3D printing biomaterials for cleft palate

Cleft palate is a component of the second most common birth defect found in humans, cleft lip and palate. The gold-standard for treating the defect for decades has been traditional flap surgeries however these have seen little modernisation and present several limitations. Recent advances in 3-dimensional (3D) printing have enabled the 3D printing of biomaterials which could be used to produce bespoke implants for patients as part of a novel, regenerative method for treating cleft palate. Sodium alginate is a biocompatible, natural polysaccharide which has previously been used in drug delivery and as part of cell scaffolds. In the presence of water, it readily forms hydrogels which can be crosslinked to further increase their strength, making it an ideal candidate for 3D printing. This project aimed to develop alginate-based biomaterials for 3D printing that could be used as part of an alternative method for treating cleft palate. Proton nuclear magnetic resonance was used to identify an ideal candidate strain for the project. Then, the relationship between sodium alginate and calcium chloride (CaCl2), a popular crosslinking agent, was studied to optimise initial hydrogel compositions and consider their suitability for 3D printing. Rheological characterisation was then conducted to further investigate the complex viscoelastic properties these hydrogels exhibited before a 3D printing assessment was performed. Secondary and tertiary crosslinking was used to increase the strength of printed samples then assessed as potential implants mechanically and biologically. Heterogenous hydrogels were successfully produced that exhibited a wide range of viscoelastic properties allowing relationships between material properties and hydrogel compositions to be established. Hydrogels that exhibited elastic-dominated properties were most applicable to 3D printing. Hydrogel compositions were shown to 3D print at high fidelity and through secondary-crosslinking were shown to be biomimetic to typical soft tissue. This project indicates that 3D printed alginate hydrogels could be accurately 3D printed in the 5 shapes and dimensions required to plug a cleft palate void as an alternative to traditional flap surgery. Secondary crosslinking of 3D printed structures produces appropriate biomimetic mechanical properties to soft tissue the obturator could be used to replace.