Influence of the Protein Content on Fiber Morphology and Heat Treatment of Electrospun Potato Protein–Maltodextrin Fibers

The production of ultrafine fibers of proteins and polysaccharides by needleless electrospinning can be performed prior to a thermal treatment to form glycoconjugates via the first stage of the Maillard reaction. The aim was to produce potato protein–maltodextrin conjugates with a varying protein content of 0.05, 0.1, 0.15, and 0.2 g/mL by needleless electrospinning and subsequent thermal treatment (0, 6, 12, 24, and 48 h at 65 °C and 75% relative humidity). The concentrations of the maltodextrins, with a dextrose equivalent of 2 and 21, were kept constant at 0.8 and 0.1 g/mL. The highest fiber production rate was achieved with a protein content of 0.1 g/mL (5.8 ± 0.4 g/h). With increasing protein content, the production rate decreased to 2.8 ± 0.5 g/h. The fibers obtained from the spinning solution containing 0.2 g/mL protein showed the largest average diameter (4.0 ± 1.5 µm) and the broadest fiber diameter distribution. The protein content of the fibers was close to that of the corresponding spinning solution. The browning index after 48 h of heating increased for all samples (9.7–14.7) compared to the unheated samples (1.1–3.3). The results indicate that the protein content has an impact on the yield, the fiber diameter, and the morphology of the fibers.

Investigation of metallic nanoparticle distribution in PAN/magnetic nanocomposites fabricated with needleless electrospinning technique

Needleless electrospinning can be used to produce polyacrylonitrile nanofibres, for example, to which magnetic nanoparticles can additionally be added. Such composite nanofibres can then be stabilised and carbonised to produce carbon composite nanofibres. The magnetic nanoparticles have an influence not only on the structure but also on the mechanical and electrical properties of the finished carbon nanofibres, as does the heat treatment during stabilisation and incipient carbonisationThe present study reports on the fabrication, heat treatment and resulting properties of poly(acrylonitrile) (PAN)/magnetic nanofibre mats prepared by needleless electrospinning from polymer solutions. A variety of microscopic and thermal characterisation methods were used to investigate in detail the chemical and morphological transition during oxidative stabilisation (280 °C) and incipient carbonisation (500 °C). PAN and nanoparticles were analysed during all stages of heat treatment. Compared to pure PAN nanofibres, the PAN/ magnetic nanofibers showed larger fiber diameters and the presence of beads and agglomerations. In this study, magnetic nanofibers were investigated in more detail with the aim of detecting undesired agglomerations. Visual observation, for example with CLSM or SEM, does not provide conclusive evidence of agglomerations in the nanofibers. But based on the capabilities of SEM/EDS many different types of samples can be easily analysed where other analytical techniques simply cannot give the fast answer.

Needleless Electrospinning of PA6 Fibers: The Effect of Solution Concentration and Electrospinning Voltage on Fiber Diameter

Needleless electrospinning is the process of forming thin material fibers from the open surface of its solution or melt in a strong electrostatic field. Electrospun non-woven materials are used in various applications that require specific fiber diameters and pore size distributions. Fiber diameter depends on the properties of the polymer solution and manufacturing conditions. A needleless electrospinning process using the Nanospider setup was investigated using the commonly used polyamide 6 (PA6) solution in a mixture of acetic and formic acids. Polymer solutions with different polymer concentrations were characterized by viscosity, surface tension and electrical conductivity. An increase in polymer content in the solution resulted in the exponential increase of the solution viscosity, polynomial increase of electrical conductivity and had almost no effect on surface tension. The effect of the polymer concentration in the solution, as well as electrospinning voltage on fiber diameter and diameter distribution, was investigated using scanning electron microscopy images. The average fiber diameter linearly increases with the increased polymer concentration and also demonstrates an increase with increased electrospinning voltage, although less pronounced. Therefore, a change in the PA6 solution concentration should be used for the robust adjustment of fiber diameter, while changes in electrospinning voltage are more appropriate for fine tuning the fiber diameter during the process of needleless electrospinning.

A Mini-Review: Needleless Electrospinning of Nanofibers for Pharmaceutical and Biomedical Applications

Electrospinning (ES) is a convenient and versatile method for the fabrication of nanofibers and has been utilized in many fields including pharmaceutical and biomedical applications. Conventional ES uses a needle spinneret for the generation of nanofibers and is associated with many limitations and drawbacks (i.e., needle clogging, limited production capacity, and low yield). Needleless electrospinning (NLES) has been proposed to overcome these problems. Within the last two decades (2004–2020), many research articles have been published reporting the use of NLES for the fabrication of polymeric nanofibers intended for drug delivery and biomedical tissue engineering applications. The objective of the present mini-review article is to elucidate the potential of NLES for designing such novel nanofibrous drug delivery systems and tissue engineering constructs. This paper also gives an overview of the key NLES approaches, including the most recently introduced NLES method: ultrasound-enhanced electrospinning (USES). The technologies underlying NLES systems and an evaluation of electrospun nanofibers are presented. Even though NLES is a promising approach for the industrial production of nanofibers, it is a multivariate process, and more research work is needed to elucidate its full potential and limitations.