4D PRINTING OF THERMORESPONSIVE HYDROGEL CONTAINING NANOCRYSTALLINE CELLULOSE FOR SCAFFOLDS PRODUCTION
Tissue engineering is a multidisciplinary area of study, and mainly involves the development of biomaterials in the form of scaffolds and their association with cells. A highlight in tissue engineering is the use of polymeric biomaterials and their interaction with cells in vitro. It is known that the maintenance of bone mass is regulated by biochemical and mechanical stimuli. One way to promote mechanotransduction in osteoprogenitor cells is through scaffolds responsible for generating mechanical efforts in a cyclic manner, resulting in tensions with preferential directions in the cells. The main objective of this project is to produce scaffolds by 4D smart hydrogel printing that respond to a certain temperature variation in order to obtain scaffolds for bone tissue regeneration. For this, an intelligent hydrogel composed of isopropylacrylamide monomers is photopolymerized by UV exposure in the presence of a network of alginate and nanocrystalline cellulose. Allied to 4D printing, 3D printing by extrusion is responsible for the proper distribution and orientation of nanocrystals to create anisotropy in the scaffolds and allows the fabrication of complex fine structures. Four hydrogels containing 0; 5; 10 and 15% (m/m) of CNC are studied. The rheological behavior of the gels is studied to verify the extrudability and stability of the gel. Photopolymerization is verified by FT-Raman spectroscopy and by the stability of hydrogels in water. 3D printing parameters are optimized to get regular filaments. The temperature response of the scaffolds produced is verified at 25 and 40 ˚C, and the lower critical solution temperature (LCST) is determined by DSC.