Structure and properties of surface adsorbed biopolymer layers – Soluble collagen adsorbed to glass

Abstract

Two methods are applied to determine the thickness of an adsorbed soluble collagen layer on glass. One involves time of flow measurements in a glass capillary. Effects due to changes in contact angle and drainage, as the meniscus advances down the instrument, are eliminated. The results are compared with a direct force/distance curve determination for soluble collagen adsorbed to mica. At low pH layer thicknesses in excess of 325 nm are found, indicating that the collagen triple helices are standing end up on the surface. The amount of collagen adsorbed is only about 1 mg/m² It can, therefore, be calculated that some 12 nm separate the soluble collagen monomers. The surface layer is very diffuse. Raising the pH reduces layer thickness. Surface heat denaturation gives 70 nm thick layers.