title: Synthesis and in vitro hydroxyapatite binding of peptides conjugated to calcium-binding moieties.
abstract: To confer bone-binding properties to proteins and other biological agents that lack specific targeting capacity, model peptide-based molecules were synthesized containing poly(aspartic acid), poly(glutamic acid), or a bisphosphonate (pamidronate). These motifs have well-documented affinities to hydroxyapatite, a property desirable for the targeting of molecules to bone for drug delivery and tissue engineering applications. Model peptides of increasing molecular mass (5-33 amino acids) were directly conjugated to eight aspartic acids (Asp8), eight glutamic acids (Glu8), or pamidronate, purified by high-performance liquid chromatography, and characterized by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy. The modified peptides were incubated with hydroxyapatite in phosphate-buffered saline at physiological conditions over 24 h. This study revealed a significant amount (>90%) of conjugated peptides adsorbed to the hydroxyapatite as compared to unmodified peptides (<5%). It was found that while there were significant differences between the different hydroxyapatite-binding and control groups for all time points, the size of the peptide had no statistical effect on peptide-hydroxyapatite binding. These results demonstrate that bisphosphonate and oligopeptide conjugates hold great promise for the development of new bioactive molecules for bone-specific applications.
authors.affiliation: Department of Bioengineering, Rice University, Houston, TX 77251-1892, USA.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Murphy
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Hartgerink
authors.forename: Achim
authors.initials: A
authors.lastname: Goepferich
authors.forename: Antonios G
authors.initials: AG
authors.lastname: Mikos
mesh_terms: D002118:Calcium / Q000737:chemistry*; D004164:Diphosphonates / Q000737:chemistry; D017886:Durapatite / Q000138:chemical synthesis* / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D023822:Tissue Engineering
chemical_list: D004164:Diphosphonates; D010455:Peptides; D017886:Durapatite; D002118:Calcium