Beach-cast seagrass wrack: A natural marine resource improving the establishment of dune plant communities under a changing climate.

Seagrass wrack plays multiple ecological roles in coastal habitats but is often removed from beaches and used for economical processing, neglecting its potential role in sustaining dune plant establishment under changing climate scenarios. Rainwater shortage is a major stress for seedlings and reduced precipitations are expected in some coastal areas. We investigated in mesocosm how wrack influenced seedling performance of Cakile maritima, Thinopyrum junceum, and Calamagrostis arenaria under current and reduced precipitation. We also assessed wrack water holding capacity and leachate chemical/physical properties. Wrack stimulated seedling growth while reduced precipitation decreased root development. Wrack mitigated the effects of reduced precipitation on T. junceum and C. arenaria biomass. Wrack retained water up to five-fold its weight, increased water pH, conductivity, and nutrient content. Wrack promotes dune colonization by vegetation even under rainwater shortage. Thus, the maintenance of this natural resource on beaches is critical for improving dune resilience against climate changes.

Additive manufacturing of wet-spun chitosan/hyaluronic acid scaffolds for biomedical applications.

Additive manufacturing (AM) holds great potential for processing natural polymer hydrogels into 3D scaffolds exploitable for tissue engineering and in vitro tissue modelling. The aim of this research activity was to assess the suitability of computer-aided wet-spinning (CAWS) for AM of hyaluronic acid (HA)/chitosan (Cs) polyelectrolyte complex (PEC) hydrogels. A post-printing treatment based on HA chemical cross-linking via transesterification with poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was investigated to enhance the structural stability of the developed scaffolds in physiological conditions. PEC formation and the esterification reaction were investigated by infrared spectroscopy, thermogravimetric analysis, evolved gas analysis-mass spectrometry, and differential scanning calorimetry measurements. In addition, variation of PMVEMA concentration in the cross-linking medium was demonstrated to strongly influence scaffold water uptake and its stability in phosphate buffer saline at 37 °C. The in vitro cytocompatibility of the developed hydrogels was demonstrated by employing the murine embryo fibroblast Balb/3T3 clone A31 cell line, highlighting that PMVEMA cross-linking improved scaffold cell colonization. The results achieved demonstrated that the developed hydrogels represent suitable 3D scaffolds for long term cell culture experiments.