IADR Abstract Archives
Antimicrobial Peptide Adsorption on Hydroxyapatite: Role of Surface Hydrophilicity/Charge
Objectives: GL13K is an antimicrobial and amphipathic peptide derived from the human parotid secretory protein. Our previous studies demonstrated that coatings of GL13K on dentin and enamel significantly reduced biofilm growth and thus might prevent infections of resin-based composite restorations. We aimed using quartz crystal microbalance with dissipation monitoring (QCM-D) to discern the role of buffer pH, surface hydrophobicity and charge on the mechanism of adsorption of GL13K on hydroxyapatite (HA). This will assist the design of more robust antimicrobial coatings.
Methods: QCM-D was set up to flow 0.1 mM GL13K solution in varied pH buffers over HA-coated sensors. The mass of GL13K adsorbed on HA was detected as a change in sensor resonant frequency (Fig.1A). Experiments were performed in triplicates in two independent experiments. Buffer solutions without GL13K were used as controls. Au sensors coated with self-assembled monolayers (SAMs) with varying charge and hydrophobicity were also tested. Water contact angles (WCA) of the sensors before and after exposure to test solutions were measured. Nanostructure of adsorbed GL13K coatings was visualized by AFM. ANOVA Tables with Tukey post-hoc test were used to assess statistically significant differences (p<0.05).
Results: A high pH buffer favored GL13K adsorption on HA (Fig.1C) and induced self-assembly of GL13K in supramolecular nanostructures (Fig.1B). These results were supported by WCA analysis as HA-coated surfaces with higher GL13K were more hydrophobic (Fig.1C). Hydrophilicity of the surface was correlated with higher GL13K adsorption, but surface charge did not affect peptide adsorption (Fig.1D).
Conclusions: The hydrophilicity of HA and the supramolecular self-assembly of GL13K in high pH buffer solutions induced high peptide adsorption. Higher number of peptides is expected to increase potency and durability of the antimicrobial coatings to protect dental tissues and restorations.
Methods: QCM-D was set up to flow 0.1 mM GL13K solution in varied pH buffers over HA-coated sensors. The mass of GL13K adsorbed on HA was detected as a change in sensor resonant frequency (Fig.1A). Experiments were performed in triplicates in two independent experiments. Buffer solutions without GL13K were used as controls. Au sensors coated with self-assembled monolayers (SAMs) with varying charge and hydrophobicity were also tested. Water contact angles (WCA) of the sensors before and after exposure to test solutions were measured. Nanostructure of adsorbed GL13K coatings was visualized by AFM. ANOVA Tables with Tukey post-hoc test were used to assess statistically significant differences (p<0.05).
Results: A high pH buffer favored GL13K adsorption on HA (Fig.1C) and induced self-assembly of GL13K in supramolecular nanostructures (Fig.1B). These results were supported by WCA analysis as HA-coated surfaces with higher GL13K were more hydrophobic (Fig.1C). Hydrophilicity of the surface was correlated with higher GL13K adsorption, but surface charge did not affect peptide adsorption (Fig.1D).
Conclusions: The hydrophilicity of HA and the supramolecular self-assembly of GL13K in high pH buffer solutions induced high peptide adsorption. Higher number of peptides is expected to increase potency and durability of the antimicrobial coatings to protect dental tissues and restorations.
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