A simple sonochemical approach to fabricate a urea biosensor based on zinc phthalocyanine/graphene oxide/urease bioelectrode

A novel zinc phthalocyanine/graphene oxide (ZnPh/GO) nanocomposite modified glassy carbon electrode (GCE) was prepared by using sonochemical approach and simple drop casting method. Urease (Urs) was used as the specific enzyme for urea detection and was physically immobilized onto the surface of ZnPh/GO nanocomposite. The fabricated ZnPh/GO/Urs matrix was successfully characterized by UV-vis-spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), raman spectrum, thermogravimetric analysis, cyclic voltammetric (CV) and amperometric techniques. The electrocatalytic performance of the ZnPh/GO/Urs electrode was investigated by urea biosensor. Our results demonstrate that the modified electrode has excellent electrocatalytic activity towards the sensing of urea in 0.1 M phosphate buffer solution (PBS, pH 7.2). The biosensor tolerated a wide linear concentration range for urea from 0.4 to 22 μM (R² = 0.991), with a detection limit of 0.034 µM (S/N = 3). The ZnPh/GO/Urs bioectrode has several excellent properties, including a fast response time, high reproducibility and stability.

Electrochemical pesticide sensor based on Langmuir–Blodgett film of cobalt phthalocyanine-anthraquinone hybrid

A cathode active and selective pesticide electrochemical sensor based on Langmuir–Blodgett (LB) film of cobalt phthalocyanine-anthraquinone hybrid (CoPc-AQ) was constructed for the first time in this study. Cobalt-based, Pc ring-based, and anthraquinone-based reduction processes of CoPc-AQ indicated suitability of the complex as a possible electrochemical catalyst and sensor for detection of target species. LB film of CoPc-AQ on ITO (ITO/CoPc-AQ electrode) was titrated with eserine and carbofuran pesticides and interaction of the electrode with these pesticides was tested with square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS), and double potential step chronocoulometry (DPSCC) techniques. ITO/CoPc-AQ electrode selectively sensed carbofuran and eserine pesticides. While ITO/CoPc-AQ electrode senses carbofuran with the voltammetric responses recorded at anodic potentials (1.20 V), eserine sensing affected antraquinone based reduction peaks recorded at cathodic potentials (-0.80 V). Modification of ITO/CoPc-AQ electrode with nano-platinum and nano-gold particles (ITO/CoPc-AQ-n Pt and ITO/CoPc-AQ-n Au ) increased the sensitivity of the electrode. All basic sensor parameters of modified electrodes were derived with different measurement techniques and compared with each other. The lowest detection limit (2.30 × 10-9 M) was recorded with EIS techniques on ITO/CoPc-AQ-n Pt electrode for sensing of eserine.