Large-Scale Development of Antibacterial Scaffolds: Gentamicin Sulfate-Loaded Biodegradable Nanofibers for Gastrointestinal Applications.

The ever-increasing demands of modern medicine drive the development of novel drug delivery materials. In particular, nanofibers are promising for such materials due to their favorable properties. However, most development is still carried out through laboratory techniques that do not allow extensive and reproducible characterization of materials, which slows medical research. In this work, we focus on the large-scale fabrication and testing of specific antibacterial nanofibrous materials to prevent the postoperative complications associated with the occurrence of bacterial infection. Poly-ε-caprolactone with gentamicin sulfate (antibiotic) in different concentrations was electrospun via a needleless device. The amount of antibiotics was proven by elemental analysis, UV spectrophotometry, and HPLC. The cytocompatibility of the materials was verified in vitro according to ISO 10993-5. The cell adhesion and proliferation were assessed after 2, 7, 14, and 21 days using the CCK-8 metabolic assay, fluorescence, and scanning electron microscopy. The tested nanofiber materials supported cell growth. Antibacterial tests were performed to confirm the release of gentamicin sulfate, and its antibacterial properties were proven toward Staphylococcus gallinarum and Escherichia coli bacteria. The effect of ethylene oxide sterilization was also studied. The sterilized nanofibrous layers are cytocompatible while antibacterial and therefore suitable for medical applications.

Production of Modified Composite Nanofiber Yarns with Functional Particles.

The study focused on the production of modified composite nanofiber yarns with fine functional particles. A device that incorporates fine functional particles into a nanofiber yarn wrapper was specially developed, which ensures the continuous production of modified yarn. It was demonstrated during the study that the specially designed equipment could be used effectively for incorporating fine functional particles into the nanofiber packaging, thus creating a unique yarn with high application potential. The use of particles with dimensions of just tens of micrometers results in the uneven flow of particles inside the chamber and the uneven supply of particles to the composite yarn. The study also determined that the number of particles incorporated into the composite yarn is affected by the particle concentration and the variation of the vortex velocity ratios in the chamber. During testing, it was also found that the nanofiber sheet of the composite yarn improves the mechanical properties of the produced yarn. In addition, the study included the semi-industrial production of a composite filter candle, which can be used for the treatment of fluids, especially air and water.

The Combination of Hydrogels with 3D Fibrous Scaffolds Based on Electrospinning and Meltblown Technology.

This study presents the advantages of combining three-dimensional biodegradable scaffolds with the injection bioprinting of hydrogels. This combination takes advantage of the synergic effect of the properties of the various components, namely the very favorable mechanical and structural properties of fiber scaffolds fabricated from polycaprolactone and the targeted injection of a hydrogel cell suspension with a high degree of hydrophilicity. These properties exert a very positive impact in terms of promoting inner cell proliferation and the ability to create compact tissue. The scaffolds were composed of a mixture of microfibers produced via meltblown technology that ensured both an optimal three-dimensional porous structure and sufficient mechanical properties, and electrospun nanofibers that allowed for good cell adhesion. The scaffolds were suitable for combination with injection bioprinting thanks to their mechanical properties, i.e., only one nanofibrous scaffold became deformed during the injection process. A computer numerical-control manipulator featuring a heated printhead that allowed for the exact dosing of the hydrogel cell suspension into the scaffolds was used for the injection bioprinting. The hyaluronan hydrogel created a favorable hydrophilic ambiance following the filling of the fiber structure. Preliminary in vitro testing proved the high potential of this combination with respect to the field of bone tissue engineering. The ideal structural and mechanical properties of the tested material allowed osteoblasts to proliferate into the inner structure of the sample. Further, the tests demonstrated the significant contribution of printed hydrogel-cell suspension to the cell proliferation rate. Thus, the study led to the identification of a suitable hydrogel for osteoblasts.

The Potential for the Direct and Alternating Current-Driven Electrospinning of Polyamides.

