The effects and mechanisms underlying collagen-binding peptides MDPs on dentin remineralization: an in vitro study

Currently, many biomimetic mineralization materials fail to bind effectively to collagen, which significantly limits their remineralization efficacy. To address this limitation, we designed MMP2-derived peptides (MDPs) on the basis of the strong affinity domain of collagen: MDP-a and MDP-3DSS. Surface plasmon resonance (SPR) was used to measure the binding force of MDPs to collagen. Inductively coupled plasma-mass spectrometer (ICP-MS) was used to evaluate the effects of peptides on the adsorption of calcium ions by collagen. Transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were employed to analyze the stabilizing effect of MDPs on amorphous calcium phosphate (ACP) and the mineralization effect on collagen. Scanning electron microscopy (SEM), mechanical tests, and the CCK-8 assay were employed to evaluate the remineralization effect of MDPs on demineralized dentin and their biocompatibility. The results of the present study demonstrated that MDPs strongly bind to collagen (18 µM for MDP-a and 18.9 µM for MDP-3DSS) and can promote calcium ion adsorption by collagen (p < 0.0001). Furthermore, MDPs have been shown to stabilize ACP and induce intrafibrillar mineralization. In vitro studies revealed that both surface and cross-sectional dentin slices treated with MDPs presented dense mineral deposition. This deposition effectively occluded the dentinal tubules and resulted in enhanced mechanical properties. The tubule plugging rate, the elastic modulus and microhardness of the MDPs group were greater than those of the control group (p < 0.01). Moreover, MDP-3DSS demonstrated the most significant remineralization potential. Additionally, MDPs treatment did not affect the activity of human dental pulp stem cells (hDPSCs) (p > 0.05). The present study successfully developed and evaluated two novel biomimetic mineralized peptides, MDP-a and MDP-3DSS. It is necessary to conduct further research to explore the possibility of clinical transformation of MDPs.