Advances in Biomaterials for 3D Printing of Scaffolds and Tissues: Advances in Biomaterials for 3D Printing of Scaffolds and Tissues I
Program Organizers: Changxue Xu, Texas Tech University; Yifei Jin, University of Nevada, Reno; Zhengyi Zhang, Huazhong University of Science and Engineering; Jun Yin, Zhejiang University

Monday 2:00 PM
March 15, 2021
Room: RM 11
Location: TMS2021 Virtual

Session Chair: Changxue Xu, Texas Tech University; Jun Yin, Zhejiang University

2:00 PM
A Bilayered GelMA/PEGDA-based Nerve Conduit with Supportive Cells for Peripheral Nerve Regeneration: Jingyi Liu¹; Yun Yin¹; ¹Zhejiang University
    Rupture of a nerve is a debilitating injury and is usually presented with poor quality of life in patients. The gold standard of repair is the use of an autologous graft. Autografts however lead to inadequate functional recovery and involve risks due to secondary surgery at the donor site. Here we report a novel 3D-printed bilayered gelatin methacrylated/Poly (ethylene glycol) diacrylate (GelMA/PEGDA)-based conduit combined with bone marrow stem cells (BMSCs). This study examined the physical, mechanical and biological properties of the conduits for neural reconstruction applications. In vitro characterization demonstrated that the conduit possessed strong mechanical strength with compressive modulus of 1.61N/mm. In vitro cell culture showed that PC12 cells attachment, spreading and proliferation on the GelMA/PEGDA seeded with BMSCs were great. Collectively, this study suggests that GelMA/PEGDA-based bilayered nerve conduit seeded with BMSC shoes great promise for improving the current state of art in peripheral nerve repair strategies.

2:20 PM
A Novel Dual-layer Hydrogel/Cell Conduit Fabrication Method for Tissue Engineering: Xixia Liu¹; Jun Yin¹; ¹Zhejiang University
    The purpose of this study was to construct a composite cell-laden dual-layer hydrogel conduit with different functional layers as a three-dimensional scaffold. Here, we developed a modified solvent casting-based method to prepare gelatin methacrylamine/polyethylene glycol diacrylate (GelMA-PEGDA)-based dual-layer conduit seeded with mesenchymal stem cells. Through the pre-designed self-made mold, the inner and outer layer materials were injected into the predetermined space step by step, and supplemented with the steps of cooling and UV exposure process to complete the solidification of the material. Characterization results of morphology, and mechanical properties, and cell behavior test indicated that the two layers of the conduit are closely adhered and combined, and the conduit have good mechanical properties, suitable elasticity, and good biological properties. The cell-laden dual-layer hydrogel conduit and the manufacturing method are expected to be widely used in the field of tubular tissue repair and regeneration.

2:40 PM
Design and Evaluations System for 3D-printed Dental Implants Based on Deep Neural Networks: Pei-Ching Kung¹; Chai-Wei Hsu¹; An-Cheng Yang²; Nan-Yow Chen²; Nien-Ti Tsou¹; ¹National Chiao Tung University; ²National Center for High-performance Computing
    In this study, a framework of deep neural networks for the custom design and evaluation of 3D-printed dental implants was proposed. The network consisted of three parts: Firstly, the evaluator successfully substitutes the mechano-regulatory method, which is one of the promising algorithms to numerically predict the corresponding implant performance indexes. High correlation coefficients were achieved for the evaluator part (greater than 0.94). Secondly, the designer well predicts the possible geometric features by giving the expected performance indexes, where high correlation coefficients can also be achieved. Finally, the generator builds a corresponding implant based on the geometric features predicted by the designer. The IoU (Intersection over Union) score of 0.997 for the generator part was also obtained. The current work provides a proof of concept that deep learning approaches can substitute the time-dependent, highly-complex, and multi-physical models/theories. Moreover, it provides an in-depth understanding of implants design with no prior professional knowledge.

3:00 PM
Mechanical Properties and Biodegradability of Porous Mg and Zn Scaffolds Fabricated by Power Bed Laser Fusion for Biomedical Applications: Muzi Li¹; Felix Benn²; Thomas Derra²; Alexander Kopp²; Jon Molina-Aldareguía¹; Javier Llorca³; ¹IMDEA Materials Institute; ²Meotec; ³IMDEA Materials Institute & Technical University of Madrid
    Lattice structures of Mg-RE and Zn-Mg alloys with different strut sizes were manufactured by Laser Powder Bed Fusion (LPBF) process. The relationship between processing conditions and the microstructure was carefully analysed by means of X-ray µtomography, scanning electron microscopy and electron-backscatter diffraction as well as transmission electron microscopy. In addition, the mechanical properties and the fracture mechanisms were ascertained by means of in situ compression tests within an X-ray µtomography system in lattices that have been immersed in simulated body fluids for different time periods. These results were used to ascertain the influence of processing parameters, lattice dimensions and heat treatments on the mechanical properties and corrosion resistance of lattice structures of Mg-RE and Zn-Mg alloys manufactured by LPBF.

3:20 PM
Mechanical Properties and Biodegradability of Porous PLA/Mg and PLA/Zn Scaffolds Fabricated by Fused Filament Deposition for Biomedical Applications: Cristina Pascual¹; Cillian Thompson¹; Jimena de la Vega¹; De-Yi Wang¹; Carlos González²; Javier Llorca²; ¹IMDEA Materials Institute; ²IMDEA Materials Institute & Technical University of Madrid
    In order to overcome the limitations of polymers and metals, biodegradable porous scaffolds of PLA/Mg and PLA/Zn were manufactured by means of by fused filament deposition. To this end, PLA filaments containing different volume fractions of either Mg or Zn particles of ≈ 40 µm in diameter were manufactured by extrusion of pellets containing a mixture PLA and Mg/Zn particles. They were used to manufacture porous scaffolds with a lattice structure. The mechanical properties and the fracture mechanisms of the scaffolds were ascertained by means of in situ compression tests within an X-ray µtomography system in lattices that have been immersed in simulated body fluids for different time periods. These results were used to ascertain the influence of processing parameters, lattice dimensions and Mg/Zn content on the mechanical properties and corrosion resistance of composites lattice structures manufactured by fused filament deposition.

3:40 PM
Laser-based Powder-bed Fusion Strategies for the Fabrication of Cellular Scaffolds with a Fine Resolution: Ebrahim Asadi¹; Fatemeh Hejripour¹; Md Abdus Salam¹; Faridreza Attarzadeh¹; Lauren Priddy²; Gary Bowlin¹; ¹University of Memphis; ²Mississippi State University
    In this talk, we present novel laser scanning strategies and their associated laser-based powder-bed fusion (L-PBF) processing parameters to fabricate Ti-6Al-4V and WE43 cellular structures with a fine resolution to mimic the resolution of human cancellous bone and improve their mechanical performance. In this study, different L-PBF scanning strategies with various laser powers and scanning speeds are defined to fabricate various cellular structures. With a constant laser spot size of ~80μm, average powder size of 34μm, and layer thickness of 30μm for all the L-PBF processes, the finest achieved resolution for the struts of the cellular structures is 120μm in this study. Furthermore, correlations between the L-PBF processing parameters/scanning strategies and physical/mechanical properties of the cellular structures are discussed for bone tissue regeneration.