Recent advances in functional nanostructures as cancer photothermal therapy.

Being a non-invasive and relatively safe technique, photothermal therapy has attracted a lot of interest in the cancer treatment field. Recently, nanostructure technology has entered the forefront of cancer therapy owing to its ability to absorb near-infrared radiation as well as efficient light to heat conversion. In this study, key nanostructures for cancer therapy including gold nanoparticles, magnetite iron oxide nanoparticles, organic nanomaterials, and novel two-dimensional nanoagents such as MXenes are discussed. Furthermore, we briefly discuss the characteristics of the nanostructures of these photothermal nanomaterial agents, while focusing on how nanostructures hold potential as cancer therapies. Finally, this review offers promising insight into new cancer therapy approaches, particularly in vivo and in vitro cancer treatments

A perspective on magnetic core–shell carriers for responsive and targeted drug delivery systems

Magnetic core–shell nanocarriers have been attracting growing interest owing to their physicochemical and structural properties. The main principles of magnetic nanoparticles (MNPs) are localized treatment and stability under the effect of external magnetic fields. Furthermore, these MNPs can be coated or functionalized to gain a responsive property to a specific trigger, such as pH, heat, or even enzymes. Current investigations have been focused on the employment of this concept in cancer therapies. The evaluation of magnetic core–shell materials includes their magnetization properties, toxicity, and efficacy in drug uptake and release. This review discusses some categories of magnetic core–shell drug carriers based on Fe2O3 and Fe3O4 as the core, and different shells such as poly(lactic-co-glycolic acid), poly(vinylpyrrolidone), chitosan, silica, calcium silicate, metal, and lipids. In addition, the review addresses their recent potential applications for cancer treatment.The authors would like to acknowledge Qatar University for funding the project: GCC Co-Fund Program Grant #GCC-2017-001 and student grant QUST-1-CAS-2019-36. The publication of this article was funded by the Qatar National Library.Scopu

Preparation and characterization of water-absorbing composite membrane for medical applications

The present work introduces a novel method for the formation of water absorbing composite membrane. The prepared composite is based on chitosan, carboxymethyl cellulose (CMC), and Montmorillonite. Prepared composite membrane exhibits high water absorbing and holding capacity with increasing clay content. The water absorbency was studied as a function of the hydrogel composition and the medium pH. Structure and morphologies of the prepared composite have been characterized by X-ray diffraction (XRD), and transmission electron microscope (TEM). TEM study showed that the formed membrane is homogenous and prepared uniformly.Keywords: Composite, clay, superabsorber, chitosan, carboxymethyl cellulose, composite membrane

PVA/Chitosan/Silver Nanoparticles Electrospun Nanocomposites: Molecular Relaxations Investigated by Modern Broadband Dielectric Spectroscopy

In this study, we used broadband dielectric spectroscopy to analyze polymer nanofibers of poly(vinyl alcohol)/chitosan/silver nanoparticles. We also studied the effect of incorporating silver nanoparticles in the polymeric mat, on the chain motion dynamics and their interactions with chitosan nanofibers, and we calculated the activation energies of the sub-Tg relaxation processes. Results revealed the existence of two sub-Tg relaxations, the first gets activated at very low temperature (−90 °C) and accounts for motions of the side groups within the repeating unit such as –NH2, –OH, and –CH2OH in chitosan and poly(vinyl alcohol). The second process gets activated around −10 °C and it is thought to be related to the local main chain segments’ motions that are facilitated by fluctuations within the glycosidic bonds of chitosan. The activation energy for the chitosan/PVA/AgNPs nanocomposite nanofibers is much higher than that of the chitosan control film due to the presence of strong interactions between the amine groups and the silver nanoparticles. Kramers–Krönig integral transformation of the ε′′ vs. f spectra in the region of the chitosan Tg helped resolve this relaxation and displayed the progress of its maxima with increasing temperature in the regular manner

Effect of flow-induced shear stress in nanomaterial uptake by cells: Focus on targeted anti-cancer therapy

