Thermodynamic Studies on the Adsorption of Fibronectin Adhesion-Promoting Peptide on Nanothin Films of Poly(2-vinylpyridine) by SPR

Abstract

This paper describes a methodology for preparing uniform, nanothin polymer films for the study of biomolecule adsorption by surface plasmon resonance spectroscopy (SPR). The methodology combines molecular self-assembly of alkanethiols on gold with surface-confined atom transfer radical polymerization (ATRP). Poly(2-vinylpyridine) was chosen to demonstrate the methodology, and growth kinetics were studied by ex situ ellipsometry. Atomic force microscopy (AFM) indicated that the polymer films were uniform with RMS roughness of ∼0.5 nm. Subsequent SPR measurements were done to determine thermodynamic adsorption properties (ΔG, ΔH, and ΔS) between fibronectin adhesion-promoting peptide and the surface-confined poly(2-vinylpyridine) at 15, 20, and 25 °C. The flexibility in synthesis conditions and the opportunities for manipulating film thicknesses and graft densities that ATRP provides to grow polymer films from gold surfaces holds advantages over conventional spin-coating and grafting to approaches in the design of model polymer films for biomolecule adsorption studies. These advantages are described.