Optimal parameter setting and evaluation for ultraviolet-assisted direct ink writing bioprinting of nHA/PEGDA scaffold

Ultraviolet-assisted Direct Ink Writing（UV-DIW）, an extrusion-based additive manufacturing technology, has emerged as a prominent 3D printing technique and is currently an important topic in bone tissue engineering research. This study focused on the printability of double-network (DN) bioink (Nano-hydroxyapatite/Polyethylene glycol diacrylate(nHA/PEGDA)). Next, we search for the optimal UV-DIW printing parameters for the scaffold formed by nHA-PEGDA. In the end, we developed a scaffold that has outstanding structural integrity and can repair bone defects. Achieving high-quality UV-DIW printing can be challenging due to a variety of factors (slurry solid content, rheology, printing conditions, etc.).At present, there are limited reports about precise parameter configurations for UV-DIW printing. We optimised the solid composition of the slurry by varying the quantities of nHA and PEGDA, establishing the maximum solid content (40 wt%) permissible for scaffold shaping. Consequently, we examined the influence of several factors (nozzle diameter, air pressure, and printing rate) on the surface morphology of the scaffolds and determined the ideal conditions to attain scaffolds with superior printing accuracy. The findings demonstrate excellent controllability, repeatability, and precision of the entire printing process. Finally, we evaluated the scaffolds that most effectively fulfilled the requirements for bone regeneration by examining their surface morphology and mechanical characteristics. The experimental findings indicate that nHA-PEGDA scaffolds fulfill the compressive strength requirements for bone tissue and possess promising applications in bone regeneration. This study demonstrates that the nHA-PEGDA bioink possesses significant potential as a scaffold material for bone tissue regeneration, exhibiting exceptional shape integrity and mechanical capabilities. The study found the optimal parameters for bio-3D printers and gave UV-DIW an exact data reference for making the nHA-PEGDA scaffold. In addition, it is a useful guide for 3D printing biomaterial scaffolds.