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Recently, nanomedicines have gained a great deal of attention in diverse biomedical applications, including anti-cancer therapy. Being different from normal tissue, the biophysical microenvironment of tumor cells and cancer cell mechanics should be considered for the development of nanostructures as anti-cancer agents. Throughout the last decades, many efforts devoted to investigating the distinct cancer environment and understanding the interactions between tumor cells and have been applied bio-nanomaterials. This review highlights the microenvironment of cancer cells and how it is different from that of healthy tissue. We gave special emphasis to the physiological shear stresses existing in the cancerous surroundings, since these stresses have a profound effect on cancer cell/nanoparticle interaction. Finally, this study reviews relevant examples of investigations aimed at clarifying the cellular nanoparticle uptake behavior under both static and dynamic conditions

Melt Electrospinning Designs for Nanofiber Fabrication for Different Applications

Nanofibers have been attracting growing attention owing to their outstanding physicochemical and structural properties as well as diverse and intriguing applications. Electrospinning has been known as a simple, flexible, and multipurpose technique for the fabrication of submicro scale fibers. Throughout the last two decades, numerous investigations have focused on the employment of electrospinning techniques to improve the characteristics of fabricated fibers. This review highlights the state of the art of melt electrospinning and clarifies the major categories based on multitemperature control, gas assist, laser melt, coaxial, and needleless designs. In addition, we represent the effect of melt electrospinning process parameters on the properties of produced fibers. Finally, this review summarizes the challenges and obstacles connected to the melt electrospinning technique

Confined Interfacial Monomicelle Assembly for Precisely Controlled Coating of Single-Layered Titania Mesopores

The development of core-shell structures has been in great demand recently owing to their integrated functionalities. However, the progress in reliable coating of porous semiconductors remains unproductive. Here, we have demonstrated a confined interfacial monomicelle assembly method for controlled coating of ordered single-layered mesoporous TiO2. The coating method can be well controlled with tunable coated layers, mesopore size, and switchable coated surfaces. The resulting mesoporous TiO2 exhibit excellent electrochemical properties as a sodium-ion anode, which is attributed to their unique mesostructures associated with accessible high surface area and ultrathin layers. Such accurately designed mesoporous core-shell nanostructures are expected to provide a useful platform to produce numerous delicate core-shell nanostructures with integrated functionalities and mesoporosities for potential applications, such as catalysts, sensors, energy storage, and energy conversion. - 2019 Elsevier Inc.Mesoporous core-shell nanostructures have recently been receiving extensive scientific interest; however, reliable approaches for coating mesoporous materials still remain exciting challenges, except for amorphous silica. We report, for the first time, a confined interfacial monomicelle assembly method for controlled coating of anatase TiO2 with single-layered ordered mesopores on diverse surfaces, opening up the area of coating ordered mesoporous crystalline materials that possess mesopores originating from self-assembled surfactant instead of accumulated nanocrystals. This facile and repeatable methodology relies on the solvent-confinement effect of glycerol during the assembly process and monomicelle hydrogel preformation by selective evaporation of double-solvent precursors. This assembly process shows precise controllability and great versatility, endowing the coated TiO2 layers with highly tunable thickness, mesopore size, and switchable coated surfaces. The ultrathin monolayered mesopores of such mesoporous TiO2 shells, in combination with their high surface area and highly crystalline nature, afford them excellent rate capability and superior cyclability for sodium-ion storage. - 2019 Elsevier Inc.We have demonstrated a confined interfacial monomicelle assembly approach for accurately coating ordered monolayered TiO2 mesopores on diverse surfaces. By regulating the synthetic conditions, the coated mesoporous TiO2 layers can be well controlled with desired thickness, mesopore size, and switchable coated surfaces. The resulting monolayered mesoporous TiO2 exhibit excellent sodium-storage properties. This unique mesoporous TiO2 coating strategy affords great potential in constructing multicomponent nanostructures with mesoporosities for advanced technologies. - 2019 Elsevier Inc.This work is supported by the State Key Basic Research Program of China ( 2017YFA0207303 ), the National Natural Science Foundation of China ( 21733003 ), the Shanghai Leading Academic Discipline Project ( B108 ), and the Science and Technology Commission of Shanghai Municipality ( 17JC1400100 ). K.L. acknowledges the financial support by the China Scholarship Council ( 201806100112 ). A.E. acknowledges Qatar University under GCC Co-Fund Program grant GCC-2017-001

