bluuebunny/crossref_metadata_2025 huggingface dataset:
Designer Exosomes for Active Targeted Chemo‐Photothermal Synergistic Tumor Therapy
Authors: Wang Jie , Dong Yue , Li Yiwei , Li Wei , Cheng Kai , Qian Yuan , Xu Guoqiang , Zhang Xiaoshuai , Hu Liang , Chen Peng , Du Wei , Feng Xiaojun , Zhao Yuan‐Di , Zhang Zhihong , Liu Bi‐Feng
Published: March 2018

Exosomes, naturally derived nanovesicles secreted from various cell types, can serve as an effective platform for the delivery of various cargoes, because of their intrinsic ability such as long blood circulation and immune escapinge. However, unlike conventional synthetic nanoparticles, drug release from exosomes at defined targets is not controllable. Moreover, endowing exosomes with satisfactory cancer‐targeting ability is highly challenging. Here, for the first time, a biological and synthetic hybrid designer exosome is described with photoresponsive functionalities based on a donor cell‐assisted membrane modification strategy. Practically, the designer exosome effectively accumulates at target tumor sites via dual ligand‐mediated endocytosis. Then the localized hyperthermia induced by the conjunct gold nanorods under near‐infrared irradiation impacts the permeability of exosome membrane to enhance drug release from exosomes, thus inhibiting tumor relapse in a programmable manner. The designer exosome combines the merits of both synthetic materials and the natural nanovesicles. It not only preserves the intrinsic functionalities of native exosome, but also gains multiple abilities for efficient tumor targeting, controlled release, and thermal therapy like synthetic nanocarriers. The versatile designer exosome can provide functional platforms by engineering with more multifarious functionalities from synthetic materials to achieve individualized precise cancer therapy in the future.
Electrophoretic Nuclei Assembly for Crystallization of High‐Performance Membranes on Unmodified Supports
Authors: He Guangwei , Dakhchoune Mostapha , Zhao Jing , Huang Shiqi , Agrawal Kumar Varoon
Published: March 2018

Metal–organic framework (MOF) films have recently emerged as highly permselective membranes yielding orders of magnitude higher gas permeance than that from the conventional membranes. However, synthesis of highly intergrown, ultrathin MOF films on porous supports without complex support‐modification has proven to be a challenge. Moreover, there is an urgent need of a generic crystallization route capable of synthesizing a wide range of MOF structures in an intergrown, thin‐film morphology. Herein, a novel electrophoretic nuclei assembly for crystallization of highly intergrown thin‐films (ENACT) approach, that allows synthesis of ultrathin, defect‐free ZIF‐8 on a wide range of unmodified supports (porous polyacrylonitrile, anodized aluminum oxide, metal foil, porous carbon and graphene), is reported. As a result, a remarkably high H2 permeance of 8.3 × 10−6 mol m−2 s−1 Pa−1 and ideal gas selectivities of 7.3, 15.5, 16.2, and 2655 for H2/CO2, H2/N2, H2/CH4, and H2/C3H8, respectively, are achieved from an ultrathin (500 nm thick) ZIF‐8 membrane. A high C3H6 permeance of 9.9 × 10−8 mol m−2 s−1 Pa−1 and an attractive C3H6/C3H8 selectivity of 31.6 are obtained. The ENACT approach is straightforward, reproducible and can be extended to a wide range of nanoporous crystals, and its application in the fabrication of intergrown ZIF‐7 films is demonstrated.
Metal–Organic Framework as a Simple and General Inert Nanocarrier for Photosensitizers to Implement Activatable Photodynamic Therapy
Authors: Hu Fang , Mao Duo , Kenry  , Wang Yuxiang , Wu Wenbo , Zhao Dan , Kong Deling , Liu Bin
Published: March 2018

