Design and Fabrication of a Biomimetic Nanochannel for Highly Sensitive Arginine Response in Serum Samples

Inspired from their biological counterparts, chemical modification of the interior surface of nanochannels with functional molecules may provide a highly efficient means to control ionic or molecular transport through nanochannels. Herein, we have designed and prepared a aldehyde calix[4]arene (C4AH), which was attached to the interior surface of a single nanochannel by using a click reaction, and that showed a high response for arginine (Arg). Furthermore, the nanofluidic sensing system has been challenged with complex matrices containing a high concentration of interfering sequences and serum. Based on this finding, we believe that the artificial nanochannel can be used for practical Arg‐sensing devices, and be applied in a biological environment.     

Engineering de novo membrane-mediated protein-protein communication networks

Mechanical properties of biological membranes are known to regulate membrane protein function. Despite this, current models of protein communication typically feature only direct protein-protein or protein-small molecule interactions. Here we show for the first time that, by harnessing nanoscale mechanical energy within biological membranes, it is possible to promote controlled communication between proteins. By coupling lipid-protein modules and matching their response to the mechanical properties of the membrane, we have shown that the action of phospholipase A(2) on acyl-based phospholipids triggers the opening of the mechanosensitive channel, MscL, by generating membrane asymmetry. Our findings confirm that the global physical properties of biological membranes can act as information pathways between proteins, a novel mechanism of membrane-mediated protein-protein communication that has important implications for (i) the underlying structure of signaling pathways, (ii) our understanding of in vivo communication networks, and (iii) the generation of building blocks for artificial protein networks.     

硅氧烷交联的咪唑基团功能化聚苯醚/聚四氟乙烯耐高温质子交换膜

以聚苯醚(PPO)为基体材料, 通过溴甲基化及咪唑基团功能化, 与聚四氟乙烯(PTFE)复合、 硅氧烷基团水解交联及磷酸掺杂, 制备了兼具高磷酸掺杂含量、 高质子电导率和良好机械性能的高温质子交换膜材料. 以甲基咪唑(MeIm)和咪唑基硅氧烷化合物(SiIm)为功能化试剂(其中咪唑基团提供了磷酸作用位点, 同时SiIm中的硅氧烷基团水解后得到Si—O—Si交联网络结构), 提高了膜材料的机械稳定性. 与PTFE的复合进一步增强了膜材料的机械强度. 结果表明, 复合膜具有较高的电导率和一定的机械强度. 当磷酸掺杂质量分数为242.5%时, PPO-50%SiIm-50%MeIm/PTFE复合膜在160 ℃不加湿条件下的电导率为0.09 S/cm, 室温下的断裂拉伸强度为3.6 MPa.     

Ion transport regulation through triblock copolymer/PET asymmetric nanochannel membrane:Model system establishment and rectification mapping

Controlling ions transport across the membrane at different pH environments is essential for the physiological process and artificial systems.Many efforts have been devoted to pH-responsive ion gating,while rarely systems can maintain the rectification in pH-changing environments.Here,a composite nanochannel system is fabricated,which shows unidirectional rectification with high performance in a wide pH range.In the system,block copolymer(BCP) and polyethylene te rephthalate(PET) are employed for the amphoteric nanochannels fabrication.Based on the composite system,a model is built for the theoretical simulation.Thereafter,rectification mapping is conducted on the system,which can provide abundant info rmation about the relations between charge distribution and ions transport prope rties.The proposed rectification mapping can definitely help to design new materials with special ion transport properties,such as high-performance membranes used in the salinity gradient power generation field.     

Ion Selectivity of Water Molecules in Subnanoporous Liquid-Crystalline Water-Treatment Membranes: A Structural Study of Hydrogen Bonding

We demonstrate hydrogen-bonded structures of water in self-organized subnanoporous water treatment membranes obtained using synchrotron-based high-resolution soft X-ray emission spectroscopy. The ion selectivity of these water treatment membranes is usually understood by the size compatibility of nanochannels in the membrane with the Stokes radius of hydrated ions, or by electrostatic interaction between charges inside the nanochannels and such ions. However, based on a comparison between the hydrogen-bonded structures of water molecules in the nanochannels of the water treatment membrane and those surrounding the ions, we propose a definite contribution of structural consistency among the associated hydrogen-bonded water molecules to the ion selectivity. Our observation delivers a novel concept to the design of water treatment membranes where water molecules in the nanochannel can be regarded as a part of the material that controls the ion selectivity.     

