Recent progress in electrospun nanofibers: Reinforcement effect and mechanical performance

Composite materials are becoming increasingly important as structural materials for aeronautical and space engineering, naval, automotive, and civil engineering, sporting goods, and other consumer products. Fiber‐based reinforcement represents one of the most effective manufacturing strategies for enhancing the mechanical strength and other properties of composite materials. Electrospinning has gained widespread interest in the last two decades because of its ability to fabricate continuous ultrafine nanofibers with unique characteristics. The impact of electrospinning on fiber synthesis and processing, characterization, and applications in drug delivery, nanofiltration, tissue scaffolding, and electronics has been extensively studied in the past. In this article, the authors have focused on a comprehensive review of the mechanical performance and properties of electrospun nanofibers as potential reinforcements as well as their advanced nanocomposites. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1171–1212     

Recent progress in conductive polymeric materials for biomedical applications

Advanced polymeric materials undoubtedly constitute one of the most promising classes of new materials due to their intriguing electronic, optical, and redox properties. The incredible progress in this area has been driven by the development of novel synthetic procedures owing to the emergence of nanotechnology and by the large array of applications. In particular, hybridization of polymeric materials with nanomaterials has allowed the production of promising functional materials with tailored properties and functionalities for targeted biomedical applications. Consequently, sufficient researchers have carried out imperative studies on these advanced polymeric materials over the last decade. Beyond scientific and fundamental interest, such advanced materials are conspicuous from technological perspectives as well. In this review, we accentuate the proliferation of advanced polymeric materials in diverse biomedical applications.     

Resorbable polymer electrospun nanofibers: History,shapes and application for tissue engineering

Resorbable polymer electrospun nanofiber-based materials/devices have high surface-to-volume ratio and often have a porous structure with excellent pore interconnectivity,which are suitable for growth and development of different types of cells.Due to the huge advantages of both resorbable polymers and electrospun nano fibers,re sorbable polymer electrospun nanofibers(RPENs)have been widely applied in the field of tissue engineering.In this paper,we will mainly introduce RPENs for tissue engineering.Firstly,the electrospinning technique and electrospun nanofiber architectures are briefly introduced.Secondly,the application of RPENs in the field of tissue engineering is mainly reviewed.Finally,the advantages and disadvantages of RPENs for tissue engineering are discussed.This review will provide a comprehensive guide to apply resorbable polymer electrospun nanofibers for tissue engineering.     

Recent progress in carbon-dots-based nanozymes for chemosensing and biomedical applications

Nanozymes are nanomaterials with enzyme-like activities that efficiently overcome the drawbacks of natural enzymes in biosensing, detection, and biomedical fields, and they are the most widely used artificial enzymes. Owing to their excellent catalytic characteristics, biocompatibility, and environmental favorability, carbon-dots-based (CDs) nanozymes have inspired a research upsurge. However, no review focusing on CDs nanozymes has been published, even though substantial advances have been achieved. Herein, the advances, catalytic activities, and applications of CDs nanozymes are highlighted and summarized. In addition, the critical issues and challenges of researching nanozymes are discussed. We hope that this review will broaden the horizons of nanozymes and CDs nanozymes, as well as promote their development.     

Polymer entanglement loss in extensional flow: Evidence from electrospun short nanofibers

High strain rate extensional flow of a semidilute polymer solution can result in fragmentation caused by polymer entanglement loss, evidenced by appearance of short nanofibers during electrospinning. The typically desired outcome of electrospinning is long continuous fibers or beads, but, under certain material and process conditions, short nanofibers can be obtained, a morphology that has scarcely been studied. Here we study the conditions that lead to the creation of short nanofibers, and find a distinct parametric space in which they are likely to appear, requiring a combination of low entanglement of the polymer chains and high strain rate of the electrospinning jet. Measurements of the length and diameter of short nanofibers, electrospun from PMMA dissolved in a blend of CHCl₃ and DMF, confirm the theoretical prediction that the fragmentation of the jet into short fibers is brought about by elastic stretching and loss of entanglement of the polymer network. The ability to tune nanofiber length, diameter and nanostructure, by modifying variables such as the molar mass, concentration, solvent quality, electric field intensity, and flow rate, can be exploited for improving their mechanical and thermodynamic properties, leading to novel applications in engineering and life sciences. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1377–1391     

