Macromolecule Orientation in Nanofibers

Influence of dopant concentration on the ammonia sensing performance of citric acid-doped polyvinyl acetate nanofibers

The chemical modification of polymer nanofiber-based ammonia sensors by introducing dopants into the active layers has been proven as one of the low-cost routes to enhance their sensing performance. Herein, we investigate the influence of different citric acid (CA) concentrations on electrospun polyvinyl acetate (PVAc) nanofibers coated on quartz crystal microbalance (QCM) transducers as gravimetric ammonia sensors. The developed CA-doped PVAc nanofiber sensors are tested against various concentrations of ammonia vapors, in which their key sensing performance parameters (i.e., sensitivity, limit of detection (LOD), limit of quantification (LOQ), and repeatability) are studied in detail. The sensitivity and LOD values of 1.34 Hz ppm^-1 and 1 ppm, respectively, can be obtained during ammonia exposure assessment. Adding CA dopants with a higher concentration not only increases the sensor sensitivity linearly, but also prolongs both response and recovery times. This finding allows us to better understand the dopant concentration effect, which subsequently can result in an appropriate strategy for manufacturing high-performance portable nanofiber-based sensing devices.

Control of Macromolecule Chains Structure in a Nanofiber

Mechanical property is one of the most important properties of nanofiber membranes. Electrospinning is widely used in the preparation of nanofibers due to its advantages such as good stability and easy operation. Compared with some nature silk, the mechanical properties of nanofibers prepared by electrospinning are poor. Based on the principle of vortex spinning and DNA structure, this paper designed an air vortex electrospinning device that can control the structure of macromolecular chains in nanofibers. When a weak air vortex is generated in the electrospinning process, the macromolecule chains will entangle with each other and form a DNA-like structure so as to improve the mechanical property. In addition, when a strong air vortex is generated during the electrospinning process, the nanofibers will adhere to each other, thereby enhancing the mechanical property and enlarging the pore size.

Electrospun Mussel-derived Silk Fibers

BACKGROUND

Though there are many patents on silk, patents on sea silk are rare. Sea silk is one of the most coveted materials in the world, and the technology to make sea silk is at an extremely high risk of extinction. Unlike spider dragline silk and silkworm silk, this natural silk has been forgotten in the academic commune for millennia, though it has many fascinating properties: high strength, remarkable adhesion, extreme lightweight, and others.

METHODS

Here we report that mussel-derived silk fibers can be fabricated by electrospinning. Instead of extracting proteins from byssus, we directly use the protein solution from alive blue mussels, which are intensely commercially used. The protein solution and the polyvinyl alcohol solution are mixed together to produce mussel-based silk fibers.

RESULTS

The mussel-based silk fibers have many special properties like high mechanical strength, remarkable super-contraction and good wetting properties.

CONCLUSION

The electrospinning mussel-based silk fibers have the potential for use as a replacement for the rarest sea silk and as a new bio-inspired material with multi-functions.

A Comprehensive Patent Review on β-cyclodextrin Cross-linked Nanosponges for Multiple Applications

BACKGROUND

Currently, the most important challenge in the development of therapeutics and actives is their poor aqueous solubility and bioavailability.

OBJECTIVE

The low aqueous solubility, poor pharmacokinetic properties, and bioavailability associated with novel actives manifest in numerous challenges in the formulation of conventional dosage forms like tablets, capsules, suspensions, emulsions, etc. Nanosponges are a novel class of drug delivery system capable of encapsulating or entrapping both lipophilic and hydrophilic drugs. Target-specific drug delivery and controlled drug release are the advantages offered by nanosponges which make them a promising anti-tumor drug delivery system.

METHODS

Nanosponges are colloidal structures comprising solid nanoparticles with cavities and meshlike structures for encapsulation of wide varieties of substances like antineoplastic agents, proteins and peptides, volatile oils, genetic material, etc. The methods of preparation of β-cyclodextrin-based nanosponges include solvent evaporation method, emulsion solvent evaporation method, ultrasound-assisted synthesis, hyper cross-linked cyclodextrin and interfacial phenomenon method. A large variety of nanosponges- based formulations are available in the market and some formulations of prostavastin, brexin, glymesason, mena-gargle, etc. are under clinical trials.

