Wound Moisture Control and Electrospun Fiber Materials


Why you should consider electrospun fiber materials when designing your next moisture controlling dressing.

The ideal environment for wound healing is one that is clean, insulated, protected from further trauma and, very importantly, moist. While moist wound healing is beneficial, an excessively damp wound environment, where the exudate is allowed to pool for example, is not ideal. This can potentially lead to maceration of the periwound. Macerated skin is vulnerable to breakdown, potentially leading to an increase in wound size, delaying the healing process. Moist wound healing is therefore a fine balancing act between avoiding maceration, while simultaneously maintaining sufficient levels of tissue hydration.

The advantages of moist wound healing have been documented extensively and the widely reported benefits include:1

  • faster wound healing,
  • promotion of epithelialization,
  • promotion of dermal/ wound bed healing responses (e.g. cell proliferation, ECM synthesis),
  • reduced scarring,
  • retention of growth factors at wound site (in wound fluid),
  • lower wound infection rates,
  • reduced pain perception, and
  • facilitation of autolytic debridement.

In today’s one-size-fits-all world, choosing an ideal wound dressing material can be difficult. It is not enough for a dressing to only maintain optimal moisture levels in the wound, ideally dressings need to:

  • promote faster healing,
  • reduce pain,
  • enhance vapor transmission rate,
  • facilitate autolytic debridement,
  • and act as a physical barrier against further trauma and infection.

An ideal dressing should allow the wound to “breathe” and prevent the wound from drying out while simultaneously allowing for the exchange of gases, particularly oxygen, CO2 and water vapour which are essential for wound healing.


  1. Moisture retaining dressings – Is there a risk of the wound site becoming too wet?

Occlusive dressings, like impermeable hydrogels, films and foams excel in the controlling the local wound environment’s exposure to pathogens. However, this occlusive nature can come at a disadvantage for both the wound and then of course the patient. When occlusive dressings are used on highly exuding wounds, they may lead to further complications such as periwound maceration and additional skin damage, resulting in an increased risk of infection.

An extract from a blog by Laurie Swezey titled: “Moisture-Associated Skin Damage: Prevention Strategies for Periwound Skin” sums it up perfectly:2

“There is both an art and a science to choosing the correct wound dressing, one that will maintain just the right amount of moisture in the wound bed without allowing the periwound to become macerated.”


  1. Breathable dressings – Do we run the risk of the wound drying out?

Typical woven or non-woven textile based dressings are able to absorb large amounts of exudate while simultaneously possessing a high water vapor transmission rate (WVTR). This rapid WVTR can lead to the excessive loss of moisture from the wound’s micro-environment and could cause the wound to dry out if not managed appropriately.

Gauze dressings have large pores and are typically highly permeable. These large pores result in open access to the wound bed for bacteria and viruses from the external environment, and can leave the wound susceptible to further infection.

The possibility of combining an occlusive dressing with a gauze or a sponge is not an ideal solution. Semi-permeable film dressings, although able to allow for gases to pass through while maintaining a barrier to pathogens, are rarely capable of absorbing much moisture.3


  1. Why you should consider electrospun fiber dressings as your next dressing for advanced wound care:

Electrospun fiber materials are ideally suited for advanced wound care. What sets it apart from conventional dressing materials, is the ease of incorporating functionalities into the framework of electrospun fiber. A combination of physical, chemical and mechanical properties allow these materials to curb bacterial colonization and infection, and can simultaneously manage controlled drug release from the porous electrospun framework. Furthermore, electrospun fiber materials’ high surface area and porosity afford these materials the potential to maintain ideal moisture levels while simultaneously allowing gases to pass through unhindered.

Properties of electrospun fiber materials that make them ideal for dressings in advanced wound care are:

  • Presence of micropores – instilled semi-permeability while maintaining a barrier to infection:
    It is important for certain gases and fluids to continuously exchange between the wound and the external environment. Electrospun fibers’ unique microporous structure make them semi-permeable, allowing these materials to facilitate the exchange of gases (oxygen, CO2 and water vapour) and fluids (exudate). The microporous structure also acts as a physical barrier preventing foreign bodies, such as bacteria, from entering the wound bed. This then promotes wound cleanliness by decreasing the risk of infection from the external environment.

