Enhancing cell membrane phase separation for inhibiting cancer metastasis with a stimuli-responsive DNA nanodevice

Phase separation in cell membranes promotes the assembly of transmembrane receptors to initiate signal transduction in response to environmental cues. Many cellular behaviors are manipulated by promoting membrane phase separation through binding to multivalent extracellular ligands. However, available extracellular molecule tools that enable manipulating the clustering of transmembrane receptors in a controllable manner are rare. In the present study, we report a DNA nanodevice that enhances membrane phase separation through the clustering of dynamic lipid rafts. This DNA nanodevice is anchored in the lipid raft region of the cell membrane and initiated by ATP. In a tumor microenvironment, this device could be activated to form a long DNA duplex on the cell membrane, which not only enhances membrane phase separation, but also blocks the interaction between the transmembrane surface adhesion receptor and extracellular matrix, leading to reduced migration. We demonstrate that the ATP-activated DNA nanodevice could inhibit cancer cell migration both in vitro and in vivo. The concept of using DNA to regulate membrane phase separation provides new possibilities for manipulating versatile cell functions through rational design of functional DNA structures.

A DNA nanodevice is developed to enhance the cell membrane phase separation in a tumor microenvironment to weaken the formation of focal adhesion. As a result, the migration of cancer cells is inhibited both in vitro and in vivo.     

Surface Functionalized Magnetic Nanoparticles as a Selective Sorbent for Affinity Fishing of PPAR-γ Ligands from Choerospondias axillaris

Coronary heart disease (CHD), which has developed into one of the major diseases, was reported to be treated by the target of peroxisome proliferators-activate receptor γ (PPAR-γ). As a natural medicine long used in the treatment of CHD, there are few studies on how to screen the target active compounds with high specific activity from Choerospondias axillaris. To advance the pace of research on target-specific active compounds in natural medicines, we have combined magnetic ligand fishing and functionalized nano-microspheres to investigate the active ingredients of PPAR-γ targets in Choerospondias axillaris. The PPAR-γ functionalized magnetic nano-microspheres have been successfully synthesized and characterized by vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The specificity, reusability, and reproducibility of the nano-microspheres were investigated with the help of the specific binding of rosiglitazone to PPAR-γ. In addition, the incubation temperature and the pH of the buffer solution in the magnetic ligand fishing were optimized to improve the specific adsorption efficiency of the analytes. Finally, with the aid of ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UHPLC-Q-Exactive Orbitrap-MS/MS), the 16 active ligands including 9 organic acids, 5 flavonoids, and 2 phenols were found in the ethanolic extracts of Choerospondias axillaris. Therefore, the study can provide a successful precedent for realizing the designated extraction and rapid isolation of target-specific active ingredient groups in the complex mixtures.     

Commutators and Semi-commutators of Monomial Toeplitz Operators on the Pluriharmonic Hardy Space

In this paper, the authors completely characterize the finite rank commutator and semi-commutator of two monomial Toeplitz operators on the pluriharmonic Hardy space of the torus or the unit sphere. As a consequence, many non-trivial examples of(semi-)commuting Toeplitz operators on the pluriharmonic Hardy spaces are given.     

动态氢气泡/牺牲铜模板法制备蜂窝AuPtCu电催化剂用于甲酸氧化

微/纳多孔金属材料具有高比表面积等优点，在电化学等领域广受关注.本工作通过动态氢气泡模板法，在镀金玻璃碳电极（Au_pla/GCE）上电沉积三维蜂窝状多孔纳米AuPtCu （3DHPN-AuPtCu）复合材料，再阳极溶出Cu，制备了3DHPN-AuPt_Cu/Au_pla/GCE.采用循环伏安法（CV）、金相显微镜、扫描电子显微镜、能量色散谱和电感耦合等离子体-原子发射光谱等手段表征了相关修饰电极.所制3DHPN-AuPt_Cu/Au_pla/GCE在含0.2 mol/L HCOOH的0.5 mol/L H₂SO₄水溶液中，电催化氧化甲酸的峰电流密度为12.5 mA·cm_Pt^-2（CV，-0.3～1.0 V，50 mV/s），优于有关对照电极和很多已报道的Pt复合物修饰电极，表明通过这种动态氢气泡/牺牲铜双模板法可制备出电催化性能优异的金属蜂窝结构.     

