The adsorption of preferential binding peptides to apatite-based materials

The objective of this work was to identify peptide sequences with high affinity to bone-like mineral (BLM) to provide alternative design methods for functional bone regeneration peptides. Adsorption of preferential binding peptide sequences on four apatite-based substrates [BLM and three sintered apatite disks pressed from powders containing 0% CO(3)(2-) (HA), 5.6% CO(3)(2-) (CA5), 10.5% CO(3)(2-) (CA10)] with varied compositions and morphologies was investigated. A combination of phage display, ELISA, and computational modeling was used to elucidate three 12-mer peptide sequences APWHLSSQYSRT (A), STLPIPHEFSRE (S), and VTKHLNQISQSY (V), from 243 candidates with preferential adsorption on BLM and HA. Overall, peptides S and V have a significantly higher adsorption to the apatite-based materials in comparison to peptide A (for S vs. A, BLM p=0.001, CA5 p<0.001, CA10 p<0.001, HA p=0.038; for V vs. A, BLM p=0.006, CA5 p=0.033, CA10 p=0.029). FT-IR analysis displayed carbonate levels in CA5 and CA10 dropped to approximately 1.1-2.2% after sintering, whereas SEM imaging displayed CA5 and CA10 possess distinct morphologies. Adsorption results normalized to surface area indicate that small changes in carbonate percentage at a similar morphological scale did not provide enough carbonate incorporation to show statistical differences in peptide adsorption. Because the identified peptides (S and V) have preferential binding to apatite, their use can now be investigated in bone and dentin tissue engineering, tendon and ligament repair, and enamel formation.