title: Incorporation of a matrix metalloproteinase-sensitive substrate into self-assembling peptides - a model for biofunctional scaffolds.
abstract: Controlling and guiding cell behavior requires scaffolding materials capable of programming the three-dimensional (3-D) extracellular environment. In this study, we devised a new self-assembling peptide template for synthesizing nanofibrous hydrogels containing cell-responsive ligands. In particular, the insertion of a matrix metalloproteinase-2 (MMP-2) labile hexapeptide into the self-assembling building blocks of arginine-alanine-aspartate-alanine (RADA) was investigated. A series of peptides, varied by the position of the MMP-2 hexapeptide substrate and the length of RADA blocks, were prepared by parallel synthesis. Their self-assembling capabilities were characterized and compared by circular dichroism spectroscopy and dynamical mechanical analysis. Among all the different insertion patterns, the sequence comprising a centrically positioned MMP-2 substrate was flanked with three RADA units on each side self-assembled into a hydrogel matrix, with mechanical properties and nanofiber morphology comparable to the native material built with (RADA)(4) alone. Exposure of the new gel to MMP-2 resulted in peptide cleavage, as confirmed by mass spectroscopy, and a decrease in surface hardness, as detected by nanoindentor, indicating that the enzyme mediated degradation was localized to the gel surface. The new design can be used for introducing biological functions into self-assembling peptides to create scaffolding materials with potential applications in areas such as tissue engineering and regenerative medicine.
authors.affiliation: Department of Chemical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chau
authors.forename: Ying
authors.initials: Y
authors.lastname: Luo
authors.forename: Alex C Y
authors.initials: AC
authors.lastname: Cheung
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nagai
authors.forename: Shuguang
authors.initials: S
authors.lastname: Zhang
authors.forename: James B
authors.initials: JB
authors.lastname: Kobler
authors.forename: Steven M
authors.initials: SM
authors.lastname: Zeitels
authors.forename: Robert
authors.initials: R
authors.lastname: Langer
mesh_terms: D002942:Circular Dichroism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013379:Substrate Specificity; D054457:Tissue Scaffolds
chemical_list: D010455:Peptides; D020778:Matrix Metalloproteinase 2