"Polymer scaffolds are playing an increasing role in tissue engineering (TE), although there is still a need to improve their biomimicry of cellular microenvironments, by having smart scaffolds with an active response, which can improve tissue regeneration. Ionic liquids (ILs) have emerged as an attractive option to achieve this due to the biodegradability and biocompatibility of many ILs, and their high electrical conductivity, while magnetic nanoparticles (NPs) are well-suited for granting magnetic properties to polymer-based materials, leading to magnetomechanical and magnetoelectric effects.
This work reports on the novel combination of poly(lactic-co-glycolide) (PLGA) with the ionic liquid (IL) choline bis(trifluoromethylsulfonyl)imide ([Chol][TFSI]) or with iron oxide (Fe3O4) NPs in order to achieve biodegradable scaffolds with electroactive and magnetoactive response, respectively.
The composites were processed into fiber and film morphologies. PLGA+IL fibers present diameters between 1.92 and 3.26 µm, decreased mechanical stiffness and elongation at yield with respect to the pristine polymer, and some fiber concentrations are not biocompatible. PLGA+IL films present a mean roughness of 6.58 nm, increased mechanical stiffness with respect to the pristine polymer and decreased elongation at yield. The inclusion of IL increased the electrical conductivity of the polymer by 4 orders or magnitude. The diameter of PL PLGA+Fe3O4 fibers ranged from 0.62 to 1.36 µm, show an effective magnetic NP content yield between 52 and 78%, decreased stiffness and increased elongation at yield. PLGA+Fe3O4 films show a mean roughness of 5.07 nm, effective NP content yield between 77 and 97%, increased stiffness and elongation at yield.
Cytotoxicity assays indicate that the PLGA+Fe3O4 materials are suitable for biomedical applications, independently of the filler content and morphology, whereas the IL containing samples are non-cytotoxic only in film morphology up to 5% wt. IL content.
Finally, it is demonstrated that dynamic magneto mechanical stimulation of the PLGA+Fe3O4 samples allows the acceleration of the degradation rate of the samples.
This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019, UID/BIA/04050/2013, UID/BIO/04469 and projects PTDC/BTM-MAT/28237/2017 and PTDC/EMD-EMD/28159/2017. The authors acknowledge funding by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43/AEI/10.13039/501100011033 and from the Basque Government Industry Department under the ELKARTEK program, respectively."