Synthesis methods of hydroxyapatite from natural sources: A review

Synthetic HAp becomes a major concern among researchers as it poses a risk of being expensive, complex, employing a time consuming method while also producing low biological activity HAp with lack of trace elements. Considering these issues, synthesizing HAp using natural resources had become a popular alternative way in order to obtain a high-performance HAp powder due to the presence of trace elements that improve the efficiency of HAp powder. However, only a few studies have focused on the synthesis of HAp by using natural sources in a simple and cost-effective manner to produce HAp with properties comparable to synthetic HAp. Thus, this review provides in depth analysis on the diverse methods that can be used to synthesize HAp from various natural resources. This would aid in finding the best method possible in synthesizing HAp with optimum properties to meet the requirements of tissue engineering applications.