Skin is the largest vital organ in the body, having as the main function the protection of the human being against the external environment[1][2][3][4][5] . Although skin has a self-regeneration ability, this capacity is strongly reduced in the case of full-thickness lesions making necessary the use of grafts or dressings [2]. The usual procedure when the skin damage occurs consists in the application of a wound dressing due their efficiency, low cost and availability [6][7]. Wound dressing made from electrospun nanofibers present advantageous properties compared to the conventional dressings such as potential to promote hemostasis phase, wound exudates absorption, semi-permeability, easy conformability to the wound, functional ability and no scar induction[8] .Gelatin nanofiber mats can mimic ECM structure of the human tissues and organs and is widely used in the tissue engineering field because of its excellent bio-affinity, biological origin, biocompatibility, non-immunogenicity, biodegradability and commercial availability[9][10]. However, gelatin is a water-soluble protein derived from partial hydrolysis of collagen and a crosslinking is needed to improve its mechanical properties, increase stability, and make gelatin meshes insoluble in water [10]. There are several crosslinking methods by adding enzyme such as transglutaminase [11][12] or chemical agents such as fructose [13], dextran dialdehyde [14], diepoxy [15], formaldehyde [16], glutaraldehyde [13][16][17], genipin [15][18][19], diisocyanates [20], or carbodiimides[21]. The traditional aldehyde-based crosslinking strategy has provided a powerful tool to tailor the physical properties of gelatin films [22][23][24] although the assumed toxicity of such chemicals makes uncertain their use [22]. Epoxy compounds are preferred as a stabilizing agent of collagen-based materials for biomedical applications due to their lower toxicity compared with commonly used dialdehydes [25][26][27]. Based on this, the search for alternative crosslinkers that present low toxicity and good stability is the objective of this work. Amongst water-soluble polyepoxides, 1,4-butanediol diglycidyl ether (BDDGE) is commercially available as a cross-linking agent in dermal filler formulations [26]. Although un-reacted BDDGE should be considered from slightly to moderately toxic [27], residual BDDGE might undergo hydrolysis yielding a diol-ether (3,3′(butane-1,4-diylbis(oxy)) bis propane-1,2-diol) which has been proved to be non-toxic limiting safety risks[26]. The present study evaluates the ability of BDDGE to crosslink gelatin nanofibers from porcine skin. The extent of crosslinking was evaluated according different Bddge concentrations at different time-points. Mechanical, thermal, physical and biological properties were investigated as well. According the results we can concluded that BDDGE showed a huge potential as gelatin crosslinker due several reasons, such as, its incorporation on electrospun fibers reducing its diameter in 37.9%, the temperature influence directly the crosslinking process accelerate the chemical reaction, range the BDDGE concentration and incubation time is possible control the extension of crosslinking reducing the un-reacted groups and consequently reducing or eliminating the toxicity. According the results achieved BDDGE can be considered a good alternative to crosslink the gelatin for tissue engineering applications.
This work is supported by a research grant (SFRH/BD/91104/2012) awarded to Juliana Dias by Portuguese FCT.
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