RESULTS

Nanosponges possess potential applications in target site-specific drug delivery to liver, spleen, and lungs. Due to the surface functionalization, nanosponges show broad applications in water purification, protein delivery, chemical sensors, detection of explosives, agriculture, etc. In the near future, nanosponges-based products will capture a huge market for commercialization due to their improved properties and advantages.

CONCLUSION

This review provides an account of the patents related to nanosponges (2006-2018) and covers the broad applications of β-cyclodextrin-based nanosponges, their roles in vaccine delivery, cancer therapy, fire engineering, water purification, etc.

Fascinated Nanofiber Yarns: From Experiment to Industrialization

BACKGROUND

Bubble electrospinning patent has been commercially used for the massproduction of various nanofibers, but its application to the fabrication of nanofiber yarns is less studied. We assume that there is great potential in this direction.

OBJECTIVE

This paper focuses on bubble electrospinning with an emphasis on new technologies for the fabrication of fascinated nanofiber yarns by the bubble electrospinning.

METHODS

The paper begins with the mechanism of the bubble electrospinning to introduce how it produces fascinated nanofiber yarns experimentally, then the industrialization of fascinated nanofiber yarns is illustrated.

RESULTS

The bubble electrospinning is extremely suitable for the fabrication of fascinated nanofiber yarns with a hierarchical structure, and the hierarchy can be designed biomimetically according to some natural fibers.

CONCLUSION

This paper sheds light on both experimental study and industrial applications of fascinated nanofiber yarns.

Electrospinning of Ethylene Vinyl Acetate/Carbon Nanotube Nanocomposite Fibers

Nanocomposites, based on an ethylene vinyl acetate (EVA) copolymer with a vinyl acetate content of 34 wt % and varying amounts of multiwall carbon nanotubes (MWCNTs), were prepared by an electrospinning method. The dispersibility of the MWCNTs in the solution was improved by using cholesteryl 1-pyrenecarboxylate (PyChol) as a compatibilizer. The transmission electron microscopy images showed that the MWCNTs were aligned inside of the elastomeric matrix by the electrospinning process. The morphologies of the fibers were evaluated by scanning electron microscopy. When the amount of MWCNTs in the polymer solution reached 3 wt %, fibers with a diameter of 846 ± 447 nm were prepared. The chemical composition of the prepared fibers was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR results confirmed the presence of a carboxyl group, originating from the presence of PyChol. XPS results showed that the EVA fibers produced by electrospinning were oxidized in ethylene units, when comparing the spectra of the original EVA granules, but the presence of MWCNTs enhanced the stability of the EVA. The thermal stabilities of the fibers were tested with thermogravimetric analysis. The results confirmed that the presence of MWCNTs inside the fibers enhanced the thermal stabilities of the prepared nanocomposites.

Effect of MWCNT on the Structure and Property of Nanofibrous Bundles by Blown Bubble Spinning

BACKGROUND

Many spinning patents and technologies have been explored to produce diverse types of nanomaterials for different applications. As a novel method, the blown bubble-spinning is a one-step process for fabrication of nanofibrous bundles.

METHOD

In this study, polyamide6/66(PA6/66) nanofibrous bundles filled with different concentrations of multi-walled carbon nanotubes (MWCNTs) were prepared by the blown bubble-spinning. The dispersion of MWCNT in nanofibers under different treatments was investigated and a detailed characterization focusing on the influence of the presence of MWCNT on the morphology, thermal property and electrical property was carried out.

RESULTS

The results showed that MWCNTs treated by Tween60 and ultrasonication were embedded in the PA6/66 nanofibers with uniform dispersion. In addition, it was observed that thermal stability and electrical conductivity of nanofibrous bundles increased with an increase in MWCNT content.

CONCLUSION

The PA6/66/MWCNT nanofibrous bundles fabricated by the blown bubble spinning have the great potential applications in sensors and supercapacitors.