Studies On Synthetic Peptides Regulated Hydroxyapatite Mineralization And The Application In Dentin Hypersensitivity Treatment

This study is about synthetic peptide’s mediation on hydroxyapatiteformation in vitro and application in treatment for dentin hypersensitivity. Apeptide DSS9with sequence (CDSSDSSDSSG) was designed and synthesizedbased on the sequence of the dentin phosphoprotein, one of the majornoncollagenous protein involved in the mineralization of the dentin extracellularmatrix during tooth development. This peptide consists of triple repeats of thetripeptide aspartate-serine-serine (DSS) which showed hydroxyaptite (HAp)binding and the sulphydryl(—HS) in cysteine which showed a specific affinityfor Au. Hence a functionalized surface onto Au(111) substrate was prepared byself-assembled monolayer/oligopeptide DSS9(DSS9-SAM) to induce thenucleation of hydroxyapatite in1.5simulated body fluid (1.5SBF) at37℃.Compared with other three kinds of functionalized surface prepared byself-assembled monolayers(SAMs) of thioalcohol terminated withcarboxyl(COOH-SAM), amino(NH2-SAM) and hydroxyl(OH-SAM),DSS9-SAM promoted the nucleation rate of hydroxyapatite significantly and alarger amount of HAp minerals with preferential orientation of (300) planeswere found on the DSS9-SAM surface after two-week biominralization. It wasconcluded that our DSS9-SAM could promote biomineralization ofhydroxyapatite due to its highly negative charged groups and less distributiondensity on the substrate.Furthermore, a novel biomimetic dental tubule occlusive biomaterial basedupon a collagen/calcium dual-affinitive peptide E8DS(EEEEEEEEDSpESpSpEEDR) and nano-hydroxyapatite (nano-HAp) flocculi hasbeen developed for treatment of dentin hypersensitivity in this study. PeptideE8DS was inspired by the functional domains of bone sialoprotein (BSP) anddentin matrix protein1(DMP1), which has strong affinities with collagen andhydroxyapatite by two binding motifs. It was found that almost half of initialE8DS peptides immobilized on exposed dentin samples remained detained aftercontinuous washing by distilled water for4weeks at a rate of1ml/min.Application of nano-hydroxyapatite in dentin restoration pre-treated by E8DSpeptide gives perfect occlusion of exposed dentinal tubules and a better performance in the longevity test of occlusive deposits against stirring PBS(phosphate buffered saline). It was concluded that our deliberately designedpeptide E8DS have the potential to be applied in the dentin hypersensitivitytreatment by improving the adhesion of hydroxyapatite on dentin collagenmatrix.