Bonding erythrocytes to plastic substrates by glow-discharge activation

A procedure was developed for attaching erythrocytes to various plastics. Plastic disks were exposed to ammonia glow discharge (AGD) and found thereafter to form weak bonds with red cells settling from a dilute saline suspension poured over the disks. When the disks were used to produce a rotating shear flow, complete cell detachment was observed for stresses exceeding 34 dynes/cm2. Far stronger bonding was achieved by treating AGD-bonded cells with glutaraldehyde, and subsequent shearing failed to detach any cells (maximum stress 58 dynes/cm2). The proposed chemical mechanism involves attachment of -NH2 groups on the plastic during AGD, and formation also of carbonyl oxygen later, to provide sites for hydrogen bonding with the cell membrane. Subsequent glutaraldehyde exposure produces crosslinking between disk and cell, as well as fixing the cell in the normal way. Thus, the initial step succeeds in attaching erythrocytes in a deformable condition but rather weakly, while the second step produces rigid cells which are also bonded more strongly.