Printed carbon based interface for protein immobilization

The aim of the investigations was to find a method of protein immobilisation in screen printed graphite layers. Three commonly used graphite powders were used to prepare conductive layers via screen printing. Several printing pastes with different carbon to polymer resin (polymethylmethacrylate) ratios were tested and the composition with the best electrical properties was selected for further investigations related to green fluorescent protein immobilisation. Six different procedures of protein immobilisation were examined including physical adsorption, electrochemical generation of carboxylic groups and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide activation, graphite functionalisation with succinic anhydride and graphite functionalisation with 3-(triethoxysilyl)propylsuccinic anhydride. Some of the functionalisation procedures were done before printing (functionalisation of graphite powders) and the others were done on printed and cured coatings. Printed graphite layers with immobilised green fluorescent proteins were studied with confocal fluorescent microscopy to assess the efficiency of the immobilisation procedures. The best results were observed for graphite functionalisation with succinic anhydride and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide activation of carboxylic groups.