A mini review on the generation of crimped ultrathin fibers via electrospinning: Materials,strategies, and applications

Structures modification of fibers has been attracting significant attention in various fields and applications. Among different techniques of fabricating ultrathin fibers, electrospinning is the most commonly adopted method because of the ease of forming fibers with a wide range of properties and its exceptional advantages, such as the ability to spin into different shapes and sizes, as well as the adaptable porosity of electrospun fiber webs. The crimped structure has been attracting the attention of scientific researchers owing to its unique properties (eg, spring‐like behavior, supreme strain, remarkable specific surface area, good piezoelectric properties, excellent biological properties, and so on). Therefore, this study summarizes a review of the strategies and methods, reported so far, of generating electrospun crimped ultrathin fibers of various polymers. The review focuses on the polymer types, formation methods, characterizations, and applications of the electrospun crimped ultrathin fibers. We believe this work can serve as an important reference for the materials, strategies, and applications of crimped fibers.     

基于静电纺丝技术的多级结构聚合物纳米纤维复合材料的研究进展

静电纺丝技术是目前制备纳米纤维最重要的方法之一,以其制备的纤维具有直径可控、比表面积大、孔隙率高等优点,因而被广泛应用于过滤、催化、传感器及生物医学等众多领域.以静电纺丝纤维为模板可进一步构建多级结构的功能性聚合物纳米纤维复合材料,拓宽其应用范围.本文着重概述了近年来基于静电纺丝技术的简单共混型、核壳结构及多级结构的聚合物纳米纤维复合材料的制备、结构及性能,并展望了其应用研究前景.     

Proton Affinity at the Porous Surface of SiO2-TiO2 Binary Oxides

SiO₂-TiO₂ binary oxides are typically used as solid supports for different applications, from catalysts to optics. Tailoring the pore diameter, pore size distribution, and surface area is of great importance for any of those applications. Tailoring the chemical properties of the porous surface, e.g. in terms of polarity or acidity, is of capital importance as well. Thus, in catalytic applications or in sensing devices, where diffusion of a solute through the matrix is required, the affinity/compatibility of the solute with the matrix porous surface will determine the proper work of the device. Moreover, when the sensor is based on the adsorption of an active organic molecule or biomolecule on the porous surface matrix, the proton concentration at the surface may also modify the behavior of the active molecule. In this work, the proton affinity of the porous surface is tailored by the preparation of number of SiO₂-TiO₂ binary oxides with different SiO₂/TiO₂ weight ratios. Proton affinity is studied through the incorporation of a pH indicator as bromocresol green.     

Microemulsion method: A novel route to synthesize organic and inorganic nanomaterials: 1st Nano Update

Synthesis of nanoparticles by microemulsion method is an area of considerable current interest. Since the discovery of microemulsions, they have attained increasing significance both in basic research and in different industrial fields. Due to their unique properties, namely, ultralow interfacial tension, large interfacial area, thermodynamic stability and the ability to solubilize otherwise immiscible liquids. The uses and applications of microemulsions are numerous in chemical and biological fields. The nanoparticles not only are of basic scientific interest, but also have resulted in important technological applications, such as catalysts, high-performance ceramic materials, microelectronic devices, high-density magnetic recording and drug delivery. The microemulsion technique promises to be one of the versatile preparation method which enables to control the particle properties such as mechanisms of particle size control, geometry, morphology, homogeneity and surface area. This review aims to give a vivid look on the use of microemulsions for synthesizing and controlling the grain size and morphology of the nanoparticles and at the same time will summarize some recent works carried out in the synthesis of organic and inorganic nanoparticles by this method.     

Thiophene-Based Covalent Organic Frameworks: Synthesis,Photophysics and Light-Driven Applications

Porous crystalline materials, such as covalent organic frameworks (COFs), have emerged as some of the most important materials over the last two decades due to their excellent physicochemical properties such as their large surface area and permanent, accessible porosity. On the other hand, thiophene derivatives are common versatile scaffolds in organic chemistry. Their outstanding electrical properties have boosted their use in different light-driven applications (photocatalysis, organic thin film transistors, photoelectrodes, organic photovoltaics, etc.), attracting much attention in the research community. Despite the great potential of both systems, porous COF materials based on thiophene monomers are scarce due to the inappropriate angle provided by the latter, which hinders its use as the building block of the former. To circumvent this drawback, researchers have engineered a number of thiophene derivatives that can form part of the COFs structure, while keeping their intrinsic properties. Hence, in the present minireview, we will disclose some of the most relevant thiophene-based COFs, highlighting their basic components (building units), spectroscopic properties and potential light-driven applications.     

