Use of Immobilized GpdQ in Filter Systems

To test whether the immobilized enzyme was still active towards organophos-phates an experimental setup had to be designed, mimicking water filtration conditions. The nanoparticles were embedded between two layers of sand in a Pasteur pipette and were held in place with a conventional magnet. The bottom of the column was connected with a small tube to a flow through UV-Vis cuvette (Fig. 8.23). A buffered solution of the organophosphate substrate BPNPP was circled thought the column and UV-vis cell with a peristaltic pump. The hydrolysis of the substrate was monitored by the formation of the nitrophenolate ion at 405 nm. 

After cycling the BPNPP solution through the column for 3 h, the column was detached from the system and washed with buffer solution and stored at 4 °C. After one week the experiment was repeated. The activity towards BPNPP was shown to be unaffected by the storage. 

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