earticle

영어

Carbon dots (CDs) are widely employed as peroxidase mimics in biosensing. However, as colloidal nanozymes, CDs suffer from the drawbacks of substrate induced aggregation and difficulties in recovery and reuse. Nanocellulose is proposed as a support material to overcome these drawbacks and two immobilization strategies were explored here. In first strategy, peroxidase mimicking Fe-doped CDs (FeCDs) were immobilized on TEMPO-oxidized cellulose nanofibrils (TOCNF) via physical entrapment involving hydrogen bonding interactions. Peroxidase activity of the composite nanopaper was evaluated using TMB as chromogenic substrate and applied to the colorimetric detection of H2O2 and glucose. Under optimal conditions, this method afforded linear ranges of 6– 42 μM and 10–70 μM and detection limits of 0.93 and 1.73 μM for the H2O2 and glucose, respectively. In another strategy, amine functionalized, Fe, N-doped CDs (FeNCDs) were immobilized on dialdehyde cellulose nanofibrils (DACNF) via Schiff base reaction and reductive amination. DACNF served as an excellent matrix for FeNCDs to retain the fluorescence and peroxidase activities. Colorimetric assays based on ABTS oxidation offered linear ranges of 10–80 μM and 50–400 μM and detection limits of 0.70 and 3.72 μM for H2O2 and cholesterol respectively. Further the nanocomposite presented a long shelf life and excellent reusability for 10 cycles. Overall, nanocellulose acted as a great support material for the colloidal nanozyme that prevented them from aggregation and made them easy to recycle and reuse.