There has been a surging interest in the synthesis of activatable photosensitizers (PSs) as they can be selectively activated with minimum nonspecific phototoxic damages for photodynamic therapy (PDT). Conventional strategies to realize activatable PSs are only applicable to a limited number of molecules. Herein, a simple and general strategy to yield activatable PSs by coupling MIL‐100 (Fe) (MIL: Materials Institute Lavoisier) with different kinds of PSs is presented. Specifically, when PSs are encapsulated into MIL‐100 (Fe), the photosensitization capability is suppressed due to their isolation from O2. After the reaction between iron(III) in MIL‐100 (Fe) and H2O2 occurs, the framework of MIL‐100 (Fe) collapses and the encapsulated PSs regain contact with O2, leading to activation of photosensitization. In addition, the decomposition of H2O2 can generate O2 to relieve tumor hypoxia and enhance PDT effect. As O2 is an indispensable factor for PDT, the activation strategy should be generally applicable to different PSs for activatable PDT.
Nanofibered Gelatin‐Based Nonwoven Elasticity Promotes Epithelial Histogenesis
Authors: Jedrusik Nicole , Meyen Christoph , Finkenzeller Günter , Stark G. Björn , Meskath Stephan , Schulz Simon Daniel , Steinberg Thorsten , Eberwein Philipp , Strassburg Sandra , Tomakidi Pascal
Published: March 2018

Regarding tissue regeneration, mechanics of biomaterials gains progressive importance. Therefore, this study reports on in situ crosslinked electrospun gelatin nonwoven mats (NWMs) whose distinct modulus of elasticity (ME) promotes epithelial tissue formation in a graded manner. NWMs, comprising fiber diameters in various distributions, yield an ME of about 2.1, 3.2, and 10.9 kPa. A two‐step approach of preclinical in vitro validation identifies the elasticity of 3.2 kPa as superior to the other, regarding the histogenetic epithelial outcome. Hence, this 3.2 kPa candidate NWM is colonized with oral mucosal epithelial keratinocytes in the absence or presence of mesenchymal fibroblasts and/or endothelial cells. Evaluation of epithelial histogenesis at days 1 to 10 occurs by colorimetric and fluorescence‐based immunohistochemistry (IHCH) of specific biomarkers. These include cytokeratins (CK) 14, CK1, and involucrin that indicate different stages of epithelial differentiation, as well as the basement membrane constituent collagen type IV and Ki‐67 as a proliferation marker. Intriguingly, histogenesis and IHCH reveal the best resemblance of the native epithelium by the NWM alone, irrespective of other cell counterparts. These findings prove the gelatin NWM a convenient cell matrix, and evidence that NWM mechanics is important to promote epithelial histogenesis in view of prospective clinical applications.
Sonochemistry‐Assembled Stimuli‐Responsive Polymer Microcapsules for Drug Delivery
Authors: Li Zhanfeng , Wang Zonghua , Du Xiaoyu , Shi Chao , Cui Xuejun
Published: March 2018

Stimuli‐responsive polymer microcapsules (PMs) fabricated by the sonochemical method have emerged for developing useful drug delivery systems, and the latest developments are mainly focusing on the synthetic strategies and properties such as structure, size, stability, loading capacity, drug delivery, and release. There, the primary attribution of sonochemistry is to offer a simple and practical approach for the preparation of PMs. Structure, size, stability, and properties of PMs are designed mainly according to synthetic materials, implementation schemes, or specific demands. Numerous functionalities of PMs based on different stimuli are demonstrated: targeting motion in a magnetic field or adhering to the living cells with sensitive sites through molecular recognition, and stimuli‐triggered release including enzymatic catalysis, chemical reaction as well as physical or mechanical process. The current review discusses the basic principles and mechanisms of stimuli effects, and describes the progress in the application such as targeted drug systems and controlled drug systems, and also gives an outlook on the future challenges and opportunities for drug delivery and theranostics.
NanoTRAIL‐Oncology: A Strategic Approach in Cancer Research and Therapy
Authors: Shi Yesi , Pang Xin , Wang Junqing , Liu Gang
Published: March 2018

