New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

Abstract

Multi-walled carbon nanotubes (MWCNT) have provided unprecedented advances in the design of electrochemical sensors. They are composed by sp2 carbon units oriented as multiple concentric tubes of rolled-up graphene, and present remarkable active surface area, chemical inertness, high strength, and low charge-transfer resistance in both aqueous and non-aqueous solutions. MWCNT are very versatile and have been boosting the development of a new generation of electrochemical sensors with application in medicine, pharmacology, food industry, forensic chemistry, and environmental fields. This work highlights the most important synthesis methods and relevant electrochemical properties of MWCNT for the construction of electrochemical sensors, and the numerous configurations and successful applications of these devices. Thousands of studies have been attesting to the exceptional electroanalytical performance of these devices, but there are still questions in MWCNT electrochemistry that deserve more investigation, aiming to provide new outlooks and advances in this field. Additionally, MWCNT-based sensors should be further explored for real industrial applications including for on-line quality control.

Synthesis and characterization of a novel non-enzymatic glucose biosensor based on polyaniline/zinc oxide/multi-walled carbon nanotube ternary nanocomposite

“…The enzyme-free detection of glucose on noble metals, thin film alloys, and metallic nanoparticles was extensively explored; however, these sensors undergo surface poisoning by adsorbed intermediates, leading to their poor sensitivity, selectivity, and stability [8][9][10]. Nevertheless, non-enzymatic electrochemical glucose sensors based on carbon nanomaterials, particularly carbon nanotubes and graphene, have attracted huge attention due to their unique properties including high surface area, chemical and electrochemical stability, exceptional electrical conductivity, superior biocompatibility, and ease of modification [11,12]. As compared to traditional electrodes, multi-walled carbon nanotubes (MWCNT) based electrochemical sensors present lower charge-transfer resistance, faster response time, and higher sensitivity for the direct oxidation of glucose owing to their one-dimensional hollow tubular nanochemistry [13].…”

Applications of Graphene Quantum Dots in Biomedical Sensors

“…Additionally, they are often used for signal amplification by serving as nanocarriers including electron transfer promoters, nanozymes, detector bioreceptors, electroactive labeling elements, and catalysts [34][35][36][37], hence offering novel strategies for biosensing platforms and their practical applicability. Over the last decade, numerous nanomaterials have been continuously studied and employed as signal-amplifying species such as nanoparticles (NPs) [38][39][40], graphene [41][42][43], nanowires [44], carbon nanotubes (CNTs) [45], magnetic beads [46,47] and quantum dots (QDs) [48,49]. Among these nanomaterials, QDs such as graphene quantum dots (GQDs) and carbon dots (CDs) are becoming quite well-known for their multifarious properties such as signal amplifying characteristics, good biocompatibility, tunable size, electro-catalytic performance as well as their capacity for the concurrent and multiple detection of biomolecules.…”

Nanomaterials towards Biosensing of Alzheimer’s Disease Biomarkers

“…CNTs are cylindrical large molecules consisting of a hexagonal arrangement of hybridized carbon atoms, which can be classified as single-walled carbon nanotubes (SWCNTs), composed of a single graphite sheet rolled into a seamless hollow nanoscale tube, and multi-walled carbon nanotubes (MWCNTs), characterized by the presence of multiple concentric tubes encircling one another [41,51,52] ( Figure 2). SWCNTs present a diameter in the range of 0.4-2 nm, while MWCNTs, depending on the number of layers, can display a diameter in the range of 2-100 nm, with the distance between each layer being approximately 0.34 nm [26,33,41,[52][53][54][55][56][57]. Since their discovery in 1991 [58], they have increasingly attracted research interest due to their high surface-to-volume ratio, exceptional electronic properties, and the presence of edge-plane-like defects which make them very interesting for biosensing applications [26,33,41,52,56,59].…”

“…SWCNTs present a diameter in the range of 0.4-2 nm, while MWCNTs, depending on the number of layers, can display a diameter in the range of 2-100 nm, with the distance between each layer being approximately 0.34 nm [26,33,41,[52][53][54][55][56][57]. Since their discovery in 1991 [58], they have increasingly attracted research interest due to their high surface-to-volume ratio, exceptional electronic properties, and the presence of edge-plane-like defects which make them very interesting for biosensing applications [26,33,41,52,56,59]. In addition, another major advantage of CNTs is that they can be easily functionalized with different chemical groups through covalent and non-covalent bonds, which will further promote the immobilization of biomolecules or organic molecules [26,33,37,56].…”