Rapid Batch Surface Modification of 3D-Printed High-Strength Polymer Scaffolds for Enhanced Bone Regeneration In Vitro and In Vivo

In the emergency treatment of acute injuries in orthopedics, 3D-printing technology shows great promise due to its ability to rapidly and mass production of implants with complex structures. However, further surface modification on 3D-printed implants can often be complicated and time-consuming, leading to a prolonged timeframe from manufacturing to implantation. Therefore, there is an urgent need for rapid batch surface modification technology that can be effectively integrated with 3D-printing technology within the field of orthopedics. In this study, air-plasma treatment was used to rapidly modify 3D-printed polyetherimide (PEI) porous scaffolds and compared it with sulfonation treatment. Both methods achieved rapid surface modification of complex porous scaffolds in seconds to minutes (10 minutes), helping establish a cell-friendly surface morphology that encourages osteogenesis. Some new functional groups such as -OH and -SO3H were also introduced to promote osteogenesis. Interestingly, the air-plasma treated group enhanced cell adhesion, as indicated by a 1.6-fold increase in the number of cells compared to the control group. While sulfonation treatment accelerated the osteogenesis process, evidenced by a 1.7-fold increase in the number of calcium nodules in the sulfonation treated group compared to the control group in 7 days. To combine the advantages of air-plasma treatment and sulfonation treatment, the biological properties of their combined application were studied in vitro and in vivo for the first time. It was surprising to find that the combined application actually decreased the biological property of the material, which was associated with the generation of new free radicals. The results of this study will hopefully be applied to the rapid batch surface modification in 3D-printed porous implants to enhance their biological activity and improve the efficiency from manufacturing to implantation.