Research

13 pages, 4301 KiB

Open AccessArticle

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

by Mohammad K. Hassan, Ahmed Abukmail, Alaa J. Hassiba, Kenneth A. Mauritz and Ahmed A. Elzatahry

Nanomaterials 2018, 8(11), 888; https://doi.org/10.3390/nano8110888 - 01 Nov 2018

Cited by 16 | Viewed by 3688

Abstract

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 [...] Read more.

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-T_g relaxation processes. Results revealed the existence of two sub-T_g 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 T_g helped resolve this relaxation and displayed the progress of its maxima with increasing temperature in the regular manner. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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18 pages, 6277 KiB

Open AccessArticle

Incorporation of PVDF Nanofibre Multilayers into Functional Structure for Filtration Applications

by Remi Roche and Fatma Yalcinkaya

Nanomaterials 2018, 8(10), 771; https://doi.org/10.3390/nano8100771 - 29 Sep 2018

Cited by 32 | Viewed by 3867

Abstract

Membranes are considered as a promising technology for separation and filtration processes. Here, novel polyvinylidene fluoride (PVDF) nanofibrous multilayer membranes were fabricated by wire-based industrial electrospinning equipment following by a lamination process. The lamination process was optimised under various applied temperature, force of [...] Read more.

Membranes are considered as a promising technology for separation and filtration processes. Here, novel polyvinylidene fluoride (PVDF) nanofibrous multilayer membranes were fabricated by wire-based industrial electrospinning equipment following by a lamination process. The lamination process was optimised under various applied temperature, force of lamination, and lamination time. Air permeability and burst-pressure tests were run to determine the optimum membranes for filtration application. The structures of the prepared membranes were characterised by scanning electron microscopy and pore-size analysis. The hydrophilic properties of the membranes were evaluated using water contact angle measurement, and the mechanical strength of the membranes was analysed. Air and water filtration tests were run to find the possible application of prepared membranes. The air filtration results showed that membranes had high filtration efficiencies: Over 99.00% for PM_2.5, and PM_0.1. The water filtration results indicated that permeability of the membranes changed from 288 to 3275 L/m²hbar. The successful preparation of such an interesting material may provide a new approach for the design and development of electrospun filter membranes. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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15 pages, 6344 KiB

Open AccessArticle

Enhancing Multiple Jets in Electrospinning: The Role of Auxiliary Electrode

by Yu-Ke Wu, Zong-Jie Li, Jie Fan, Zhao-Peng Xia and Yong Liu

Nanomaterials 2018, 8(10), 768; https://doi.org/10.3390/nano8100768 - 28 Sep 2018

Cited by 6 | Viewed by 3006

Abstract

An auxiliary electrode introduced in traditional spinneret electrospinning is an effective and powerful technique to improve the production rate of nanofibers. In this work, the effects of the arrangement of auxiliary electrode, applied voltage, injection speed, and the distance between the electrode tip [...] Read more.

An auxiliary electrode introduced in traditional spinneret electrospinning is an effective and powerful technique to improve the production rate of nanofibers. In this work, the effects of the arrangement of auxiliary electrode, applied voltage, injection speed, and the distance between the electrode tip and the spinneret tip (ESD) on the jet number and the morphology of polyvinyl alcohol (PVA) nanofibers were investigated systematically. The results showed that the number of jets firstly increased and then decreased with the increase of applied voltage and ESD, respectively, while increasing with the injection speed in both the auxiliary electrode in the vertical position and parallel position. The average nanofiber diameter decreased with increasing of applied voltage and injection speed, but decreasing in ESD in these two positions. The numerical simulation results revealed that the auxiliary electrode primarily influenced the electric field intensity in the spinning area. This work provides a deep understanding of multiple jets in electrospinning. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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11 pages, 4159 KiB

Open AccessArticle

Self-Cleaning Properties of Electrospun PVA/TiO₂ and PVA/ZnO Nanofibers Composites

by Muhammad Qamar Khan, Davood Kharaghani, Sana Ullah, Muhammad Waqas, Abdul Malik Rehan Abbasi, Yusuke Saito, Chunhong Zhu and Ick Soo Kim

Nanomaterials 2018, 8(9), 644; https://doi.org/10.3390/nano8090644 - 22 Aug 2018

Cited by 54 | Viewed by 6383

Abstract

In this report, polyvinyl alcohol/zinoxide (PVA/ZnO) & polyvinyl alcohol/titanium dioxide (PVA/TiO₂) nanofibers were manufactured in three different concentrations of ZnO and TiO₂ NPs for the application of self-cleaning properties because metallic oxides, specifically ZnO & TiO₂, have the [...] Read more.

