Coaxial electrospinning with sodium dodecylbenzene sulfonate solution for high quality polyacrylonitrile nanofibers

Development and Characterization of pH-Dependent Cellulose Acetate Phthalate Nanofibers by Electrospinning Technique

The aim of this work was to obtain pH-dependent nanofibers with an electrospinning technique as a novel controlled release system for the treatment of periodontal disease (PD). Cellulose acetate phthalate (CAP) was selected as a pH-sensitive and antimicrobial polymer. The NF was optimized according to polymeric dispersion variables, polymer, and drug concentration, and characterized considering morphology, diameter, entrapment efficiency (EE), process efficiency (PE), thermal properties, and release profiles. Two solvent mixtures were tested, and CHX-CAP-NF prepared with acetone/ethanol at 12% w/v of the polymer showed a diameter size of 934 nm, a uniform morphology with 42% of EE, and 55% of PE. Meanwhile, CHX-CAP-NF prepared with acetone/methanol at 11% w/v of polymer had a diameter of 257 nm, discontinuous nanofiber morphology with 32% of EE, and 40% of PE. EE and PE were dependent on the polymer concentration and the drug used in the formulation. Studies of differential scanning calorimetry (DSC) showed that the drug was dispersed in the NF matrix. The release profiles of CHX from CHX-CAP-NF followed Fickian diffusion dependent on time (t^0.43−0.45), suggesting a diffusion–erosion process and a matrix behavior. The NF developed could be employed as a novel drug delivery system in PD.

Electrospun PVP-Core/PHBV-Shell Fibers to Eliminate Tailing Off for an Improved Sustained Release of Curcumin

Tailing off release in the sustained release of water-insoluble curcumin (Cur) is a significant challenge in the drug delivery system. As a novel solution, core-shell nanodrug containers have aroused many interests due to their potential improvement in drug-sustained release. In this work, a biodegradable polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and hydrophilic polyvinylpyrrolidone (PVP) were exploited as drug delivery carriers by coaxial electrospinning, and the core-shell drug-loaded fibers exhibited improved sustained release of Cur. A cylindrical morphology and a clear core-shell structure were observed by scanning and transmission electron microscopies. The X-ray diffraction pattern and infrared spectroscopy revealed that Cur existed in amorphous form due to its good compatibility with PHBV and PVP. The in vitro drug release curves confirmed that the core-shell container manipulated Cur in a faster drug release process than that in the traditional PHBV monolithic container. The combination of the material and structure forms a novel nanodrug container with a better sustained release of water-insoluble Cur. This strategy is beneficial for exploiting more functional biomedical materials to improve the drug release behavior.

In Situ Synthesis of Silver Nanoparticles on Amino-Grafted Polyacrylonitrile Fiber and Its Antibacterial Activity

In this study, amino hyperbranched polymers (HBP)-grafted polyacrylonitrile (PAN) fiber was prepared through an amidation reaction in an autoclave. The prepared PAN-G-HBP fiber can complex Ag⁺ through amino groups of amino HBP, and in a hot steaming condition, Ag⁺ can be converted to Ag0 through the reducibility of HBP. PAN-G-HBP and Ag nanoparticles (NPs)-coated fibers were then characterized through FTIR, UV-VIS DRS, FE-SEM, EDS, XPS and antibacterial measurement. FTIR results confirmed HBP was grafted on the surface of PAN fiber. FE-SEM showed that after grafting with HBP, the average diameter of PAN fibers was amplified. EDS, XPS, and UV-VIS DRS method indicated that under hot steaming condition and with the reducibility of HBP, Ag NPs uniform coating on the PAN-G-HBP. Ag NPs-coated fibers exhibits excellent antibacterial property against Escherichia coli and Staphylococcus aureus. Even under 20 times home washing conditions, the antibacterial reduction of Ag NPs-coated PAN fiber can achieved more than 98.94%.

Beyond the Single-Nozzle: Coaxial Electrospinning Enables Innovative Nanofiber Chemistries, Geometries, and Applications

With an ever increasing scientific, technological, and industrial interest in high surface area, porous nanofiber mats, electrospinning has emerged as a popular method to produce fibrous assemblies for use across biomedical, energy, and environmental applications. However, not all precursor solutions nor complex geometries can be easily fabricated using the traditional single-nozzle apparatus. Therefore, coaxial electrospinning, a modified version of electrospinning that features a concentrically aligned dual nozzle, has been developed. This review will first describe the mechanism of electrospinning two precursor solutions simultaneously and the operational parameters that need to be optimized to fabricate continuous fibers. Modifications that can be made to the coaxial electrospinning process, which enable the fabrication of uniform fibers with improved properties, as well as the fabrication of fibers that are hollow, functionalized, and from "nonspinnable precursors" will be discussed as a means of promoting the advantages of using a coaxial setup. Examples of how coaxially electrospun nanofibers are employed in diverse applications will be provided throughout this review. We conclude with a timely discussion about the current limitations and challenges of coaxial electrospinning.

