Immobilization of enzymes on polypropylene bead surfaces by anhydrous ammonia gaseous plasma technique

Introduction of functional groups onto polypropylene and polyethylene surfaces for immobilization of enzymes

Polypropylene and polyethylene surfaces are activated by introducing an active functional group through 1-fluoro-2 nitro-4-azidobenzene by UV irradiation. Horseradish peroxidase and glucose oxidase are immobilized onto the activated surfaces, simply by incubating the enzymes at 37 degrees C. When untreated surfaces are used, insignificant immobilization of the enzymes is observed.

Amination of polycarbonate surface and its application for cell attachment

The polycarbonate sheet was modified with ammonia gaseous plasma and characterized by the contact angle measurement and ESCA analysis. The contact angles decreased significantly from 77 degrees to about 20 degrees-40 degrees, indicate that the polycarbonate sheet become more hydrophilic after plasma treatment. The ESCA analysis results showed that the hydrophilicity was mainly derived from the amino groups on the modified surface. In this study, a flow-chamber system was also constructed to evaluate the 3T3 fibroblast cells attachment phenomena on these modified sheets. Before the experimental run, the parameters of inoculated cell number and cell passage were examined previously. The results revealed that these two parameters are independent in shear experiment. And besides, 3-hours plating time has the better adhering fraction. The experimental results showed that the 3T3 fibroblast cells adhesion strength increased significantly on the plasma modified sheet.

Spacer effects on enzymatic activity of papain immobilized onto porous chitosan beads

Papain was covalently immobilized onto the surface of porous chitosan beads without or with spacers of different lengths. The relative activity of the immobilized papain was found to be high toward a small ester substrate, N-benzyl-L-arginine ethyl ester (BAEE), but rather low toward casein, a high molecular weight substrate. Papain immobilized with spacer gave an almost constant activity, in marked contrast with the immobilized papain without spacer, whose activity monotonously decreased with decreasing surface concentration. The relative activity of the immobilized papain for hydrolysis of a high molecular weight substrate greatly depended on the length of the spacer. The pH, thermal and storage stabilities of the immobilized papain were higher than those of the free one, and ths papain immobilized directly to the chitosan beads' surface without any spacer gave a higher stability than those immobilized with spacer. The spacer's effect on the activity could be explained in terms of mobility of the immobilized papain molecule.

The enhanced attachment and growth of endothelial cells on anhydrous ammonia gaseous plasma modified surfaces of polystyrene and poly(tetrafluoroethylene)

Anhydrous ammonia gaseous plasma technique was used for the surface modification of polystyrene petri dishes and poly(tetrafluoroethylene) (PTFE) membranes. Amino groups were added onto surfaces by exposing them to ammonia plasma. Plasma modified polymeric surfaces and control polymeric surfaces were seeded with bovine pulmonary artery endothelial cells (EC). It was found that attachment of EC to control polystyrene surface was negligible. On the plasma modified polystyrene surface, there was improved attachment and growth of EC. At 96 hours, plasma modified surfaces yielded an order of 3 magnitudes more cells compared to those on control. Twenty four hours after seeding the cells, the percentage of EC attachment to control PTFE surfaces and modified surfaces were found to be about 36% and 92% respectively.

Towards an artificial cornea: surface modifications of optically clear, oxygen permeable soft contact lens materials by ammonia plasma modification technique for the enhanced attachment and growth of corneal epithelial cells

The advent of high water content, oxygen permeable contact lens materials has made the intracorneal implants more feasible. A major obstacle encountered is the regrowth of a stable epithelium over the implant. Therefore, ammonia gaseous plasma modification technique was used to modify the surface chemical properties of soft contact lens material such as poly(2-hydroxyethyl methacrylate and methacrylic acid), PHEMA-MAA copolymer, in an attempt to enhance the cell attachment and growth of rabbit corneal epithelial cells.