三维MXene多孔结构的构建与应用研究进展

MXene作为一种新型二维（2D）纳米材料以其独特的高导电性、高电化学表面活性等特性在多个领域引起了广泛关注。然而,MXene纳米片在自组装过程中出现的紧密堆叠现象导致比表面积急剧下降,降低了活性表面积,从而严重阻碍了它们在能源储存、电磁屏蔽、吸附等领域的潜在应用。构建三维多孔结构是解决MXene组装过程中自堆叠问题的一种有效途径,而且通过不同的组装方法可以实现对多孔宏观结构组成成分、孔径分布以及孔径大小的调控,使得MXene多孔材料在机械性能、电学性能以及光热转换性能等方面得到更好的调整,从而满足不同应用领域的需求。本综述以Ti₃C₂T_x MXene为主要研究材料总结了各种多孔MXene宏观结构的制备方法,讨论了其在电池/超级电容器、电磁屏蔽与吸收、海水淡化、光催化以及传感和环境修复等方面的应用,阐述了MXene多孔结构在各种应用中的贡献与意义,并针对MXene多孔结构的制备、结构调控和应用等方面的机遇和挑战作了论述。     

Post-Synthetic Modification of ZIF-8 Crystals and Films through UV Light Photoirradiation: Impact on the Physicochemical Behavior of the MOF

The physicochemical modification of Metal-Organic Frameworks (MOFs) is a current challenge in the search to improve their performance in different technological applications. In this work we analyze the post-synthetic modification of ZIF-8 crystals and films through a simple and clean treatment that involves the exposure to a UV lamp under environmental conditions. It is demonstrated that a short treatment alters the MOF structure and chemistry, providing a modified ZIF-8 due to partial disconnections of its structure which increase the amount of terminal surface species such as Zn−OH and −C=N-H, but without compromising the overall MOF structure, specific surface area or thermal stability. Additionally, it leads to changes in several properties of the ZIF-8, such as its capacity to accumulate charge through pseudocapacitive processes, its interaction with nitric oxide and its light absorption behavior. This strategy of modifying ZIF-8 without the use of chemicals through a gentle disconnection of its own structure could open new perspectives of post-functionalization of crystals and films of ZIF-8 to be used in a wide range of applications.     

金属有机框架材料在分离分析领域的研究进展

金属有机框架材料是由金属离子节点和有机配体通过配位键连接形成的具有序多孔骨架的材料, 因其具有比表面积大、 孔隙可调及表面性质可控等优点而备受关注. 通过对有机配体和金属离子进行选择及对金属有机框架材料进行后修饰处理, 可实现对金属有机框架材料表面性质的调控, 以提升其选择性吸附及特异性识别等性能, 进而拓展其在分离分析等领域的应用. 本文从金属有机框架材料的表面性质调控出发, 介绍了其表面性质与分离分析性能的关系, 总结了近年来该领域的代表性工作, 并展望了金属有机框架材料在分离分析领域的应用前景.     

Protein adsorption isotherm behavior in hydrophobic interaction chromatography

The adsorption behavior of proteins in hydrophobic interaction chromatography (HIC) was evaluated by determining the isotherms of a wide range of proteins on various HIC resin systems. Parallel batch experiments were carried out with eleven proteins on three hydrophobic resins with different ligand chemistries and densities. The effects of salt concentration, resin chemistry and protein properties on the isotherms were also examined. The resulting isotherms exhibited unique patterns of adsorption behaviors. For certain protein-resin combinations, a "critical salt behavior" was observed where the amount of protein bound to the resin increased significantly above this salt concentration. Proteins that exhibited this behavior tended to be relatively large with more solvent accessible hydrophobic surface area. Further, calculations indicated that under these conditions the occupied surface area of the adsorbed protein layer could exceed the accessible surface area. The establishment of unique classes of adsorption behavior may shed light on our understanding of the behavior of proteins in HIC systems.     

