Self-Assembly of Nano Hydroxyapatite or Aragonite Induced by Molecular Recognition to Soy Globulin 7S or 11S

Molecular self-assembly is emerging as a viable 'bottom-up' approach to build stable organic/inorganic nanometer-scale blocks. Herein, under the conditions of appropriate pH and ionic strength, soy globulin 7S or 11S were coprecipitated with hydroxyapatite (HAp) or aragonite (Arag), respectively, to fabricate two organic/inorganic hybrids: 7S/HAp and 11S/Arag. Results from high-resolution transmission electron microscopy show that the hybrids exhibit a nanosized core-shell structure with globulin monomer 7S or 11S as core and HAp or Arag as shells. 7S/HAp and 11S/Arag present a disk and hexagon shape, respectively. After calcinations, monodispersed HAp without support from globulins existed as nanospheres. It was revealed that the globulin as host induces the self-assembly and growth layer by layer of HAp or Arag nanocrystals. The factors of molecular recognition and surface potential definitely affected the size and shape of the hierarchical blocks. This work provided a novel pathway to controllably synthesize a wide variety of precise plant protein/biomineral hybrid biomaterials.