Melt-based, solvent-free additive manufacturing of biodegradable polymeric scaffolds with designer microstructures for tailored mechanical/biological properties and clinical applications

Biodegradable scaffolds are considered as the key component of tissue engineering which serve as temporary structural supports for tissue regeneration. The mechanical/biological properties of artificial synthetic polymeric scaffolds are highly dependent on their structural organisations. Additive manufacturing (AM) techniques have provided unprecedented opportunities to customise patient-specific scaffolds with complex architectures in a reproducible manner. Here we provide a state-of-the-art review on the recent development and application of melt-based, solvent-free AM techniques to produce biodegradable polymeric scaffolds for better understanding their structure–property-function relationships for different tissue regeneration. Typical biodegradable polymers for melt-based AM are introduced, and key melt-based AM techniques including extrusion-based printing, selective laser sintering and high-resolution electrohydrodynamic bioprinting are highlighted. The critical strategies by structural design to regulate the mechanical/biological properties of as-fabricated biodegradable scaffolds in vitro and in vivo are summarised. The clinical trials as well as potential challenges of the resultant scaffolds were finally reviewed and discussed.