Ionic liquid-based electroactive materials: a novel approach for cardiac tissue engineering strategies

Cardiac tissue regeneration strategies are increasingly taking advantage of electroactive scaffolds to actively recreate tissue microenvironment. In this context, this work reports on advanced materials based on two different ionic liquids (ILs), 2- hydroxyethyl-trimethylammonium dihydrogen phosphate ([Ch][DHP]) and choline bis(trifluoromethylsulfonyl)imide ([Ch][TFSI]), combined with poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) for the development of ionic electroactive IL/polymer hybrid materials for cardiac tissue engineering (TE). The morphological, physico-chemical, thermal and electrical properties of the hybrid materials, as well as their potential use as scaffolds for cardiac TE applications were evaluated. Besides of inducing changes in the surface topography, roughness and wettability of the composites, the incorporation of [Ch][DHP] and [Ch][TFSI] allows to increase surface (σsurface) and volume (σvolume) electrical conductivity. Further, washing the hybrid samples with phosphate-buffered saline solution strongly decreases the σsurface, whereas σsurface and σvolume of the composites remains almost unaltered after exposure to ultraviolet sterilization treatment. Additionally, it is verified that the IL incorporation influences the P(VDF-TrFE) microstructure and crystallization process, acting as defect during its crystallization. Cytotoxicity assays revealed that just [Ch][DHP] based hybrid films are not cytotoxic. These films also support H9c2 myoblast cell adhesion and proliferation,demonstrating their suitability for cardiac TE strategies based on electroactive microenvironments.This work was supported by FCT - FundacAo para a Ciencia e Tecnologia (FCT): strategic funding UID/FIS/04650/2020 unit, projects PTDC/BTM-MAT/28237/2017, grants SFRH/BD/148655/2019 (R.M.M) and SFRH/BPD/121526/2016 (D.M.C) and contract 2020.04163.CEECIND (C.R). Funding by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD): PID2019-106099RB-C43/AEI/10.13039/501100011033 and the Basque Government Industry Department (ELKARTEK program) and Education Department (Grant PRE_2020_1_0201, A.G.D) is acknowledged