Zein-Fibrous Clays Biohybrid Materials

The present work introduces a new type of biohybrid materials that is based on the combination of fibrous clays (sepiolite or palygorskite) with zein, a highly hydrophobic protein extracted from corn. C, H, N, and S chemical analyses, FTIR spectroscopy, 13C solid-state NMR spectroscopy, field-emission scanning electron microscopy (FESEM), thermal analysis, as well as dynamic vapor sorption were employed in the characterization of the resulting biohybrids to discern the type of interaction between the protein and the clay fibers and to evaluate the reduced hydrophilic character of the novel biohybrids in comparison to the pristine clays. With the aim of profiting from such a property, zeinfibrous clay biohybrids were tested as additives in the preparation of nanocomposites. For this purpose, alginate was chosen as a model polymer matrix, as it forms suitable self-supporting films and is a biocompatible and biodegradable material; but one of its main drawbacks for applications is its high hydrophilic character. In a similar way to conventional organoclays that are based on alkylammonium compounds, the zeinclay biohybrids reported here were effective in improving several features of the biopolymer matrix, mainly those related to mechanical and barrier properties. In addition, the nontoxic character of zein-based bioorganoclays is an advantageous feature that would allow the application of these new eco-friendly materials in the food-packaging sector.