The paper provides a description of the potential for the direct current- and alternating current-driven electrospinning of various linear aliphatic polyamides (PA). Sets with increasing concentrations of selected PAs were dissolved in a mixture of formic acid and dichloromethane at a weight ratio of 1:1 and spun using a bar electrode applying direct and alternating high voltage. The solubility and spinnability of the polyamides were investigated and scanning electron microscopy (SEM) images were acquired of the resulting nanofiber layers. The various defects of the spun fibers and their diameters were detected and subsequently measured. Moreover, the dynamic viscosity and conductivity were also subjected to detailed investigation. The most suitable concentrations for each of the PAs were determined according to previous findings, and the solutions were spun using a NanospiderTM device at the larger scale. The fiber diameters of these samples were also measured. Finally, the surface energy of the fiber layers produced by the NanospiderTM device was measured aimed at selecting a suitable PA for a particular application.

The wettability of electron spun membranes by synovial fluid.

Aseptic loosening due to periprosthetic osteolysis has been accepted as one of the leading causes of revision procedures in patients with previous joint arthroplasty. Recently, several strategies for suppression of osteolysis were proposed, mostly based on biological treatment such as mitigation of chronic inflammatory reactions. However, these biological treatments do not stop the debris migration but only reduce the inflammatory reaction. To address this shortcoming, we propose the concept of ultrahigh molecular weighted polyethylene particles filtration storage by electrospun membranes. Firstly, the surface tension of synovial fluid (SF) is obtained by use of a pendant droplet. Secondly, the contact angle of the electrospun membranes wetted by two different liquids is measured to obtain the free surface energy using of the Owens-Wendt model. Additionally, the wettability of electrospun membranes by SF as a function of technology parameters is studied.

Preparation of a Hydrogel Nanofiber Wound Dressing.

The study addressed the production of a hydrogel nanofiber skin cover and included the fabrication of hydrogel nanofibers from a blend of polyvinyl alcohol and alginate. The resulting fibrous layer was then crosslinked with glutaraldehyde, and, after 4 h of crosslinking, although the gelling component, i.e., the alginate, crosslinked, the polyvinyl alcohol failed to do so. The experiment included the comparison of the strength and ductility of the layers before and after crosslinking. It was determined that the fibrous layer following crosslinking evinced enhanced mechanical properties, which acted to facilitate the handling of the material during its application. The subsequent testing procedure proved that the fibrous layer was not cytotoxic. The study further led to the production of a modified hydrogel nanofiber layer that combined polyvinyl alcohol with alginate and albumin. The investigation of the fibrous layers produced determined that following contact with water the polyvinyl alcohol dissolved leading to the release of the albumin accompanied by the swelling of the alginate and the formation of a hydrogel.

Preparation of a Composite Scaffold from Polycaprolactone and Hydroxyapatite Particles by Means of Alternating Current Electrospinning.

This research involved the production of polycaprolactone fiber layers via the alternating current electrospinning method. To construct the micro/nanofiber scaffold, mixtures of two molecular weight solutions, M n 45 000 and M n 80 000, were spun in differing proportions in a solvent system containing acetic acid, formic acid, and acetone in a ratio of 1:1:1. The composite fiber materials with hydroxyapatite particles were prepared from a solution that combined the different molecular weight solutions at a ratio of 1:3. The study resulted in the preparation of fiber layers containing 0, 5, 10, and 15% (wt) hydroxyapatite particles from the dry mass of the polycaprolactone. The strength, wettability, and surface energy of the composite materials were examined, and the results demonstrated that hydroxyapatite affects the fiber diameters, strength, and surface energy and, thus, the wettability of the fiber layers. The fibrous layers produced were further tested for cytotoxicity and cell viability and proliferation. The results obtained thus strongly indicate that the resulting bulky micro/nanofiber layers are suitable for further testing with a view to their eventual application in the field of bone tissue engineering.