关键词: 釉原蛋白, 寡肽, 自组装, 仿生矿化, amelogenin, oligopeptide, self-assembly, biomimetic mineralization

Abstract: Objective Construct a self-assembly amelogenin-inspired oligopeptide amphiphile as organic matrix template for simulating mineralization of enamel. Methods Inspired by amelogenin that self-assembles into nanospherical supermolecular structures in enamels and according to the design features of "self-assembly polypeptide biological materials", a novel biomineralization template of "amelogenin-like oligopeptide amphiphile" was designed. The oligopeptide amphiphile was synthesized by standard solid-phase peptide synthesis, purified and characterized by high performance liquid chromatography (HPLC) and mass spectrometry (MS). Peptide self-assembly was induced with 1 M CaCl2 solution and characterized with scanning electron microscope (SEM) and transmission electron microscope (TEM). Ca2+-induced self-assembled peptides were smeared onto a holey carbon-coated TEM grid and fixed with 2.5% glutaraldehyde at room temperature for 1 h. Grids loaded with self-assembled peptide were immersed in 10 mM CaCl2 solution for one hour at room temperature or 40 oC in oven and then rinsed in deionized water. The samples were then exposed to 5 mM Na2HPO4 solution as did in CaCl2 solution followed by rinsing. This cycle was repeated five times, after which the specimens were removed, washed with deionized water, dried in atmospheric conditions, and examined with SEM, TEM and energy dispersive spectrometer (EDS). Results The sequence of the amelogenin-inspired oligopeptide amphiphile was C18H35O-Thr-Lys-Arg-Glu-Glu-Val-Asp. Peptide molecule weight (MV) and purity were 1142.41 and 98.29% accordingly, identified with MS and HPLC respectively. The oligopeptide amphiphile could self-assemble into a gel by Ca2+ induction. TEM showed that the self-assembly hydrogel consisted a β-sheet conformation nanofiber networks; the peptide fiber could adsorb calcium and phosphate ions from the solution. Then, minerals crystals nucleated, grew on the surfaces of the peptide fibers, and orientated along the fibers. Conclusions A novel amelogenin-inspired oligopeptide amphiphile was designed and synthesized, which could be a specific template for biomimetic mineralization of enamel, and could be useful in the study of inducing enamels' remineralization .