Efficient removal of radiocobalt and manganese from their binary aqueous solutions by batch adsorption process using PAN/HDTMA/KCuHCF composite

Simultaneous removal of radiocobalt and manganese by adsorption onto polyacrylonitrile/hexadecyltrimethylammonium bromide/potassium copper hexacyanoferrate (PAN/HDTMA/KCuHCF) composite was studied. The synthesized composite was characterized by Fourier-transformed infrared (FT-IR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The influence of the solution pH was studied in the range 1.5–7.8 and the results showed the effectiveness of the synthesized composite for simultaneous adsorption of radiocobalt and manganese in the pH range 2.5–6 at an adsorbent mass of 4 g/L. Adsorption kinetic data of manganese at the studied concentrations were best fitted by pseudo-second-order kinetic model and the diffusion study showed that the adsorption process was controlled by film diffusion. Thermodynamic parameters (ΔGo, ΔHo and ΔSo) were estimated and the results indicated that adsorption processes of the concerned (radio)toxicants were spontaneous and endothermic in nature. Of the studied isotherm models, Freundlich and Langmuir were the best ones for describing the adsorption isotherm data of radiocobalt and manganese, respectively. The adsorption capacity of PAN/HDTMA/KCuHCF was found to be 23.629 (for radiocobalt) and 62.854 (for manganese). Desorption of Radiocobalt and manganese loaded onto PAN/HDTMA/KCuHCF composite was studied using various desorbing agents at different concentrations.

Electrospun amorphous solid dispersions of poorly water-soluble drugs: A review

The development of oral dosage forms for poorly water-soluble active pharmaceutical ingredients (APIs) is a persistent challenge. A range of methods has been explored to address this issue, and amorphous solid dispersions (ASDs) have received increasing attention. ASDs are typically prepared by starting with a liquid precursor (a solution or melt) and applying energy for solidification. Many techniques can be used, with the emergence of electrospinning as a potent option in recent years. This method uses electrical energy to induce changes from liquid to solid. Through the direct applications of electrical energy, electrospinning can generate nanofiber-based ASDs from drug-loaded solutions, melts and melt-solutions. The technique can also be combined with other approaches using the application of mechanical, thermal or other energy sources. Electrospinning has numerous advantages over other approaches to produce ASDs. These advantages include extremely rapid drying speeds, ease of implentation, compatibility with a wide range of active ingredients (including those which are thermally labile), and the generation of products with large surface areas and high porosity. Furthermore, this technique exhibits the potential to create so-called 'fifth-generation' ASDs with nanostructured architectures, such as core/shell or Janus systems and their combinations. These advanced systems can improve dissolution behaviour and provide programmable drug release profiles. Additionally, the fiber components and their spatial distributions can be precisely controlled. Electrospun fiber-based ASDs can maintain an incorporated active ingredient in the amorphous physical form for prolonged periods of time because of their homogeneous drug distribution within the polymer matrix (typically they comprise solid solutions), and ability to inhibit molecular motion. These ASDs can be utilised to generate oral dosage forms for poorly water-soluble drugs, resulting in linear or multiple-phase release of one or more APIs. Electrospun ASDs can also be exploited as templates for manipulating molecular self-assembly, offering a bridge between ASDs and other types of dosage forms. This review addresses the development, advantages and pharmaceutical applications of electrospinning for producing polymeric ASDs. Material preparation and analysis procedures are considered. The mechanisms through which performance has been improved are also discussed.

Covalent streptavidin immobilization on electrospun poly(m-anthranilic acid)/polycaprolactone nanofibers and cytocompatibility

An electrospun poly( m-anthranilic acid)/poly(ε-caprolactone) nanofiber mat was fabricated with functionalization of the surface with streptavidin which can enhance the cell attachment and proliferation. Poly(ε-caprolactone) as biodegradable, biocompatible, and electrospinnable polymer was blended with poly( m-anthranilic acid) because of the carboxylic acid (–COOH) groups on its backbone which allow the covalent immobilization of streptavidin onto nanofibers. 1-Ethyl-3-(dimethyl-aminopropyl) carbodiimide hydrochloride/ N-hydroxyl succinimide coupling reaction was used for immobilization and the presence of bound protein was investigated by Fourier transform infrared–attenuated total reflection spectroscopy and electrochemical impedance spectroscopy, as well as the confocal microscopy. Human osteoblast-like cells (SaOS2) were cultured on poly( m-anthranilic acid)/poly(ε-caprolactone) and streptavidin-immobilized poly( m-anthranilic acid)/poly(ε-caprolactone) nanofibers to evaluate the in vitro biocompatibility of nanofibers. Fluorescence staining of F-actin was performed to observe the cell morphology. The results confirmed the successful immobilization of streptavidin on the nanofibers and streptavidin immobilization enhanced the cell attachment and proliferation onto the poly( m-anthranilic acid)/poly(ε-caprolactone) nanofibers.

