Polylactic acid (PLA) is a key biopolymer with potential uses in numerous sectors, since it is biocompatible and both biobased and biodegradable. However, brittleness limits its industrial applications where plastic deformation at high impact rates or high elongation is required, for instance, flexible food packaging. In order to overcome this drawback and potentially expand the PLA market, we developed flexible PLA materials plasticized with renewable and biodegradable epoxidized soybean oil methyl ester reaching elongations at break of almost 800%. The use of amorphous PLA in combination with the lubricating effect of the plasticizer allowed the more sustainable extrusion at a low temperature of 140 °C, preventing the degradation of PLA and at the same time saving energy. Moreover, plasticized films produced, upon handling, significantly less acoustic noise than pure PLA, which is of great importance for food packaging applications. Morphology, thermomechanical and barrier properties, and migration levels were evaluated as a function of plasticizer content.

The waste stream of low-grade wool is an underutilized source of keratin-rich materials with appropriate methods for upcycling into high value-added products still being an open challenge. In the present work, keratins were precipitated from their water solution to produce hierarchical keratin particles via isoelectric precipitation. Matrix-assisted laser desorption/ionization coupled with time-of-flight tandem mass spectrometry analysis (MALDI-TOF/TOF MS/MS) showed the presence of the amino acid sequence leucine–aspartic acid–valine (LDV) in the extracted keratin. This well-known cell adhesion motif is recognized by the cell adhesion molecule α4β1 integrin. We showed that keratin particles had this tripeptide exposed on the surface and that it could be leveraged, via patterns obtained with microcontact printing, to support and facilitate dermal fibroblast cell adhesion and direct their growth orientation. The zeta potential, isoelectric point, morphological structures, chemical composition, and biocompatibility of keratin particles and the influence of the surfactant sodium dodecyl sulfate (SDS) were investigated. An appropriate ink for microcontact printing of the keratin particles was developed and micron-sized patterns were obtained. Cells adhered preferentially to the patterns, showing how this strategy could be used to functionalize biointerfaces.