  • Tailored moisture control ability:
    The water vapor permeability of a dressing is important to maintain required moisture levels, prevent excessive water loss, prevent the wound drying out and prevent exudate buildup.The wound surface moisture can therefore be regulated through the use of various wound dressings with different WVTRs.Electrospun fiber materials can be made with various WVTR and reports of 900 – 1000 g/m2/24h and 3290 – 3378 g/m2/24h are found in literature with different fiber forming materials and additives influencing the WVTR values.4

    • The WVTR of healthy skin is reported as being between 240 g/m2/24h and 1,920 g/m2/24h and for open wounds it has been reported as being around 4800 g/m2/24h.5
    • WVTR between 2000 g/m2/24h and 2500 g/m2/24h has been suggested to be the preferred WVTR for injured skin, as it provides adequate moisture levels without risking the wound drying out.6

    Having the benefit of design flexibility allows for the tailoring of the WVTRs of electrospun fibers by modifying the fiber diameter, web density and polymer type.A hydrophilic fiber forming material, coupled with the inherent property of having a high surface area to volume ratio, makes it possible for these materials to absorb large amounts of exudate. Traditional films, although great barriers to infection, only allow for minimal water absorption. By contrast, electrospun fiber materials can absorb water in the range of 18-213 wt%7 with upwards of 2000 wt%8 being reported for highly absorbing polymers.If the fiber forming material is hydrophobic, the exudate can pass straight through, thereby allowing the exudate to be absorbed by a secondary dressing intended to assist with exudate control. This potentially allows the number of primary dressing changes to be minimized.

  • Drug incorporation – infection control:
    Electrospun fiber materials are excellent candidates for the delivery of therapeutic agents in the local wound environment. The ability to tailor these fibers to contain specific degradation characteristics, coupled with modifiable drug delivery profiles, make electrospun fibers superior to polymeric films and particles when it comes to the delivery of certain therapeutic agents.9 The potential to incorporate drugs into the electrospun fiber framework to help with infection control, in either the wound micro-environment or from the external environment during dressing changes, further adds to the appeal of using these materials in dressings for advanced wound care.
  • Flexibility of design:
    Multi-layered materials can be designed to simultaneously address multiple challenges, eg.:

    • wound contact layers (moist but permeable),
    • overlays (protect but keep periwound dry),
    • softness, extremely gentle on fragile compromised periwound skin.

Through expert design, electrospun fiber dressings have the potential to be an all-encompassing solution for wound healing, specifically when it comes to wounds where moisture control is important. By tailoring electrospun fiber materials to specific functions, these materials can reduce the guesswork associated with wound dressing selection, assisting wound care practitioners by handling virtually all aspects of wound care.

Lastly, I leave you with a quote from Dr. Eugene Smit (PhD) – CEO, SNC:

“It is exactly this kind of art vs. science aspect of wound care that needs to be fixed to turn wound care into wound cure. We need to design dressings that do it right, no uncertainty.”

In future posts we will delve deeper into the individual aspects of electrospun fiber materials as wound dressings. Please feel free to send us a request if you would like specific topics covered in the use of electrospun fiber materials as dressings for advanced wound care.

References:

  1. Ousey, K. et al., J. Wound Care. 2016, 25, 122-130
  2. http://www.woundsource.com/blog/moisture-associated- skin-damage- prevention-strategies-periwound- skin
  3. https://woundeducators.com/semipermeable-film- dressings/
  4. http://electrospintech.com/wounddressing.html#.WtVYMmaB21s
  5. Sussman, G., Wounds International. 2010, 1, 23-25
  6. Queen, D. et al, Biomaterials. 1987, 8, 367-371
  7. Abdelhady, S. et al., J. Eng. Fiber Fabr. 2015, 10, 179-193
  8. Yadav, S. et al., Appl. Mater. Today. 2016, 4, 62-70
  9. Joshi, M. et al., J. Nanosci. Nanotechnol. 2014, 14, 853-867


Dr. Hennie Kotzé
Dr. Hennie Kotzé
Hennie Kotzé (PhD) – Senior Scientist, SNC