Drug-loaded zein nanofibers prepared using a modified coaxial electrospinning process

This study investigated the preparation of drug-loaded fibers using a modified coaxial electrospinning process, in which only unspinnable solvent was used as sheath fluid. With zein/ibuprofen (IBU) co-dissolving solution and N, N-dimethylformamide as core and sheath fluids, respectively, the drug-loaded zein fibers could be generated continuously and smoothly without any clogging of the spinneret. Field emission scanning electron microscopy and transmission electron microscopy observations demonstrated that the fibers had ribbon morphology with a smooth surface. Their average diameters were 0.94±0.34 and 0.67±0.21 μm when the sheath-to-core flow rate ratios were taken as 0.11 and 0.25, respectively. X-ray diffraction and differential scanning calorimetry verified that IBU was in an amorphous state in all fiber composites. Fourier transform infrared spectra showed that zein had good compatibility with IBU owing to hydrogen bonding. In vitro dissolution tests showed that all the fibers could provide sustained drug release files via a typical Fickian diffusion mechanism. The modified coaxial electrospinning process reported here can expand the capability of electrospinning in generating fibers and provides a new manner for developing novel drug delivery systems.

Electrospun biphasic drug release polyvinylpyrrolidone/ethyl cellulose core/sheath nanofibers

The capability of core/sheath nanofibers prepared using coaxial electrospinning to provide adjustable biphasic drug release was investigated. Using ketoprofen (KET) as the model drug, polyvinylpyrrolidone as the sheath polymer, and ethyl cellulose as the core matrix, the coaxial process could be conducted smoothly and continuously without spinneret clogging. Scanning electron microscopy and transmission electron microscopy revealed linear nanofibers with homogeneous and clear core/sheath structures. Differential scanning calorimetry and X-ray diffraction verified that the core/sheath nanofibers were nanocomposites, with the drug present in the polymer matrix in an amorphous state. Attenuated total reflectance-Fourier transform infrared spectra demonstrated that the sheath polymer and core matrix were compatible with KET owing to hydrogen bonding. In vitro dissolution tests showed that the core/sheath nanofibers could provide typical biphasic drug release profiles consisting of an immediate and sustained release. The amount of drug released in the first phase was tailored by adjusting the sheath flow rate, and the remaining drug released in the second phase was controlled by a typical diffusion mechanism. The present study shows a simple and useful approach for the systematic design and fabrication of novel biomaterials with structural characteristics for providing complicated and programmed drug release profiles using coaxial electrospinning.

Ferulic Acid-Loaded Shellac Microparticles Prepared Using Electrohydrodynamic Atomization

An Electrohydrodynamic atomization (EHDA) process was exploited to prepare ferulic acid (FA)-loaded shellac microparticles. SEM observations showed that all the particles were round and solid with their sizes gradually increased from 0.68 ± 0.21 to 2.75 ± 0.64 μm as the concentrations of shellac and FA in ethanol raised from 20% to 50% (w/v). Wide-angle X-ray diffraction analyses demonstrated that FA had been totally converted into an amorphous state in the shellac matrix microparticles. Attenuated total reflectance Fourier transform infrared analysis disclosed that the hydrogen bonding presented between FA and shellac molecules. In vitro dissolution tests verified that all the microparticles were able to provide a fine sustained drug release profile. The release time periods had a close relationship with the diameters of microparticles. All the microparticles released the loaded FA via a typical Fickian diffusion mechanism. The present study provides an easy way to develop novel drug delivery microparticles for providing sustained drug release profiles.

Electrospun hybrid nanofibers doped with nanoparticles or nanotubes for biomedical applications

Electrospinning is a powerful technique to produce fibers with a diameter ranging from tens of nanometers to several micrometers. Compared with single-component nanofibers, composite or hybrid nanofibers are promising due to the unique properties possessed by both the host and the guest materials. Doping nanoparticles (NPs) or nanotubes (NTs) have excellent optical, mechanical, electrical or catalytic properties within polymer nanofibers, which makes it possible to produce functional nanofibers with promising applications. In this review, followed by a brief introduction of basic theory of electrospinning techniques, we give a literature survey of the NP- or NT-doped electrospun polymer nanofibers in terms of the producing methods and potential applications in the fields of tissue engineering, wound dressing and drug-delivery systems. Some of the aspects related to the improved protein adsorption capability, mechanical durability and, thus, improved cell attachment and proliferation of the NT-doped polymer nanofibers, as well as the significantly decreased burst-release profile of the NT-doped polymer nanofibers used as drug-delivery systems are discussed.