Structural, Mechanical, and Biological Characterization of Polycaprolactone (PCL) Scaffolds for Dynamic Cell Cultures, Toward Dental Applications

Abdulkareem Alotaibi; Yash Desai; Jae Choi; Alexander Tsouknidas; Jacob Miszuk; Konstantinos Michalakis

Abstract:

Introduction
Alveolar bone loss after tooth extraction is a challenge for predictable implant placement. Bone grafting is widely used but limited by resorption, availability, and donor site morbidity. Bio-mimetic scaffolds with engineered structural, mechanical, and biological properties offer alternatives by supporting cell adhesion, proliferation, and tissue formation. Polycaprolactone (PCL), a biodegradable polymer with established biocompatibility, is widely applied in tissue engineering. This study examined the effect of PCL concentration on scaffold properties relevant to alveolar bone regeneration.

Methodology
Scaffolds were fabricated using Thermally Induced Phase Separation (TIPS) with PCL dissolved in a THF/water solvent at 8%, 9%, and 10% (w/w). Mechanical properties were assessed by compression testing at 1 mm/min and 25 °C. Morphology was examined by Scanning Electron Microscopy (SEM), and porosity measured with AccuPyc II. Biological performance was evaluated by MTT assay, where cells were incubated with MTT solution for 3 h at 37 °C before absorbance at 590 nm. Confocal microscopy was performed with MC3T3-E1 pre-osteoblast cells stained with Texas Red™-X Phalloidin (591 nm) and DAPI.

Results
The 9% PCL scaffold demonstrated the most consistent mechanical behavior, with a modulus ranging from 2.81 to 3.40 MPa. Statistical analysis (ANOVA, p < 0.05) confirmed that the 9% PCL group had a significantly higher modulus than both 8% and 10%, while no significant difference was observed between 8% and 10%. SEM analysis revealed interconnected pore structures with porosity ranging from 84% to 87%, supporting tissue ingrowth. The MTT assay confirmed good cell viability across all groups, with the 9% PCL group nearly matching the control. Cytotoxicity remained low (0.31%–8.50%), with the 9% showing the lowest value and the 8% group the highest. Confocal microscopy, after seeding 100,000 cells (MC3T3-E1) per scaffold, showed strong cell attachment and penetration, indicating effective scaffold–cell interaction.

Conclusion
The 9% PCL scaffold demonstrated optimal mechanical stability and biological performance, making it a promising candidate for alveolar bone regeneration. Nevertheless, in vivo validation is required to confirm translational potential.