DEVELOPMENT OF HYDROGEL ASSEMBLY AND SYNTHESIS FOR TISSUE ENGINEERING APPLICATIONS
- DEVELOPMENT OF HYDROGEL ASSEMBLY AND SYNTHESIS FOR TISSUE ENGINEERING APPLICATIONS
- Other Titles
- 조직 공학 응용을 위한 하이드로젤의 조립과 합성 기술 개발
- Alternative Author(s)
- Prof. Bong Geun Chung
- Issue Date
- Development of Hydrogel Assembly and Synthesis for Tissue Engineering Applications
Prof. Bong Geun Chung
Department of Bionano Engineering
Graduate School of Engineering
Hanyang University, South Korea
Hydrogels have received significant attention because of their exceptional promise in biomedical applications. There are various types of hydrogels but poly ethylene glycol (PEG) and gelatin hydrogels are extensively used in biological fields. We used PEG for the development of hydrogel assembly, whereas gelatin for the creation of core-shell nanofiber and porous core-shell fiber networks for tissue engineering applications.
In the first chapter of this dissertation, we developed hydrogel assembly of cell-laden individual building blocks. Bottom-up approach is a potentially useful tool for hydrogel assembly of cell-laden individual building blocks. In this work, we assembled individual building blocks of photocrosslinkable microgels in a rapid and controlled manner. Individual building blocks of poly (ethylene glycol) (PEG) microgels with square and hexagonal shapes were fabricated by using a photolithography technique. Individual building blocks of PEG microgels were assembled on a hydrophobic mineral oil phase in a bioreactor with a magnetic stirrer. The hydrophobic mineral oil minimized the surface free energy to assemble hydrophilic PEG microgels on a two-phase oil-aqueous solution interface. We used the hydrophobic effect as a driving force for the hydrogel assembly. Various types of the hydrogel assembly were generated by controlling the stirring rate. As stirring speed increased, the percentage of linear, branched, and closely pack hydrogel assembly was increased. However, the percentage of random assembly was reduced by increasing stirring rate. The stirring time also played an important role in controlling the types of hydrogel assembly. The percentage of linear, branched, and closely packed hydrogel assembly was improved by increasing stirring time. Therefore, we performed directed cell-laden hydrogel assembly using a two-phase bioreactor system and optimized the stirring rate and time to regulate the desired types of hydrogel assembly. Furthermore, we analyzed cell viability of hydrogel linear assembly with square shapes, showing highly viable even after secondary photocrosslinking reaction. This bioreactor system-based hydrogel assembly could be a potentially powerful approach for creating tissue microarchitectures in a three-dimensional (3D) manner.
In the second chapter of this dissertation, we synthesized highly porous core-shell polymeric fiber net works using gelatin (hydrogel) as core and PCL as shell. Core-shell nanofibers are of great interest in the field of tissue engineering and cell biology. We fabricated porous core-shell fiber networks using an electrospinning system with a water-immersed collector. We hypothesized that the phase separation and solvent evaporation process would enable the control of the pore formation on the core-shell fiber networks. To synthesize porous core-shell fiber networks, we used polycaprolactone (PCL) and gelatin. Quantitative analysis showed that the sizes of gelatin-PCL core-shell nanofibers increased with PCL concentrations. We also observed that the shapes of the pores created on the PCL fiber networks were elongated, whereas the gelatin-PCL core-shell fiber networks had circular pores. The surface areas of porous nanofibers were larger than those of the non-porous nanofibers due to the highly volatile solvent and the phase separation process. The porous core-shell fiber network was also used as a matrix to culture various cell types, such as embryonic stem cells, breast cancer cells, and fibroblast cells. Therefore, this porous core-shell polymeric fiber network could be a potentially powerful tool for tissue engineering and biological applications.
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- GRADUATE SCHOOL[S](대학원) > BIONANOTECHNOLOGY(바이오나노학과) > Theses (Master)
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