The Impact of Helium and Nitrogen Plasmas on Electrospun Gelatin Nanofiber Scaffolds for Skin Tissue Engineering Applications

This study explores the fabrication of tannic acid-crosslinked gelatin nanofibers via electrospinning, followed by helium and nitrogen plasma treatment to enhance their biofunctionality, which was assessed using fibroblast cells. The nanofibers were characterized using scanning electron microscopy, atomic force microscopy, attenuated total reflection Fourier transform infrared spectroscopy, X-ray diffraction, and water contact angle measurements before and after treatment. Helium and nitrogen gas plasma were employed to modify the nanofiber surfaces. Results indicated that helium and nitrogen plasma treatment significantly increased the hydrophilicity and biofunctionality of the nanofibers by 5.1° ± 0.6 and 15.6° ± 2.2, respectively, making them more suitable for human skin fibroblast applications. To investigate the impact of plasma treatment on gelatin, we employed a computational model using density functional theory with the B3LYP/6-31+G(d) method. This model represented gelatin as an amino acid chain composed of glycine, hydroxyproline, and proline, interacting with plasma particles. Vibrational analysis of these systems was used to interpret the vibrational spectra of untreated and plasma-treated gelatin. To further correlate with experimental findings, molecular dynamics simulations were performed on a system of three interacting gelatin chains. These simulations explored changes in amino acid bonding. The computational results align with experimental observations. Comprehensive analyses confirmed that these treatments improved hydrophilicity and biofunctionality, supporting the use of plasma-treated gelatin nanofibers in skin tissue engineering applications. Gelatin's natural biopolymer properties and the versatility of plasma surface modification techniques underscore its potential in regenerating cartilage, skin, circulatory tissues, and hamstrings.

Evolution of Electrospinning in Liver Tissue Engineering

The major goal of liver tissue engineering is to reproduce the phenotype and functions of liver cells, especially primary hepatocytes ex vivo. Several strategies have been explored in the recent past for culturing the liver cells in the most apt environment using biological scaffolds supporting hepatocyte growth and differentiation. Nanofibrous scaffolds have been widely used in the field of tissue engineering for their increased surface-to-volume ratio and increased porosity, and their close resemblance with the native tissue extracellular matrix (ECM) environment. Electrospinning is one of the most preferred techniques to produce nanofiber scaffolds. In the current review, we have discussed the various technical aspects of electrospinning that have been employed for scaffold development for different types of liver cells. We have highlighted the use of synthetic and natural electrospun polymers along with liver ECM in the fabrication of these scaffolds. We have also described novel strategies that include modifications, such as galactosylation, matrix protein incorporation, etc., in the electrospun scaffolds that have evolved to support the long-term growth and viability of the primary hepatocytes.

Peripheral Nerve Conduit: Materials and Structures

Peripheral nerve injuries (PNIs) are the most common injury types to affect the nervous system. Restoration of nerve function after PNI is a challenging medical issue. Extended gaps in transected peripheral nerves are only repaired using autologous nerve grafting. This technique, however, in which nerve tissue is harvested from a donor site and grafted onto a recipient site in the same body, has many limitations and disadvantages. Recent studies have revealed artificial nerve conduits as a promising alternative technique to substitute autologous nerves. This Review summarizes different types of artificial nerve grafts used to repair peripheral nerve injuries. These include synthetic and natural polymers with biological factors. Then, desirable properties of nerve guides are discussed based on their functionality and effectiveness. In the final part of this Review, fabrication methods and commercially available nerve guides are described.

Biofunctionalisation of polymeric scaffolds for neural tissue engineering

Patients who experience injury to the central or peripheral nervous systems invariably suffer from a range of dysfunctions due to the limited ability for repair and reconstruction of damaged neural tissue. Whilst some treatment strategies can provide symptomatic improvement of motor and cognitive function, they fail to repair the injured circuits and rarely offer long-term disease modification. To this end, the biological molecules, used in combination with neural tissue engineering scaffolds, may provide feasible means to repair damaged neural pathways. This review will focus on three promising classes of neural tissue engineering scaffolds, namely hydrogels, electrospun nanofibres and self-assembling peptides. Additionally, the importance and methods for presenting biologically relevant molecules such as, neurotrophins, extracellular matrix proteins and protein-derived sequences that promote neuronal survival, proliferation and neurite outgrowth into the lesion will be discussed.

