RESUMEN
Introduction: Bone defects remain a thorny challenge that clinicians have to face. At present, scaffolds prepared by 3D printing are increasingly used in the field of bone tissue repair. Polylactic acid (PLA) has good thermoplasticity, processability, biocompatibility, and biodegradability, but the PLA is brittle and has poor osteogenic performance. Beta-tricalcium phosphate (ß-TCP) has good mechanical properties and osteogenic induction properties, which can make up for the drawbacks of PLA. Methods: In this study, photocurable biodegradable polylactic acid (bio-PLA) was utilized as the raw material to prepare PLA/ß-TCP slurries with varying ß-TCP contents (ß-TCP dosage at 0%, 10%, 20%, 30%, 35% of the PLA dosage, respectively). The PLA/ß-TCP scaffolds were fabricated using liquid crystal display (LCD) light-curing 3D printing technology. The characterization of the scaffolds was assessed, and the biological activity of the scaffold with the optimal compressive strength was evaluated. The biocompatibility of the scaffold was assessed through CCK-8 assays, hemocompatibility assay and live-dead staining experiments. The osteogenic differentiation capacity of the scaffold on MC3T3-E1 cells was evaluated through alizarin red staining, alkaline phosphatase (ALP) detection, immunofluorescence experiments, and RT-qPCR assays. Results: The prepared scaffold possesses a three-dimensional network structure, and with an increase in the quantity of ß-TCP, more ß-TCP particles adhere to the scaffold surface. The compressive strength of PLA/ß-TCP scaffolds exhibits a trend of initial increase followed by decrease with an increasing amount of ß-TCP, reaching a maximum value of 52.1 MPa at a 10% ß-TCP content. Degradation rate curve results indicate that with the passage of time, the degradation rate of the scaffold gradually increases, and the pH of the scaffold during degradation shows an alkaline tendency. Additionally, Live/dead staining and blood compatibility experiments suggest that the prepared PLA/ß-TCP scaffold demonstrates excellent biocompatibility. CCK-8 experiments indicate that the PLA/ß-TCP group promotes cell proliferation, and the prepared PLA/ß-TCP scaffold exhibits a significant ability to enhance the osteogenic differentiation of MC3T3-E1 cells in vitro. Discussion: 3D printed LCD photocuring PLA/ß-TCP scaffolds could improve surface bioactivity and lead to better osteogenesis, which may provide a unique strategy for developing bioactive implants in orthopedic applications.
RESUMEN
In this study, the surface of aluminum powder was uniformly coated with in situ reduced graphene oxide (r-GO) sheets (Al/r-GO). The Ni powder, Al2O3 powder, and Al/r-GO powders were mixed uniformly in a mass ratio of 20:6:4. In situ rGO-reinforced Ni-Al intermetallic composite coatings were successfully prepared using low-pressure cold spraying and subsequent heat treatment. The microstructure and phase of the composite coatings were characterized using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The high-temperature wear test was conducted at 200 °C, 400 °C, and 600 °C to understand the mechanism. The results indicate that the in situ rGO-reinforced Ni-Al intermetallic composite coatings exhibit a 33.3% lower friction coefficient and 26% lower wear rate in comparison to pure Ni-Al intermetallic coatings, which could be attributed to the generation of an easy-shearing transferred film between the coating and grinding ball.