An In Vitro Study of Antibacterial Properties of Electrospun Hypericum perforatum Oil-Loaded Poly(lactic Acid) Nonwovens for Potential Biomedical Applications

The growth of population and increase in diseases that cause an enormous demand for biomedical material consumption is a pointer to the pressing need to develop new sustainable biomaterials. Electrospun materials derived from green polymers have gained popularity in recent years for biomedical applications such as tissue engineering, wound dressings, and drug delivery. Among the various bioengineering materials used in the synthesis of a biodegradable polymer, poly(lactic acid) (PLA) has received the most attention from researchers. Hypericum perforatum oil (HPO) has antimicrobial activity against a variety of bacteria. This study aimed to investigate the development of an antibacterial sustainable material based on PLA by incorporating HPO via a simple, low-cost electrospinning method. Chemical, morphological, thermal, thickness and, air permeability properties, and in vitro antibacterial activity of the electrospun nonwoven fabric were investigated. Scanning electron microscopy (SEM) was used to examine the morphology of the electrospun nonwoven fabric, which had bead-free morphology ultrafine fibers. Antibacterial tests revealed that the Hypericum perforatum oil-loaded poly(lactic acid) nonwoven fabrics obtained had high antibacterial efficiency against Escherichia coli and Staphylococcus aureus, indicating a strong potential for use in biomedical applications.

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.

Bamboo Charcoal/Poly(L-lactide) Fiber Webs Prepared Using Laser-Heated Melt Electrospinning

Although several studies have reported that the addition of bamboo charcoal (BC) to polylactide (PLA) enhances the properties of PLA, to date, no study has been reported on the fabrication of ultrafine BC/poly(L-lactide) (PLLA) webs via electrospinning. Therefore, ultrafine fiber webs of PLLA and BC/PLLA were prepared using PLLA and BC/PLLA raw fibers via a novel laser electrospinning method. Ultrafine PLLA and BC/PLLA fibers with average diameters of approximately 1 μm and coefficients of variation of 13–23 and 20–46% were obtained. Via wide-angle X-ray diffraction (WAXD) analysis, highly oriented crystals were detected in the raw fibers; however, WAXD patterns of both PLLA and BC/PLLA webs implied an amorphous structure of PLLA. Polarizing microscopy images revealed that the webs comprised ultrafine fibers with uniform diameters and wide variations in birefringence. Temperature-modulated differential scanning calorimetry measurements indicated that the degree of order of the crystals in the fibers was lower and the molecules in the fibers had higher mobilities than those in the raw fibers. Transmittance of BC/PLLA webs with an area density of 2.6 mg/cm2 suggested that the addition of BC improved UV-shielding efficiencies.

Analysis of the association of parameters in the formation of ultrafine fibers from PEI and PMMA

Objective: The aim of the study was to fabricate and morphologically characterize ultrafine Polyetherimide fibers (PEI) associated with Polymethylmethacrylate (PMMA) – PP (group formed by the association of PEI with PMMA), produced by the electrospinning process. Material and Methods: A solution of PEI (0.562 g) + PMMA (0.377 g) dissolved in 2.5 mL of chloroform, 0.85 mL of Dimethylformamide (DMF) and 0.85 mL of 1.1.2.2 Tetrachloroethane (TCE) was prepared. For the electrospinning process, different continuous voltages (10 to 18 kV) and two different distances (8 and 12 cm) between the needle tip and the collecting apparatus were used, giving rise to 6 distinct groups of ultrafine fibers (PP 1 to 6) that were observed in Scanning Electron Microscopy to check for defects and calculate the average diameter of the fibers. Results: The best parameter, the parameter that was most effective for the production of fibers, observed was subjected to Energy Dispersion X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Contact Angle Analysis tests. The data were analyzed using the ANOVA and Tukey test (p <0.05). From the comparative analysis of the pre-established parameters, the pattern of PP4 ultrafine fibers was shown to be more effective. Conclusion: The PP4 standard (13 kV – 12 cm) had an average diameter of 0.37 µm. An adequate parameter to electrospinning was able to produce ultrafine fibers of PMMA/PEI. Keywords Polymethylmethacrylate; Scanning electron microscopy; Polyetherimide; Electrospinning process.

Nanomodified rapid hardening concretes reinforced with dispersed basaltic fibers

The article considers modern perspectives and directions of using fast – hardening high – strength concretes for protection against striking factors of action of different types of weapons. It is shown that the use of concrete materials in weapons and military equipment is one of the important components of defense structures and protective fortifications during hostilities as platoons and bases, and structures for the protection of civilians. The possibility of obtaining such concretes for the creation of special purpose fortifications is shown. Developed concrete structures have increased strength and impact resistance to high-speed impact. Due to the reinforcement of the concrete structure with mineral and chemical additives and ultrafine fibers, high rates of early strength, viscosity, crack resistance and impact resistance are achieved. The paper presents the main indicators of water consumption, strength and impact resistance of high-strength concrete. The results of the experimental study of samples of the destroyed concrete elements are presented and the corresponding conclusions concerning the use of various types of fibers for reinforcement of such concretes and increase of their crack resistance by basalt fibers are made. It is shown that a high-strength concrete with high construction and technical performance can be successfully used to create protective fortifications and fortifications for special purposes.