State-of-the-Art Review of Electrospun Gelatin-Based Nanofiber Dressings for Wound Healing Applications

Electrospun nanofiber materials have been considered as advanced dressing candidates in the perspective of wound healing and skin regeneration, originated from their high porosity and permeability to air and moisture, effective barrier performance of external pathogens, and fantastic extracellular matrix (ECM) fibril mimicking property. Gelatin is one of the most important natural biomaterials for the design and construction of electrospun nanofiber-based dressings, due to its excellent biocompatibility and biodegradability, and great exudate-absorbing capacity. Various crosslinking approaches including physical, chemical, and biological methods have been introduced to improve the mechanical stability of electrospun gelatin-based nanofiber mats. Some innovative electrospinning strategies, including blend electrospinning, emulsion electrospinning, and coaxial electrospinning, have been explored to improve the mechanical, physicochemical, and biological properties of gelatin-based nanofiber mats. Moreover, numerous bioactive components and therapeutic agents have been utilized to impart the electrospun gelatin-based nanofiber dressing materials with multiple functions, such as antimicrobial, anti-inflammation, antioxidation, hemostatic, and vascularization, as well as other healing-promoting capacities. Noticeably, electrospun gelatin-based nanofiber mats integrated with specific functions have been fabricated to treat some hard-healing wound types containing burn and diabetic wounds. This work provides a detailed review of electrospun gelatin-based nanofiber dressing materials without or with therapeutic agents for wound healing and skin regeneration applications.

Non-Toxic Crosslinking of Electrospun Gelatin Nanofibers for Tissue Engineering and Biomedicine-A Review

Electrospinning can be used to prepare nanofiber mats from diverse polymers, polymer blends, or polymers doped with other materials. Amongst this broad range of usable materials, biopolymers play an important role in biotechnological, biomedical, and other applications. However, several of them are water-soluble, necessitating a crosslinking step after electrospinning. While crosslinking with glutaraldehyde or other toxic chemicals is regularly reported in the literature, here, we concentrate on methods applying non-toxic or low-toxic chemicals, and enzymatic as well as physical methods. Making gelatin nanofibers non-water soluble by electrospinning them from a blend with non-water soluble polymers is another method described here. These possibilities are described together with the resulting physical properties, such as swelling behavior, mechanical strength, nanofiber morphology, or cell growth and proliferation on the crosslinked nanofiber mats. For most of these non-toxic crosslinking methods, the degree of crosslinking was found to be lower than for crosslinking with glutaraldehyde and other common toxic chemicals.

One-step electrospun scaffold of dual-sized gelatin/poly-3-hydroxybutyrate nano/microfibers for skin regeneration in diabetic wound

This work aimed to implement an electrospinning protocol that allows simultaneous production of micro- and nanofibers in a single scaffold to mimic the extracellular matrix (ECM) combining biodegradable polymers and proteins, and to evaluate its capability to manage diabetic wounds. Poly-3-hydroxybutyrate (PHB) and gelatin (Ge) were chosen to prepare micro- and nanofibers, respectively. Electrospinning conditions were optimized testing various polymer concentrations, voltages, and flow rates. One-step dual-size fibers were obtained from 8%w/v PHB in chloroform (microfibers, 1.25 ± 0.17 μm) and 30%w/v gelatin in acetic acid (75%w/v) (nanofibers, 0.20 ± 0.04 μm), at 0.5 mL/h and 25 kV. A chemical characterization, swelling, hydrophilicity of scaffolds made of PHB-microfibers, Ge-nanofibers and their combination (Ge-PHB) were evaluated before and after crosslinking with genipin. All scaffolds showed excellent fibroblasts viability and attachment after incubation for 1, 3, and 7 days, and low levels of hemolysis. In vivo wound healing was evaluated in diabetic rats for 21 days. Ge-containing scaffolds promoted faster healing. The wounds treated with the Ge-PHB scaffolds proved to be in a late proliferative stage showing higher content of hair follicles and sweat glands and lower content in fibroblast compared with the control wounds.

Electrospun gelatin-polyethylenimine blend nanofibrous scaffold for biomedical applications

In this study, gelatin-polyethylenimine blend nanofibers (GEL/PEI) were fabricated via electrospinning with different ratios (9:1, 6:1, 3:1) to integrate the properties of both the polymers for evaluating its biomedical application. From scanning electron microscopy, the average diameter of blend nanofibers (265 ± 0.074 nm to 340 ± 0.088 nm) was observed to be less than GEL nanofibers (403 ± 0.08 nm). The incorporation of PEI with gelatin resulted in improved thermal stability of nanofibers whereas the Young's modulus was observed to be higher at 9:1 ratio when compared with other ratios. The in vitro studies showed that the GEL/PEI nanofibers with 9:1 ratio promoted better cell adhesion and viability. GEL/PEI nanofibers with 9:1 and 6:1 showed hemolysis within the permissible limits. From the results, it could be interpreted that GEL/PEI nanofibers with 9:1 ratio proved to be a better scaffold thereby making them a potential candidate for tissue engineering applications.