Highly sensitive,stretchable and durable strain sensors based on conductive double-network polymer hydrogels

Hydrogel-based strain sensors have been attracting immense attention for wearable electronic devices owing to their intrinsic soft characteristics and flexibility. However, developing hydrogel sensors with hightensile strength, stretchability, and strain sensitivity remains a great challenge. Herein, we report a technique to synthesize highly sensitive hydrogel-based strain sensors by integrating carbon nanofibers (CNFs) with a double-network (DN) polymer hydrogel matrix comprising of a physically cross-linked agar network and a covalently cross-linked polyacrylamide (PAAm) network. The resultant nanocomposite sensors display superior piezoresistive sensitivity with a hightrue gauge factor (GF_T = 1.78) at an ultrahigh strain of 1,000%, a fast response time and linear correlation of ln(R/R₀) and ln(L/L₀) up to 1,000% strain. Most significantly, these sensors possess highmechanical strength (~0.6 MPa) and superb durability (>1,000 cycles at strain of 100%), stemming from the effective energy dissipation mechanism of the first agar network acting as sacrificial bonds and the CNFs serving as dynamic nanofillers. The combination of highstrain sensitivity and ultrahigh stretchability of hydrogel sensors makes it possible to sense both small mechanical deformations induced by human motions and large strain up to 1,000%.     

Computational Study of spx(x=1–3)-Hybridized Be−Be Bonds Stabilized by Amidinate Ligands

Complexes containing odd-electron Be−Be bonds are still rare until now. Hereby, a series of neutral di-beryllium amidinate complexes containing a Be−Be bond were explored theoretically. The complexes with direct chelation with the Be₂ dimer by the bidentate amidinate (AMD) ligands are always corresponding to their global minimum structures. The detailed bonding analyses reveal that the localized electrons of the Be−Be fragment can be adjusted by the amount of AMD ligands because each AMD ligand only takes one electron from the Be₂ fragment. Meanwhile, the hybridization of the central Be atom also changes as the number of AMD ligands increases. In particular, the sp³-hybridized single-electron Be−Be bond is firstly identified in the tri-AMD-ligands-chelated neutral D_3h- Be₂(AMD)₃ complex, which also possesses the higher stability compared to its monoanionic D_3h- Be₂(AMD)₃ ⁻ and monocationic C₃- Be₂(AMD)₃ ⁺ analogues. Importantly, our study provides a new approach to obtain a neutral odd-electron Be−Be bond, namely by the use of radical ligands through side-on chelation.     

Facile Synthesis of Au/Ni(OH)2 Nanocomposites and its Application in Nonenzymatic Glucose Sensing

Journal of Cluster Science - A simple and environment-friendly autocatalytic reduction process was developed for synthesis of Au/Ni(OH)2 nanocomposites. The nanocomposites were characterized by...     

Cytotoxic cytochalasans from Aspergillus flavipes PJ03-11 by OSMAC method

Two new cytochalasans flavichalasine N (1), flavichalasine O (2), together with six known cytochalasans (3–8), were isolated from Aspergillus flavipes PJ03-11 through the application of OSMAC (one strain many compounds) strategy. Flavichalasine O (2) represented the first example of cytochalasans possessing a nitrogen-oxygen heterocycle at the macrocyclic ring part. Their structures were established on the base of extensive spectroscopic analysis. Compounds 1–4 exhibited significant cytotoxic activities against three human cancer cell lines (THP1, HL-60 and PC3) with IC₅₀ values ranging from 3.00 to 15.10?μM.     

