AVS 46th International Symposium
    Biomaterial Interfaces Group Friday Sessions
       Session BI-FrM

Paper BI-FrM2
Plasma Co-polymer Surfaces for the Controlled Adsorption of Common Proteins

Friday, October 29, 1999, 8:40 am, Room 613/614

Session: Interface, Properties, and Modification
Presenter: J.D. Whittle, University of Sheffield, UK
Authors: J.D. Whittle, University of Sheffield, UK
R.D. Short, University of Sheffield, UK
C.W.I. Douglas, University of Sheffield, UK
J. Davies, Johnson and Johnson Orthoclinical Diagnostics, UK
Correspondent: Click to Email
The topic of protein adsorption is of key interest in biomaterials science, since it is generally believed that subsequent surface reactions are guided by the composition of adsorbed proteins. This is especially pertinent in immunodiagnostics, where nonspecific and poorly characterised protein binding may lead to false positives and poor signal-noise ratios. We are interested in controlling the passive adsorption of several common proteins from single solutions through the molecular engineering of surfaces by means of plasma. We utilise continuous wave rf plasma copolymerisation to allow us to synthesise ultra-thin plasma polymer (PP) films of controllable surface chemistry, from various starting 'monomers'. The plasma polymers are analysed by XPS to allow us to estimate the proportion of different functional groups present in the deposited surface. In this experiment we examine surfaces deposited from plasmas of allyl alcohol and acrylic acid. A range of surface functionalities was produced by copolymerising the functional monomer with 1,7-octadiene. Protein adsorption was estimated by an Enzyme Immunoassay (EIA) after exposing the surfaces to single solutions of human albumin, fibrinogen, vitronectin and IgG overnight at a temperature of 37°C and a pH of 7.0. Results show that the amount of protein adsorbed depends not only upon the protein being investigated, but also the characteristics of the polymer surface, with a clear correlation between functional group concentration and the adsorption of fibrinogen, vitronectin and IgG. The adsorption of albumin is not affected by the funtionality of the surface, however this may reflect a limitation in the technique. SPR measurements suggest that even at low concentrations albumin can form a multilayer on these plasma deposited surfaces, which would lead to poor sensitivity of the assay.