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.

Snapshots of lignin oxidation and depolymerization in archaeological wood: an EGA-MS study

Evolved gas analysis-mass spectrometry (EGA-MS) was used for the first time to study archaeological wood, in order to investigate its chemical degradation. The archaeological wood was from an oak pile from a stilt house found in the Neolithic 'La Marmotta' village (Lake Bracciano, Rome, Italy). The sampling was performed from the external to the internal part of the pile, following the annual growth rings in groups of five. In addition, sound oak wood and isolated wood components (holocellulose and cellulose) were also analyzed, and the results were used to highlight differences because of degradation. Our study demonstrated that EGA-MS provides information on the thermo-chemistry of archaeological wood along with in-depth compositional data thanks to the use of MS. Our investigations not only highlighted wood degradation in terms of differences between carbohydrates and lignin content, but also showed that lignin oxidation and depolymerization took place in the archaeological wood. Mass spectral data revealed differences among the archaeological samples from the internal to the external part of the pile. An increase in the formation of wood pyrolysis products bearing a carbonyl group at the benzylic position and a decrease in the amount of lignin dimers were observed. These were related to oxidation and depolymerization reactions, respectively.