3D‐Printed Polyurethane Tissue‐Engineering Scaffold with Hierarchical Microcellular Foam Structure and Antibacterial Properties

Abstract

This work proposes a facile fabrication strategy of polyurethane (TPU) tissue‐engineering scaffold with hierarchical structure, designed by combination of the fused deposition modeling (FDM) 3D printing and supercritical microcellular foaming by carbon dioxide (CO2). Further surface modification of TPU scaffold with graphene oxide (GO) was carried out by in situ polymerization of polydopamine (PDA) to ensure stable loading of GO with antibacterial properties. The influence of 3D‐printing temperature and speed on the microcellular cell morphology of TPU scaffold was investigated and optimized. The microcellular foaming and expansion process was indicated to compensate mechanical loss because of the gaps of stacking layers by FDM printing, and the reported tensile strength of 28 MPa matched well with that of natural cartilage tissue constructs. More interesting, the formation of interconnected open pores on the surface of foamed TPU scaffold shows much more enhanced cell adhesion because of the bigger specific surface area of microcellular structure. Similarly, the foamed TPU scaffold exhibits good absorption of GO nanosheets by the synthesized PDA on the surface and antibacterial properties, compared with the unfoamed TPU scaffold. This work offers a strategy for designing and manufacturing polymer tissue‐engineering scaffold with hierarchical structure and good antibacterial property.

Research progress of 3D printing combined with thermoplastic foaming

“…As shown in Figure 10, Li et al (2020) reported using polyetherimide and polylactic acid (PLA) filaments to manufacture hierarchical porous portions that were impregnated with CO 2 gas. Zhang et al (2022) offered a simple solution by combining 3D FFF printing with supercritical microcellular foaming to address the primary obstacle for tissue-engineering scaffolds with hierarchical topologies. As seen Figure 11 (Zhang et al, 2022), the flexibility of additive manufacturing design results in pores are larger than microns due to layer stacking, whereas microcellular structures result in pores smaller than microns due to foaming.…”

“…Zhang et al (2022) offered a simple solution by combining 3D FFF printing with supercritical microcellular foaming to address the primary obstacle for tissue-engineering scaffolds with hierarchical topologies. As seen Figure 11 (Zhang et al, 2022), the flexibility of additive manufacturing design results in pores are larger than microns due to layer stacking, whereas microcellular structures result in pores smaller than microns due to foaming. In-situ foam 3D printing requires an additional stage of gas impregnation before printing and the gas-saturated filaments commence to release gas as soon as they are removed from the high-pressure chamber, which is one of its biggest advantages.…”

In Situ Foam 3D Printing of Microcellular Structures Using Material Extrusion Additive Manufacturing

“…Overall, three approaches can be used to fabricate foamed parts in the material extrusion AM process: (a) prefoaming, (b) postfoaming, − and (c) in situ foaming. − In the prefoaming approach, the feedstock filament is usually foamed during filament fabrication and used as feedstock for 3D printing. The issue with this approach will be the lack of foaming control during the actual printing process, which limits the range of cellular structures that can be obtained.…”

“…Li et al reported CO 2 gas-impregnated polyetherimide and polylactic acid (PLA) filaments that were used to print foamed parts. Zhang et al also demonstrated the preparation of polyurethane foamed scaffolds using a similar approach . The cell nucleation, growth, and stabilization occurred as the CO 2 -saturated filament was heated during printing.…”

“…Zhang et al also demonstrated the preparation of polyurethane foamed scaffolds using a similar approach. 35 The cell nucleation, growth, and stabilization occurred as the CO 2 -saturated filament was heated during printing. The challenge with the use of a gas as a blowing agent is the need for an additional gas impregnation step before printing.…”