Production and characterization of bactericidal wound dressing material based on gelatin nanofiber

Gelatin is a biocompatible and biodegradable natural polymer obtained by collagen. Gelatin nanofibers meet all the necessary requirements when used as wound dressing material. However, their lack of antimicrobial properties limits their use. The purpose of this study is to expand the field of use of gelatin by providing it with antimicrobial properties. For this purpose, poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (PMETAC), was used. In this study, the polymers were dissolved in formic acid-acetic acid and nanofibers were synthesized by electrospinning. The obtained nanofibers were characterized with SEM, FTIR, and TGA. The antibacterial effect, degradation tests, and cell viability, adhesion and proliferation were investigated. The SEM studies show that the nanofibers are homogeneous and smooth. At the end of 14 days, all nanofibers lost >90% of their mass. The nanofibers containing PMETAC showed good bactericidal activity against Staphylococcus aureus, Escherichia coli, methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii. MTT test demonstrated that low doses of the nanofibers were biocompatible. The cell adhesion study has been shown that many cells attachment and proliferate on the surface of nanofibers. It has been found that the obtained nanofibers can be used safely and effectively as antimicrobial wound dressing material.

Naturally-derived electrospun wound dressings for target delivery of bio-active agents

Electrospun nanofibers are known as the advanced means for wound dressing. They have represented remarkable potency to encapsulate and deliver biomolecules promoting the wound healing process. Compared to synthetic polymers, naturally derived polymers (NDP) are more qualified candidates for fabrication of biomedical electrospun scaffolds. Not only nanofibers of NDP illustrate higher biocompatibility and biodegradability rates, but also they mimic the native extracellular matrix more closely, which leads to the wound closure acceleration by enhancing tissue regeneration. Aside, incorporation of bioactive molecules and therapeutic agents into the nanofibers can generate innovative bioactive wound dressings with significantly improved healing potentials. This paper starts with a brief discussion on the steps and factors influencing the wound healing process. Then, the recent applications of electrospun nanofibers as wound dressing with healing accelerating properties are reviewed. Further, the various healing agents and alternative strategies for modification and functionalization of bioactive naturally-derived electrospun nanofibers are discussed.

Antioxidative study of Cerium Oxide nanoparticle functionalised PCL-Gelatin electrospun fibers for wound healing application

Skin wound healing involves a coordinated cellular response to achieve complete reepithelialisation. Elevated levels of reactive oxygen species (ROS) in the wound environment often pose a hindrance in wound healing resulting in impaired wound healing process. Cerium oxide nanoparticles (CeNPs) have the ability to protect the cells from oxidative damage by actively scavenging the ROS. Furthermore, matrices like nanofibers have also been explored for enhancing wound healing. In the current study CeNP functionalised polycaprolactone (PCL)-gelatin nanofiber (PGNPNF) mesh was fabricated by electrospinning and evaluated for its antioxidative potential. Wide angle XRD analysis of randomly oriented nanofibers revealed ∼2.6 times reduced crystallinity than pristine PCL which aided in rapid degradation of nanofibers and release of CeNP. However, bioactive composite made between nanoparticles and PCL-gelatin maintained the fibrous morphology of PGNPNF upto 14 days. The PGNPNF mesh exhibited a superoxide dismutase (SOD) mimetic activity due to the incorporated CeNPs. The PGNPNF mesh enhanced proliferation of 3T3-L1 cells by ∼48% as confirmed by alamar blue assay and SEM micrographs of cells grown on the nanofibrous mesh. Furthermore, the PGNPNF mesh scavenged ROS, which was measured by relative DCF intensity and fluorescence microscopy; and subsequently increased the viability and proliferation of cells by three folds as it alleviated the oxidative stress. Overall, the results of this study suggest the potential of CeNP functionalised PCL-gelatin nanofibrous mesh for wound healing applications.

An update on clinical applications of electrospun nanofibers for skin bioengineering

Mimicking morphological similarities of the natural extra cellular matrix (ECM), described by ultrafine continuous fibers, high surface to volume ratio, and high porosity is valuable for effective regeneration of injured skin tissue. Electrospun nanofibers, being one of the most favorable and fast developing products of technology today, display a tremendous potential in wound healing and skin tissue engineering. Under the remarkable attention being given to electrospun nanofibrous scaffolds in promoting wound healing and skin regeneration, this review focuses on the potential of the electrospinning technique as a promising tool for constructing polymeric nanofibrous scaffolds with the favorable physicochemical properties needed for skin bioengineering. In addition, current applications of electrospun nanofibrous matrices for skin bioengineering are detailed in this review.