TRAIL is a member of the tumor necrosis factor superfamily that can largely trigger apoptosis in a wide variety of cancer cells, but not in normal cells. However, insufficient exposure to cancer tissues or cells and drug resistance has severely impeded the clinical application of TRAIL. Recently, nanobiotechnology has brought about a revolution in advanced drug delivery for enhanced anticancer therapy using TRAIL. With the help of materials science, immunology, genetic engineering, and protein engineering, substantial progress is made by expressing fusion proteins with TRAIL, engineering TRAIL on biological membranes, and loading TRAIL into functional nanocarriers or conjugating it onto their surfaces. Thus, the nanoparticle‐based TRAIL (nanoTRAIL) opens up intriguing opportunities for efficient and safe bioapplications. In this review, the mechanisms of action and biological function of TRAIL, as well as the current status of TRAIL treatment, are comprehensively discussed. The application of functional nanotechnology combined with TRAIL in cancer therapy is also discussed.
Nanomeshes at Liquid Interfaces: From Free‐Standing Hole Arrays toward Metal–Insulator–Metal Architectures
Authors: Stelling Christian , Retsch Markus
Published: March 2018

The superior optical properties of metamaterials often rely on hierarchical structures in the sub‐wavelength regime comprising stacks of individually patterned layers. For the fabrication of metamaterials in the visible regime, specific top‐down lithographic methods have been developed. These techniques, however, have several inherent drawbacks such the lack of scalability and low production speeds. Here, a simple and modular approach for the construction of multilayer metal–insulator–metal structures based on the transfer of metal nanohole arrays via liquid interfaces is demonstrated. Gold nanohole arrays are used as model systems that are prepared via nanosphere lithography on a zinc oxide sacrificial layer. Exploiting an interface mediated method, the prepared nanohole arrays are subsequently transferred onto arbitrary hydrophilic or hydrophobic substrates without compromising the high quality of the nanomeshes. Two approaches to stack such nanostructured layers with nanometer precision in a rapid way are demonstrated. Finally, the high mechanical stability of only 100 nm thick gold nanohole arrays allows for the preparation of free‐standing nanomeshes in the order of several hundreds of square‐micrometers.
vasQchip: A Novel Microfluidic, Artificial Blood Vessel Scaffold for Vascularized 3D Tissues
Authors: Kappings Vanessa , Grün Christoph , Ivannikov Darja , Hebeiss Isabella , Kattge Saskia , Wendland Ina , Rapp Bastian E. , Hettel Matthias , Deutschmann Olaf , Schepers Ute
Published: March 2018

To date, tissue engineering and organ‐on‐a‐chip devices become more powerful as replacements for animal testings in high throughput drug screenings. However, the majority of the devices are either based on static 2D or 3D cell cultures or on microfluidic channel systems that are usually rectangular and do not fit to the geometry of natural blood vessels. Therefore, a semicircular microfluidic blood vessel scaffold (vasQchip) with a surrounding microfluidic compartment for vascularized 3D cell culture was developed, which resembles the curvature of natural blood vessels. vasQchip is composed of a porous microchannel which is produced by micro‐thermoforming of polycarbonate membranes. The pores generated by ion track technology allow for the support of nutrients and gases as well as for the exchange of growth factors or immune cells with the surrounding compartment. Eventually the surrounding compartment can be used for the establishment of 3D cell cultures in order to reconstruct vascularized tissues. Here, the vasQchip for its biocompatibility is characterized to somatic primary cells, the diffusion of molecules through the artificial blood vessels and its suitability for 3D cell culture. In addition, shear stress and flow regimes are simulated in order to mimic the natural environment of vascularized tissues.
Tailoring Surface Frustrated Lewis Pairs of In2O3−x(OH)y for Gas‐Phase Heterogeneous Photocatalytic Reduction of CO2 by Isomorphous Substitution of In3+ with Bi3+
Authors: Dong Yuchan , Ghuman Kulbir Kaur , Popescu Radian , Duchesne Paul N. , Zhou Wenjie , Loh Joel Y. Y. , Ali Feysal M. , Jia Jia , Wang Di , Mu Xiaoke , Kübel Christian , Wang Lu , He Le , Ghoussoub Mireille , Wang Qiang , Wood Thomas E. , Reyes Laura M. , Zhang Peng , Kherani Nazir P. , Singh Chandra Veer , Ozin Geoffrey A.
Published: March 2018

