Suk-Hee Park

Microstructured scaffold coated with hydroxyapatite/collagen nanocomposite multilayer for enhanced osteogenic induction of human mesenchymal stem cells

Three dimensional microstructured scaffolds with precisely defined architectures have many promising features for tissue engineering applications, such as controllable porosity, optimal mechanical strength, and adjustable contour fitting to a tissue defect site. However, for enhanced cell adhesion and differentiation, surface modified scaffolds with bioactive agents are additionally required. In this study, we present an osteogenic nanocomposite coating strategy on the surface of a microstructured scaffold for applications in bone tissue engineering. A layer-by-layer multilayer assembly method was employed to coat the scaffold surface with hydroxyapatite and collagen. The amount of the two components in the multilayer could be easily controlled by adjusting the number of deposition layers, leading to improved adhesion, proliferation, and differentiation of seeded mesenchymal stem cells. The hydroxyapatite/collagen nanocomposite coated scaffold showed enhanced osteogenic activities compared to bare scaffold, allowing great potential for bone regeneration.

Hierarchical multilayer assembly of an ordered nanofibrous scaffold via thermal fusion bonding

A major challenge in muscle tissue engineering is mimicking the ordered nanostructure of native collagen fibrils in muscles. Electrospun nanofiber constructs have been proposed as promising candidate alternatives to natural extracellular matrix. Here, we introduce a novel method to fabricate a two-dimension (2D) sheet-type and three-dimensionally integrated nanofibrous scaffolds by combining electrospinning and rapid prototyping. The aligned 2D nanofiber mats can be processed into different configurations by the CAD/CAM-based deposition of thermally extruded microstructures. We demonstrate the feasibility of these microstructures for application in muscle tissue engineering by culturing C2C12 myoblasts and then evaluating their viability and alignment. Highly aligned cellular morphologies were successfully achieved along the direction of the nanofibers in all types of scaffolds. The hybrid scaffolds provided mechanical support and served as a topographical guide at the nanoscale, exhibiting their potential to meet the requirements for practical use in tissue engineering applications.

Development of pre-/post-processors for 3D numerical simulation using cut cell method

Abstract Today, in the casting engineering field, various heat flow simulations are being applied to manufacturing processes. The most general flow simulation techniques have been improved and developed according to the characteristics where they are applied in the casting industry. In this study, the authors have developed a pre-/post-processing system to use a cut cell method, which is one of the finite volume methods among the numerical analysis methods mentioned above. In this paper, the authors will briefly introduce a pre-processor that requires only the user’s simple input information to automatically generate meshes and performs simulation and post-processing, which maps the simulation result data into an original computer aided design file directly. This paper will also examine a few cases of actual application of these technologies to casting products.

Enhanced Solubility of the Support in an FDM-Based 3D Printed Structure Using Hydrogen Peroxide under Ultrasonication

Fused deposition modeling (FDM), one of the archetypal 3D printing processes, typically requires support structures matched to printed model parts that principally have undercut or overhung features. Thus, the support removal is an essential postprocessing step after the FDM process. Here, we present an efficient and rapid method to remove the support part of an FDM-manufactured product using the phenomenon of oxidative degradation of hydrogen peroxide. This mechanism was significantly effective on polyvinyl alcohol (PVA), which has been widely used as a support material in the FDM process. Compared to water, hydrogen peroxide provided a two times faster dissolution rate of the PVA material. This could be increased another two times by applying ultrasonication to the solvent. In addition to the rapidness, we confirmed that amount of the support residues removed was enhanced, which was essentially caused by the surface roughness of the FDM-fabricated part. Furthermore, we demonstrated that there was no deterioration with respect to the mechanical properties or shape geometries of the obtained 3D printed parts. Taken together, these results are expected to help enhance the productivity of FDM by reducing the postprocessing time and to allow the removal of complicated and fine support structures, thereby improving the design capability of the FDM technique.

Recent Progress in the Nanoscale Additive Layer Manufacturing Process Using Two- Photon Polymerization for Fabrication of 3D Polymeric, Ceramic, and Metallic Structures

1 한국과학기술원 기계항공시스템학부 (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology)2 삼성디스플레이 LCD사업부 (Divison of LCD, Samsung Display)3 한국생산기술연구원 마이크로나노공정그룹 (Micro/Nanoscale manufacturing R&D Group, Korea Institute of Industrial Technology)4 부산대학교 기계공학부 / 정밀정형 및 금형가공연구소 (School of Mechanical Engineering, ERC/NSDM, Pusan National University) Corresponding author: sanghu@pusan.ac.kr, Tel: +82-51-510-1011

Development of 3D printed biomimetic scaffold for tissue engineering

One of the major challenges in tissue engineering is to mimic nanoarchitecture of native collagen fibrils in human body, as well as to fabricate three-dimensional outer shape to be regenerated. Here, we introduced a novel three-dimensional (3D) fabrication method for biomimetic scaffold by combining 3D printing and electrospinning process with using biocompatible polymers. Electrospun nanofiber construct has been believed to be a promising candidate for the simulation of natural extracellular matrix (ECM) structure. The random and aligned nanofiber mats were prepared for mimicking the nanofibril ECM structure respectively in cartilage and skeletal muscle. Then, they were packed by the 3D printing process. Microscopic pore morphology and macroscopic framework could be finely tuned by 3D printing process. By culturing chondrocyte and C2C12 myoblasts on the developed scaffolds, the each scaffold showed its feasibility for the application to tissue engineering. The hybrid scaffolds containing 3D microscale framework and nanofiber mats entailed both features of mechanical support and nanofibrous topographical guide, and thus could potentially meet the requirements for practical use of tissue engineering scaffolds.