Add time:08/21/2019         Source:sciencedirect.com

Degradable elastomers with elastic properties close to those of soft tissues are necessary for tissue engineering. Most degradable elastomers developed so far are based on functional low–molecular-weight prepolymers that are combined with molecular crosslinkers to yield the elastomeric three-dimensional networks. To overcome this limitation, we present in this work the concept of star-shaped macromolecular multi(aryl azide) photo-crosslinker that has the ability to efficiently cross-link any polymer containing C-H bonds independently of its molecular weight and without the need for prefunctionalization. This concept of universal crosslinking agent is illustrated with a star-shaped block copolymer composed of an 8-arm poly(ethylene glycol) core and poly(lactide) side arms functionalized with aryl azide moieties (PEG8arm-PLA-fN3). It was selected due to its macromolecular nature that allows for an easy processing of electrospun photo-crosslinked scaffolds, while making it possible to adapt its chemical nature with one of the polymer matrices. A parameter study is first carried out on PEG8arm-PLA-fN3/PLA-Pluronic®-PLA films to evaluate the impact of the polymers' molecular weight, PEG/PLA ratios, and UV irradiation conditions on the crosslinking efficiency. This study confirms that high crosslinking efficiencies can be obtained with PEG8arm-PLA-fN3 (60%) compared with commercially available bis(aryl azide) photo-crosslinker (below 15%). Optimal conditions are then used to yield electrospun microfibers (1–2 μm) crosslinked with PEG8arm-PLA-fN3, resulting in biocompatible and highly elastomeric scaffolds (εy>100%) compared with uncrosslinked scaffolds (εy<10%). In addition, we show that the degradation rate can be controlled overtime depending on the blend content of PEG8arm-PLA-fN3. Taken together, these results demonstrate the potential of macromolecular multi(aryl azide) photo-crosslinkers to develop original degradable elastomeric scaffolds for soft tissue reconstruction.

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