Nanohydroxyapatite and its composite scaffold for bone tissue engineering application: a systematic review

Osteoporosis, osteomyelitis disease, bone tumors, bacterial infections, and accidents are posing a great challenge in the orthopedic field. For decades, autograft and allograft transplant techniques have been considered gold-standard treatments for bone problems. Given these limitations and increased medical demand for bone substitute material, the orthopedic field has sparked rapid interest in building safe and biocompatible materials. In search of alternatives, biomaterials such as bioactive glasses, hydroxyapatite (HAp), calcium silicate, β-tricalcium phosphate, etc., offer new insights for bone regeneration. In particular, HAp [Ca₁₀(PO₄)₆(OH)₂] has drawn considerable attention because the bone has HAp as a major inorganic component. In addition, HAp has bioactivity, biocompatibility, and osteointegration properties. Further, to enhance the biological properties of the HAp, it has been modified to a nanoscale level and named nanohydroxyapatite (nHAp). The nHAp has a larger surface area, which helps to facilitate drug loading, gene delivery, and fast recovery of injured bone. Thus, the present review spotlights a brief introduction to HAp and nHAp, their history, basic properties, synthesis methods, and composites with metals, polymers, ceramics, growth factors, etc., for bone tissue engineering applications.