利用AgVO3改性MoS2增强活性氧产生及其光催化性能的提高

随着全球工业化进程的发展,环境污染问题日益严重,已经成为21世纪影响人类生存与发展的重要问题.光催化氧化技术被认为是解决环境问题最有应用前景的技术之一,已经成为环境领域的研究热点.众所周知,二硫化钼(MoS2)可以被可见光激发产生电子-空穴对,但是由于其氧化还原电势并不高,抑制了氧分子活化的量子效率,且激发后的光生载流子容易复合,导致光催化效率不高.因此,迫切需要对MoS2光催化材料进行修饰与改性,采用提高光催化过程中活性氧(ROSs)的量来提高其光催化活性.银钒氧化物(AgVO3,Ag2V4O11,Ag3VO4和Ag4V2O7等)因其在锂电池、传感器和光催化剂领域的应用而引起了人们的关注.其中,AgVO3具有较窄的带隙和高度分散的价带,具有潜在的应用价值.本文采用水热法成功制备了AgVO3/MoS2复合光催化剂,并采用X射线粉末衍射、扫描电子显微、透射电子显微镜和紫外-可见漫反射光谱等表征技术研究了所制光催化剂的物相结构、样品形貌和光学性能.以四环素为研究对象,将其应用于AgVO3/MoS2复合光催化剂的降解实验.结果表明,随着AgVO3质量比从1.0 wt%增加到3.0 wt%,所得催化剂的光催化活性不断提高;当进一步增加AgVO3的质量时,复合催化剂的活性逐渐降低.这是由于过多的AgVO3的引入导致在光催化剂表面形成电子-空穴对复合中心,增加了载流子复合几率.因此,AgVO3/MoS2复合光催化剂中AgVO3的最佳质量比为3.0 wt%,其降解速率常数为0.0087 min–1,分别是MoS2(0.00509 min–1)和AgVO3(0.00495 min–1)的1.71和1.76倍.由于AgVO3改性后的MoS2具有优异的光催化性能,能促进O2的吸附/活化,加速MoS2表面生成H2O2的双电子氧还原反应,从而产生更多的ROSs.利用电子自旋共振光谱、POPHA荧光检测和自由基捕获实验相结合的方法来阐明ROSs的形成机理.同时,ROSs的产生会加速消耗AgOV3导带上的电子,为降解污染物留下更多的空穴.本文为表面催化工程促进ROSs生成的合理设计提供了新的思路,有望在环境治理中得到实际应用.     

Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>/BiFeO<Subscript>3</Subscript> heterostructure: preparation,characterization, and photocatalytic activity

Bi₂O₃/BiFeO₃ composite was successfully fabricated by a conventional sol–gel method and structural properties were characterized based on X-ray diffractometer, scanning electron microscope, transmission electron microscope, energy-dispersive X-ray analyzer, nitrogen adsorption–desorption measurement, and UV–visible diffuse reflectance spectroscopy. Bi₂O₃/BiFeO₃ had a good absorption for visible light, which was benefit to photocatalytic activity. The highest degradation efficiency was obtained when the content of Bi₂O₃ in Bi₂O₃/BiFeO₃ was 63.9%. Effect of experimental conditions was investigated, and the highest photocatalytic activity of Bi₂O₃/BiFeO₃ was observed at photocatalyst dosage of 0.5 g/L, initial BPA concentration of 10 mg/L, and solution pH of 6.3. Bi₂O₃/BiFeO₃ photocatalyst exhibited enhanced photocatalytic activity for BPA, and the reaction rate constant over Bi₂O₃/BiFeO₃ composite was 2.23, 3.65, and 8.71 times higher than that of BiFeO₃, Bi₂O₃ and commercial TiO₂ (P25), respectively. Bi₂O₃/BiFeO₃ showed high photocatalytic activity after three cycles, suggesting that it was a stable photocatalyst. The possible photocatalytic mechanism has been discussed on the basis of the theoretical calculation and the experimental results. The hydroxyl and superoxide radicals together with photogenerated holes played significant roles in the photocatalytic reaction.