Synthesis of Nanostructured Hydroxyapatite: A Comparative Study between Sol-Gel and Aqueous Solution Precipitation

Abstract

Particle size is one of the most important factors to the successful application of calcium phosphate bioceramics as it may have an important role on its final properties such as mechanical resistance and reactivity. Thus, a process which results on very small and homogeneous particles is required, since it avoids further contamination derived from long milling times. On this context, a process such as sol-gel synthesis may be feasible, due to its simplicity on handling and its well known characteristic of producing homogeneous nanoparticles. Moreover, precipitated HA also may lead to satisfactory results regarding particle size and phase purity. The aim of this article was to demonstrate a preliminary characterization study of powders obtained by both methods and to compare them to a commercial sample available in Brazil. Characterization was made by XRD, Scherrer’s equation, XRF, SEM-LV, SEM-FEG and SEM-EDS. It has been found out that all samples consist of pure nanostructured hydroxyapatite with crystallite size between 37nm and 62nm.

Eggshell-Derived Hydroxyapatite

“…[18][19][20]23 Eggshell-derived hydroxyapatite seems to be promising graft material with excellent properties for grafting [18][19][20]23 with viable various production techniques. [25][26][27][28][29][30][31][32][33][34][35] Lack of disease transfer risks, biocompatibility, and ease of use makes EHA a viable choice as regenerative material. Eggshell-derived hydroxyapatite is hydrophilic in nature, absorbed by body fluids and blood, so that handling becomes easy for placing it in the surgical site.…”

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…Most of these techniques produced rod-like crystals or whiskers, while plate-like shapes were obtained in just a few studies [335,345,347]. Other preparation methods of nanodimensional and/or nanocrystalline apatites of various states, shapes and sizes include sol-gel [30,188,231,232,270,328,[360][361][362][363][364][365][366][367][368][369][370][371][372][373][374][375][376], co-precipitation [271,333,334,[377][378][379][380], mechanochemical approach[65, 250,343,348,[381][382][383][384][385][386][387], mechanical alloying [388,389], ball milling [348,383,…”

“…An interesting approach using sitting drop vapor diffusion technique should be mentioned as well [471]. A comparison between the sol-gel synthesis and wet chemical precipitation technique was performed and both methods appeared to be suitable for synthesis of nanodimensional apatite [328]. By means of these methods, a variety of nanodimensional calcium orthophosphate building blocks with various structures and morphologies have been synthesized, including needle-like, spherical, fibrous and mesoporous nano-sized crystals, as well as nano-sized rods, hollow spheres, layered structures and flowers as shown in Fig.…”

Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

“…To prepare nanodimensional and/or nanocrystalline apatites, methods of wet chemical precipitation [62,71,73,86,119,121,155,156,157,160,166,186,187,237,246,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288], sol-gel synthesis [30,176,210,211,242,288,289,290,291,292,293,294,295,296,297,298,299], co-precipitation [243,300…”