3D Bioprinting of fast gelling collagen

One of the greatest challenges faced in 3D bioprinting is the development of suitable materials to be used as bioinks. Collagen is a natural hydrogel material that has excellent cytocompatibility. This suggests the potential that collagen has of being used as an apt bioink material. However, research done on the viability of collagen as a bioink discovered two large drawbacks, the lack of mechanical strength and slow gelation time [1]. The latter drawback makes the building up of layers very difficult to achieve. In this study, bioprinting was carried out using type I collagen precursor modified to have fast gelation properties. The printing material used was purchased from ORION. No prior research has been done using this fast gelling collagen precursor as the bioink material to do bioprinting. The objective of this study was to find out the properties of this fast gelling collagen precursor and develop a direct printing process for collagen by printing alternating layers of fast gelling collagen precursor and buffer to attain a 3D printed construct with a certain height and resolution. Line printing done using fast gelling collagen precursor showed that by lowering printing parameters such as air pressure, opening time, frequency and feedrate, the fidelity of printed line was improved. Optimal ratio of fast gelling collagen precursor to buffer was found to be 9:1. Frequency sweep test done on collagen gel formed from 6:1 ratio and 9:1 ratio showed that the storage modulus value(G’) of 9:1 collagen gel was at least times four times higher than 6:1. These results supports the findings that the optimal ratio is 9:1. Collagen gel was observed to be formed almost immediately after collagen precursor comes into contact with buffer solution. It was discovered that the buffer solution cannot be printed out at 0.25MPa as pressure is insufficient to overcome surface tension at nozzle orifice. 2D grid pattern was printed and splashing was observed. 30 layers of a square pattern were printed in an attempt to form a 3D construct. The printed 3D construct has a height of around 2mm. Some fluid found surrounding the construct may be caused from errors in dispensing buffer or high printing pressures of buffer. In short, the elimination of slow gelation property of collagen does help to achieve a better build height and the 3D construct has a good printed shape. Further studies such as cell viability when printing with the optimised printing parameters can be conducted.Bachelor of Engineering (Mechanical Engineering