Graft copolymerization of acrylamide onto a polyethylene surface pretreated with glow discharge

Cell behaviour on polymer surfaces grafted with non-ionic and ionic monomers

Following exposure to corona discharge, a polyethylene film was graft polymerized with different water-soluble monomers such as acrylamide (non-ionic), acrylic acid (anionic), 2-acrylamide-2-methyl propane sulphonic acid (anionic), styrene sulphonic acid sodium salt (anionic) and N,N-dimethylaminopropyl acrylamide (cationic). Attachment and proliferation of HeLa S3 cells were studied for grafted surfaces with different zeta potentials and contact angles. The polyethylene surface graft polymerized with styrene sulphonic acid sodium salt exhibited high cell attachment and protein adsorption, whereas the cells did not adhere to the 2-acrylamide-2-methyl propane sulphonic acid graft-polymerized surface, although both surfaces had high negative zeta potentials. Graft polymerization of acrylamide reduced the zeta potential of surface close to zero and rejected the cell attachment. The polyethylene surface became highly cell-adhesive through graft polymerization of the cationic N,N-dimethylaminopropyl acrylamide monomer, but too much grafting killed the attaching cells. Once the cells attached to a surface without being killed, they could proliferate at the same growth rate, whatever their surface zeta potential.

Low-frictional catheter materials by photo-induced graft polymerization

To develop low-frictional catheters, photo-induced graft polymerization of N,N-dimethylacrylamide (DMAA) was performed on to films and tubes of ethylene-vinyl acetate copolymer (EVA) and poly(vinyl chloride) (PVC). Their surfaces became very slippery, when the materials were preirradiated with UV from a low-pressure mercury lamp, followed by graft polymerization with DMAA in the presence of small amount of riboflavin without degassing. Although no significant difference was observed in surface lubrication between the EVA film and the tube, the latter required an additional procedure for the graft polymerization, that is, removal of air trapped inside the tube. The surfaces of EVA and PVC tubes grafted with DMAA were found to exhibit frictional forces around 0.5 N against a PVC and a silicone surface under wet conditions, whereas the frictional force of the ungrafted tubes against the same substrates was 10 and 20 N for PVC and EVA, respectively.