In this report, polyvinyl alcohol/zinoxide (PVA/ZnO) & polyvinyl alcohol/titanium dioxide (PVA/TiO₂) nanofibers were manufactured in three different concentrations of ZnO and TiO₂ NPs for the application of self-cleaning properties because metallic oxides, specifically ZnO & TiO₂, have the properties to remove the contaminants by hydroxyl radical (OH⁻¹), which degrades the contaminants into small molecules and finally into CO₂ and H₂O. Therefore, these composites were manufactured by electrospinning. The resultant nanofibers were characterized for morphology by scan electron microscopy (SEM) & transmission electron microscopy (TEM), chemical interactions by Fourier-transform infrared (FT-IR) spectra, crystalline structure by X-ray diffraction (XRD) spectra water absorbency was evaluated by water contact angle, self-cleaning by solar simulator, and thermal degradation was done by thermogravimetric analysis (TGA) for the sake of nanoparticles the content. On the base of the characterization results it was concluded that these PVA/ZnO & PVA/TiO₂ nanofibers have self cleaning properties, but PVA/ZnO nanofibers have higher self-cleaning properties than PVA/TiO₂ nanofibers because PVA/ZnO nanofibers have 95% self-cleaning properties, which is higher than PVA/TiO₂ nanofibers. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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13 pages, 5300 KiB

Open AccessArticle

Piezoresponse, Mechanical, and Electrical Characteristics of Synthetic Spider Silk Nanofibers

by Nader Shehata, Ishac Kandas, Ibrahim Hassounah, Patrik Sobolčiak, Igor Krupa, Miroslav Mrlik, Anton Popelka, Jesse Steadman and Randolph Lewis

Nanomaterials 2018, 8(8), 585; https://doi.org/10.3390/nano8080585 - 01 Aug 2018

Cited by 10 | Viewed by 4873

Abstract

This work presents electrospun nanofibers from synthetic spider silk protein, and their application as both a mechanical vibration and humidity sensor. Spider silk solution was synthesized from minor ampullate silk protein (MaSp) and then electrospun into nanofibers with a mean diameter of less [...] Read more.

This work presents electrospun nanofibers from synthetic spider silk protein, and their application as both a mechanical vibration and humidity sensor. Spider silk solution was synthesized from minor ampullate silk protein (MaSp) and then electrospun into nanofibers with a mean diameter of less than 100 nm. Then, mechanical vibrations were detected through piezoelectric characteristics analysis using a piezo force microscope and a dynamic mechanical analyzer with a voltage probe. The piezoelectric coefficient (d₃₃) was determined to be 3.62 pC/N. During humidity sensing, both mechanical and electric resistance properties of spider silk nanofibers were evaluated at varying high-level humidity, beyond a relative humidity of 70%. The mechanical characterizations of the nanofibers show promising results, with Young’s modulus and maximum strain of up to 4.32 MPa and 40.90%, respectively. One more interesting feature is the electric resistivity of the spider silk nanofibers, which were observed to be decaying with humidity over time, showing a cyclic effect in both the absence and presence of humidity due to the cyclic shrinkage/expansion of the protein chains. The synthesized nanocomposite can be useful for further biomedical applications, such as nerve cell regrowth and drug delivery. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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15 pages, 6268 KiB

Open AccessArticle

Performance Assessment of Ordered Porous Electrospun Honeycomb Fibers for the Removal of Atmospheric Polar Volatile Organic Compounds

by Yixin Wang, Hong Tao, Dengguang Yu and Changtang Chang

Nanomaterials 2018, 8(5), 350; https://doi.org/10.3390/nano8050350 - 21 May 2018

Cited by 18 | Viewed by 4343

Abstract

This study explored a new facile method of preparing ordered porous electrospun honeycomb fibers to obtain the most promising composites for maximal adsorption of volatile organic compounds (VOCs). The self-assembly ordered porous material (OPM) and polyacrylonitrile (PAN) were formulated into a blend solution [...] Read more.

This study explored a new facile method of preparing ordered porous electrospun honeycomb fibers to obtain the most promising composites for maximal adsorption of volatile organic compounds (VOCs). The self-assembly ordered porous material (OPM) and polyacrylonitrile (PAN) were formulated into a blend solution to prepare honeycomb fibers. SEM and TEM images showed that OPM was effectively bonded in PAN fibers because of the composite’s structure. Acetone was used as a model to assess the VOC adsorption performances of electrospun honeycomb fibers with different OPM contents. Experimental results revealed that the adsorption capacity of honeycomb fibers increased with the increase of loaded OPM within the PAN fibers. The highest adsorption capacity was 58.2 μg g⁻¹ by the fibers containing with 60% OPM in weight. After several recycling times, the adsorption capacities of the reused honeycomb fibers were almost the same with the fresh fibers. This finding indicated that the electrospun honeycomb fibers have potential application in removing VOCs in the workplace, and promote the performance of masks for odor removal. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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19 pages, 13457 KiB

Open AccessArticle

Finite Element Analysis of Electrospun Nanofibrous Mats under Biaxial Tension

by Yunlei Yin and Jie Xiong

Nanomaterials 2018, 8(5), 348; https://doi.org/10.3390/nano8050348 - 19 May 2018

Cited by 20 | Viewed by 5316

Abstract

Due to the non-uniform material properties of electrospun nanofibrous mats and the non-linear characteristics of single fibers, establishing a numerical model that can fully explain these features and correctly describe their properties is difficult. Based on the microstructure of electrospun nanofibrous mats, two [...] Read more.

