Abstract
The interest in developing functional biomaterials based on designed peptides has been increasing in recent years. The amphiphilic and anionic β-sheet peptide Pro-Asp-(Phe-Asp)5-Pro, denoted FD, was previously shown to assemble into a hydrogel that induces adsorption of calcium and phosphate ions and formation of the bone mineral hydroxyapatite. In this study the integrin binding peptide, Arg-Gly-Asp (RGD), was incorporated into the hydrogel to assess its influence on an osteoblast culture. In solutions and in hydrogels FD fibrils dominated the assembly structures for up to 25 mol% FD-RGD incorporation. The cellular density of osteoblasts cultured in hydrogels composed of 25 mol% FD-RGD in FD was higher than that of only FD hydrogel cultures. These results demonstrate that RGD and possibly other cell binding motifs can be combined into amphiphilic and anionic β-sheet hydrogels, using the design principles of FD and FD-RGD systems, to enhance interactions with cells.
Highlights
In recent years there has been an increasing interest in developing functional biomaterials, based on designed b-sheet peptides.[1,2,3,4,5,6,7] In aqueous solutions, amphiphilic peptides with sequences of alternating hydrophobic and hydrophilic amino acids tend to assemble into brils composed of b-sheet bilayers
These structures are stabilized by both layers' hydrophilic side chains pointing to the aqueous phase, and hydrophobic side chains zipping the interior of the layers, shielded from the solution (Fig. 1A)
In order to assess the effect of FD-RGD content on the tendency of the mixed peptide system to form b-sheet structures, we plotted the circular dichroism (CD) absorption minima at 218 nm as function of FD-RGD mol% fraction (Fig. 2C)
Summary
In recent years there has been an increasing interest in developing functional biomaterials, based on designed b-sheet peptides.[1,2,3,4,5,6,7] In aqueous solutions, amphiphilic peptides with sequences of alternating hydrophobic and hydrophilic amino acids tend to assemble into brils composed of b-sheet bilayers. Peptide hydrogels were prepared by adding weighed powder of FD or FD and FD-RGD, followed by dissolution in an 80% v/v of the total nal solvent (either water, cell culture medium or NaOH 0.1 mM) followed by sonication for 10 min (Elmasonic S10, Elma, Singen, Germany). One hundred ml of FD and 25 mol% FD-RGD hydrogels were prepared for the cell culture experiment with medium (80% v/v) and supplemented with 0.1 M CaCl2 (20% v/v) to reach a nal concentration of 20 mM. FD (100 ml, 21 mM) and 25 mol% FD-RGD (21 mM FD and 7 mM FD-RGD) were prepared with medium (80% v/v) for the 3D cell culture experiment These were transferred to a 6 well confocal plate, inside the glass area, and 0.1 M CaCl2 (20% v/v) was added. Live cell volume was calculated by Imaris 8.0.1 program
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