IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Tuesday Sessions
       Session BI-TuA

Paper BI-TuA7
XPS-Mediated Robust Design Used to Optimize Hyaluronic Acid Surface Immobilization

Tuesday, October 30, 2001, 4:00 pm, Room 102

Session: Non Fouling Surfaces and Theoretical Concepts
Presenter: T.A. Barber, University of California, Berkeley
Authors: T.A. Barber, University of California, Berkeley
R.A. Stile, Northwestern University
D.G. Castner, University of Washington
K.E. Healy, University of California, Berkeley
Correspondent: Click to Email
A major limitation of scaffold-based cartilage tissue engineering approaches is the inability of the delivery scaffolds to adhere to the tissue lining cartilaginous defects. Previously, thermo-responsive P(NIPAAm-co-AAc) hydrogels were engineered to support chondrocyte viability and promote articular cartilage-like tissue formation in vitro. An objective of the current research is to functionalize these hydrogels with bioactive peptides to support specific interactions with components found in cartilaginous extracellular matrix (specifically Hyaluronic Acid (HA)). It is hypothesized that these interactions will significantly enhance scaffold-defect adhesion. A model HA surface was developed to test this hypothesis by quantifying these interactions. A commonly used strategy for HA surface immobilization exploits a carbodiimide reaction between the carboxylic acid groups present in HA, and an aminofunctional surface. However, a wide variety of reaction conditions have been reported, and it is unclear which elements are critical to this HA-grafting approach. Consequently, Robust Design methods were employed to optimize the HA-grafting procedure on aminofunctional glass substrates. First, a 4-factor, 3-level orthogonal array (L@sub9@) was constructed to monitor the effects of HA concentration, coupling buffer (CB), CB pH, and Carbodiimide/N-Hydroxysulfo-succinimide concentration ([EDC/NHS]) on HA-grafting success. XPS C/Si ratios were used to assess factor effects. Deconvolution of the L@sub9@ identified HA concentration, CB, and [EDC/NHS] as the dominant process variables. Subsequently, a 3-factor, 2-level orthogonal array (L@sub4@) was used to further refine the HA-grafting conditions. Evaluation of the L@sub4@ suggested optimal levels for HA concentration (2.5µM), CB (10mM HEPES), and [EDC/NHS] (100mM/25mM). Optimal grafting conditions will be utilized for preparing model surfaces to evaluate the adhesive properties of the functionalized gels using JKR adhesion testing.