Carbon Nanotube Microelectrode Set: Detection of Biomolecules to Heavy Metals

Abstract

An ultrasensitive electrochemical microelectrode set (μ-ES), where all three electrodes are made of highly densified carbon nanotube fiber (HD-CNTf) cross sections (length ∼40 μm), embedded in an inert polymer matrix, and exposed open-ended CNTs at the interface, is presented here. Bare open ends of HD-CNTf rods were used as the working (∼40 μm diameter) and counter (∼94 μm diameter) electrodes, while the cross section of a ∼94 μm diameter was electroplated with Ag/AgCl and coated with Nafion to employ as a quasi-reference electrode. The Ag/AgCl/Nafion-coated HD-CNTf rod quasi-reference electrode provided a very stable potential comparable to the commercial porous-junction Ag/AgCl reference electrode. The HD-CNTf rod μ-ES has been evaluated by electrochemical determination of biologically important analytes, i.e., dopamine (DA), β-nicotinamide adenine dinucleotide (NADH), a diuretic drug, i.e., furosemide, and a heavy metal, i.e., lead ions (Pb2+). Different voltammetric techniques were employed during the study, i.e., cyclic voltammetry (CV), square wave voltammetry (SWV), amperometry, and square wave anodic stripping voltammetry (SWASV). The direct metallic connection to CNTs gives access to the exceptional properties of highly ordered open-ended CNTs as electrochemical sensors. The distinct structural and electronic properties of aligned HD-CNTf rods in the μ-ES demonstrate fast electron transfer kinetics and offer excellent detection performance during testing for different analytes with wide linear ranges, excellent sensitivity, and very low limits of detection.

Recent Progress in Nanotechnology-Based Approaches for Food Monitoring

“…The limit of detection of cadmium and lead was 1.06 ppb and 0.72 ppb, respectively. Alternatively, ultrasensitive electrochemical microelectrodes modified by carbon nanotubes were used to detect lead with a limit of detection as low as 400 ppt, which is well below the permissible limit for lead (10 ppb) reported by the WHO [ 193 ]. The modified electrodes with carbon nanotubes also pose electrochemical performance with great sensitivity for antibiotics detection.…”

Non-enzymatic biosensor based on F,S-doped carbon dots/copper nanoarchitecture applied in the simultaneous electrochemical determination of NADH, dopamine, and uric acid in plasma

“…NADH (nicotinamide adenine dinucleotide or diphosphopyridine nucleotide) is an essential neurotransmitter that presents a vital role and directly links to over 300 dehydrogenase enzymes that catalyze oxidation-reduction reactions in all living cells. [1][2][3] Dopamine is a neurotransmitter belonging to the catecholamines, which is a group of monoamines derived from the amino acid tyrosine and performs essential functions. 3 Nicotinamide adenine nucleotide (NADH) and dopamine play crucial roles in this sense.…”

Creating covalent bonds between Cu and C at the interface of metal/open-ended carbon nanotubes

“… 6 CNTs have been employed as a superior material to conventional metals and semiconductors for the development of conductive wires, 7 transistors, 8 wearable devices, 9 energy storage devices, 10 and sensors. 11 However, various challenges have delayed the widespread utilization of CNTs in commercial applications. For instance, the controlled synthesis of CNTs is challenging, with particular difficulties associated with regulating the diameter, type, and chirality of CNTs during synthesis processes.…”