Posokhina E, Ronzhin N, Mogilnaya O, Baron A, Bondar V (2019) A Supramolecular Indicator System for Detecting Urea Based on the Cellulose-Nanodiamond Composite Material and Urease. Int J Med Nano Res 6:029.


© 2019 Posokhina E, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

RESEARCH ARTICLE | OPEN ACCESS DOI: 10.23937/2378-3664.1410029

A Supramolecular Indicator System for Detecting Urea Based on the Cellulose-Nanodiamond Composite Material and Urease

Ekaterina Posokhina1,2, Nikita Ronzhin1*, Olga Mogilnaya1, Alexey Baron1,2 and Vladimir Bondar1

1Institute of Biophysics, Federal Research Center "Krasnoyarsk Science Center, Siberian Branch of the Russian Academy of Sciences, Russia

2Siberian Federal University, Russia


A supramolecular indicator system (cellulose-nanodiamonds-urease) for reusable biochemical detection of urea has been fabricated using sequential immobilization of the components. Modified nanodiamonds (MNDs) were covalently immobilized onto DEAE cellulose granules via the nucleophilic addition reaction. At DEAE cellulose: MND ratio of 4:1 (w/w), up to 110 µg of nanoparticles bound onto 1 mg of the polymer during the addition reaction. Urease was immobilized by covalent conjugation onto the polymer-MND composite with the benzoquinone-activated surface. In comparative experiments, the enzyme was immobilized onto initial polymer granules via nonspecific adsorption and covalent conjugation. However, when these indicator systems were repeatedly used to detect the analyte, the enzyme was considerably inactivated, and that was evidenced by a decrease in the colored product yield. At the same time, the enzyme covalently bound onto the DEAE cellulose-MND composite showed higher functional efficacy and enabled more stable yields of the colored product in repeated urea assays. Comparative experiments with the indicator systems repeatedly used to detect urea at 37 ºC demonstrated that the enzyme covalently conjugated onto the DEAE cellulose-MND composite showed greater thermo stability, and its activity was reduced at a much slower rate than the activity of the enzyme covalently bound to the polymer. The data obtained in the present study offer the prospect of designing a new type of reusable indicator assay systems (polymer carrier-nanodiamond-biomarker supramolecular systems) for biomedical analytical applications.