Orientation selective immobilization of human erythrocyte membranes on ultrathin cellulose films

We report the orientation selective immobilization of human erythrocyte mem branes on planar solid supports. The orientation of the immobilized membran e was identified with selective fluorescence labels. When the right-side-ou t (RSO) ghosts were incubated with planar glass cover slides, no adsorption or rupture of erythrocytes could be observed. To increase the interfacial attraction between cells and the surface, two types of hydrated polymer fil ms were deposited on the glass cover slides; (a) physisorbed films of catio nic polylysine, and (b) Langmuir-Blodgett (LB) films of cellulose derivativ es. On polylysine films, patches of the ruptured membranes could be observe d, but the surface coverage still remained poor. On the other hand, RSO gho sts were likely to coat the surface of cellulose films more continuously. T he fluorescence labeling demonstrated that immobilized erythrocyte membrane s selectively inverted their native orientation. Tentatively, we interprete d this larger surface coverage on the cellulose film in terms of the "wetti ng affinity" between the cell surface glycocalix and the polysaccharides. S uch ultrathin (thickness 5-10 nm), biological polysaccharide films have a l arge potential to immobilize native cell membranes without denaturing their structure, membrane orientation, and functions.