Scanning electron microscopy and atomic force microscopy observations of surface morphology for articular cartilages of dog's knee and poly(vinyl alcohol) hydrogels

Articular cartilages of dog's knee and poly(vinyl alcohol) (PVA) hydrogels prepared by low temperature crystallization have been investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the results have been compared. Translucent PVA hydrogels with high strength and high water content were prepared by freezing the concentrated aqueous PVA solutions below their freezing points, followed by slow crystallization of frozen polymer above their freezing points. The transparent PVA hydrogels with high water content and high strength were prepared by low temperature crystallization of PVA solutions in mixed solvent consisting of water and dimethyl sulfoxide. It was confirmed that the transparent PVA hydrogel surface has porous structure and that the pore size is smaller for more highly concentrated PVA hydrogel. On the other hand, transparent PVA hydrogels had the smooth surface morphology. It is concluded that the transparent PVA hydrogels are more similar to articular cartilage than translucent PVA hydrogel in terms of surface morphology.