Role of chemical crosslinking in material-driven assembly offibronectin (nano)networks: 2D surfaces and 3D scaffolds

Abstract

Poly(ethyl acrylate) (PEA) induces the formation of biomimetic fibronectin (FN) (nano)networks uponsimple adsorption from solutions, a process referred to as material-driven FN fibrillogenesis. The ability ofPEA to organize FN has been demonstrated in 2D and 2.5D environments, but not as yet in 3D scaffolds,which incorporate three-dimensionality and chemical crosslinkers that may influence its fibrillogenicpotential. In this paper we show for the first time that while three-dimensionality does not interferewith PEA-induced FN fibrillogenesis, crosslinking does, and we determined the maximum amount ofcrosslinker that can be added to PEA to maintain FN fibrillogenesis. For this, we synthesised 2D substrateswith different amounts of crosslinker (1 10% of ethylene glycol dimethacrylate) and studied the role ofcrosslinking in FN organization using AFM. The glass transition temperature was seen to increase withcrosslinking density and, accordingly, polymer segmental mobility was reduced. The organization ofFN after adsorption (formation of FN fibrils) and the availability of the FN cell-binding domain werefound to be dependent on crosslinking density. Surface mobility was identified as a key parameter for FNsupramolecular organization. PEA networks with up to 2% crosslinker organize the FN in a similar way tonon-crosslinked PEA. Scaffolds prepared with 2% crosslinker also had FN (nano)networks assembled ontheir walls, showing PEA s ability to induce FN fibrillogenesis in 3D environments as long as the amountsof crosslinker is low enough.