Novel Nanocomposite PLA Films with Lignin/Zinc Oxide Hybrids: Design, Characterization, Interaction with Mesenchymal Stem Cells
: Herein we present the production of novel nanocomposite films consisting of polylactic acid (PLA) polymer and the inclusion of nanoparticles of lignin (LNP), ZnO and hybrid ZnO@LNP (ZnO, 3.5% wt, ICP), characterized by similar regular shapes and different diameter distribution (30&ndash;70 nm and 100&ndash;150 nm, respectively). The obtained set of binary, ternary and quaternary systems were similar in surface wettability and morphology but different in the tensile performance: while the presence of LNP and ZnO in PLA caused a reduction of elastic modulus, stress and deformation at break, the inclusion of ZnO@LNP increased the stiffness and tensile strength (&sigma;b = 65.9 MPa and EYoung = 3030 MPa) with respect to neat PLA (&sigma;b = 37.4 MPa and EYoung = 2280 MPa). Neat and nanocomposite PLA-derived films were suitable for adult human bone marrow-mesenchymal stem cells and adipose stem cell cultures, as showed by their viability and behavior comparable to control conditions. Both stem cell types adhered to the films&rsquo; surface by vinculin focal adhesion spots and responded to the films&rsquo; mechanical properties by orchestrating the F-actin&ndash;filamin A interaction. Collectively, our results support the biomedical application of neat- and nanocomposite-PLA films and, based on the absence of toxicity in seeded stem cells, provide a proof of principle of their safety for food packaging purposes.