Chemoselective Peptide Functionalization of starPEG-GAG Hydrogels

Abstract

Glycosaminoglycan (GAG)-based hydrogels gain increasing interest in regenerative therapies. To support specific applications, the biomolecular functionality of gel matrices needs to be customized via conjugation of peptide sequences that mediate cell adhesion, expansion and differentiation. Herein, we present an orthogonal strategy for the formation and chemoselective functionalization of starPEG-GAG hydrogels, utilizing the uniform and specific conjugation of peptides and GAGs for customizing the resulting materials. The introduced approach was applied for the incorporation of three different types of RGD peptides to analyze the influence of peptide sequence and conformation on adhesion and morphogenesis of endothelial cells (ECs) grown on the peptide-containing starPEG-GAG hydrogels. The strongest cellular response was observed for hydrogels functionalized with cycloRGD followed by linear forms of RGDSP and RGD, showing that morphogenesis and growth rate of ECs is controlled by both type and quantity of the conjugated peptides.

Glycosaminoglycan‐Based Biohybrid Hydrogels: A Sweet and Smart Choice for Multifunctional Biomaterials

“…Accordingly, a fraction of the carboxylic acid groups of the HEP building block were pre-functionalized with maleimide groups to allow the chemoselective coupling of peptides containing cysteine as a bioinert linker group together with adhesion sequences. [22] This concept allows the subsequent oriented coupling of lysine-containing sequences and was, for example, used to orthogonally couple different RGD peptides (cycloRGDYC, GCWGGRGDSP, and GRGDGWGCG) in a Michael-type addition reaction with the maleimide and the SH group of the peptide's cysteine. It was shown that endothelial cell adhesion (cell density after 7 days) was enhanced in the order cycloRGD > looped RGDSP > linear RGD, which is consistent with earlier findings on the activity of structurally different RGD peptides.…”

Chemical Derivatization of Sulfated Glycosaminoglycans

“…The maleimido appendages exposed by the resulting hydrogel network were then exploited to attach oligopeptides containing the RGD sequence (useful for cell adhesion) and a cysteine residue, by taking advantage of a Michael addition of the peptide thiol group. The specific nature of the attached RGD‐containing peptide was found to be critical in tuning the extents of adhesion of endothelial cells . Hydrogel structures obtained by EDC‐mediated condensation of heparin structures and aminated star‐shaped PEG were also investigated for their ability to release FGF2.…”

Responsive hybrid (poly)peptide–polymer conjugates

“…Their results indicated that at a 1 mol peptide/mol heparin, cyclo-RGDYC was the most effective system, yielding confluent cell layer, compared to lower concentrations of RGD, or the non-cyclical peptides. 144 UV-initiated thiol-ene chemistry has been used for conjugation of an RGD peptide to a linear poly(allyl glycidyl ether) (PAGE) for platelet adhesion. An N-terminal cysteine was added to the RGD sequence, which was subsequently reacted with PAGE, although the peptide conjugation to PAGE was reportedly low.…”