Agar-supported lipid bilayers — basic structures for biosensor design. Electrical and mechanical properties

The lipid bilayer is widely accepted as the basic structure of all biological membranes. Known as BLM (bilayer lipid membrane), it can be prepared artificially. Suitably modified, the BLM serves as a very appropriate model for biological membranes. Recent investigations have verified the high analytical potential of artificial lipid membranes. With a structure and composition almost identical to the lipid moiety of biomembranes, the BLM may serve as an ideal host for receptor molecules of biological origin, thus becoming a transducer which could “see” the environment the way the living cell does. For the construction of lipid bilayer based biosensors; however, stable, easy to prepare and long-lasting lipid membranes are required. With this aim in mind, we have prepared lipid bilayer membranes which use an agar gel as support. This as-BLM (agar-supported BLM) has been shown to possess the same electrical, mechanical and dynamic properties the conventional BLM is famous for, along with the benefits of long-term stability and considerably elevated breakdown voltages. Its preparation on the tip of an agar-filled Teflon tube of 0.5 mm diameter is easy and can be performed even by less-skilled personnel.

In an attempt of further miniaturization the concept of the as-BLM was applied to thin-film micro-systems manufactured by standard micro-electronic techniques. The result is a lipid bilayer system, which, while preserving all the essential properties of the bilayer lipid membrane, can serve as a basic building block for cheap, disposable biosensoric systems.     

Light‐Induced Ion Rectification in Zigzag Nanochannels

Ion transport through nanoporous systems has attracted broad interest due to its crucial role in physiological processes in living organisms and artificial bionic devices. In this work, a nanochannel system with a zigzag inner surface was fabricated by using a two‐step anodizing technique. The rectification performance of the zigzag channels was observed by I–V measurement in KCl solution. Unlike channels with asymmetric geometry, the mechanism was analyzed based on the “point effect” of charge distribution and “shape effect” of the zigzag channel. The current rectification ratio decreases from nearly 3.0 to 1.0 when the KCl concentration increased from 0.1 mm to 100 mm . The fabrication of different nanopore systems and exploration of novel mechanisms will help to develop biomimetic membranes for practical applications.     

Synthesis of novel perfluorosulfonamide monomers and their application

The novel perfluorosulfonamide monomers and their preparation methods have been developed. The ternary-copolymer membranes, utilizing the perfluorosulfonamide monomers as the cross-linking site, can be efficiently converted to the cross-linked membranes with the strictly controlled structure. The novel cross-linking method has proved to be effective for the improvement of the mechanical properties at high temperature, while keeping its high proton conductivity.     

支化型聚苯并咪唑高温质子交换膜的制备与性能研究

通过引入1,3,5-苯三酸作为支化结构,制备了一种新型的支化型聚醚聚苯并咪唑(OPBI)高温燃料电池质子交换膜,并对支化OPBI质子交换膜的磷酸掺杂率、抗氧化稳定性、机械性能以及质子传导率等一系列性质进行了深入研究.与线型聚苯并咪唑(PBI)相比,支化OPBI具有独特的三维空间结构,极大地提高了磷酸掺杂量,随着支化度的提高,磷酸掺杂率和质子传导率随之提高.支化度为9%时,聚合物的磷酸掺杂率高达9.2 PRU?1,质子传导率达到0.0314 S/cm.此外,支化OPBI膜的溶解性较线型PBI也有较大的改善,进一步提高了聚合物的可加工性.同时,支化OPBI膜的热稳定性和抗氧化稳定性也得到了一定程度的提高,虽然机械性能略有下降,但仍能满足高温燃料电池的使用要求.     

纳通道的物质传输特性及应用

近年来,随着材料科学、微纳加工技术和微纳尺度物质传输理论的发展,纳通道技术得到了越来越多的研究和关注。纳通道包括生物纳通道和人工纳通道,其孔径通常为1~100 nm。在这一尺度下,通道表面与通道内物质之间的作用概率大大增强,使得纳通道表现出许多与宏观体系不同的物质传输特性,例如通道表面电荷与通道内离子之间的静电作用产生了离子选择性,通道内电化学势的不对称分布产生了离子整流特性,物质传输过程中占据通道产生了阻塞脉冲特性等。纳通道中的这些物质传输特性在传感、分离、能源等领域具有广泛应用,例如通过对纳通道进行功能化修饰可以实现门控离子传输;利用亚纳米尺度的通道可以实现单分子传感;利用通道与传输物质之间的相互作用可以实现离子、分子、纳米粒子的分离;利用纳通道的离子选择性可以在通道内实现电荷分离,将不同形式的能量（如光、热、压力、盐差等）高效转化为电能。纳通道技术是化学、材料科学、纳米技术等多学科的交叉集合,在解决生物、环境、能源等基本问题方面具有良好的前景。该文综述了近10年来与纳通道物质传输理论以及纳通道技术应用相关的前沿研究,梳理了纳通道技术的发展过程,并对其在各个领域的应用进行了总结与展望。     

