KRSR and RGD Adsorption on TiO₂ and Influence of Ion Concentration: A Molecular Dynamics Study

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Computational Biology

Background:

• Bioactive peptide coatings on titanium dioxide (TiO2) surfaces are crucial for modulating cell-implant interactions.
• Current molecular studies often overlook physiological electrolyte concentrations, limiting the design of effective peptide-functionalized implants.

Purpose of the Study:

• To investigate the impact of varying ionic strength on the adsorption behavior of bioactive peptides (KRSR and RGD) on amorphous TiO2 surfaces.
• To understand how electrolyte concentrations influence peptide-surface interactions at a molecular level.

Main Methods:

• Classical molecular dynamics simulations of an amorphous TiO2 surface in explicit water.
• Simulations performed across nine different NaCl concentrations.
• Analysis of peptide backbone root-mean-square deviation (RMSD), minimum peptide-surface distance, and adsorption time ratio.

Main Results:

• Peptide backbone RMSD remained stable and showed no significant correlation with NaCl concentration for both peptides.
• KRSR peptide exhibited increased minimum distance and decreased adsorption time ratio with higher NaCl concentrations, indicating weaker surface interaction.
• RGD peptide showed no significant dependence on ionic strength within the tested range.

Conclusions:

• KRSR peptide adsorption on TiO2 is more sensitive to ionic strength than RGD, attributed to KRSR's stronger net positive charge and electrostatic interactions.
• These findings are critical for designing titanium implants with optimized peptide coatings for physiological environments.