Fabrication of polymeric scaffold via additive manufacturing
Foo, Yong Sheng
Date of Issue2014
School of Mechanical and Aerospace Engineering
Cardiovascular disease is the number one cause of the death in the world today. The most common form of the disease is atherosclerosis which is the narrowing of the blood vessels due to the deposition of plague on the vessel walls. Treatment of the disease is dependent on its severity and often involves the prescription of drugs in minor cases and bypass surgery in severe cases. In bypass surgery, the patient’s own blood vessels is often used as the first choice, however, if the patient does not have sufficient quality blood vessels due to previous operations or injury, artificial blood vessels may be used. Although there are already artificial blood vessels available in the market made of Teflon and Dacron, they are only suitable to be used in larger diameter blood vessels. When used to replace blood vessels of smaller diameter, thrombosis (i.e. the formation of blood clot) tends to occur. Hence there is a continuous effort of scientist around the world to search for the solution to this problem through tissue engineering. Through tissue engineering, three dimensional scaffolds can be fabricated. In the case of artificial blood vessels, the scaffolds should provide properties such as mechanical stability when being subjected to cyclic stresses and strains, biocompatibility and bioactivity. The main objective of this study is to design and fabricate a mandrel with special features on which biodegradable poly (L-lactide-co-ε-caprolactone) (PLCL) copolymers will be drawn on into a tubular scaffold using the melt drawing technique. The special features in the form of exolongitudinal channels will act as guides to the direction of growth of the smooth muscle cells. Firstly, the designs of the mandrel were performed on SolidWorks 2013 and fabricated using a 3D printer. Next, tubular scaffolds were fabricated by drawing PLCL fibres around the rotating mandrel with diameter of 36.06mm. Scaffold dimensions after shrinking due to residual tensile stress were obtained to be 9.39mm in diameter and the cell guiding grooves were found to have an average size of 492.33±19.50µm. The diameters of the PLCL fibres were determined by scanning electron microscope to be 23.981±0.774µm. Samples of the melt drawn tubular scaffold were tested for its mechanical properties. The tensile stress and strain at break were obtained to be 10.541±0.714MPa and 247±36% respectively which exceeded the values of native human arterial tissues. This is the first report which shows that a scaffold with exolongitudinal grooves and endocircular microfibers can be fabricated by means of drawing PLCL fiber around a mandrel with grooves. This paves the way for the future works in which tubular scaffold with multiple surface topologies for cellular guidance can be fabricated.
DRNTU::Engineering::Materials::Material testing and characterization
Final Year Project (FYP)
Nanyang Technological University