2, Mechanical Engineering, California State University, Chico, Chico, California, United States
Regenerative medicine bridges the engineering and life sciences to do organ or tissue regeneration. In this field, role of biomaterials, cell-cell interaction, and cell-scaffold interaction play a vital role in tissue regeneration. Biomaterials can be either synthetic materials or natural materials and they are widely used to either substitute a living system or fabricate the scaffolds. Scaffolds can be designed in the computer environment and they can be fabricated in the laboratory environment. In this research, scaffolds were designed with Lindenmayer Systems (L-Systems) and they were fabricated with photolithography. L-systems are rewriting processes that are used to design the fractals. Firstly, a single strut was drawn with the L-Systems and it was printed out by a 3-D printer. Then a y-shape, a trunk with three branches and a trunk with four branches were designed by L-Systems and they were also printed out with a 3-D printer. In this process, dissolvable filaments were used to print out the 3-D designs. Next, each of them inserted into liquid form of poly(ethylene glycol) diacrylate (PEGDA) and 2,2-dimethoxy-2-phenylacetophenone (DMPA) mixture and exposed to the UV light for about 4 minutes. Because of interaction between UV light and PEGDA-DMPA mixture, polymerization occurred and the 3-D printed parts were trapped within the solidified hydrogel. Then, fabricated scaffolds were placed into the limonene bath, which helped to dissolve the filament away. These results showcases that PEGDA based hydrogel scaffolds can be designed with L-Systems to control the internal architecture of scaffolds and they can be fabricated with photolithography.