Characterization and development of RGD-peptide-modified poly(lactic acid-co-lysine) as an interactive, resorbable biomaterial

• Published in: Journal of biomedical materials research 1997-06, Vol.35 (4), p.513-523
• Main Authors: Cook, Alonzo D., Hrkach, Jeffrey S., Gao, Nicholas N., Johnson, Ivette M., Pajvani, Utpal B., Cannizzaro, Scott M., Langer, Robert
• Format: Article
• Language: English
• Subjects: Animals; Biocompatible Materials - chemistry; Calorimetry, Differential Scanning; Cattle; Cell Adhesion; Cell Movement; Cells, Cultured; Colorimetry; Endothelium, Vascular - cytology; Hot Temperature; Microscopy, Electron, Scanning; Oligopeptides - chemistry; Polylysine - chemistry; Polymers - chemistry; Spectrometry, X-Ray Emission
• ISSN: 0021-9304; 1097-4636
• DOI: 10.1002/(SICI)1097-4636(19970615)35:4<513::AID-JBM11>3.0.CO;2-C

The design of biomaterials containing specific ligands on the surface offers the possibility of creating materials that can interact with and potentially control mammalian cell behavior. Biodegradable materials further provide the significant advantage that the polymer will disappear in vivo, obviating long‐term negative tissue responses as well as the need for retrieval. In earlier studies we synthesized and characterized arginine—glycine—aspartic acid (RGD) peptide‐modified poly(lactic acid‐co‐lysine) (PLAL). In this study, both bulk properties and surface features have been characterized, with a focus on surface analysis as a means of interpreting observed changes in cell behavior. Bulk peptide attachments were performed using 1,1′‐carbonyldiimidazole (CDI). Amino groups were measured using colorimetric assays and X‐ray photoelectron spectroscopy (XPS). Peptides were measured by incorporating iodine into the peptide as a distinct elemental marker for use with XPS. Typical samples contained 13 ± 4 pmol/cm2 of amino groups and 4 ± 0.2 pmol/cm2 of peptides, as calculated from XPS measurements of nitrogen and iodine. The wettability and crystallinity of the samples were determined by contact angles and differential scanning calorimetry, respectively. Wettability and crystallinity were not altered by the incorporation of lysine or peptides. After incubating bovine aortic endothelial (BAE) cells for 4 h on surfaces with RGD‐containing peptides, the mean spread cell area increased from 77 ± 2 μm2 to 405 ± 29 μm2 compared to 116 ± 11 μm2 on poly(lactic acid), 87 ± 4 μm2 on PLAL, and 105 ± 4 μm2 on surfaces with RDG‐containing (control) peptides. The significance of this work is that the first synthetic interactive, resorbable biomaterial has been developed, and use of this material to control cell behavior has been demonstrated. © 1997 John Wiley & Sons, Inc.