A Multifunctional Antibacterial Peptide With Hydroxyapatite-Binding And Remineralizing Effects

The research aim is to establish a multifunctional short peptide with pH-responsive antibacterial effect to target cariogenic bacteria, with remineralizing effect to repair etched enamel and with hydroxyapatite-binding effect to protect tooth surface from biofilm colonization. A short pH-responsive antibacterial peptide was de-novo designed. The pH-response was determined using bacterial susceptibility assay and spot assay . The pH-responsive mechanisms were observed using transmission electron microscopy (TEM), and membrane potential and membrane permeabilization assays. The selective inhibition was determined using bacterial susceptibility assay with multiple caries-associated bacteria. The hydroxyapatite-binding and antibiofouling effects were explored using confocal laser scanning microscope, scanning electron microscope (SEM), Live/Dead staining and molecular dynamics simulation. The remineralizing effects were tested using turbidimetry of nucleation, TEM and SEM. The peptide possessed acid-activated antibacterial effects by perturbing bacterial membranes, causing increased permeation and destroying bacteria in response to the acidified microenvironment, and showed selective inhibition on cariogenic bacteria. It could bind to hydroxyapatite discs and prevent further biofilm formation, of which the mechanism might be the molecular interactions between the peptide and hydroxyapatite. It could increased the nucleation of calcium-phosphorus product, stabilize the crystal for a period, modulate the morphology and promote remineralization of etched enamel. The peptide integrates pH-responsive and selective antibacterial activity, hydroxyapatite-binding capability, and remineralization regulation property, demonstrating potential microecologyical regulation, in situ anti-caries effects, and biomimetic mineralization effects for caries prevention.