New crosslinkers for electrospun chitosan fibre mats. Part II: mechanical properties

Abstract

Few studies exist on the mechanical performance of crosslinked electrospun chitosan (CS) fibre mats. In this study, we show that the mat structure and mechanical performance depend on the different crosslinking agents genipin, epichlorohydrin (ECH), and hexamethylene-1,6-diaminocarboxysulphonate (HDACS), as well as the post-electrospinning heat and base activation treatments. The mat structure was imaged by field emission scanning electron microscopy and the mechanical performance was tested in tension. The elastic modulus, tensile strength, strain at failure and work to failure were found to range from 52 to 592 MPa, 2 to 30 MPa, 2 to 31 per cent and 0.041 to 3.26 MJ m 23 , respectively. In general, neat CS mats were found to be the stiffest and the strongest, though least ductile, while CS -ECH mats were the least stiff, weakest, but the most ductile, and CS -HDACS fibre mats exhibited intermediary mechanical properties. The mechanical performance of the mats is shown to reflect differences in the fibre diameter, number of fibre-fibre contacts formed within the mat, as well as varying intermolecular bonding and moisture content. The findings reported here complement the chemical properties of the mats, described in part I of this study.

Phosphate salts facilitate the electrospinning of hyaluronic acid fiber mats

“…In previous work, we have determined that Young's modulus of fiber mats can be greatly affected by the quantity of fiber junctions formed and their interconnectivity [24]. The HA-phosphate mats displayed varying morphologies depending upon the type and quantity of phosphate incorporated into the spinning solution.…”

“…Stress (r = F/A) was calculated using the voltage (load) output (F) from Labview divided by the cross sectional area (A) of each fiber mat tested. Cross sectional area was calculated using the dimensions of the fiber mat, including the measured thickness and the weight [24]. The thickness of the mats varied based on phosphate HA-GP (249 ± 167 lm); HA-TPP (68 ± 21 lm); and HA-SP (18 ± 2 lm).…”

“…Methods described by Donius et al [24] were utilized. HA-phosphate solutions were electrospun for 8 h to produce a robust mat.…”

Osteoblast biocompatibility of premineralized, hexamethylene-1,6-diaminocarboxysulfonate crosslinked chitosan fibers

“…Tensile tests were performed with a 500 g load cell at a strain rate of 0.02 s −1 at 21°C and 65% relative humidity (RH). The force-displacement data were corrected for slack and converted into engineering stress and strain using the mat’s initial effective cross-sectional area, calculated from the area density of the samples according to the previously reported method [32]; the frame opening of 25 mm was used as the gauge length. The modulus of the mat is the initial linear slope of the stress-strain curve, the maximum stress, which the mat could support, is its tensile strength (σ UTS ).…”

“…Both crosslinkers have been previously utilized for chitosan gels and films [31]. Moreover, both have been favored over the more commonly used glutaraldehyde, due to their lower cytotoxicity, ability to react under a wide range of pH and temperature, and to improve the chemical and mechanical properties of the scaffolds [32]. …”