Electrochemical Sensors Continuously Monitor Magnesium Biodegradation under Cell Culture Conditions

Magnesium (Mg) and its alloys have increasingly been considered as implant materials for orthopedic, craniofacial, and cardiovascular applications. These materials generally have mechanical properties close to those of human bone and they biodegrade in aqueous environments. The biodegradation properties can be tailored to fit the desired application by changing the alloying elements and/or by addition of surface coatings. To test and compare the biodegradation properties of different materials, immersion tests in solutions ranging from simple salt solutions to complex biological media are commonly done that yield some information about the biodegradation rate and the biodegradation products on the surface after completion of the test. Here we report on a method that allows the continuous real‐time monitoring of the biodegradation process using electrochemical sensors for pH and H₂ during immersion of Mg samples in the cell culture medium DMEM/F12 with different concentrations of fetal bovine serum and in the presence of living cells. The sensors effectively indicated the biodegradation behavior of Mg samples in real‐time. This system could be very useful for immersion tests and even supporting biocompatibility testing of implant materials.     

Nanoparticles: Properties,applications and toxicities

This review is provided a detailed overview of the synthesis, properties and applications of nanoparticles (NPs) exist in different forms. NPs are tiny materials having size ranges from 1 to 100 nm. They can be classified into different classes based on their properties, shapes or sizes. The different groups include fullerenes, metal NPs, ceramic NPs, and polymeric NPs. NPs possess unique physical and chemical properties due to their high surface area and nanoscale size. Their optical properties are reported to be dependent on the size, which imparts different colors due to absorption in the visible region. Their reactivity, toughness and other properties are also dependent on their unique size, shape and structure. Due to these characteristics, they are suitable candidates for various commercial and domestic applications, which include catalysis, imaging, medical applications, energy-based research, and environmental applications. Heavy metal NPs of lead, mercury and tin are reported to be so rigid and stable that their degradation is not easily achievable, which can lead to many environmental toxicities.     

表面活性剂的QSAR/QSPR研究进展*

本文综述了表面活性剂定量结构-活性/性质相关(QSAR/QSPR)研究的最新进展,以及相关结构描述符在表面活性剂QSAR/QSPR研究中的应用.重点介绍了表面活性剂的cmc和表面张力γ与分子结构的定量关系、离子型表面活性剂电荷分布的定量计算及其对胶体结构与性质的影响.对表面活性剂分子结构与活性/性质的定量相关研究的发展趋势进行了展望.     

正负离子表面活性剂复配系统*

正负离子表面活性剂复配系统,由于其带有相反电荷的离子头基间的强静电相互作用,具有强协同效应和高表面活性,在水溶液中可形成丰富的微观结构,表现出复杂的相行为。本文在相关研究的基础上,对于正负离子表面活性剂复配系统在表面（界面）性质,囊泡的制备及稳定性,虫状胶束的生成和性质,双水相系统的性质及其在萃取方面的应用,拟相分离模型、热力学胞腔模型、分子热力学模型及分子模拟等理论研究和作为模板合成纳米材料等方面的研究进展进行了综述。对于双水相系统的研究,指出了一些有待于进一步解决的问题。     

Synthesis,Properties, and Applications of Amino Acids Based Surfactants: A Review

Amino acids based surfactants belong to the class of surfactants with high biodegradability, low toxicity and excellent surface active properties. They possess excellent emulsifying, detergency properties and form fine lather. These surfactants are environment friendly, mild to skin and eyes, and have hard water tolerance. This article reviews types, synthesis, various surface properties such as cmc (critical micelle concentration), surface tension, phase behavior, Krafft temperature, and interfacial adsorption of these surfactants. The biological properties such as antimicrobial activity, aquatic toxicity, biodegradability and hemolytic activity have also been focused. The various applications of amino acid based surfactants in the area of life sciences such as gene transfection, formation of liposomes, and drug delivery systems have also been reviewed.     

Graphene Oxide-Based Stimuli-Responsive Platforms for Biomedical Applications

Graphene is a two-dimensional sp² hybridized carbon material that has attracted tremendous attention for its stimuli-responsive applications, owing to its high surface area and excellent electrical, optical, thermal, and mechanical properties. The physicochemical properties of graphene can be tuned by surface functionalization. The biomedical field pays special attention to stimuli-responsive materials due to their responsive abilities under different conditions. Stimuli-responsive materials exhibit great potential in changing their behavior upon exposure to external or internal factors, such as pH, light, electric field, magnetic field, and temperature. Graphene-based materials, particularly graphene oxide (GO), have been widely used in stimuli-responsive applications due to their superior biocompatibility compared to other forms of graphene. GO has been commonly utilized in tissue engineering, bioimaging, biosensing, cancer therapy, and drug delivery. GO-based stimuli-responsive platforms for wound healing applications have not yet been fully explored. This review describes the effects of different stimuli-responsive factors, such as pH, light, temperature, and magnetic and electric fields on GO-based materials and their applications. The wound healing applications of GO-based materials is extensively discussed with cancer therapy and drug delivery.     

