Fabrication and evaluation of combined 3D printed/pamidronate-layered double hydroxides enriched electrospun scaffolds for bone tissue engineering applications

The combination of commonly used fabrication technologies, including electrospinning and additive manufacturing, is a new approach to produce tissue engineering scaffolds resembling the heterogeneous tissue structure. This study presents the fabrication and characterization of novel 3D-structured scaffolds of pamidronate (PAM)-loaded layered double hydroxides (LDH)/polycaprolactone (PCL) electrospun nanofibers combined with micro-strand PCL 3D printed grids. PAM-LDH was synthesized through the coprecipitation method, and the intercalation of PAM into LDH was confirmed via XRD and FTIR analysis. PCL and PAM-LDH/PCL nanofiber mats were fabricated by electrospinning. Adding PAM-LDH to PCL decreased fiber diameter from 527 ± 24 nm to 289 ± 43 nm and increased the surface roughness from 33.5 ± 17 nm to 65.6 ± 24 nm. Circular PCL grids, including strands of 400 μm width, were fabricated using a 3D printer system. The final structure of the scaffolds was obtained by gluing the nanofiber mats between 3D printed micro-strand grids. FESEM images showed the nanofiber mats fully covered the pores of 3D printed grids while the morphology of the fibers remained the same. BET analysis was conducted to calculate the mean pore diameter, total pore volume, and surface area of the scaffolds. Monitoring the in vitro release of PAM showed mainly two stages; water penetration-controlled for early hours and a degradation-controlled release stage up to 28 days. The biocompatibility of the scaffolds was assessed by culturing the MG-63 cell lines. Scaffolds with PAM-LDH containing nanofiber mats highly supported cell adhesion and improved alkaline phosphatase activity, an indicator of osteoconductivity. Given the results, these novel 3D structured scaffolds have the potential application to be used as bone tissue engineering scaffolds.