The Amphoteric Nature of Phospholipid Bilayer Verified by the Surface Energy

Abstract

Background The surface energy the phospholipidic spherical membrane vs. pH, see Fig. 4A helped us to understand amphoteric character of cartilage surface (introduced together first time in literature) [4]. Methods The samples of articular cartilage were taken from the knees of an aged one to two-years-old ox. Friction coefficient (cartilage/cartilage) pair and the interfacial energy of a spherical lipid bilayer curves vs pH have “a bell-shaped curve” expressing amphoteric cartilage nature by the isoelectric point (IEP). Results It was found that the lowest energy values cover working conditions at pH 7.3 (±) 1.0 of natural joints, see Fig.4 A, B. The obtained “a bell-shaped curve” for (cartilage/cartilage) pair friction and spherical PLs bilayer is a novelty in this paper. Conclusions The observations have led to the conclusion that friction coefficient (cartilage/cartilage) pair and surface energy of a spherical lipid bilayer curves vs pH have (IEP) and expressing amphoteric surfaces character. The surface energy corresponds well with friction coefficient phospholipid amphoteric bilayer surface.