A Facile Method to\nQuantify Synthetic Peptide Concentrations\non Biomaterials

While it is well understood that peptides can greatly\nimprove cell–material\ninteractions, it is often challenging to determine the concentration\nof the peptide which decorates a material. Herein, we describe a straightforward\nmethod using readily, synthetically accessible Fmoc peptides and commercially\navailable reagents to measure the concentration of peptides on nanoparticles,\nsurfaces, and hydrogels. To achieve this, the Fmoc protecting group\nfrom immobilized peptides is removed under optimized basic conditions.\nThe dibenzofulvene released can be quantified by HPLC or UV–vis\nspectroscopy, enabling a direct experimental measurement of the concentration\nof the peptide. We show that we can measure the concentration of a\nBMP-2 peptide mimic on a hydrogel to determine the concentration required\nto stimulate osteogenesis of human mesenchymal stem cells. We envision\nthat this methodology will enable a more thorough understanding of\nthe concentration of synthetic peptides decorated on many biomaterials\n(e.g., nanoparticles, surfaces, hydrogels) to improve deconvolution\nof the interactions at the cell–material interface.