133Trung KienNGUYEN 134Thi Thu HuyenNGUYENThe study on the mechanical and geometry properties of PCL-based scaffold from powder mixtures for tissue engineering applications(Project 2023)Modification of perovskite-based photocatalyst for the degradation of dye under visible light(Project 2023)I. Evaluation of the geometry and mechanical properties of PCL-based scaffold using circle and honeycomb structuresThe 3D FDM printing method provides favorable conditions for researching the fabrication of complex-shaped scaffolds. The current challenge is to experiment with new structures and materials as well as optimize geometric accuracy. In this study, scaffolds were printed from PCL biopolymer combined with TCP using two internal structure forms: circle and honeycomb. The shape characteristics of the test samples were compared and evaluated against the design parameters and actual outcomes. Compression tests revealed that changes in structure and filament spacing affected the compression modulus. Specifically, the compression modulus of honeycomb structures ranged from 25.06 + 0.47 MPa to 63.36 + 3.48 MPa, while circle samples ranged from 15.84 + 1.16 MPa to 52.99 + 3.76 MPa. This research demonstrates the suitability of circle and honeycomb structures for manufacturing scaffolds in biotechnology.II. Fabrication and printability of PCL/TCP filament for tissue engineering applicationPolycaprolactone (PCL) is widely used in tissue engineering and regenerative medicine due to its biodegradability and biocompatibility. However, PCL has limitations in terms of mechanical properties and hydrophobicity, leading to challenges in bone tissue engineering applications and low cell adhesion. To enhance the properties of PCL, other materials such as ceramics and hydro-gels are mixed with it. Materials in filament form are commonly available only for pure PCL, not for composite materials. To enable the use of PCL composites on conventional FDM 3D printers and expand the application range of these printers with biocompatible materials, this study focuses on the design and fabrication of an 3D bioprinter and a filament generator to directly produce PCL-based composite scaffollds from a powder mixture. Experiments evaluating the uniformity and printability of fabricated filament were conducted, demonstrating the potential application of the filament generator and composite filament in tis-sue engineering. In this study, GdFeO3 (GFO) and Mn-doped GdFeO3 (Mn/GFO) photocatalysts were prepared via hydrothermal method for photo-Fenton degradation of Methyl orange (MO). Different characterization techniques were employed to confirm Mn was successfully incorporated into the lattice of GdFeO3 perovskite. The influence of Mn doping on the photo-Fenton catalytic activity of Mn/GFO was also studied. The experimental results showed that the Mn-doped GdFeO3 photocatalyst exhibited greater photo-Fenton catalytic performance under visible light irradiation than undoped GdFeO3 sample. Particularly, the MO degradation rate of 10Mn-doped GdFeO3 could reach up to 97.2 %. And the first order kinetic constant of optimized conditions (0.0456 min-1) using 10Mn-doped GdFeO3 was about 4.97 times than that of pure GdFeO3. Besides, the as-prepared photocatalyst possessed favorable stability and reusability after four cycles of use. This work presents the potential application of Mn-doped GdFeO3 in the degradation of dye in visible region.88
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