Electroenzymatic sensing of urea using CP/MWCNT-inulin-TiO2 bioelectrode

Abstract

The present study is aimed at developing a sensitive biosensor for urea by the incorporation of MWCNT- Inulin-TiO2 and urease (Ur) onto carbon paste matrix and to propose a suitable mechanism of interaction. Multi-Walled Carbon nanotubes (MWCNTs) were considered as a novel nanomaterial owing to their unique properties but their hydrophobicity limit their applications. A successful strategy to improve their hydrophilicity is to modify MWCNTs with biopolymers. Inulin (Inu), a versatile carbohydrate polymer was extracted from Allium sativum L. and used for anchoring TiO2. The prepared Inu-TiO2 composite was used to modify MWCNTs in order to synergistically improve the stability and the biocompatibility. The MWCNT-Inu-TiO2 bio-nanocomposite was characterized by UV–vis, FT-IR, micro-Raman, XRD, SEM, TEM and TGA techniques. Differential Pulse Voltammetric (DPV) studies were carried out to show the sensitivity of the fabricated CP/MWCNT-Inu-TiO2/Ur bioelectrode towards urea. The fabricated bioelectrode exhibited wide linear range (0.083 mM to 25 mM) with low detection limit (0.9 μM), good sensitivity (29.6 mA mM−1 cm-2), high storage stability (120 days) and good selectivity (in presence of biointerferences like ascorbic acid, uric acid, glucose, lactose, Na+ and K+). The fabricated bioelectrode was also effectively applied for the sensing of urea as an adulterant in milk samples.