A renewable resource based carbon dot decorated hydroxyapatite nanohybrid and its fabrication with waterborne hyperbranched polyurethane for bone tissue engineering

Use of renewable resources in material science creates new opportunities for fabricating novel biomaterials. In this context, a carbon dot (CD) decorated hydroxyapatite (HAp) nanohybrid (CD@HAp) was synthesized by a simple one pot hydrothermal process. Different bio-based and waste materials were used in the synthesis of the nanohybrid. The aqueous extract of corms of Colocasia esculenta was used as the CD precursor, whereas egg shell was used to obtain CaO, which served as the precursor for HAp. The synthesized nanohybrid was characterized by using different analytical and spectroscopic techniques viz. FTIR, XRD, TEM, SEM/EDX and Raman spectroscopy. TEM and HRTEM images confirmed the formation of needle shaped HAp (length 60-80 nm, average diameter 20-30 nm) with decorated CDs over its surface. Elemental analysis showed a Ca/P ratio of 1.69, which is close to the Ca/P ratio (1.67) found in natural bone. Biological assessment of the nanohybrid demonstrated excellent cytocompatibility, cell proliferation and alkaline phosphatase activity against MG 63 osteoblast cell line. Synthesized CD@HAp was fabricated in situ with a tannic acid based waterborne hyperbranched polyurethane. Substantial improvement in the mechanical properties of the nanocomposite was perceived. These nanocomposite films were tested for osteogenic activities and the results confirmed its utility as a bone regenerating material. The overall results thus endorse development of a sustainable nanocomposite with high load bearing ability and profound bioactivity which can be employed for bone tissue engineering application.