Novel polycaprolactone (PCL)-type I collagen core-shell electrospun nanofibers for wound healing applications

The Effects of Pulsed Electrospinning Process Variables on the Size of Polymer Fibers Established with a 23 Factorial Design

In the present study, the influence of the electrical parameters of the pulsed electrospinning process, such as the electrical voltage, the frequency of pulses, and the pulse duration, on the structure of obtained nonwovens was determined for the first time. It was found that all the parameters studied strongly influence the average diameter of the obtained fibers and that the pulsed electrospinning process carried out under specific conditions makes it possible to obtain, among other things, bimodal nonwovens. A 23 factorial design was used to determine how the selected electrical parameters of the pulsed electrospinning process affect the structure of the resulting electrospun mats. It is shown, among other things, that by appropriately selecting the parameters of the electrospinning process, the thickness of fibers can be controlled, resulting in nonwovens with a desired morphology.

Adhesive Antibacterial Moisturizing Nanostructured Skin Patch for Sustainable Development of Atopic Dermatitis Treatment in Humans

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex etiology that lacks effective treatment. The therapeutic goals include alleviating symptoms, such as moisturizing and applying antibacterial and anti-inflammatory medications. Hence, there is an urgent need to develop a patch that effectively alleviates most of the AD symptoms. In this study, we employed a "green" cross-linking approach of poly(vinyl alcohol) (PVA) using glycerol, and we combined it with polyacrylonitrile (PAN) to fabricate core-shell (CS) nanofibers through electrospinning. Our designed structure offers multiple benefits as the core ensures controlled drug release and increases the strength of the patch, while the shell provides skin moisturization and exudate absorption. The efficient PVA cross-linking method facilitates the inclusion of sensitive molecules such as fermented oils. In vitro studies demonstrate the patches' exceptional biocompatibility and efficacy in minimizing cell ingrowth into the CS structure containing argan oil, a property highly desirable for easy removal of the patch. Histological examinations conducted on an ex vivo model showed the nonirritant properties of developed patches. Furthermore, the eradication of Staphylococcus aureus bacteria confirms the potential use of CS nanofibers loaded with argan oil or norfloxacin, separately, as an antibacterial patch for infected AD wounds. In vivo patch application studies on patients, including one with AD, demonstrated ideal patches' moisturizing effect. This innovative approach shows significant promise in enhancing life quality for AD sufferers by improving skin hydration and avoiding infections.

Electrospun fibers for the treatment of skin diseases

Skin diseases are among the most common diseases in the global population and with the growth of the aging population, they represent an increasing burden to healthcare systems worldwide. Even though they are rarely life-threatening, the suffering for those affected is high due to the visibility and physical discomfort related to these diseases. Typical symptoms of skin diseases include an inflamed, swollen or itchy skin, and therefore, there is a high demand for effective therapy options. In recent years, electrospinning has attracted considerable interest in the field of drug delivery. The technique allows producing multifunctional drug-loaded fibrous patches from various natural and synthetic polymers with fiber diameters in the nano- and micrometer range, suitable for the treatment of a wide variety of skin diseases. The great potential of electrospun fiber patches not only lies in their tunable drug release properties and the possibility to entrap a variety of therapeutic compounds, but they also provide physical and mechanical protection to the impaired skin area, exhibit a high surface area, allow gas exchange, absorb exudate due to their porous structure and are cytocompatible and biodegradable. In the case of wound healing, cell adhesion is promoted due to the resemblance of the electrospun fibers to the structure of the native extracellular matrix. This review gives an overview of the potential applications of electrospun fibers in skin therapy. In addition to the treatment of bacterial, diabetic and burn wounds, focus is placed on inflammatory diseases such as atopic dermatitis and psoriasis, and therapeutic options for the treatment of skin cancer, acne vulgaris and herpes labialis are discussed. While we aim to emphasize the great potential of electrospun fiber patches for the treatment of skin diseases with this review paper, we also highlight challenges and limitations of current research in the field.

