Systematic d-Amino Acid Substitutions to Control Peptide and Hydrogel Degradation in Cellular Microenvironments

Enzymaticallydegradable peptides are commonly used as linkerswithin hydrogels for biological applications; however, controllingthe degradation of these engineered peptides with different contextsand cell types can prove challenging. In this work, we systematicallyexamined the substitution of d-amino acids (D-AAs) for different l-amino acids in a peptide sequence commonly utilized in enzymaticallydegradable hydrogels (VPMS down arrow MRGG) to create peptide linkerswith a range of different degradation times, in solution and in hydrogels,and investigated the cytocompatibility of these materials. We foundthat increasing the number of D-AA substitutions increased the resistanceto enzymatic degradation both for free peptide and peptide-linkedhydrogels; yet, this trend also was accompanied by increased cytotoxicityin cell culture. This work demonstrates the utility of D-AA-modifiedpeptide sequences to create tunable biomaterials platforms temperedby considerations of cytotoxicity, where careful selection and optimizationof different peptide designs is needed for specific biological applications.