Frustrated Lewis pairs (FLPs) created by sterically hindered Lewis acids and Lewis bases have shown their capacity for capturing and reacting with a variety of small molecules, including H2 and CO2, and thereby creating a new strategy for CO2 reduction. Here, the photocatalytic CO2 reduction behavior of defect‐laden indium oxide (In2O3−x(OH)y) is greatly enhanced through isomorphous substitution of In3+ with Bi3+, providing fundamental insights into the catalytically active surface FLPs (i.e., InOH···In) and the experimentally observed “volcano” relationship between the CO production rate and Bi3+ substitution level. According to density functional theory calculations at the optimal Bi3+ substitution level, the 6s2 electron pair of Bi3+ hybridizes with the oxygen in the neighboring InOH Lewis base site, leading to mildly increased Lewis basicity without influencing the Lewis acidity of the nearby In Lewis acid site. Meanwhile, Bi3+ can act as an extra acid site, serving to maximize the heterolytic splitting of reactant H2, and results in a more hydridic hydride for more efficient CO2 reduction. This study demonstrates that isomorphous substitution can effectively optimize the reactivity of surface catalytic active sites in addition to influencing optoelectronic properties, affording a better understanding of the photocatalytic CO2 reduction mechanism.
Reduction of Parasitic Capacitance in Indium‐Gallium‐Zinc Oxide (a‐IGZO) Thin‐Film Transistors (TFTs) without Scarifying Drain Currents by Using Stripe‐Patterned Source/Drain Electrodes
Authors: Lee Suhui , Chen Yuanfeng , Jeon Jaekwon , Park Chanju , Jang Jin
Published: March 2018

A new device structure of oxide thin‐film transistor (TFT) having lower overlap capacitance without scarifying the drain current is proposed. This can be used for high‐speed circuits and high frame rate displays using the conventional TFT manufacturing process. The existence of spreading currents in amorphous indium‐gallium‐zinc oxide (a‐IGZO) TFTs with stripe‐patterned source/drain (S/D) electrodes is demonstrated. The device performances of the a‐IGZO TFTs with various widths of stripe‐patterned S/D electrodes and open spaces between them are compared. The drain currents of the a‐IGZO TFTs are almost same when the width of open space changes from 0 to 10 µm because of the existence of spreading currents. The overlap capacitance between gate and S/D of the a‐IGZO TFTs can be significantly reduced without scarifying drain currents by using stripe‐patterned S/D electrodes. The operation frequency of the ring oscillator made of the TFTs with stripe S/D electrodes with 10 µm open space width is 2.5 times that made of the conventional a‐IGZO TFTs. This spreading current concept can be widely used for the design of oxide TFT array with low RC (resistance capacitance product) delay for high‐speed circuits.
Computational Studies of Electrode Materials in Sodium‐Ion Batteries
Authors: Bai Qiang , Yang Lufeng , Chen Hailong , Mo Yifei
Published: March 2018

Sodium‐ion batteries have attracted extensive interest as a promising solution for large‐scale electrochemical energy storage, owing to their low cost, materials abundance, good reversibility, and decent energy density. For sodium‐ion batteries to achieve comparable performance to current lithium‐ion batteries, significant improvements are still required in cathode, anode, and electrolyte materials. Understanding the functioning and degradation mechanisms of the materials is essential. Computational techniques have been widely applied in tandem with experimental investigations to provide crucial fundamental insights into electrode materials and to facilitate the development of materials for sodium‐ion batteries. Herein, the authors review computational studies on electrode materials in sodium‐ion batteries. The authors summarize the current state‐of‐the‐art computational techniques and their applications in investigating the structure, ordering, diffusion, and phase transformation in cathode and anode materials for sodium‐ion batteries. The unique capability and the obtained knowledge of computational studies as well as the perspectives for sodium‐ion battery materials are discussed in this review.
Experimental Studies on Work Functions of Li+ Ions and Electrons in the Battery Electrode Material LiCoO2: A Thermodynamic Cycle Combining Ionic and Electronic Structure
Authors: Schuld Stephan , Hausbrand René , Fingerle Mathias , Jaegermann Wolfram , Weitzel Karl‐Michael
Published: March 2018

