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All-lignocellulose composites, meaning densified fiber or fibril materials without added binder, show interesting mechanical properties and can be eco-friendly. Composites based on hot-pressed microfibrillated lignocellulose (MFLC) and lignocellulosic wood fiber (WF) reinforcements are compared with respect to processing, structure, mechanical properties, and eco-indicators. Also, these reinforcements are compared in hot-pressed degradable lignocellulosic crosslinked polycaprolactone (c-PCL) biocomposites based on in-situ polymerization of new caprolactone oligomers. The intermediate lignin content (≈11%) was favorable for MFLC preparation, although the cumulative energy demand was high for mechanical disintegration from unbleached softwood kraft pulp. The mechanical properties were much better for random-in-plane MFLC compared with WF composites due to lower porosity, better interfiber bonding, and smaller-scale defects. Data for strain-field development during tensile tests was in support of these findings. For c-PCL biocomposites, much higher ultimate strength was obtained for the c-PCL/MFLC composites compared with c-PCL/WF. The most important reason was the strainhardening behavior combined with higher strain to failure, since the scale of developing defects was much smaller with MFLC reinforcement., Kompositer baserade på enbart lignocellulosa, dvs pressade fiber- eller fibrillmaterial utan tillsatt bindemedel, har intressanta mekaniska egenskaper och är ofta miljövänliga material. Varmpressad mikrofibrillerad lignocellulosa (MFLC) och varmpressade träfibrer (WF) jämförs med avseende på process, struktur, mekaniska egenskaper och ekoindikatorer. De jämförs också i varmpressade nedbrytbara c-PCL-biokompositer baserade på in-situ polymerisation av nya kaprolakton-oligomerer. Ett optimum i ligninhalt (≈11%) var gynnsamt för MFLC-framställning, även om det kumulativa energibehovet var högt för mekanisk sönderdelning till MFLC från oblekt barrvedsmassa. De mekaniska egenskaperna var mycket bättre för MFLC jämfört med WF-kompositer för slumpmässig fiberorientering i planet. Orsakerna är lägre porositet, bättre bindning mellan fibrer och att storleken på materialdefekterna är små för MFLC. Data för töjningsfältsutveckling under dragförsök gav stöd för dessa förklaringar. För biokompositer baserade på c-PCL var hållfastheten mycket högre för c-PCL/MFLC-kompositer jämfört med cPCL/WF. Den viktigaste orsaken var starkt töjningshårdnande i kombination med högre töjning till brott, vilket troligen beror på att defekterna som utvecklas under mekanisk belastning av c-PCL/MFLC är mycket mindre än för c-PCL/WF, vid jämförbar töjning., QC 2022-05-17

The lack of bioactivity in three-dimensional (3D)-printing of poly-epsilon-caprolactone (PCL) scaffolds limits cell-material interactions in bone tissue engineering. This constraint can be overcome by surface-functionalization using glycosaminoglycan-like anionic polysaccharides, e.g., carboxymethyl cellulose (CMC), a plant-based carboxymethylated, unsulfated polysaccharide, and kappa-carrageenan, a seaweed-derived sulfated, non-carboxymethylated polysaccharide. The sulfation of CMC and carboxymethylation of kappa-carrageenan critically improve their bioactivity. However, whether sulfated carboxymethyl cellulose (SCMC) and carboxymethyl kappa-carrageenan (CM-kappa-Car) affect the osteogenic differentiation potential of pre-osteoblasts on 3D-scaffolds is still unknown. Here, we aimed to assess the effects of surface-functionalization by SCMC or CM-kappa-Car on the physicochemical and mechanical properties of 3D-printed PCL scaffolds, as well as the osteogenic response of pre-osteoblasts. MC3T3-E1 pre-osteoblasts were seeded on 3D-printed PCL scaffolds that were functionalized by CM-kappa-Car (PCL/CM-kappa-Car) or SCMC (PCL/SCMC), cultured up to 28 days. The scaffolds' physicochemical and mechanical properties and pre-osteoblast function were assessed experimentally and by finite element (FE) modeling. We found that the surface-functionalization by SCMC and CM-kappa-Car did not change the scaffold geometry and structure but decreased the elastic modulus. Furthermore, the scaffold surface roughness and hardness increased and the scaffold became more hydrophilic. The FE modeling results implied resilience up to 2% compression strain, which was below the yield stress for all scaffolds. Surface-functionalization by SCMC decreased Runx2 and Dmp1 expression, while surface-functionalization by CM-kappa-Car increased Cox2 expression at day 1. Surface-functionalization by SCMC most strongly enhanced pre-osteoblast proliferation and collagen production, while CM-kappa-Car most, QC 20221116