Biomimetic polycaprolactone‐graphene oxide composites for 3D printing bone scaffolds

Bone shows a radial gradient architecture with the exterior densified cortical bone and the interior porous cancellous bone. However, previous studies presented uniform designs for bone scaffolds that do not mimic natural bone's gradient structure. Hence, mimicking native bone structures is still challenging in bone tissue engineering. In this study, a novel biomimetic bone scaffold with Haversian channels is designed, which approximates mimicking the native bone structure. Also, the influence of adding graphene oxide (GO) to polycaprolactone (PCL)-based scaffolds are investigated by preparing PCL/GO composite ink containing 0.25% and 0.75% GO and then 3D printing scaffolds by an extrusion-based machine. Scanning electron microscopy (SEM) is used for morphological analysis. SEM reveals good printability and interconnected pore structure. The contact angle test shows that wettability reinforces with the increase of GO content. The mechanical behavior of the scaffolds under compression is examined numerically and experimentally. The results indicate that incorporation of GO can affect bone scaffolds' Young's modulus and von Mises stress distribution. Moreover, the biodegradation rates accelerate in the PCL/GO scaffolds. Biological characterizations, such as cell growth, viability, and attachment, are performed utilizing osteoblast cells. Compared to pure PCL, an enhancement is observed in cell viability in the PCL/GO scaffolds

INFLUENCE OF THE PREPARATION METHOD ON THE STRUCTURE,PHASE FORMATION AND MAGNETIC PROPERTIES OF TEMPLATED CUFE2O4 SPINEL

The synthesis of mesoporous CuFe2O4 spinel by several nanocasting strategies (i.e., multi-step nanocasting, one step nanocasting, modified solid-liquid), in which copper and iron nitrates are used as precursors and Pluronic P123 as surfactant, is explored. We have also checked the effect of pH, citric acid and sodium citrate in multi-step nanocasting method. The modified solid-liquid method which contains impregnating mesoporous silica by molten state salts in a non-ionic solvent seems to be the best choice to obtain single phase ordered mesoporous copper ferrite. Other methods suffer from the presence of copper oxide or hematite as impurities or lack of integrity in the mesoporous structure. Increasing pH up to 9.5 does not enhance the phase formation inside the pores of the silica matrix. The citric acid yields a fine structure but does not facilitate the phase formation. Adding sodium citrate neither heals the phase formation nor the structure of the final product. Moreover, vinyl- functionalized mesoporous silica exploited in this study as a hard template entraps both metal nitrates in the pores, assisting impregnation procedur

Alginate-magnetic short nanofibers 3D composite hydrogel enhances the encapsulated human olfactory mucosa stem cells bioactivity for potential nerve regeneration application

The design of 3D hydrogel constructs to elicit highly controlled cell response is a major field of interest in developing tissue engineering. The bioactivity of encapsulated cells inside pure alginate hydrogel is limited by its relatively inertness. Combining short nanofibers within a hydrogel serves as a promising method to develop a cell friendly environment mimicking the extracellular matrix. In this paper, we fabricated alginate hydrogels incorporating different magnetic short nanofibers (M.SNFs) content for olfactory ecto-mesenchymal stem cells (OE-MSCs) encapsulation. Wet-electrospun gelatin and superparamagnetic iron oxide nanoparticles (SPIONs) nanocomposite nanofibers were chopped using sonication under optimized conditions and subsequently embedded in alginate hydrogels. The storage modulus of hydrogel without M.SNFs as well as with 1 and 5 mg/mL of M.SNFs were in the range of nerve tissue. For cell encapsulation, OE-MSCs were used as a new hope for neuronal regeneration due to their neural crest origin. Resazurin analyses and LIVE/DEAD staining confirmed that the composite hydrogels containing M.SNFs can preserve the cell viability after 7 days. Moreover, the proliferation rate was enhanced in M.SNF/hydrogels compared to alginate hydrogel. The presence of SPIONs in the short nanofibers can accelerate neural-like differentiation of OE-MSCs rather than the sample without SPIONs. © 2020 Elsevier B.V

An injectable anisotropic alginate hydrogel containing oriented fibers for nerve tissue engineering

There is a growing research interest on designing a tissue regenerative matrix that can be injected and forms an anisotropic network for effective nerve injury repair. Here, an injectable alginate hydrogel composed of magnetic polycaprolactone (PCL) short nanofibers were fabricated. Nanocomposite PCL centrifugal spun fibers containing superparamagnetic iron oxide nanoparticles (SPIONs) were cut into short nanofibers (SFs) through micro-cutting technique and subsequently incorporated into alginate hydrogels. Doping SPION into short PCL fibers allows the SFs alignment by external magnetic fields in the millitesla (mT) order within the hydrogel. The effect of SFs lengths (5, 25 and 50 µm) as well as magnetic short fibers (M.SFs) concentration (0.5, 1, 2.5, 5 and 10 mg / ml) inside alginate hydrogel on fiber orientation under external magnetic field were investigated by measuring angular deflection of nanofibers. The results revealed that 5 and 25 µm M.SFs with 5 mg/ml concentration have the lowest angular deflection of 1.1� and 6.8�, respectively. The mechanical properties of prepared hydrogels revealed that both oriented 5 and 25 µm M.SFs, have higher storage modulus (G�) and loss modulus (G�) values than the random ones and by increasing M.SFs length from 5 µm to 25 µm, G� and G� values displayed descending trend. The fluorescence microscopy of olfactory ecto-mesenchymal stem cells (OE-MSCs) encapsulated in hybrid hydrogels containing oriented M.SFs showed the possibility of preserving cell viability after 7 days. Following 14-day of induction, the oriented 25 µm M.SF led to the acceleration of neural differentiation of OE-MSCs versus the random one. Therefore, it was expected that ordered injectable alginate/M.SFs hybrid hydrogels function as a minimal invasive constructs for the regeneration of neural tissues. © 2021 Elsevier B.V