The release of Li+ from stoichiometric LiCoO2 (LCO) – a typical battery electrode material – is investigated by means of thermionic emission. Analysis of the data leads to an ionic work function of wLi+(LCO) = 4.1 eV. Combination of this value with the electronic work function we− (LCO) = 5.1 eV, also measured in this work by photoelectron spectroscopy, and with information available from the literature allows the set up, for the first time, of a complete thermodynamic cycle for a Li//LiCoO2 battery. An open circuit cell voltage of 2.4 eV is derived in line with available literature information. The proof‐of‐principle study presented here provides experimental data on the binding energy values, i.e., chemical potentials, of Li+‐ions and electrons and thus of Li‐atoms in LiCoO2 as a battery cathode and is expected to open access to a better understanding and thus to a better design of battery materials.
In Situ Exfoliating and Generating Active Sites on Graphene Nanosheets Strongly Coupled with Carbon Fiber toward Self‐Standing Bifunctional Cathode for Rechargeable Zn–Air Batteries
Authors: Hang Chao , Zhang Jian , Zhu Jiawei , Li Wenqiang , Kou Zongkui , Huang Yunhui
Published: March 2018

The self‐standing electrode nanomaterials with highly effective bifunctional electrocatalysis for oxygen reduction and evolution reactions (ORR/OER) are important for practical applications in metal–air batteries. Herein, a defect‐enriched and pyridinic‐N (PN) dominated bifunctional electrocatalyst with novel core–shell architecture (DN‐CP@G) is successfully fabricated by in situ exfoliating graphene from carbon paper followed by high temperature ammonia treatment. Benefitting from its strongly coupled core–shell structure, abundant defective sites and high‐content PN dopants, the DN‐CP@G displays an excellent electrocatalytic (ORR and OER) activity and stability in alkaline media, which are comparable to commercial Pt/C and Ir/C catalysts. The experiment, and theoretical calculations demonstrate that the electrocatalytic activities of carbon materials strongly depend on their defective sites and PN dopants. By directly using DN‐CP@G as a self‐standing electrode, the assembled zinc–air battery demonstrates a high discharge performance and outstanding long‐term cycle stability with at least 250 cycles, which is much superior to the mixed Pt/C and Ir/C electrodes. Remarkably, the DN‐CP@G based all‐solid‐state battery also reveals a good discharge and cycle performance. A facile and cost‐efficient approach to prepare highly effective bifunctional self‐standing electrode is provided by in situ generation of active sites on carbon support for metal–air batteries.
Thermally Stable All‐Polymer Solar Cells with High Tolerance on Blend Ratios
Authors: Zhang Yannan , Xu Yalong , Ford Michael J. , Li Fangchao , Sun Jianxia , Ling Xufeng , Wang Yongjie , Gu Jinan , Yuan Jianyu , Ma Wanli
Published: March 2018

