Artificial bone nanocomposite and method of manufacture

Abstract

A composition suitable for bone replacement is provided. The composition is a nanocomposite matrix, resembling both the structure and the properties of natural bone, including morphology, composition and mechanical characteristics. The nanocomposite is preferably porous and comprises: (1) micro or nano scale cellulose crystals or fibres; (2) hydroxyapatite nanoparticles; (3) Poly L-Lactide Acid or poly glycolic acid; and (4) a coupling agent, for example a surfactant, preferably an anionic surfactant such as sodium dodecyl sulfate. The composition is useful as an artificial bone replacement or bone graft, is preferably biomimetic, and can be suitable for use, for example, in trabecular bone substitution and osteoanagenesis applications. A method of fabrication of the nanocomposite is also provided.

1 . Method of preparing a composition including
 (i) Poly L-Lactide acid (PLLA), or poly glycolic acid (PLGA),   (ii) micro or nano scale cellulose crystals or fibers,   (iii) hydroxyapatite (HA) nanoparticles, and   (iv) a coupling agent,   the method comprising:   (a) pretreating the cellulose crystals or fibers and the HA nanoparticles to promote disaggregation; and   (b) dispersing the cellulose crystals or fibers and the HA nanoparticles in a matrix of the PLLA or PLGA in a generally homogeneous manner.   
     
     
         2 . The method of  claim 1 , wherein the pretreating comprises ultrasonication and/or incorporation of the coupling agent. 
     
     
         3 . The method of  claim 1 , further comprising:
 dissolution of the PLLA or PLGA in an organic solvent to form a dissolved PLLA or PLGA;   drying the HA nanoparticles to remove water, then transferring the HA nanoparticles to a solvent to form a dispersion of HA nanoparticles in said solvent;   ultrasonicating the cellulose crystals or fibers in solvent to form a ultrasonicated cellulose dispersion in said solvent;   combining the dispersion of HA nanoparticles and the ultrasonicated cellulose dispersion and adding the coupling agent to form a combined dispersion;   combining the dissolved PLLA or PLGA and the combined dispersion to obtain a generally homogeneous colloidal suspension;   optionally adding a porogen;   molding and freezing the generally homogeneous colloidal suspension to form a solidified nanocomposite mass;   freeze drying the solidified nanocomposite mass to sublimate the solvent under vacuum and form the composition; and   optionally removing excess coupling agent by floating the resultant composition in water.   
     
     
         4 . The method of  claim 3 , wherein the organic solvent and the solvent are both 1,4-dioxane. 
     
     
         5 . The method of  claim 3 , wherein the drying is by a solvent extraction. 
     
     
         6 . The method of  claim 5 , wherein the solvent extraction uses, sequentially, water, acetone, ethanol, and 1,4-dioxane. 
     
     
         7 . The method of  claim 3 , wherein the coupling agent is SDS. 
     
     
         8 . The method of  claim 3 , wherein the porogen is a sodium chloride salt or a sugar.