Matrices of Acidic β-Sheet Peptides as Templates for Calcium Phosphate Mineralization† Academic Article uri icon

abstract

  • Designed biomaterials that accelerate mineralization under physiological conditions may provide new multifunctional biomimetic scaffolds amenable for bone tissue regeneration. Bone and teeth dentin are composite biomaterials composed of carbonated apatite crystals that are aligned within type-I collagen fibrils of the extracellular matrix. [1‐3] Non-collagenous proteins isolated from bone extracellular matrices that are rich in acidic amino acids [4] have been proposed to be involved in the nucleation and growth of carbonated apatite. [5] Despite numerous studies aiming at unraveling the principles of apatite biomineralization, detailed mechanisms that account for the role of acid rich proteins in this process are yet to be elucidated. Addadi and Weiner have proposed that acidic proteins locked in an ordered and rigid conformation present favorable sites for heterogeneous nucleation of calcium minerals, whereas a flexible polypeptide chain in solution may inhibit crystallization. [6,7] Rigid interfaces of biomaterial may induce biomineralization processes through selective electrostatic accumulation of the mineral ionic components and by structural correspondence with specific planes in the crystal. The inhibition of crystal growth along certain directions in solution was demonstrated by tailor-made additives that adsorbed specifically by structural matching to planes of a mature crystal. [8] Biomineralization in general has been linked to acidic proteins in b-sheet conformation. The major acidic protein of tooth enamel, enamelin, has been shown to fold into b-sheet structure during enamel formation. [9] Other acidic, extracellular matrix macromolecules have been found to adopt the b-sheet structure in the presence of calcium salts. [6] Designed peptides that assume b-sheet structures have been showntoform assemblies withunique structural characteristics at the nanometer scale. [10‐14] Several families of amphiphilic

publication date

  • January 1, 2008