Electrospun fibers have emerged as a transformative platform in wound care, offering a precisely tunable vehicle for the controlled release of therapeutic agents. By mimicking the native extracellular matrix and providing a high surface area for drug loading, these nanofibrous mats enable sustained delivery of antibiotics, growth factors, and anti-inflammatory compounds directly at the wound site. This localized, controlled release enhances healing outcomes, reduces infection risk, and minimizes systemic side effects, making electrospun fiber dressings a cornerstone of advanced wound management.

What Are Electrospun Fibers?

Electrospinning is a versatile, electric-field-driven process that produces continuous fibers with diameters ranging from tens of nanometers to several micrometers. In a typical setup, a high-voltage electric field is applied to a polymer solution or melt ejected through a spinneret. The charged jet is drawn toward a grounded collector, undergoing rapid stretching and solvent evaporation to form solid, randomly oriented or aligned fibers. The resulting nonwoven mat possesses a highly porous structure (pore sizes of 1–10 μm) and extremely high surface-area-to-volume ratios (often exceeding 10–40 m²/g). These physical attributes make electrospun scaffolds ideal for tissue engineering and drug delivery because they closely resemble the architecture of the natural extracellular matrix, promote cell adhesion and proliferation, and provide a reservoir for sustained drug release.

Advantages of Electrospun Fibers in Wound Healing

Electrospun dressings offer several unique advantages over traditional wound care products such as gauze, hydrogels, or foam dressings:

  • High surface area and porosity: The nanofibrous network maximizes drug loading capacity and facilitates efficient gas exchange (oxygen and carbon dioxide) while absorbing excess wound exudate. The interconnecting pores also allow moisture vapor transmission, preventing maceration.
  • Mimicry of the extracellular matrix: The fibrous topography encourages keratinocyte and fibroblast migration, angiogenesis, and re-epithelialization. This biomimetic environment accelerates the transition from the inflammatory to the proliferative phase of healing.
  • Biocompatibility and biodegradability: A wide range of natural and synthetic polymers can be processed, many of which degrade into non-toxic byproducts that are metabolized or excreted. This eliminates the need for secondary removal procedures.
  • Controlled and sustained release: Unlike bolus administration (e.g., topical ointments), electrospun fibers can deliver drugs at a predefined rate over days or weeks. This maintains therapeutic concentrations at the wound bed while reducing dosing frequency.
  • Customizable mechanical and physical properties: Fiber alignment, diameter, thickness, and chemical composition can be adjusted to match specific wound types—e.g., flexible mats for joints, thicker scaffolds for deep chronic wounds, or layered structures for sequential release of multiple drugs.

Controlled Release in Wound Healing

The ability to program drug release kinetics is arguably the most compelling feature of electrospun fiber dressings. Controlled release localizes therapy, reduces systemic toxicity, and improves patient compliance. The design of such release profiles depends on the polymer properties, drug characteristics, and fiber morphology.

Mechanisms of Drug Release

Drug release from electrospun fibers occurs through one or more of the following mechanisms:

  • Diffusion-controlled release: The drug molecules dissolved or dispersed within the polymer matrix diffuse through the fiber network into the surrounding environment (wound exudate). For non-degrading polymers, release follows first-order or Fickian kinetics. Core–shell electrospinning can produce a reservoir design (drug-rich core) that slows diffusion and yields near-zero-order release.
  • Degradation-controlled release: As biodegradable polymers—such as poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL)—hydrolyze or undergo enzymatic cleavage, the matrix erodes and releases entrapped drugs. This mechanism can be tailored by adjusting polymer molecular weight, copolymer ratio (e.g., PLA:PGA), and fiber crystallinity to provide release over weeks to months.
  • Swelling-controlled release: Hydrophilic polymers (e.g., gelatin, alginate) absorb wound fluid, swell, and form a hydrogel layer that acts as a diffusion barrier, slowing transient burst release. Swelling also increases mesh size, allowing larger molecules to diffuse out.
  • Stimuli-responsive release: Advanced fiber systems incorporate polymers or additives that respond to wound microenvironmental cues such as pH (chronic wounds are often alkaline), temperature, enzyme activity (e.g., matrix metalloproteinases), or glucose concentration. These “smart” dressings release drugs only when needed—for example, antibiotic release triggered by bacterial infection-induced low pH.

