Degradable multi(aryl-azide) star copolymer as universal photo-crosslinker for elastomeric scaffolds

Mater. Today Chem. 12, 209-221, (2019)

Gangolphe L., Déjean S., Bethry A., Hunger S., Pinese C., Garric X., Bossard F., Nottelet B.

ABSTRACT

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 pre-polymers that are combined with molecular crosslinkers to yield the elastomeric 3D 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 crosslink any polymer containing C-H bonds independently of its molecular weight and without the need for pre-functionalization. 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 the one of the polymer matrix. 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 to commercially availabe 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 (ε_y>100%) compared to uncrosslinked scaffolds(ε_y<10%). In addition, we show that the degradation rate can be controlled over time 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.