Kappa-carrageenan/chitosan/gelatin scaffolds enriched with potassium chloride for bone tissue engineering

Kappa-carrageenan is a biocompatible natural polysaccharide able to form hydrogels for tissue regeneration. In bone tissue engineering, achieving a bioactive microenvironment with appropriate mechanical properties in polysaccharide-based scaffolds remains a challenge. This study aims to fabricate 3D scaffolds comprising kappa-carrageenan, chitosan and gelatin, crosslinked with KCl, and evaluate their mechanical and biological properties for bone tissue engineering. The produced scaffolds include kappa-carrageenan/chitosan (KC), kappa-carrageenan/chitosan/gelatin (KCG), kappa-carrageenan/chitosan/gelatin enriched with KCl (KCG-KCl), and chitosan/gelatin (CG). All scaffolds present degradation rates ranging from 30% weight loss on day 21, pore size distribution in the range of 100-160 μm and porosity above 80%. The Young modulus values range from 9 to 256 kPa, with the KCl-containing KCG scaffolds demonstrating the highest values, validating the role of KCl in the coil to helix transition of kappa-carrageenan leading to firmer structures. In vitro biological evaluation indicates that pre-osteoblasts proliferate significantly from day 3 up to day 14 on all scaffold compositions. The alkaline phosphatase activity shows a significant increase up to day 14. The calcium production displays a constant increase from day 14 up to day 28, proving that all scaffold compositions support the osteogenic differentiation potential.