Tuning the blend composition is an essential step to optimize the power conversion efficiency (PCE) of organic bulk heterojunction (BHJ) solar cells. PCEs from devices of unoptimized donor:acceptor (D:A) weight ratio are generally significantly lower than optimized devices. Here, two high‐performance organic nonfullerene BHJ blends PBDB‐T:ITIC and PBDB‐T:N2200 are adopted to investigate the effect of blend ratio on device performance. It is found that the PCEs of polymer‐polymer (PBDB‐T:N2200) blend are more tolerant to composition changes, relative to polymer‐molecule (PBDB‐T:ITIC) devices. In both systems, short‐circuit current density (Jsc) is tracked closely with PCE, indicating that exciton dissociation and transport strongly influence PCEs. With dilute acceptor concentrations, polymer‐polymer blends maintain high electron mobility relative to the polymer‐molecule blends, which explains the dramatic difference in PCEs between them as a function of D:A blend ratio. In addition, polymer‐polymer solar cells, especially at high D:A blend ratio, are stable (less than 5% relative loss) over 70 d under continuous heating at 80 °C in a glovebox without encapsulation. This work demonstrates that all‐polymer solar cells show advantage in operational lifetime under thermal stress and blend‐ratio resilience, which indicates their high potential for designing of stable and scalable solar cells.
Sulfur/Oxygen Codoped Porous Hard Carbon Microspheres for High‐Performance Potassium‐Ion Batteries
Authors: Chen Mei , Wang Wei , Liang Xiao , Gong Sheng , Liu Jie , Wang Qian , Guo Shaojun , Yang Huai
Published: March 2018

Potassium‐ion batteries (KIBs) are very promising alternatives to lithium‐ion batteries (LIBs) for large‐scale energy storage. However, traditional carbon anode materials usually show poor performance in KIBs due to the large size of K ions. Herein, a carbonization‐etching strategy is reported for making a class of sulfur (S) and oxygen (O) codoped porous hard carbon microspheres (PCMs) material as a novel anode for KIBs through pyrolysis of the polymer microspheres (PMs) composed of a liquid crystal/epoxy monomer/thiol hardener system. The as‐made PCMs possess a porous architecture with a large Brunauer–Emmett–Teller surface area (983.2 m2 g−1), an enlarged interlayer distance (0.393 nm), structural defects induced by the S/O codoping and also amorphous carbon nature. These new features are important for boosting potassium ion storage, allowing the PCMs to deliver a high potassiation capacity of 226.6 mA h g−1 at 50 mA g−1 over 100 cycles and be displaying high stability by showing a potassiation capacity of 108.4 mA h g−1 over 2000 cycles at 1000 mA g−1. The density functional theory calculations demonstrate that S/O codoping not only favors the adsorption of K to the PCMs electrode but also reduces its structural deformation during the potassiation/depotassiation. The present work highlights the important role of hierarchical porosity and S/O codoping in potassium storage.
The trail of perfumes
Authors: Pereira Joana , Costa Patrícia , Coimbra Maria C. , Rodrigues Alírio E.
Published: March 2018

A methodology is proposed for modeling the diffusion of fragrances released from a moving source. First, we started with a one‐dimensional model considering molecular diffusion of α‐pinene in air as the only mass transport mechanism. The validation was performed in a diffusion tube, and a system was developed to move the scented source along the axial direction. Results showed that experimental data fitted well with the numerical simulation, suggesting this model as a valid tool to describe the trail of a fragrance released from a moving source for low Re of the order of 10. In the case of a person walking at the speed of 1.34 m/s in a room or corridor inside a building, three‐dimensional models are required and mass transport of the perfume to the surrounding air will be dominated by turbulent diffusion or eddy diffusion Dt which is two orders of magnitude higher than molecular diffusion. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2890–2897, 2018
Stereoselective Construction of Cisoidal Bisspiroacetal Frameworks through Magnesium Coordination of the Bilateral Acetal Oxygen Atoms
Authors: Yasukawa Yoshifumi , Tsuchikawa Hiroshi , Todokoro Yasuto , Murata Michio
Published: March 2018

The cisoid‐selective construction of a tricyclic bisspiroacetal framework was demonstrated using MgBr2 as a cisoid stabilizer through chelation of the oxygen atoms of lateral acetal rings in the cisoid configuration. The method was also successfully applied to substrates with different ring sizes and substituents. Thus, this method serves as a useful synthetic strategy for the total synthesis of bisspiroacetal‐containing natural products.
Avoiding Thiol Compound Interference: A Nanoplatform Based on High‐Fidelity Au–Se Bonds for Biological Applications
Authors: Hu Bo , Kong Fanpeng , Gao Xiaonan , Jiang Lulu , Li Xiaofeng , Gao Wen , Xu Kehua , Tang Bo
Published: March 2018