Due to the non-uniform material properties of electrospun nanofibrous mats and the non-linear characteristics of single fibers, establishing a numerical model that can fully explain these features and correctly describe their properties is difficult. Based on the microstructure of electrospun nanofibrous mats, two macroscopic continuum finite element (FE) models with a uniform or oriented nanofiber distribution were established to describe the mechanical behavior of nanofibrous mats under biaxial tension. The FE models were verified by biaxial tension experiments on silk fibroin/polycaprolactone nanofibrous mats. The developed FE models expressed the mechanical behaviors of the mats under biaxial tension well. These models can help clarify the structure–property relationship of electrospun nanofibrous mats and guide the design of materials for engineering applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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11 pages, 8549 KiB

Open AccessArticle

Electrospun Blank Nanocoating for Improved Sustained Release Profiles from Medicated Gliadin Nanofibers

by Xinkuan Liu, Wenyi Shao, Mingyi Luo, Jiayin Bian and Deng-Guang Yu

Nanomaterials 2018, 8(4), 184; https://doi.org/10.3390/nano8040184 - 22 Mar 2018

Cited by 37 | Viewed by 4347

Abstract

Nanomaterials providing sustained release profiles are highly desired for efficacious drug delivery. Advanced nanotechnologies are useful tools for creating elaborate nanostructure-based nanomaterials to achieve the designed functional performances. In this research, a modified coaxial electrospinning was explored to fabricate a novel core-sheath nanostructure [...] Read more.

Nanomaterials providing sustained release profiles are highly desired for efficacious drug delivery. Advanced nanotechnologies are useful tools for creating elaborate nanostructure-based nanomaterials to achieve the designed functional performances. In this research, a modified coaxial electrospinning was explored to fabricate a novel core-sheath nanostructure (nanofibers F2), in which a sheath drug-free gliadin layer was successfully coated on the core ketoprofen (KET)-gliadin nanocomposite. A monolithic nanocomposite (nanofibers F1) that was generated through traditional blending electrospinning of core fluid was utilized as a control. Scanning electron microscopy demonstrated that both nanofibers F1 and F2 were linear. Transmission electron microscopy verified that nanofibers F2 featured a clear core-sheath nanostructure with a thin sheath layer about 25 nm, whereas their cores and nanofibers F1 were homogeneous KET-gliadin nanocomposites. X-ray diffraction patterns verified that, as a result of fine compatibility, KET was dispersed in gliadin in an amorphous state. In vitro dissolution tests demonstrated that the thin blank nanocoating in nanofibers F2 significantly modified drug release kinetics from a traditional exponential equation of nanofibers F1 to a zero-order controlled release model, linearly freeing 95.7 ± 4.7% of the loaded cargoes over a time period of 16 h. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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17 pages, 6612 KiB

Open AccessArticle

The Effect of Laminin Surface Modification of Electrospun Silica Nanofiber Substrate on Neuronal Tissue Engineering

by Wen Shuo Chen, Ling Yu Guo, Chia Chun Tang, Cheng Kang Tsai, Hui Hua Huang, Ting Yu Chin, Mong-Lin Yang and Yui Whei Chen-Yang

Nanomaterials 2018, 8(3), 165; https://doi.org/10.3390/nano8030165 - 14 Mar 2018

Cited by 27 | Viewed by 6149

Abstract

In this study, we first synthesized a slow-degrading silica nanofiber (SNF2) through an electrospun solution with an optimized tetraethyl orthosilicate (TEOS) to polyvinyl pyrrolidone (PVP) ratio. Then, laminin-modified SNF2, namely SNF2-AP-S-L, was obtained through a series of chemical reactions to attach the extracellular [...] Read more.

In this study, we first synthesized a slow-degrading silica nanofiber (SNF2) through an electrospun solution with an optimized tetraethyl orthosilicate (TEOS) to polyvinyl pyrrolidone (PVP) ratio. Then, laminin-modified SNF2, namely SNF2-AP-S-L, was obtained through a series of chemical reactions to attach the extracellular matrix protein, laminin, to its surface. The SNF2-AP-S-L substrate was characterized by a combination of scanning electron microscopy (SEM), Fourier transform–infrared (FTIR) spectroscopy, nitrogen adsorption/desorption isotherms, and contact angle measurements. The results of further functional assays show that this substrate is a biocompatible, bioactive and biodegradable scaffold with good structural integrity that persisted beyond 18 days. Moreover, a synergistic effect of sustained structure support and prolonged biochemical stimulation for cell differentiation on SNF2-AP-S-L was found when neuron-like PC12 cells were seeded onto its surface. Specifically, neurite extensions on the covalently modified SNF2-AP-S-L were significantly longer than those observed on unmodified SNF and SNF subjected to physical adsorption of laminin. Together, these results indicate that the SNF2-AP-S-L substrate prepared in this study is a promising 3D biocompatible substrate capable of sustaining longer neuronal growth for tissue-engineering applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)

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