Speaker
Description
Introduction: Electrospun wound dressings are emerging as promising candidates in the field of wound care since they present a similar architecture to natural extracellular matrix (ECM). Their composition can include both synthetic and natural polymers, the latter enabling a biological other than structural mimicking of ECM. Due to the high surface-to-volume ratio, electrospun matrices can absorb a large amount of wound exudate and favor gaseous exchanges, with an anti-scarring and hemostatic potential. Notwithstanding the considerable benefits of using natural polymers (proteins and polysaccharides), their electrospinnability is impaired by their basically high viscosity, surface tension, or conductivity. For this reason, the combination with synthetic polymers beyond the addition of surfactants has been proven to be an efficient strategy to improve the electrospinning process. Furthermore, the presence of water-soluble polysaccharides affects matrix stability in aqueous environment, thus requiring additional crosslinking steps to stabilize the final structure and allow wound protection.
Methodology: Hyaluronic acid/lactose-modified chitosan electrospun matrices were produced by using polyethylene oxide as synthetic support and Tween®20 as surfactant. Polycaprolactone matrices (pristine, air plasma-activated, or polysaccharide-coated), polysaccharide-based freeze-dried membranes, and Chitoderm® were used as comparison. Considering the polysaccharide-based membranes instability in aqueous environment, several crosslinking strategies were pursued ranging from traditional chemical (glutaraldehyde, genipin, EDC/NHS) and physical (heat) methods to innovative chemical crosslinkers in the field of electrospinning, namely carbonyldiimidazole (CDI) and methacrylic anhydride (MA). The ability of CDI- and MA-crosslinked mats to absorb exudates as well as their degradation behavior were tested both in water and saline solution. In addition, the water vapor transmission ability was evaluated.
Results: Membranes with thin, uniform, and defect-free nanofibers, were obtained. Due to their complete instability in water, different crosslinking methods already reported in literature were attempted, with unsatisfying results. Indeed, glutaraldehyde, genipin, EDC-NHS, or thermal treatment were unable to stabilize the final structure, leading to the loss of the fibrous morphology and to an immediate dissolution in water. For this reason, two novel crosslinkers, namely CDI and MA, were tested, obtaining better results than the traditional methods. Indeed, MA allowed to maintain a proper nanofibrous structure after crosslinking but did not ensure long-term stability in aqueous environment. On the other hand, CDI crosslinking was responsible for a partial loss of the fibrous structure, although guaranteeing its stabilization. This morphological alteration did not affect matrix fluid retention, being three times higher than non-electrospun products and the commercial product Chitoderm®. Likewise, electrospun products revealed an optimal water vapor transmission ability, being halfway between the total evaporation and the absence of transmission.
Conclusions: Polysaccharidic electrospun wound dressings with suitable properties in terms of ECM mimicking, exudate absorption, and gas permeation were produced, by exploiting several crosslinking strategies with the aims of stabilizing the final structure and obtaining an optimal compromise between nanofibrous architecture maintenance and aqueous stability. The conformability to the wound and the mechanical properties of the synthetized dressings could be enhanced in a biphasic system where the polysaccharidic matrix is linked to a synthetic counterpart, able to provide mechanical strength.
73296319089