Tensile versus AFM testing of electrospun PVA nanofibers: Bridging the gap from Microscale to nanoscale

Design and application of mechanically extraordinary nanofibers requires their full comprehension, based on conclusive testing methods. Electrospun polymer nanofibers, for instance, show a progressive and pronounced increase in their Young's moduli when diameters decrease below the µm scale. Measurement of mechanical properties in this diameter range is challenging and in the vast majority of reports, two classes of methods are commonly used: highly sensitive tensile testing and atomic force microscopy three‐point deformation testing. Despite the methods' inherent dissimilarity, we resolve their conformity for the first time, with respect to the determination of Young's moduli. Here, we benchmark them against each other for electrospun polyvinyl‐alcohol nanofibers, a well‐defined model system. Our results provide an experimental basis for a comprehensive understanding of nanofiber structures and its implications on their mechanical properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2418–2424     

Decoration of electrospun polyacrylonitrile nanofibers with ZnO nanoparticles and their application for removal of Pb ions from waste water

The adsorption behavior of lead (II) from aqueous solutions utilizing ZnO/polyacrylonitrile (PAN) nanofibers was studied. ZnO/PAN nanofibers were prepared by electrospinning method. The changes of the parameters of adsorbent amount, pH, contact time, and temperature were tested in the adsorption experiments. The adsorption was well described by the Langmuir adsorption isotherm model. The thermodynamic parameters indicate that the adsorption process is exothermic. The dynamic behavior of the lead (II) ions adsorption by PAN/ZnO nanofibers was well described by the pseudo-second-order kinetic model. The adsorbent can be regenerated by suitable desorption processes for multiple uses without significant loss of its adsorption capacity.     

Generation of activated carbon nanofibers from electrospun polyacrylonitrile-zinc chloride composites for use as anodes in lithium-ion batteries

Activated carbon nanofibers (CNFs) with large surface areas and small pores were prepared by electrospinning and subsequent thermal and chemical treatments. These activated CNFs were examined as anodes for lithium-ion batteries (LIBs) without adding any non-active material. Their electrochemical behaviors show improved lithium-ion storage capability and better cyclic stability compared with unactivated counterparts. The results demonstrate that the unique structures and properties of these materials make them promising candidates as anodes in LIBs.     

Recent progress in the application of analytical techniques to anticancer metallodrug proteomics

Interactions of therapeutic drugs containing metals with proteins are known to exert a great impact on the mode of action of these compounds, including drug metabolism, delivery, cell processing, and targeting. Modern analytical techniques applied to proteomic studies of metallodrugs may improve our understanding of accompanying biochemical processes, which is essential for the efficiency of treatment, the proper dosing of established metal-based cancerostatic agents, and the design and development of new drugs. Such methods basically rely on the application of mass spectrometry (or a few alternative detection techniques) for species identification, characterization, quantification, and measuring the binding parameters, directly or after separation of free parent drug and protein-bound drug fractions, using the principles of electrophoresis, chromatography or ultrafiltration.This review focuses on the development and recent advances in the field of “metallodrug proteomics” from the implementation of advanced analytical methodologies. Also addressed are emerging issues of metallodrug binding toward cellular protein targets and within real-world biological samples.     

Recent progress in the application of atomic force microscopy for supported lipid bilayers

In the past two decades, atomic force microscopy has been widely used for studying supported lipid bilayer related research, including the structure and dynamics of membranes and membrane proteins, and the interaction of membranes with chemical and biological molecules. The focus of this minireview is on the recent progress in the application of atomic force microscopy for supported lipid bilayers. Such progress mainly includes the application in the following aspects: submolecular-resolution imaging, in situ observation, and nanomechanics measurement.     

