A novel synthetic oligopeptide for biomimetic remineralization of dentine

Abstract

Background: Dentine matrix protein 1 (DMP1) binds to collagen fibrils and regulates dentine bio-mineralization. Amelogenin is the principal enamel protein which interacts with calcium ions and initiates hydroxyapatite (HAP) nucleation. Objectives: To fabricate and to describe the properties of a new synthetic oligopeptide which could bind to collagen fibrils and induce nucleation and growth of HAP on dentine surface.

Methods: An oligopeptide which connected the collagen binding domain of DMP1 to the hydrophilic C-terminal of amelogenin was prepared by standard solid-phase peptide synthesis and proceeded in a C-terminal to N-terminal fashion step-by-step using automated synthesizers. Human dentine slices were completely demineralised by hydrochloric acid to expose the dentine collagen. Fluorescein isothiocyanate (FITC) coupled oligopeptide was applied to the exposed dentine collagen. Fluorescent microscopy was used to examine the ability of the oligopeptide to bind to the dentine collagen. Nucleation and growth of HAP crystals was initiated by immersing the oligopeptide in calcium chloride solution followed by sodium hypophosphate solution. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area diffraction (SAD) were used to study the HAP formed. Human dentine slices were acid-etched, coated with the oligopeptide, and then immersed into metastable calcium phosphate solution. Precipitation of HAP on dentine was evaluated by SEM, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).

Results: Fluorescent dentine collagen was identified in the demineralized dentine specimens to validate the ability of the oligopeptide to bind to the dentine collagen. Nucleation and growth of crystals formed were detected under SEM and TEM. SAD confirmed the crystals were HAP. Under SEM, HAP precipitation was observed on oligopeptide coated dentine surface in the presence of metastable calcium phosphate. Results of XRD and FTIR evaluations corroborated the precipitated crystals were HAP.

Conclusions: A novel oligopeptide has been fabricated and it can foster biomimetic mineralization on dentine.

(Supported by NSFC/RGC Grant N_HKU776/10 and #81061160511)