Evaluation of polycaprolactone nanofibers' spinnability using green solvent systems by solution blow spinning (SBS)

Solution blow spinning (SBS) is a promising alternative to produce fibrous matrices for a wide range of applications, such as packaging and biomedical devices. Polycaprolactone (PCL) is a biodegradable polyester commonly used for spinning. The usual choices for producing PCL solutions include chlorinated solvents (CS), such as chloroform. However, the high toxicity of CS makes it difficult for biological and green applications. This work evaluates the influence of two less toxic solvents, acetic acid (AA) and acetone (Acet), and their mixtures (AA/Acet) on the properties of PCL fibers produced by SBS. The results showed that Acet does not cause degradation of the PCL chains, in opposition to AA. Furthermore, adding acetone to the acetic acid tended to preserve the size of PCL chains. It was not possible to produce fibers using PCL in 100% acetone. However, the AA/Acet mixture allowed the efficient production of PCL fibers. The proportion of Acet and AA in the mixture modulated the fiber morphology and orientation, making it possible to use this green solvent system according to the desired application.

Fabrication and multiscale modeling of polycaprolactone/amniotic membrane electrospun nanofiber scaffolds for wound healing

BACKGROUND

Enhancing the efficiency of cell-based skin tissue engineering (TE) approaches is possible via designing electrospun scaffolds possessing natural materials like amniotic membrane (AM) with wound healing characteristics. Concentrating on this aim, we fabricated innovative polycaprolactone (PCL)/AM scaffolds through the electrospinning process.

METHODS

The manufactured structures were characterized by employing scanning electron microscope (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, tensile testing, Bradford protein assay, etc. In addition, the mechanical properties of scaffolds were simulated by the multiscale modeling method.

RESULTS

As a result of conducting various tests, it was concluded that the uniformity and distribution of fibers decreased with an increase in the amniotic content. Furthermore, PCL-AM scaffolds contained amniotic and PCL characteristic bands. In the case of protein release, greater content of AM led to the release of higher amounts of collagen. Tensile testing revealed that scaffolds' ultimate strength increased when the AM content augmented. The multiscale modeling demonstrated that the scaffold had elastoplastic behavior. In order to assess cellular attachment, viability, and differentiation, human adipose-derived stem cells (ASCs) were seeded on the scaffolds. In this regard, SEM and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays showed significant cellular proliferation and viability on the proposed scaffolds, and these analyses illustrated that higher cell survival and adhesion could be achieved when scaffolds possessed a larger amount of AM. After 21 days of cultivation, particular keratinocyte markers, such as keratin I and involucrin, were identified through utilizing immunofluorescence and real-time polymerase chain reaction (PCR) tests. The markers' expressions were higher in the PCL-AM scaffold with a ratio of 90:10 v v-1 compared with the PCL-epidermal growth factor (EGF) structure. Moreover, the presence of AM in the scaffolds resulted in the keratinogenic differentiation of ASCs even without employing EGF. Consequently, this state-of-the-art experiment suggests that the PCL-AM scaffold can be a promising candidate in skin bioengineering.

CONCLUSION

This study showed that mixing AM with PCL, a widely used polymer, in different concentrations can overcome PCL disadvantages such as high hydrophobicity and low cellular compatibility.

Electrospinning of collagen: enzymatic and spectroscopic analyses reveal solvent-independent disruption of the triple-helical structure

Electrospinning has become a well-established method for creating nanofibrous meshes for tissue-engineering applications. The incorporation of natural extracellular components, such as electrospun pure collagen nanofibers, has proven to be particularly challenging, as electrospun collagen nanofibers do not constitute native collagen fibers anymore. In this study, we show that this detrimental effect is not only limited to fluorinated solvents, as previously thought. Rat tail collagen was dissolved in acetic acid and ethanol and electrospun at various temperatures. Electrospun collagen mats were analyzed using circular dichroism, enzymatic digestion, SDS-PAGE, western blotting, and Raman spectroscopy and compared to heat-denaturated and electrospun collagen in HFIP. Our data suggest that even non-fluorinated electrospinning solvents, such as acid-based solvents, do not yield structurally intact fibers. Interestingly, neither epithelial cells nor fibroblasts displayed a different cellular response to electrospun collagen compared to collagen-coated polyurethane scaffolds in F-actin staining and metabolic analysis using fluorescent lifetime imaging. The disruption of the structural integrity of collagen might therefore be underestimated based on the cell-material interactions alone. These observations expose the larger than anticipated vulnerability of collagen in the electrospinning process. Based on these findings, the influence of the electrospinning process on the distinct biochemical properties of collagen should always be considered, when ECM-mimicking fibrous constructs are manufactured.