Gold nanoparticles (Au NPs) assembled through Au−S covalent bonds have been widely used in biomolecule‐sensing technologies. However, during the process, detection distortions caused by high levels of thiol compounds can still significantly influence the result and this problem has not really been solved. Based on the higher stability of Au−Se bonds compared to Au−S bonds, we prepared selenol‐modified Au NPs as an Au‐Se nanoplatform (NPF). Compared with the Au‐S NPF, the Au‐Se NPF exhibits excellent anti‐interference properties in the presence of millimolar levels of glutathione (GSH). Such an Au‐Se NPF that can effectively avoid detection distortions caused by high levels of thiols thus offers a new perspective in future nanomaterial design, as well as a novel platform with higher stability and selectivity for the in vivo application of chemical sensing and clinical therapies.
A Monoaryllead Trichloride That Resists Reductive Elimination
Authors: Olaru Marian , Kather Ralf , Hupf Emanuel , Lork Enno , Mebs Stefan , Beckmann Jens
Published: March 2018

Transmetallation of Pb(OAc)4with R2Hg (1), followed by treatment with HCl in Et2O, provided RPbCl3(2), the first kinetically stabilized monoorganolead trihalide that resists reductive elimination under ambient conditions. The kinetic stabilisation relies on an intramolecularly coordinating O‐donor substituent (R=6‐Ph2P(O)‐Ace‐5‐). The gram‐scale preparation of2was key for the synthesis of unsymmetrically substituted diaryllead dichlorides RR′PbCl2(3 a, R′=Ph;3 b, R′=4‐MeOC6H4;3 c, R′=4‐Me2NC6H4).
Structure and properties of porous poly(vinyl alcohol) hydrogel beads prepared through a physical–chemical crosslinking method
Authors: Liao Honghui , Liu Yuan , Wang Qi , Duan Wenfeng
Published: March 2018

Porous poly(vinyl alcohol) (PVA) hydrogel beads (PC beads) are potential microorganism carriers applied in wastewater treatment industries. However, improving the mechanical strength and stability of traditional PVA hydrogel beads in water is still a challenge. In this research, a new kind of PC bead was successfully prepared by a combination of physical and chemical crosslinking methods. The structures and properties of the PC beads and conventional PVA beads obtained by individual chemical (boric acid) or physical (cyclic freezing and thawing) processes were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and hydraulic stability testing. Compared with the conventional products, the PC beads displayed a more homogeneous and porous structure, bigger surface area, higher hydraulic stability, and better mechanical properties and showed better applicability for the water treatment field. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46402.
Morphology, drug release behavior, thermal, and mechanical properties of poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blends
Authors: Naghdi Sedeh Negar , Entezam Mehdi , Hassan Jafari Seyed , Khonakdar Hossein‐Ali , Abdouss Majid
Published: March 2018

Poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blends containing different amounts of PVP (0, 10, 25, 50, and 100 wt %) prepared by a solution casting method were characterized in terms of microstructure, thermal, and mechanical properties along with their drug release behavior. Fourier‐transform infrared spectroscopy results confirmed formation of hydrogen bonds between PEO and PVP. Although scanning electron microscopy micrographs showed no phase separation in the blends, the elemental analysis data obtained by energy dispersive X‐ray technique revealed partial miscibility between the blend components. The miscibility of the blend and degree of crystallinity of PEO component of the blend were decreased with increasing PVP content of the blend. The nucleating role of PVP in crystallization of PEO was confirmed by differential scanning calorimetry analysis. A synergistic effect on mechanical properties was obtained as a result of blending PVP with PEO. The results of curcumin release studies from the films indicated that, the blends have lower diffusion coefficients and slower drug release rate as compared to the neat PEO. Theoretical analysis of the drug release data using Peppas's model revealed that the kinetic of drug release from all the films is governed by a non‐Fickian diffusion mechanism. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46403.
Suspension polymerization of itaconic acid diesters
Authors: Chakraborty Sanjiban , Ju Lin , Galuska Alan A. , Moore Robert B. , Turner S. Richard
Published: March 2018

