In the Anthropocene, plastic pollution is a worldwide concern that must be tackled from different viewpoints, bringing together different areas of science. Microbial transformation of polymers is a broad-spectrum research topic that has become a keystone in the circular economy of fossil-based and biobased plastics.

Nutraceutical formulations based on probiotic microorganisms have gained significant attention over the past decade due to their beneficial properties on human health. Yeasts offer some advantages over other probiotic organisms, such as immunomodulatory properties, anticancer effects and effective suppression of pathogens. However, one of the main challenges for their oral administration is ensuring that cell viability remains high enough for a sustained therapeutic effect while avoiding possible substrate inhibition issues as they transit through the gastrointestinal (GI) tract. Here, we propose addressing these issues using a probiotic yeast encapsulation strategy, Kluyveromyces lactis, based on gelatin hydrogels doubly cross-linked with graphene oxide (GO) and glutaraldehyde to form highly resistant nanocomposite encapsulates. GO was selected here as a reinforcement agent due to its unique properties, including superior solubility and dispersibility in water and other solvents, high biocompatibility, antimicrobial activity, and response to electrical fields in its reduced form. Finally, GO has been reported to enhance the mechanical properties of several materials, including natural and synthetic polymers and ceramics. The synthesized GO-gelatin nanocomposite hydrogels were characterized in morphological, swelling, mechanical, thermal, and rheological properties and their ability to maintain probiotic cell viability. The obtained nanocomposites exhibited larger pore sizes for successful cell entrapment and proliferation, tunable degradation rates, pH-dependent swelling ratio, and higher mechanical stability and integrity in simulated GI media and during bioreactor operation. These results encourage us to consider the application of the obtained nanocomposites to not only formulate high-performance nutraceuticals but to extend it to tissue engineering, bioadhesives, smart coatings, controlled release systems, and bioproduction of highly added value metabolites.

This research reports the influence of polar monomer contents in ethylene vinyl acetate copolymer (EVA) and ethylene vinyl alcohol copolymer (EVOH) on the morphology, mechanical and barrier properties of polypropylene/ethylene copolymer (PP) reinforced with organically modified montmorillonite (MMT). PP/EVA and PP/EVOH (75/25 wt %) blends were reinforced with 3 wt % MMT in an internal mixer system. Samples were compression-molded into films of 300μ$\mathsf{\mu }\mathrm{m}$. The structural characterization was made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the mechanical properties were obtained by tension tests and the barrier properties by oxygen transmission rate (OTR). XRD patterns showed a combination of intercalated/exfoliated morphologies for the MMT, with higher d-001 interplanar distance increments for the blends with higher content of polar functional groups. SEM and TEM micrographs complement the results of the XRD analysis and show differences in the morphologies depending on the miscibility of the polyolefin and the polar monomer copolymer. Mechanical properties and oxygen permeability of composites exhibited a higher improvement, by the addition of MMT, for higher intermolecular interactions and most miscible polymeric system of the EVA. These results show that the higher the number of interactions, given by the VA or OH polar functional groups, the morphology and the miscibility between polyolefin and copolymer imply dispersion improvements of the nanocomposites and, in consequence, a higher improvement on the mechanical and barrier properties of the composite material.