Preparation and characterization of inorganic–organic hybrid proton exchange membranes based on phosphorylated PVA and PEG-grafted silica particles

We reported proton-conducting membranes with novel microstructure based on partially phosphorylated poly(vinyl alcohol) (P-PVA) and polyethylene glycol (PEG) grafted silica (PEG-SiO₂) particles. The PEG-SiO₂ particles were synthesized through acid catalyzed hydrolysis and condensation reactions. The membranes were characterized for their mechanical, structural, morphological, and electrical properties by employing tensile test, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), impedance analyzer, respectively. In these membranes, P-PVA acts as the proton source and PEG act as the proton solvent. The PEG-riched phases in the hybrid membrane form continuous ionic conducting pathways and subsequently give high ionic conductivity. The results suggest that the obtained membrane shows good thermal stability, excellent mechanical property and high ionic conductivity, and the low-cost hybrid membrane can be a promising candidate for intermediate temperature fuel cell systems.     

Confinement Effect of Organic Nanotubes Toward Green Fluorescent Protein (GFP) Depending on the Inner Diameter Size

Transportation, release behavior, and stability of a green fluorescent protein (GFP, 3×4 nm) in self‐assembled organic nanotubes with three different inner diameters (10, 20, and 80 nm) have been studied in terms of novel nanocontainers. Selective immobilization of a fluorescent acceptor dye on the inner surface enabled us to not only visualize the transportation of GFP in the nanochannels but to also detect release of the encapsulated GFP to the bulk solution in real time, based on fluorescence resonance energy transfer (FRET). Obtained diffusion constants and release rates of GFP markedly decreased as the inner diameter of the nanotubes was decreased. An endo‐sensing procedure also clarified the dependence of the thermal and chemical stabilities of the GFP on the inner diameters. The GFP encapsulated in the 10 nm nanochannel showed strong resistance to heat and to a denaturant. On the other hand, the 20 nm nanochannel accelerated the denaturation of the encapsulated GFP compared with the rate of denaturation of the free GFP in bulk and the encapsulated GFP in the 80 nm nanochannels. The confinement effect based on rational fitting of the inner diameter to the size of GFP allowed us to store it stably and without denaturation under high temperatures and high denaturant concentrations.     

Preparation and Properties of Hybrid Silane-crosslinked Sulfonated Poly(aryl ether ketone)s as Proton Exchange Membranes

A series of novel organic-inorganic hybrid proton-conducting electrolyte membranes with silane-crosslinked sulfonated poly(aryl ether ketone)(SC-SPAEK) networks was prepared via a simple procedure that includes solution casting and acid treatment. The organosilicon pendants of the silane-grafted SPAEK, which were expected to serve as coupling and crosslinking agents, were found to play a key role in the homogenous dispersion of inorganic particles and improved the performance of hybrid membranes. The hybrid membranes exhibited enhanced proton conductivity, and SC-SPAEK/TiO2-4 showed an extremely high proton conductivity of 0.1472 S/cm at 100℃. The crosslinked hybrid membranes also demonstrated good chemical resistance, oxidative stability, and mechanical properties. The crosslinked hybrid membranes with excellent comprehensive performance may be a promising material for proton exchange membrane fuel cells.     

Aluminosilicate and aluminosilicate based polymer composites: Present status,applications and future trends

Aluminosilicates have traditionally been important materials for applications related to adsorbents, water softeners, catalysis and mechanical and thermal reinforcement due to their high surface area, excellent thermal/hydrothermal stability, high shape-selectivity and superior ion-exchange ability. Recently, their use as polymer fillers has allowed to increasingly extending their application range to innovative areas such as medical and biological fields as well as in sensors, filtration membranes, energy storage and novel catalysis routes. Further, the large versatility and tailoring possibilities of both filler and matrix indicates this area as one of the enabling key technologies of the near future.This work summarizes the main developments up to date in this increasingly interesting field, focuses on the main applications already developed as well as on the key challenges for the near future.     