Adsorption of dyes on carbon xerogels and templated carbons: influence of surface chemistry

The removal of textile dyes by adsorption onto carbon materials with extended mesoporosity is addressed in the present work. Two types of high surface area carbon adsorbents were prepared, namely a carbon xerogel and a templated carbon. Both materials were subsequently subjected to appropriate treatments in order to modify their surface chemistries, while keeping their textural properties relatively unchanged. The carbon adsorbents were extensively characterized by different techniques in order to correlate their adsorption performances with the corresponding surface properties. The behavior of the different materials was evaluated by determining equilibrium adsorption isotherms of two anionic dyes (Reactive Red 241 and Acid Blue 113) at different pH values. The results are compared with data previously obtained with commercial activated carbons subjected to the same treatments, and discussed in terms of the carbon surface chemistry and the interaction between the dye molecules and the adsorbent surface (dispersive and electrostatic interactions).     

The oil-absorbing property of polyhydroxyalkanoate films and its practical application: a refreshing new outlook for an old degrading material

Polyhydroxyalkanoates (PHAs) have attracted the attention of academia and industry because of their plastic-like properties and biodegradability. However, practical applications as a commodity material have not materialized because of their high production cost and unsatisfactory mechanical properties. PHAs are also believed to have high-value applications as an absorbable biomaterial for tissue engineering and drug-delivery devices because of their biocompatibility. However, research in these areas is still in its very early stages. The main problem faced by proponents of PHAs is the lack of a niche area where PHAs will be the most desired material in terms of its function during use rather than because of its eco-friendly virtues after use. Here, we report on the oil-absorbing property of PHA films and its potential applications. By comparing with some of the existing commercial products, the potential application of PHAs as cosmetic oil-blotting films is revealed for the first time. Besides having the ability to rapidly absorb and retain oil, PHA films also have a natural oil-indicator property, showing obvious changes in opacity following oil absorption. Surface analysis revealed that the surface structures such as porosity and smoothness exert great influence on the rapid oil-absorption properties of the PHA films. These newly discovered properties could be exploited to create a niche area for the practical applications of PHAs.     

Thin films of discotic liquid crystals and their applications

ABSTRACT

Discotic liquid crystals (DLCs) are considered as fascinating systems due to their unique property of self-assembly to yield different columnar structures. DLCs are organic semiconductors and create pathways for the development of numerous optical and electrical devices. The thin films of DLCs can be considered as low dimensional system which can exhibit remarkable optical and physical properties. In this article, we present a review on ultrathin films of some interesting DLC molecules at air–water and air–solid interfaces. The Langmuir monolayer and Langmuir–Blodgett films of DLC molecules are extensively studied. The ultrathin films of DLC molecules can yield highly anisotropic layer wherein the molecular orientation and aggregation can have large impact on the physicochemical properties of the film. Different surface phases with different molecular orientations as function of surface density and temperature can be obtained by forming the Langmuir monolayer of the DLC molecules at the air–water interface. The Langmuir monolayer in a particular phase can be deposited onto the active area of a device layer-by-layer by employing a highly controlled Langmuir–Blodgett technique. Here, we report some interesting results related on molecular orientation of the DLC molecules at different interfaces. Such aggregation of DLC molecules in ultrathin films may find applications in thin film-based electro-optical devices.     

Bioinert surface to protein adsorption with higher generation of dendrimer SAMs

Interactions between proteins and biomaterial surfaces correlate with many important phenomena in biological systems. Such interactions have been used to develop various artificial biomaterials and applications, in which regulation of non-specific protein adsorption has been achieved with bioinert properties. In this research, we investigated the protein adsorption behavior of polymer brushes of dendrimer self-assembled monolayers (SAMs) with other generations. The surface adsorption properties of proteins with different pI values were examined on gold substrates modified with poly(amidoamine) dendrimer SAMs. The amount of fibrinogen adsorption was greater than that of lysozyme, potentially because of the surface electric charge. However, as the generations increased, protein adsorption decreased regardless of the surface charge, suggesting that protein adsorption was also affected by density of terminal group.