Three-Dimensional Printing of Polycaprolactone Scaffolds with Multiscale Porosity for Bone Tissue Engineering

Extrusion-based three-dimensional printing enables the fabrication of patient-specific scaffolds. Polycaprolactone (PCL)-based scaffolds have been widely used for the treatment of bone defects. However, extruded filaments are typically nonporous, which can prolong their degradation, limit cell adhesion and infiltration, and therefore interrupt normal tissue regeneration. Here, we present a simple and scalable method to generate polymeric scaffolds with hierarchical porosity by incorporating sacrificial sugar particles in a printable PCL ink. Microstructural analysis by SEM demonstrates an average pore size of around 10 μm with increased pore density at higher porogen fractions. Porous PCL improved apparent wettability and protein adsorption, accelerated hydrolytic degradation by more than five-fold, and enabled tunable mechanical properties. Printability testing shows improved filament stability and reduced fusion at higher porogen loading, enabling significantly higher printing resolution. In vitro evaluation demonstrates enhanced early preosteoblast attachment on porous scaffolds (>three-fold), without loss of cytocompatibility. Importantly, porous scaffolds support osteogenic differentiation of the cells and mineralization. This study provides a practical framework for creating intrafilamentary porosity into 3D-printed PCL scaffolds with improved surface-mediated biological performance.