Alkali-stable high-pI isoelectric membranes for isoelectric trapping separations

Alkali-stable, high-pI isoelectric membranes have been synthesized from quaternary ammonium derivatives of cyclodextrins and poly(vinyl alcohol), and bifunctional cross-linkers, such as glycerol-1,3-diglycidyl ether. The new, high-pI isoelectric membranes were successfully applied as cathodic membranes in isoelectric trapping separations in place of the hydrolytically more labile, polyacrylamide-based cathodic isoelectric membranes, and permitted the use of catholytes as alkaline as 1 M NaOH. The new high-pI isoelectric membranes have shown excellent mechanical stability, low electric resistance and long life times, even when subjected to electrophoresis with current densities as high as 80 mA/cm2.     

Conventional processes and membrane technology for carbon dioxide removal from natural gas:A review

Membrane technology is becoming more important for CO 2 separation from natural gas in the new era due to its process simplicity,relative ease of operation and control,compact,and easy to scale up as compared with conventional processes.Conventional processes such as absorption and adsorption for CO 2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance.Polymeric membranes are the current commercial membranes used for CO 2 separation from natural gas.However,polymeric membranes possess drawbacks such as low permeability and selectivity,plasticization at high temperatures,as well as insufficient thermal and chemical stability.The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives,especially inorganic membranes due to their higher thermal stability,good chemical resistance to solvents,high mechanical strength and long lifetime.Surface modifications can be utilized in inorganic membranes to further enhance the selectivity,permeability or catalytic activities of the membrane.This paper is to provide a comprehensive review on gas separation,comparing membrane technology with other conventional methods of recovering CO 2 from natural gas,challenges of current commercial polymeric membranes and inorganic membranes for CO 2 removal and membrane surface modification for improved selectivity.     

水通道蛋白启发下的人工水通道研究进展

受水通道蛋白(AQP)结构与功能启发,含有生物水通道或人工水通道(AWC)的仿生膜近年来取得了显著进展.借鉴AQP的传输特性,所制备的AWC获得了高度的选择性及水快速运输能力.通过对AQP的结构原型进行分析,对标AWC中H2O分子选择性和渗透特性,尝试提出了"门控效应"、"润湿效应"和"排队效应"3种效应,并对现有嵌入...     

Modification of collagen-chitosan membrane by oxidation sodium alginate and in vivo/ in vitro evaluation for wound dressing application

Collagen-chitosan (COL-CS) membranes materials without a cross-linking agent have poor mechanical properties. In this paper, COL-CS membranes were modified by a novel naturally-derived crosslinker, alginate dialdehyde (ADA) with different oxidation degree, and the COL-CS-ADA films were obtained. COL-CS-ADA films were characterized by Fourier transform attenuation total reflection infrared spectroscopy (ATR-FTIR), differential calorimetric scanning (DSC), thermogravimetric analysis (TG), tensile testing, and cross-link density testing. The modification of ADA exhibited positive effects on mechanical properties, the thermal stability of COL-CS membranes. The cross-linking degree between ADA and COL-CS membranes increased significantly with an increase in the oxidation degree. COL-CS-ADA films showed no cytotoxicity toward L929 fibroblasts and had good biocompatibility. The animal experiments showed that COL-CS-ADA film could promote wound healing.     

Comb-shaped 2-Methylimidazolium Poly(arylene ether sulfone) Anion Exchange Membranes with High Alkaline Stability

A series of comb-shaped poly(arylene ether sulfone)s containing pendant 2-methyl-3-alkylimidazolitun group(ImPAES-Cx,x=1,6,10)was prepared and characterized as novel anion exchange membranes.These Im-PAES-Cx membranes were obtained by benzylic bromination and imidazolium functionalization.The characteristic nano-phase separation structure was formed in membranes with longer alkyl side chains,as confmned by small-angle X-ray scattering.The nano-phase separation structures endowed ImPAES-Cx membranes with improved ionic conductivity,dimensional stability(at least 60% decrease water uptake and swelling ratio at 60℃)and mechanical properties,together with excellent alkaline stability.Especially,ImPAES-C6 membranes possessed enhanced hydroxide conductivity and chemical stability simultaneously.These results suggest that it is a feasible strategy to introduce appropriate length of alkyl side chains into anion exchange membranes(AEMs)to improve the performance.