The isopropylation of naphthalene with propene over H-mordenite: The catalysis at the internal and external acid sites

The isopropylation of naphthalene (NP) with propene over H-Mordenite (MOR) was studied under a wide range of reaction parameters: temperature, propene pressure, period, and NP/MOR ratio. Selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) was observed at reaction conditions, such as at low reaction temperature, under high propene pressure, and/or with high NP/MOR ratio. However, the decrease in the selectivities for 2,6-DIPN was observed at reaction conditions such as at high temperature, under low propene pressure, and/or with low NP/MOR ratio. The selectivities for 2,6-DIPN in the encapsulated products were remained high and constant under all reaction conditions. These results indicate that the selective formation of 2,6-DIPN occurs through the least bulky transition state due to the exclusion of the bulky isomers by the MOR channels. The decrease in the selectivities for 2,6-DIPN are due to the isomerization of 2,6-DIPN to 2,7-DIPN at the external acid sites, directing towards thermodynamic equilibrium of DIPN isomers

Synthesis, characterization, and antimicrobial properties of novel double layer nanocomposite electrospun fibers for wound dressing applications

Herein, novel hybrid nanomaterials were developed for wound dressing applications with antimicrobial properties. Electrospinning was used to fabricate a double layer nanocomposite nanofibrous mat consisting of an upper layer of poly(vinyl alcohol) and chitosan loaded with silver nanoparticles (AgNPs) and a lower layer of polyethylene oxide (PEO) or polyvinylpyr- rolidone (PVP) nanofibers loaded with chlorhexidine (as an antiseptic). The top layer containing AgNPs, whose purpose was to protect the wound site against environmental germ invasion, was prepared by reducing silver nitrate to its nanoparticulate form through interaction with chitosan. The lower layer, which would be in direct contact with the injured site, contained the antibi- otic drug needed to avoid wound infections which would otherwise interfere with the healing process. Initially, the upper layer was electrospun, followed sequentially by electrospinning the second layer, creating a bilayer nanofibrous mat. The morphology of the nanofibrous mats was studied by scanning electron microscopy and transmission electron microscopy, showing successful nanofiber production. X-ray diffraction confirmed the reduction of silver nitrate to AgNPs. Fourier transform infrared spectroscopy showed a successful incorporation of the material used in the produced nanofibrous mats. Thermal studies carried out by thermogravi- metric analysis indicated that the PVP–drug-loaded layer had the highest thermal stability in comparison to other fabricated nanofibrous mats. Antimicrobial activities of the as-synthesized nanofibrous mats against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans were determined using disk diffusion method. The results indicated that the PEO–drug-loaded mat had the highest antibacterial activity, warranting further attention for numerous wound-healing applications.QUST-CAS-SPR-14\15-

Broadening microwave absorption via a multi-domain structure

Materials with a high saturation magnetization have gained increasing attention in the field of microwave absorption; therefore, the magnetization value depends on the magnetic configuration inside them. However, the broad-band absorption in the range of microwave frequency (2-18 GHz) is a great challenge. Herein, the three-dimensional (3D) Fe/C hollow microspheres are constructed by iron nanocrystals permeating inside carbon matrix with a saturation magnetization of 340 emu/g, which is 1.55 times as that of bulk Fe, unexpectedly. Electron tomography, electron holography, and Lorentz transmission electron microscopy imaging provide the powerful testimony about Fe/C interpenetration and multi-domain state constructed by vortex and stripe domains. Benefiting from the unique chemical and magnetic microstructures, the microwave minimum absorption is as strong as -55 dB and the bandwidth (<-10 dB) spans 12.5 GHz ranging from 5.5 to 18 GHz. Morphology and distribution of magnetic nano-domains can be facilely regulated by a controllable reduction sintering under H2/Ar gas and an optimized temperature over 450-850 C. The findings might shed new light on the synthesis strategies of the materials with the broad-band frequency and understanding the association between multi-domain coupling and microwave absorption performance.This work was supported by the Ministry of Science and Technology of China (973 Project Nos. 2013CB932901 and 2016YFE0105700) and the National Natural Science Foundation of China (Nos. 51672050 and 51172047) and NSAF-U1330118. The authors extend their appreciation to the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP# 0018.Scopu