Enhanced conductivity composites for aircraft applications: carbon nanotube inclusion both in epoxy matrix and in carbonized electrospun nanofibers

The potential of carbonized electrospun nanofiber mats to render epoxy resin composites for aircraft applications electrically and thermally more conductive was investigated. The effect of carbon nanotube inclusion both inside the carbon nanofiber and in the epoxy resin matrix material was studied, in order to reveal any synergistic effects of multilevel presence of nanosized reinforcements on the conductivity and mechanical properties. The carbon nanotube inclusion into the carbonized nanofibers increased the electrical conductivity of the samples by 20–50% and the thermal conductivity by approximately three times leading to a higher value than that of the conventional composites. The preparation of layered composites with a conductive upper layer containing nonwoven carbon nanofabric and a load bearing lower layer with conventional unidirectional carbon fiber reinforcement can offer a cost‐effective and weight‐saving solution for the replacement of metal meshes in structural aircraft composites. Copyright © 2014 John Wiley & Sons, Ltd.     

Bioconjugation of alkaline phosphatase to mechanically processed, aqueous suspendible electrospun polymer nanofibers for use in chemiluminescent detection assays

Aqueous suspendible polymer nanostructures were prepared by simple microtome processing of electrospun nylon 6 nanofibers and were used to immobilize calf intestinal alkaline phosphatase (ALP) by either covalent or noncovalent bioconjugation chemistries. It was found that noncovalent immobilization of ALP to the mechanically cut nanofibers (mean length approximately 4 microm; mean diameter approximately 80 nm) using a multi-stacked, layer-by-layer (LBL) approach with the cationic polymer Sapphire II resulted in the highest enzyme loading (48.1 +/- 0.4 microg . mg(-1) nanofiber) when compared to other covalent immobilization methods based on glutaraldehyde crosslinking. The biofunctionalized nanofibers were also characterized for their chemiluminescent activity with the dioxetane substrate, CSPD. The results indicate that the kinetic parameters, K(m) and V(max), for the catalytic activity of the nanostructure-bound ALP enzyme were influenced by the particular types of immobilization methods employed. In terms of the overall catalytic performance of the various immobilized ALP systems, a single-stacked LBL assembly approach resulted in the highest level of enzymatic activity per unit mass of nanofiber support. To the best of our knowledge, this study represents the first report examining the preparation of mechanically shortened, aqueous dispersed electrospun polymer nanofibers for potential application as enzyme scaffolds in chemiluminescent-based assay systems.     

Recent progress in the application of in situ atomic force microscopy for rechargeable batteries

High energy density batteries are urgently required for sustainable life. The intrinsic understanding of the reaction mechanism at the interfaces is essential for the progress. In this short overview, recent advances in rechargeable batteries by in situ atomic force microscopy are summarized, providing nanoscale information on the solid product evolution and metal plating/stripping inside working batteries. Besides, the multifunctional imaging of the morphology along with mechanical and electrical properties can be achieved to assist further interfacial design. Extensive applications of in situ atomic force microscopy are encouraged to explore the electrochemical mechanism and advanced engineering.     

Rehydratable agarose gels: application to isoelectric focusing in 9 molar urea

A method is described for the preparation of rehydratable agarose gels, with specific application to the direct incorporation of 9 M urea and carrier ampholytes into rehydratable agarose gels for use in isoelectric focusing. After drying the agarose gel containing an uncharged linear polyacrylamide, one gel volume of a 9 M urea-carrier ampholyte solution is absorbed directly into the gel in 60 min, eliminating equilibration or dialysis of the gel in larger volumes of the 9 M urea-carrier ampholyte solution. Proteins with a molecular mass of 970,000 Da can be separated by isoelectric focusing in these rehydratable gels. The focused proteins can then be quantitatively transferred to nitrocellulose in less than 10 min, and any immunostaining procedure can be used to probe the blotted proteins. These agarose gels are easy to make, they rehydrate rapidly and they can be used in applications other than isoelectric focusing.     

二氧化碳的间接利用:碳酸乙烯酯应用研究进展

以二氧化碳(CO2)为主的温室气体排放所导致的全球气候和生态系统变异问题正得到普遍重视,全球CO2年排放量已达数百亿吨[1].控制CO2排放量,对其回收、固定、利用及再资源化,已成为世界各国严重关切的问题.同时,从资源化角度出发,CO2是世界上最为丰富和廉价的碳一(C1)资源[2,3],因此,大力发展二氧化碳的绿色化利用技术,开发绿色高新精细化工产业链,提高产品的附加值,具有重要的意义.     

