Electroanalytical Sensor Technology

Enhanced Electrocatalytic Detection of Choline Based on CNTs and Metal Oxide Nanomaterials

“…The analysis response times of these sensors are relatively fast with superior sensitivity and selectivity, and at low cost in contrast to conventional methods. However, in order to enhance the performance of these sensors, nanomaterials such as carbon nanotubes (CNTs), which could be single walled (SWCNT) or multi-walled (MWCNT), and metal oxide nanomaterials are coupled with the sensors to improve their performance [38]. Examples of applied metal oxide nanomaterials in choline sensors include oxides of manganese, zirconium, zinc, iron (III) and nickel (MnO 2 , ZrO 2 , ZnO, Fe 3 O 4 and NiO, respectively) [39][40][41][42][43][44].…”

“…A biosensor is a self-contained integrated device that provides information of an analyte in the form of an electrical signal, with the aid of biological sensing elements (biomolecules) such as enzymes, antibodies, proteins, microbes and deoxyribonucleic acid (DNA) immobilized on the transducer (electrode or set of electrodes), which is an electrochemical method [38,46]. These biological sensing elements enhance the specificity and sensitivity of biosensors [38]. The electrical signal is proportional to the concentration of the detected analytes resulting from the interaction of the analytes with the immobilized biomolecules on the electrode [38,46].…”

“…These biological sensing elements enhance the specificity and sensitivity of biosensors [38]. The electrical signal is proportional to the concentration of the detected analytes resulting from the interaction of the analytes with the immobilized biomolecules on the electrode [38,46]. Great attention is drawn to electrochemical biosensors, particularly the amperometric choline oxidase (ChOx) base, in which the choline concentration is determined indirectly depending on the determination of hydrogen peroxide (H 2 O 2 ) from the catalytic oxidation of choline in the presence of oxygen [11,47,48], as represented in Equation (1).…”

“…Recently, nanomaterials such as carbon nanotubes (single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs)), polymer (polyaniline, chitosan, polyallylamine, polyvinyl sulphate) nanowires, graphene oxide and Prussian blue, together with metal and metal oxide nanoparticles such as gold (Au), platinum (Pt), zinc oxide (ZnO), zirconium (IV) oxide (ZrO 2 ), manganese (IV) oxide (MnO 2 ) and nickel oxide (NiO), have been incorporated in biosensors due to their possession of a high electrocatalytic effect, biocompatibility, fascinating electronic and optical properties, chemical/physical stability and high degree of electron transfer between biomolecules and the electrode surface [11,[38][39][40][41]43,51]. These nanomaterials significantly impact the catalytic activities of the enzymes and increase the stability of the enzymes, which, in turn, results in an improved sensitivity and specificity of biosensors [11].…”

“…The principle of electrochemical sensors is based on the reaction of the analytes of interest at the sensing electrode with a resulting electrical signal which corresponds to the concentration of analytes [54]. Signals of electrochemical sensors are amplified by modifying the sensing electrode surface with nanocatalysts, also known as nanomaterials (CNTs, metals, metal oxide nanoparticles, conducting polymers) [38]. This is due to their high electrocatalytic effect, tensile strength, chemical stability and high electron transfer rate between biomolecules and the electrode surface ascribed to the large surface area [38].…”