No abstract

No abstract

No abstract

Monitoring implanted stem cells in bone regeneration and other cell therapies is of great importance to reveal the mechanism of tissue repair and to optimize clinical treatments. However, big challenge still remained in lacking an imaging nanoprobe. Herein, we designed surface modified upconversion nanoparticles (UCNs) with multimodal imaging capabilities of fluorescence, magnetic resonance imaging (MRI) and dual-energy computed tomography (CT). It was found that the UCNs can label stem cells in an efficient (over 200 pg/cell) and long-term (at least 14 days) manner, with almost no influence on the viability, cell cycle, apoptosis, and multilineage differentiation. Thus, clinical dual-energy CT and MRI were successfully applied to observe the migration of labeled cells on a bone-defect model of rabbit for at least 14 days. The results visualized the gathering of stem cells at the defect site of cortical bone, and the in vivo images were well-correlated with the in vitro fluorescence observation without extra staining. Therefore, a potentially translatable nanoprobe was developed for noninvasive and real-time tracking of cells, which may be meaningful for understanding the bone regeneration in clinic and shed light on the visualization of cells in other cell therapies.

The diversity of filament consumables is the basis for developing of fused deposition modeling (FDM) 3D printing industry. At the same time, the blending of matrix materials and the addition of reinforcing materials are the manufacturing difficulties of this composite 3D printing consumable. In this article, poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU)/organic montmorillonite (OMMT) composites were manufactured to systematically study the characteristics and laws of these composites. Both the rigid matrix PLA and the flexible matrix TPU played advantages in multi-component composites, while the blended matrix balanced their characteristics. OMMT added with 5% wt not only improved the mechanical and thermal properties of matrix materials but also affected the processability and practicability of composite consumables. The distribution of OMMT particles in the composites was quantitatively analyzed through image processing technology. PLA/TPU/ OMMT FDM 3D printed samples as a representative composite system were selected to evaluate the general performance of particle-reinforced 3D printed composites, and to provide reference for the research and development based on this type of 3D printed products.