Synthesis of Chondroitin Sulfate Conjugated Nanofiber Shish Kebabs as a Biomimetic Bone Template

Synthetic polymeric bone grafts have emerged as a promising strategy for bone tissue engineering. Polycaprolactone (PCL) nanofiber shish kebab (NFSK) templates were fabricated as synthetic bone scaffolds via polymer crystallization of a block copolymer (BCP) of PCL-b-polyacrylic acid (PAA). The BCP-functionalized NSFKs provide a unique template that allows for the spatial and orientational control of the nanosized mineral crystals in the PAA anionic galleries, mimicking the molecular structure of bone. The objective of this study was to use this platform to design biomimetic bone templates by modifying the surface with biomimetic functional groups. As a result, chondroitin sulfate (CS) was conjugated onto the kebabs via 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) crosslinking of the CS terminal amine group and the PAA carboxylic acid group. Fourier-transform infrared spectroscopy (FTIR) and mass balance showed the formation of an amide bond and an increase in mass after conjugation. MC3T3 E1 pre-osteoblast cells were cultured on the CS-NFSK templates and showed that the presence of CS promoted alkaline phosphatase (ALP) activity and cell proliferation. Osteogenic gene expression, including RUNX2, ALP, COL1, and BGLAP, were upregulated in the CS-NFSK templates. For the first time, CS-NFSK was molecularly engineered to mimic the bone structure and matrix, showing promise as a biomimetic bone template.