Dimethyl itaconate and dicyclohexyl itaconate monomers are polymerized successfully for the first time via suspension polymerization. The obtained polymers possess significantly higher molecular weights and more narrow polydispersities compared to itaconate polymers prepared in solution or in bulk. The yields of these polymers from the suspension process are higher than the polymers synthesized from bulk. Solution cast films of both polymers were too brittle for mechanical properties characterization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46417.
Design and study of the potential of crosslinked cationic polymers as drug delivery systems for dermal application
Authors: Kostova Bistra , Georgieva Dilyana , Dundarova Maria , Ivanova Sijka , Ivanova‐Mileva Krasimira , Tzankova Virginia , Christova Darinka
Published: March 2018

Crosslinked carriers based on cationic monomer [2‐(acryloyloxy)ethyl]trimethylammonium chloride or 2‐(dimethylamino)ethyl methacrylate were developed and investigated as new platform for ibuprofen transdermal delivery. Series of networks of varied composition and structure were synthesized and characterized by FTIR spectroscopy and following swelling kinetics in different solvents. Dermal safety tests to examine the skin irritation and sensitization potential of the network films were performed in vivo. Chosen network compositions were loaded with ibuprofen by swelling in its ethanol solution. The structures of the drug carriers were investigated by scanning electron microscopy. Ibuprofen release from the developed drug delivery systems was followed in phosphate buffer solution at 37 °C. The investigation proved the feasibility of the developed cationic copolymer networks as effective platforms with modified ibuprofen release for potential dermal application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46420.
High oxygen barrier multilayer EVOH/LDPE film/foam
Authors: Feng Jingxing , Li Zhenpeng , Olah Andrew , Baer Eric
Published: March 2018

High oxygen barrier film/foam system had been developed using multilayer coextrusion technology. The film/foams contained alternating ethylene–vinyl alcohol (EVOH) copolymer film layers and low‐density polyethylene (LDPE) foam layers. To ensure good adhesion and layer integrity, the LDPE was preblended with LDPE grafted maleic anhydride. The layered structure of film/foam was characterized by scanning electron microscopy. The film/foams showed adjustable density, oxygen permeability, and mechanical properties by changing the film and foam composition. Film/foam with 10% EVOH film layer was successfully thermoformed at room temperature. The cells in the foam layer were observed to deform during the mechanical forming process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46425.
N‐methylation in amino acids and peptides: Scope and limitations
Authors: Sharma Anamika , Kumar Ashish , Abdel Monaim Shimaa A. H. , Jad Yahya E. , El‐Faham Ayman , de la Torre Beatriz G. , Albericio Fernando
Published: March 2018

Active pharmaceutical ingredients (APIs) can be divided into two types, namely chemical and biological entities. Traditionally, the former has been associated with the so‐called small molecules. The revival of peptides in pharmaceutical industry results from their importance in many biological roles. However, low metabolic stability and the lack of oral availability of most peptides is the main drawback for peptide to fulfill that paradigmatic situation. In this regard, efforts are being channeled into addressing this issue by introducing restrictions into the flexible peptide backbone, mainly through N‐methyl amino acids (NMAAs) or development of small cyclic peptides. In many cases, both the above restrictions are combined with the aim to enhance oral availability. The synthesis of NMAAs is complex and their introduction into the peptide chain brings additional synthetic challenges and also sometimes leads to side‐reactions. Here we discuss the most efficient methods for the synthesis of NMAAs (either in solution or in solid phase) and also their introduction into peptide sequences. Special attention is also given to the detection of side reactions and the most efficient way to prevent them.