The designing of supramolecular indicator system ‘cellulose - nanodiamond - urease’

A supramolecular indicator system (cellulose - nanodiamond - urease) for biochemical determination of urea was constructed by layer-by-layer immobilization of the com- ponents. Modified nanodiamonds (MND) were covalently immobilized on polymeric carrier (DEAE-cellulose granules) using nucleophilic addition reaction. It was established that during the reaction carried out at a weight ratio of components 4:1 (DEAE-cellulose : MND) up to 110 µg of the nanoparticles can be immobilized on 1 mg of the polymer. Biomarker (ure- ase) was covalently immobilized on the surface of polymer- MND composite previously activated by benzoquinone. In comparative experiments the enzyme was immobilized on initial polymeric granules using nonspecific adsorption and covalent immobilization. The enzyme activity in obtained supramolecular complexes was assessed spectrophotometrically in the size of optical density of formed colored reaction product using urease salicylate-hypochlorite method. It was shown that urease molecules can be immobi- lized on DEAE-cellulose granules by adsorption and covalent immobilization, exhibiting their functional activity in both cas- es...