Factors Influencing Release Profiles

Several processing and material parameters can be adjusted to achieve desired release kinetics:

  • Fiber diameter (smaller fibers have higher surface area and faster release)
  • Drug loading method (blending vs. coaxial vs. surface adsorption)
  • Polymer composition (hydrophilic/hydrophobic balance)
  • Crosslinking density (higher crosslinking reduces swelling and slows release)
  • Porosity and fiber orientation (aligned fibers may allow directional release)

Materials Used in Electrospinning for Wound Healing

Selection of the polymer base is critical because it determines biocompatibility, degradation rate, mechanical integrity, and drug compatibility. Both natural and synthetic polymers are widely used, often in combination to leverage their complementary properties.

Natural Polymers

  • Collagen: The primary structural protein of the ECM. Electrospun collagen scaffolds promote cell adhesion, migration, and hemostasis. However, rapid degradation and poor mechanical strength often necessitate crosslinking (e.g., using EDC/NHS) or blending with synthetic polymers.
  • Chitosan: Derived from chitin, chitosan is biocompatible, biodegradable, and possesses intrinsic antimicrobial activity against bacteria and fungi. Its cationic nature enables electrostatic interactions with anionic drugs or growth factors, providing sustained release.
  • Gelatin: Denatured collagen, gelatin is water-soluble and easily electrospun. It exhibits excellent cell compatibility but degrades quickly; crosslinking with glutaraldehyde or genipin extends stability.
  • Alginate: An anionic polysaccharide from seaweed that forms hydrogels in the presence of divalent cations (e.g., Ca²⁺). Electrospun alginate fibers are used for exudate management and as carriers for hydrophilic drugs and growth factors.
  • Silk fibroin: Natural protein from silkworm cocoons with remarkable mechanical strength, slow degradation, and minimal inflammation. Silk fibroin fibers have been employed in long-term wound dressings and as scaffolds for tissue regeneration.

Synthetic Polymers

  • Poly(lactic acid) (PLA): A degradable polyester derived from renewable resources. PLA fibers offer good mechanical properties and processability, but release acidic degradation products that may lower local pH.
  • Poly(glycolic acid) (PGA) and PLGA: PGA degrades rapidly; copolymerization with PLA (PLGA) allows tunable degradation half-lives from days to months. PLGA is a gold standard in controlled release research.
  • Polycaprolactone (PCL): A semi-crystalline polyester with a slow degradation rate (months to years) and good elasticity. PCL fibers are often used for long-term, stable dressings or as structural supports blended with faster-degrading polymers.
  • Polyvinyl alcohol (PVA): A water-soluble, biocompatible polymer that can be crosslinked to form hydrogels. PVA electrospun mats are commonly used for moisture-retentive dressings and immediate drug release.
  • Polyurethane: Provides excellent flexibility and oxygen permeability; segmented polyurethane fibers are used in breathable, elastomeric wound dressings that conform to irregular wound shapes.

Composite and Hybrid Materials

To overcome the limitations of single polymers, researchers frequently blend natural and synthetic polymers. For example, gelatin/PCL blends combine the bioactivity of natural proteins with the mechanical robustness of synthetic polyesters. Additives such as bioactive glass nanoparticles, carbon nanotubes, or metallic nanoparticles (silver, zinc oxide) can impart antimicrobial, angiogenic, or conductive properties. The integration of two or more components in coaxial or tri-axial fibers enables spatial control—loading one drug in the core and a different agent in the shell—for programmed sequential release (e.g., first an anti-inflammatory, later a growth factor).

Clinical Applications and Current Research

Electrospun dressings have been tested for a wide range of wound types, from acute surgical incisions to chronic diabetic ulcers and infected burn wounds. Key therapeutic agents delivered include:

Antibiotics

To prevent or treat wound infections, electrospun fibers have been loaded with broad-spectrum antibiotics such as gentamicin, ciprofloxacin, vancomycin, or tetracycline. Sustained release reduces bacterial burden without the high peak concentrations typical of systemic administration. Recent work has focused on dual-drug dressings (e.g., ciprofloxacin + silver nanoparticles) that combat both planktonic bacteria and biofilm formation.

Growth Factors

Recombinant human epidermal growth factor (rhEGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) have been incorporated into electrospun scaffolds. Because these proteins have short half-lives in vivo, controlled release is essential. Studies in diabetic wound models show that growth-factor-loaded fibers significantly accelerate re-epithelialization and neovascularization compared to topical application. For example, a 2018 study using core–shell PCL/gelatin fibers delivering bFGF and silver sulfadiazine demonstrated complete wound closure in 14 days in diabetic rats.