Fiber diameters control osteoblastic cell migration and differentiation in electrospun gelatin

Defined electrospinning conditions were used to create scaffolds with different fiber diameters to investigate their interactions with osteoblastic MG63 cells. Nonwoven gelatin scaffolds were electrospun with varied fiber diameters to investigate the effect of fiber size and resultant porosity on cell proliferation, viability, migration, and differentiation. The low toxicity solvent acetic acid:ethyl acetate:water ratio and gelatin concentrations were optimized to create small and large diameter fibers. The fiber diameters obtained by this procedure were 110 +/- 40 nm for the small and 600 +/- 110 nm for the large fibers. Cell viability assays showed that MG63 cells grew similarly on both fibers at the early time point (day 3) but preferred the scaffold with large diameter fibers by the later time points (day 5 and day 7). Confocal microscopic imaging showed that MG63 cells migrated poorly (maximum depth of 18 microm) into the scaffold of small diameter fibers, but readily penetrated (maximum depth of 50 microm) into the scaffold of large diameter fibers. Alkaline phosphatase (ALP) assays showed that MG63 cells differentiated on scaffolds made from both diameter fibers. In longer term experiments, MG63 cells differentiated to a greater extent on scaffolds made from small diameter fibers compared to large diameter fibers at days 3 and 7, but the ALP levels were the same for both diameter fibers by day 14. These results indicate that cells can perceive differences in the diameter and resultant pore size of electrospun gelatin fibers and that they process this information to alter their behavior.

Fiber scaffolds of polysialic acid via electrospinning for peripheral nerve regeneration

Fiber scaffolds of bioactive polysialic acid have been prepared via electrospinning for peripheral nerve regeneration. The diameter, morphology and alignment of fibers in scaffolds were adjusted by variation of electrospinning parameters, which are decisive for the cell-scaffold interaction. Due to the high water solubility of polysialic acid (poly-alpha-2,8-N-acetylneuraminic acid) a photoactive derivative (poly-alpha-2,8-N-pentenoylneuraminic acid) was used to obtain stable fiber scaffolds in water by photochemical crosslinking. At the optimized fiber scaffolds good cell viability and directed cell proliferation along the fibers was achieved by cell tests with immortalized Schwann cells.

Preparation and Surface Modification of Poly(acrylonitrile-co-acrylic acid) Electrospun Nanofibrous Membranes

Poly(acrylonitrile-co-acrylic acid) (PANCAA) was synthesized and fabricated into nanofibrous membranes by an electrospinning technique. Scanning electron microscopy revealed that membranes composed of uniformly thin and smooth nanofibres were obtained under optimized processing parameters. Surface modification with chitosan on these nanofibrous membranes was accomplished by a coupling reaction between the carboxylic groups of PANCAA and the primary amino groups of chitosan. Fluorescent labelling, weight measurement, FT-IR/ATR spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used to confirm the modification process and determine the immobilization degree of chitosan. Platelet adhesion experiments were further carried out to evaluate the hemocompatibility of the studied nanofibrous membranes. Preliminary results indicated that the immobilization of chitosan on the PANCAA nanofibrous membranes was favourable for platelet adhesion.

Electrospinning: A Fascinating Method for the Preparation of Ultrathin Fibers

Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers. This technique is applicable to virtually every soluble or fusible polymer. The polymers can be chemically modified and can also be tailored with additives ranging from simple carbon-black particles to complex species such as enzymes, viruses, and bacteria. Electrospinning appears to be straightforward, but is a rather intricate process that depends on a multitude of molecular, process, and technical parameters. The method provides access to entirely new materials, which may have complex chemical structures. Electrospinning is not only a focus of intense academic investigation; the technique is already being applied in many technological areas.

A review on electrospinning design and nanofibre assemblies

Although there are many methods of fabricating nanofibres, electrospinning is perhaps the most versatile process. Materials such as polymer, composites, ceramic and metal nanofibres have been fabricated using electrospinning directly or through post-spinning processes. However, what makes electrospinning different from other nanofibre fabrication processes is its ability to form various fibre assemblies. This will certainly enhance the performance of products made from nanofibres and allow application specific modifications. It is therefore vital for us to understand the various parameters and processes that allow us to fabricate the desired fibre assemblies. Fibre assemblies that can be fabricated include nonwoven fibre mesh, aligned fibre mesh, patterned fibre mesh, random three-dimensional structures and sub-micron spring and convoluted fibres. Nevertheless, more studies are required to understand and precisely control the actual mechanics in the formation of various electrospun fibrous assemblies.