Our goal is development of a new class of synthetic biomaterials based on self-assembly of oligopeptides in aqueous environments. Our central hypothesis is that we can alter key macroscopic properties of these materials by designed changes in amino acid sequence, peptide length and concentration, and degree of crosslinking. We will test this hypothesis by the following Specific Aims. A. Synthesis and structural characterization -- Two series of peptides will be synthesized in order to test whether: (a) mechanical strength of these materials can be increased by progressively greater cross-linking via cysteine thiol groups; (b) cell adhesiveness to these materials is affected by the charge distribution on the peptides. Structural characteristics of the fabricated matrices, including fiber diameter, length, elasticity, and volume fraction, will be determined using quantitative image analysis of scanning electron microphotographs. B. Physical properties These studies will test whether matrix physical properties can be controlled by four design parameters: peptide concentration and length, amino acid sequence, and extent of cross-linking; we will determine: (a) elastic properties using cylinders of self-assembled matrix materials while individually varying each of the design parameters; (b) macromolecular permeability using diffusion of fluorescently - or radioactively -labeled tracers; (c) degradation rates in proteolytic environments to estimate time-scales for reabsorption; (d) scaling laws for elasticity and permeability to aid in interpretation and generalization of the experimental results from (a) -(c). C. Cell interaction Adhesiveness of the Hs68 human fibroblast cell line will be studied on Series #2 materials in order to test the hypothesis that cell interaction with these materials is mediated by """"""""non-specific"""""""" charge-based mechanisms rather than common integrin-based receptor/ligand binding mechanisms. (a) Solution competitor peptides containing different known integrin-binding motifs (RGD, IQAGDV, LDV/IDS, RLD/KRLGS, YYGDLR/FYFDLR) will be employed to test whether any of these motifs are involved in the interactions from the material side. (b) Monoclonal antibodies directed against integrins relevant to tissue fibroblasts (a5 b1 a1 a2b1) will be employed to test whether the interactions are receptor -specific.
| Caplan, Michael R; Schwartzfarb, Elissa M; Zhang, Shuguang et al. (2002) Effects of systematic variation of amino acid sequence on the mechanical properties of a self-assembling, oligopeptide biomaterial. J Biomater Sci Polym Ed 13:225-36 |
| Caplan, Michael R; Schwartzfarb, Elissa M; Zhang, Shuguang et al. (2002) Control of self-assembling oligopeptide matrix formation through systematic variation of amino acid sequence. Biomaterials 23:219-27 |
| Caplan, M R; Moore, P N; Zhang, S et al. (2000) Self-assembly of a beta-sheet protein governed by relief of electrostatic repulsion relative to van der Waals attraction. Biomacromolecules 1:627-31 |