Anti-Inflammatory Agents

Steroidal (dexamethasone) and non-steroidal (ibuprofen, curcumin) anti-inflammatory drugs are commonly loaded into dressing materials. Curcumin-loaded PCL/chitosan fibers have been shown to reduce pro-inflammatory cytokines and promote wound contraction in burn models.

Antimicrobial Peptides and Natural Extracts

Because of rising antibiotic resistance, antimicrobial peptides (e.g., LL-37, defensins) and plant extracts (e.g., aloe vera, propolis, essential oils) are gaining attention. Electrospinning preserves the bioactivity of these sensitive compounds, offering an alternative to conventional antibiotics.

Hemostatic Agents

For traumatic or surgical wounds, hemostatic electrospun fibers loaded with kaolin, chitosan, or thrombin rapidly achieve blood coagulation. Such dressings are being developed for military and emergency medicine.

Challenges and Limitations

Despite substantial progress, several hurdles prevent widespread clinical translation of electrospun wound dressings:

  • Scalability: Laboratory-scale electrospinning produces small (e.g., 10×10 cm) mats at low throughput (0.1–1 g/h). Industrial-scale systems such as multi-jet or needleless electrospinning are under development but often suffer from fiber quality inconsistency, solvent recovery issues, and high costs.
  • Uniformity and reproducibility: Environmental factors (humidity, temperature) and process parameters (voltage, flow rate, distance) must be tightly controlled to ensure batch-to-batch reproducibility. Variations in fiber diameter and porosity directly affect drug release kinetics.
  • Burst release: Immediate release of a significant drug fraction (often 20–50% within the first hour) is a common problem. Strategies to mitigate burst release—coaxial spinning, crosslinking, or coating—add complexity and cost.
  • Sterilization and stability: Conventional sterilization methods (e.g., gamma irradiation, ethylene oxide) may degrade polymers or denature fragile biologics. Alternative methods (supercritical CO₂, electron beam) require careful optimization for each material.
  • Regulatory and quality control: Class III medical devices require rigorous characterization of drug release, biocompatibility, and sterility. Establishing standard test methods for in vitro release from nanofibers remains an active area of regulatory science.
  • Limited handling and mechanical performance: Dry electrospun mats can be brittle or friable, making application difficult. Some dressings require a backing layer or reinforcement (e.g., knits, films) to improve tear resistance.

Future Directions and Smart Dressings

Next-generation electrospun dressings aim to address these challenges through innovation in materials, structure, and functionality:

Stimuli-Responsive (Smart) Systems

Dressings that respond to wound pH, temperature, enzymes, or bacterial metabolites can deliver therapeutics on demand. For instance, pH-responsive polymers (e.g., Eudragit, poly(methacrylic acid)) release antibiotics only when the wound becomes infected and turns alkaline. Glucose-responsive dressings containing insulin or glucose oxidase are being explored for diabetic wounds.

Multifunctional Composite Dressings

Combining controlled release with electrical stimulation (via conductive polymers like polyaniline), oxygen generation (using peroxide-loaded fibers), or photothermal therapy (using gold nanorods) creates “all-in-one” dressings that address multiple aspects of healing simultaneously.

Personalized Medicine

3D electrospinning and additive manufacturing techniques (e.g., melt electrowriting) enable the fabrication of patient-specific wound dressings with custom shapes, fiber orientations, and drug release gradients. Patient-derived cells or growth factors could be incorporated for autologous therapy.

Advanced Release Kinetics

Zero-order release, pulsatile release, and sequential release of multiple agents (e.g., first debriding enzymes, then antibiotics, then growth factors) are being achieved using multi-layer and core–shell architectures. Programmable release using embedded microchips or shape-memory polymers is also on the horizon.

Regulatory and Clinical Translation

Industry–academia partnerships are driving pilot-scale manufacturing and clinical trials. Early-stage human studies (e.g., a trial of PLGA-based growth factor dressings for chronic venous ulcers) have shown safety and preliminary efficacy. As manufacturing processes mature, electrospun dressings are expected to enter the wound-care market within the next five to ten years.

Conclusion

Electrospun fibers represent a highly adaptable platform for the controlled release of therapeutic agents in wound healing. Their ability to mimic the native extracellular matrix, coupled with tunable drug release kinetics, makes them superior to conventional dressings in managing infection, inflammation, and tissue regeneration. Research continues to address scalability, burst release, and complex release profiles through advanced fiber architectures and smart materials. With ongoing clinical studies and process improvements, electrospun fiber dressings are poised to become a standard-of-care option for acute, chronic, and infected wounds, ultimately improving patient outcomes and reducing healthcare burdens.