular orbital breaking in the ferroelectric field remain blank. Here, for the first time, a new mechanism of ferroelectrics—dual breaking of molecular orbitals and spatial symmetry, demonstrated in a photochromic organic crystal with light‐induced polarization switching, is formally proposed. By alternating the ultraviolet/visible light irradiation, the states of electron spin and the radial distribution p atomic orbitals experience a change, showing a reversible switch from “shoulder‐to‐shoulder” form to a “head‐to‐head” form. This reflects a reversible conversion between π and σ bonds, which induces and couples with the variation of spatial symmetry. The intersection of spatial symmetry breaking and molecular orbital breaking in ferroelectrics present in this work will be more conducive to data encryption and anticounterfeiting.
Dual breaking of molecular orbitals and spatial symmetry enables the optical control of two ferroelectric states between the closed‐ring and open‐ring forms of a photochromic organic ferroelectric, which is an unprecedented mechanism in ferroelectrics and brings a new paradigm for manipulating ferroelectric polarization.
Dynamic assembly and disassembly of primary cilia controls embryonic development and tissue homeostasis. Dysregulation of ciliogenesis causes human developmental diseases termed ciliopathies. ...Cell-intrinsic regulatory mechanisms of cilia disassembly have been well-studied. The extracellular cues controlling cilia disassembly remain elusive, however. Here, we show that lysophosphatidic acid (LPA), a multifunctional bioactive phospholipid, acts as a physiological extracellular factor to initiate cilia disassembly and promote neurogenesis. Through systematic analysis of serum components, we identify a small molecular-LPA as the major driver of cilia disassembly. Genetic inactivation and pharmacological inhibition of LPA receptor 1 (LPAR1) abrogate cilia disassembly triggered by serum. The LPA-LPAR-G-protein pathway promotes the transcription and phosphorylation of cilia disassembly factors-Aurora A, through activating the transcription coactivators YAP/TAZ and calcium/CaM pathway, respectively. Deletion of Lpar1 in mice causes abnormally elongated cilia and decreased proliferation in neural progenitor cells, thereby resulting in defective neurogenesis. Collectively, our findings establish LPA as a physiological initiator of cilia disassembly and suggest targeting the metabolism of LPA and the LPA pathway as potential therapies for diseases with dysfunctional ciliogenesis.
Since the discovery of the first ferroelectric Rochelle salt, most ferroelectrics have been investigated showing thermally triggered symmetry‐breaking phase transition. Although photochromism arising ...from geometrical isomerization was reported as early as 1867, such photoswitchable ferroelectric crystals have scarcely been developed to date. Herein, we report that salicylideneaniline is a photochromic ferroelectric crystal. Upon photoirradiation, the dielectric constant shows obvious switching between high and low dielectric states, and more importantly, the ferroelectric polarization demonstrates quick and reversible switching. This work opens the gate to developing photoswitchable ferroelectrics, which holds great potential for applications in optically controlled smart devices.
Salicylideneaniline has been discovered to be an organic photoswitchable ferroelectric crystal with a type of photo‐induced enol−keto structural isomerization accompanied by evident photochromism, which is different from the thermodynamic order‐disorder or displacive one. The microscopic ferroelectric polarization can be quickly and reversibly switched upon UV light irradiation, holding great promise for developing optical control of smart devices in the future.
Brassinosteroid (BR) has been shown to modulate plant tolerance to various stresses. S‐nitrosoglutathione reductase (GSNOR) is involved in the plant response to environment stress by fine‐turning the ...level of nitric oxide (NO). However, whether GSNOR is involved in BR‐regulated Na+/K+ homeostasis to improve the salt tolerance in halophyte is unknown. Here, we firstly reported that high salinity increases the expression of BR‐biosynthesis genes and the endogenous levels of BR in mangrove Kandelia obovata. Then, salt‐induced BR triggers the activities and gene expressions of GSNOR and antioxidant enzymes, thereafter decrease the levels of malondialdehyde, hydrogen peroxide. Subsequently, BR‐mediated GSNOR negatively regulates NO contributions to the reduction of reactive oxygen species generation and induction of the gene expression related to Na+ and K+ transport, leading to the decrease of Na+/K+ ratio in the roots of K. obovata. Finally, the applications of exogenous BR, NO scavenger, BR biosynthetic inhibitor and GSNOR inhibitor further confirm the function of BR. Taken together, our result provides insight into the mechanism of BR in the response of mangrove K. obovata to high salinity via GSNOR and NO signaling pathway by reducing oxidative damage and modulating Na+/K+ homeostasis.
Summary Statement
Salinity increases brassinosteroid (BR)‐biosynthesis genes expression and endogenous BR in mangrove Kandelia obovata.
BR enhances the activity and gene expression of S‐nitrosoglutathione reductase that negatively regulates nitric oxide signaling and reactive oxygen species level, while, BR regulates antioxidant enzymes and Na+/K+ homeostasis.
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