Recent progress of astatine-211 in endoradiotherapy: Great advances from fundamental properties to targeted radiopharmaceuticals

Astatine-211 (²¹¹At, t_1/2 = 7.21 h) emitting two α particles with energies of 5.87 and 7.45 MeV, can lead to a high linear energy transfer (LET = 98.84 keV/µm) and short tissue range (50～90 µm). Since the 1950s, ²¹¹At had stepped into endoradiotherapy and has always been regarded as one of the most promising α-emitters for targeted-alpha therapy (TAT) in various malignancies. In the past two decades, ²¹¹At related radiopharmaceuticals have achieved great progress in the studies of basic physicochemical properties of astatine, ²¹¹At labeling strategies, preclinical and clinical studies, producing profound effects in nuclear medicine. This work will give a panorama of ²¹¹At-related researches in the recent 20 years, which will cover both the fundamental insights of ²¹¹At radiochemistry and applied labeling compounds. It can provide some important hints for the studies of TAT and other radiopharmaceuticals applied in tumor radiotherapy.     

Recent progress in the development,characterization and application of polymeric pseudophases for electrokinetic chromatography

This review article details the development, characterization and application of polymeric materials as pseudostationary phases for electrokinetic chromatography over the past two years. Recent developments in cationic polymers and anionic siloxane, acrylamide and polymerized surfactants (micelle polymers) are reviewed. Also reviewed is recent progress in the development and characterization of chiral polymeric phases for chiral separations by electrokinetic chromatography, and application of a polymeric pseudophase with electrospray ionization mass spectrometric detection.     

Recent progress in the shape deformation of polymeric hydrogels from memory to actuation

Shape deformation hydrogels, which are one of the most promising and essential classes of stimuli-responsive polymers, could provide large-scale and reversible deformation under external stimuli. Due to their wet and soft properties, shape deformation hydrogels are anticipated to be a candidate for the exploration of biomimetic materials, and have shown various potential applications in many fields. Here, an overview of the mechanisms of shape deformation hydrogels and methods for their preparation is presented. Some innovative and efficient strategies to fabricate programmable deformation hydrogels are then introduced. Moreover, successful explorations of their potential applications, including information encryption, soft robots and bionomic systems, are discussed. Finally, remaining great challenges including the achievement of multiple stable deformation states and the combination of shape deformation and sensing are highlighted.

Shape deformation hydrogels, which are one of the most promising and essential classes of stimuli-responsive polymers, could provide large-scale and reversible deformation under external stimuli.     

Nanogel engineering for new nanobiomaterials: from chaperoning engineering to biomedical applications

Nanosize hydrogels (nanogels) are polymer nanoparticles with three‐dimensional networks, formed by chemical and/or physical cross‐linking of polymer chains. Recently, various nanogels have been designed, with a particular focus on biomedical applications. In this review, we describe recent progress in the synthesis of nanogels and nanogel‐integrated hydrogels (nanogel cross‐linked gels) for drug‐delivery systems (DDS), regenerative medicine, and bioimaging. We also discuss chaperone‐like functions of physical cross‐linking nanogel (chaperoning engineering) and organic‐inorganic hybrid nanogels. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.201000008     

Recent progress in methane dehydroaromatization: From laboratory curiosities to promising technology

Direct conversion of methane to benzene or other valuable chemicals is a very promising process for the efficient application of natural gas. Compared with conversion processes that require oxidants, non-oxidative direct conversion is more attractive due to high selectivity to the target product. In this paper, an alternative route for methane dehydrogenation and selective conversion to benzene and hydrogen without the participation of oxygen is discussed. A brief review of the catalysts used in methane dehydroaromatization (MDA) is first given, followed by our current understanding of the location and the active phase of Mo species, the reaction mechanism, the mechanism of carbonaceous deposit and the deactivation of Mo/zeolite catalysts are systematically discussed. Ways to improve the catalytic activity and stability are described in detail based on catalyst and reaction as well as reactor design. Future prospects for methane dehydroaromatization process are also presented.