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 sc anning electron microscopy (SEM) and atomic force microscopy (AFM), and the results have been compared. Translucent PVA hydrogels with high strength a nd high water content were prepared by freezing the concentrated aqueous PV A solutions below their freezing points, followed by slow crystallization o f 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 surf ace 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 hy drogels are more similar to articular cartilage than translucent PVA hydrog el in terms of surface morphology.