Biomimetic Mineralization of Three-Dimensional Printed Alginate/TEMPO-Oxidized Cellulose Nanofibril Scaffolds for Bone Tissue Engineering

Abstract

The three-dimensional (3D) printed scaffolds were prepared by partial cross-linking of TEMPO-oxidized cellulose nanofibril/alginate hydrogel using calcium ions for printing the hydrogel while maintaining its shape, fidelity, and preventing the collapse of the filaments. The prepared scaffolds were fully cross-linked using calcium ions immediately after printing to provide the rigidity of the hydrogel and give it long-term stability. The composition of the prepared pastes was adjusted in view of the description of the hydrogel and 3D printing parameters. The rheological properties in terms of thixotropic behavior and viscosity recovery of hydrogels were investigated by performing steady shear rate experiments. The results show that the viscosity recovery for pure alginate hydrogel was only about 16% of the initial value, whereas it was 66% when adding cellulose nanofibrils to alginate. Consequently, the shape of the pure alginate scaffold was soft and easy to collapse contrarily to the composite scaffold. The biomimetic mineralization process of printed scaffolds using simulated body fluid, mimicking the inorganic composition of human blood plasma, was performed and the hydroxyapatite nucleation on the hydrogel was confirmed. The strength properties of the fabricated scaffolds in terms of compressive strength analysis were also investigated and discussed. The results show that the alginate/TEMPO-oxidized cellulose nanofibril system may be a promising 3D printing scaffold for bone tissue engineering.

3D printed hydrogels with oxidized cellulose nanofibers and silk fibroin for the proliferation of lung epithelial stem cells

“…However, an OBC paste of 7 wt% (0SF-1OBC) exhibited not only shear thinning behavior, but also high zero shear viscosity, as shown in Fig. 2 d. Therefore, cellulose nanofibril pastes were an ideal choice as inks for 3D bioprinting, also commonly used to modify the rheological behavior of 3D printing materials (Abouzeid et al 2018 ; Markstedt et al 2015 ; Ojansivu et al 2019 ). The SF-OBC composite inks displayed similar shear-thinning behavior and high zero shear viscosity properties of the OBC paste alone, as shown in Fig.…”

Polysaccharide-Based Systems for Targeted Stem Cell Differentiation and Bone Regeneration

“…The best printable composition was found to be 50% alginate/50% nanofibrils and printed scaffolds were cross-linked by soaking in CaCl 2 . Compressive strength increased with the addition of nanofibrils and scaffolds exhibited hydroxyapatite mineralization in SBF with crystallite sizes of around 25 nm [74]. The suitability of cross-linked alginate scaffolds compared to collagen scaffolds was evaluated using human mesenchymal stem cells (hMSC), human umbilical vein endothelial cells (HUVEC) and RNA determination in vitro.…”

Dynamic viscosity recovery of electrospinning solution for stabilizing elongated ultrafine polymer nanofiber by TEMPO-CNF

“…It has recently been exploited to enable ice cream to maintain its shape, preventing deformation due to melting until it receives some stress 21 . 2,2,6,6-tetramethylpiperidin-1-oxyl (commonly known as TEMPO)-oxidized cellulose nanofibers (CNF) added aqueous solution is well-known to have this property 22 , 23 . With this in mind, we conceived the idea of adding cellulose into a low-concentration PVP solution to alter the electrospinning solution thixotropic, in order to stabilize the ultrafine nanofibers elongated during electrospinning and prevent the fragmentation of the fiber into beads.…”