OBJECTIVETo design a kind of biomimetic polypeptide of dentin matrix protein-1 (DMP-1), which can bind to dentine collagen fibers and initiate mineralization.

METHODSA novel polypeptide was developed by connecting the collagen binding domain of DMP-1 "DSESSEEDR" to the hydrophilic C-terminal of amelogenin "TKREEVD". The polypeptide was synthetically prepared by standard solid-phase peptide synthesis. Human dentine slices were completely demineralized by hydrochloric acid to expose the dentine collagen. Fluorescein isothiocyanate coupled polypeptide was applied to the exposed dentine collagen. Fluorescent microscopy was used to examine the polypeptide specially bond to the dentine collagen. Nucleation and growth of hydroxyapatite was initiated by immersing the polypeptide into calcium chloride and sodium hypophosphate solutions respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area diffraction (SAD) were used to examine the hydroxyapatites formed. RESULTS Fluorescent dentine collagen was identified in the demineralized dentine specimens. Nucleation and growth of crystals were detected after immersing the polypeptide into calcium chloride and sodium hypophosphate solutions by SEM and TEM. SAD confirmed the crystals were hydroxyapatites.

CONCLUSIONThe polypeptide of "DSESSEEDRTKREEVD" can simulate DMP-1 binding collagen and initiate hydroxyapatite nucleation and growth. It may be a potential molecular tool for dentine remineralization.