Development of eco-sustainable methodologies for innovative materials inspired by cellulose fibers

Abstract

This PhD is an “Industrial-PhD”, carried out in collaboration between University of Basilicata and LUCART S.p.A (Porcari, Lucca, Italy), in that case with the plant located at Avigliano (Potenza, Italy). The scholarship was financed by “Regione Basilicata” and the working time was shared between the company and the University. The goal of the thesis was the development of eco-sustainable methodologies for the production of innovative materials based on cellulose fibers. As a matter of fact, the aim of the work was to produce cross-linked electrospun hybrid scaffolds composed of gelatin/poly(D,L-lactic) acid (PDLLA), gelatin/PDLLA/cellulose nanocrystals (CNCs), and gelatin/PDLLA/cellulose nanocrystals/elastin as wound dressing materials. Fourier transform infrared spectroscopy, X-ray diffraction, and high-performance liquid chromatography demonstrated the complete embedding of each component in the hybrid scaffolds. The degree of cross-linking was quantified by the 2,4,6-trinitrobenzenesulfonic acid assay, and attenuated total reflectance spectroscopy revealed the effectiveness of the cross-linking reaction. Notably, the interconnected porous structure revealed in un-cross-linked scaffolds persisted even after cross linking. Scaffolds were characterized in water through their contact angle showing total wettability. We investigated their mechanical properties by uniaxial tensile testing, which showed that even in the dry state, nanocellulose- and elastin-containing scaffolds exhibit higher elongation at rupture compared to those with pure gelatin/PDLLA. Therefore, we succeeded in tuning the toughness of the scaffolds by modulating the composition. In order to use scaffolds as medical devices, we assayed fibroblasts on scaffold extraction media, indicating that they were noncytotoxic. Finally, the attachment and proliferation of fibroblasts on the surface of different scaffolds were evaluated. During the six months spent at Centre inter universitaire des matériaux (CIRIMAT) of Université Paul Sabatier-Toulouse (France), electrospun scaffolds at different CNCs percentage (w/w) were produced and thermal stability, physical structure and their mechanical behavior were studied. The results suggested that the electrospun scaffolds are characterized by improved thermal and mechanical properties in comparison with bulk materials. We found that the scaffolds containing 3% (w/w) of CNCs showed best hydrophilic and thermo-mechanical properties. ... [edited by Author]