Bioactive Surface Gradients to Investigate Cell-Substrate Interactions
Nathan D. Gallant, Matthew L. Becker, Eric J. Amis
Biomaterials Group, Polymers Division, MSEL, NIST
Immobilizing specific biomolecules onto substrates in a controlled orientation and concentration offers a robust strategy for investigating ligand dependent cell function. We have designed a versatile process to produce density gradients of surface-bound species that elicit specific responses through well-characterized receptor-ligand interactions. For instance, the Arg-Gly-Asp (RGD) tripeptide sequence is found in a variety of extracellular matrix (ECM) proteins and is recognized by a number of integrins. Increasing concentrations of this adhesive peptide may alter cell functions such as proliferation or matrix production, and optimal surface presentation may improve tissue formation in tissue engineering applications. This approach will be used to quantify cell function dependence on peptide concentration and mixed ligand ratios, how the tether orientation effects signaling, and the utility of gradient methodologies to rapidly screen and optimize biomaterial surface properties.
We quantified the number of adherent cells as well as cell spreading with increasing RGD peptide density on 40 mm gradients. The number of adherent cells remains at background levels before increasing upon reaching a threshold, while the projected cell area increases before reaching saturation. Images of cells stained for vinculin containing focal adhesions taken at intervals along the gradient also indicate possible surface dependent changes in cell shape and migratory behavior. Peptide functionalized gradient substrates have shown the ability to control cell adhesion and therefore provide a tool for screening surface directed cell function. Furthermore, this work extends the NIST combinatorial approach to materials characterization to an investigation of cell-material interactions.
Name: Nathan D. Gallant
Mentor: Eric J. Amis
Division: Polymers Division (854)
Laboratory: Materials Science and Engineering Laboratory (MSEL)
Location: Room A109, Bldg 224, MS 8543
Phone: (301) 975-4370
Fax: (301) 975-4977
Sigma Xi: Not a member