Diamine Oxidase-Conjugated Multiwalled Carbon Nanotubes to Facilitate Electrode Surface Homogeneity

Carbon nanomaterials have gained significant interest over recent years in the field of electrochemistry, and they may be limited in their use due to issues with their difficulty in dispersion. Enzymes are prime components for detecting biological molecules and enabling electrochemical interactions, but they may also enhance multiwalled carbon nanotube (MWCNT) dispersion. This study evaluated a MWCNT and diamine oxidase enzyme (DAO)-functionalised screen-printed electrode (SPE) to demonstrate improved methods of MWCNT functionalisation and dispersion. MWCNT morphology and dispersion was determined using UV-Vis spectroscopy (UV-Vis) and scanning electron microscopy (SEM). Carboxyl groups were introduced onto the MWCNT surfaces using acid etching. MWCNT functionalisation was carried out using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by DAO conjugation and glutaraldehyde (GA) crosslinking. Modified C-MWNCT/EDC-NHS/DAO/GA was drop cast onto SPEs. Modified and unmodified electrodes after MWCNT functionalisation were characterised using optical profilometry (roughness), water contact angle measurements (wettability), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) (vibrational modes and elemental composition, respectively). The results demonstrated that the addition of the DAO improved MWCNT homogenous dispersion and the solution demonstrated enhanced stability which remained over two days. Drop casting of C-MWCNT/EDC-NHS/DAO/GA onto carbon screen-printed electrodes increased the surface roughness and wettability. UV-Vis, SEM, Raman and EDX analysis determined the presence of carboxylated MWCNT variants from their non-carboxylated counterparts. Electrochemical analysis demonstrated an efficient electron transfer rate process and a diffusion-controlled redox process. The modification of such electrodes may be utilised for the development of biosensors which could be utilised to support a range of healthcare related fields.

Electrochemical Sensors and Biosensors for the Analysis of Tea Components: A Bibliometric Review

Tea is a popular beverage all around the world. Tea composition, quality monitoring, and tea identification have all been the subject of extensive research due to concerns about the nutritional value and safety of tea intake. In the last 2 decades, research into tea employing electrochemical biosensing technologies has received a lot of interest. Despite the fact that electrochemical biosensing is not yet the most widely utilized approach for tea analysis, it has emerged as a promising technology due to its high sensitivity, speed, and low cost. Through bibliometric analysis, we give a systematic survey of the literature on electrochemical analysis of tea from 1994 to 2021 in this study. Electrochemical analysis in the study of tea can be split into three distinct stages, according to the bibliometric analysis. After chromatographic separation of materials, electrochemical techniques were initially used only as a detection tool. Many key components of tea, including as tea polyphenols, gallic acid, caffeic acid, and others, have electrochemical activity, and their electrochemical behavior is being investigated. High-performance electrochemical sensors have steadily become a hot research issue as materials science, particularly nanomaterials, and has progressed. This review not only highlights these processes, but also analyzes and contrasts the relevant literature. This evaluation also provides future views in this area based on the bibliometric findings.

Electrochemical performance of composite electrodes based on rGO, Mn/Cu metal–organic frameworks, and PANI

Benzendicarboxylic acid (BDC)-based metal–organic frameworks (MOFs) have been widely utilized in various applications, including supercapacitor electrode materials. Manganese and copper have solid diamond frames formed with BDC linkers among transition metals chosen for MOF formation. They have shown the possibility to enlarge capacitance at different combinations of MOFs and polyaniline (PANI). Herein, reduced graphene oxide (rGO) was used as the matrix to fabricate electrochemical double-layer SCs. PANI and Mn/Cu-MOF's effect on the properties of electrode materials was investigated through electrochemical analysis. As a result, the highest specific capacitance of about 276 F/g at a current density of 0.5 A/g was obtained for rGO/Cu-MOF@PANI composite.

Electrochemical Determination of Famotidine in Real Samples Using rGO/Cu2O Nanocomposite Modified Carbon Paste Electrode

Here, we developed a sensitive electrochemical sensor for famotidine (FAT) using Cu2O nanoparticles and reduced graphene oxide (rGO) as a sensing platform. The Cu2O nanoparticles and rGO were synthesized through a simple process and characterized by versatile analytical methods. The prepared Cu2O nanoparticles and rGO were taken to modify the carbon paste electrode (Cu2O/rGO/CPE) and developed for the electrochemical analysis of the FAT at pH 6.0. Cu2O/rGO/CPE showed superior electrocatalytic activity for detecting FAT, attributed to the high surface area of rGO and the electrocatalytic properties of Cu2O nanoparticles. The designed FAT sensor exhibited two linear ranges from 0.1-3 µM and 3-50 µM with a detection limit of 0.08 µM (S/N=3) using a differential pulse voltammetry. The proposed sensor also showed a repeatable and stable response over one month with negligible interference from usual organic and inorganic species. The sensor was also validated measuring FAT in real samples (urine, serum and pharmaceutical tablet) with good recovery values from 99.6 to 110.9%.

Copper(II) tetrakis(pentafluorophenyl)porphyrin: Highly Active Copper-based Molecular Catalyst for Electrochemical CO2 Reduction

We report a highly active copper-based catalyst for electrochemical CO2 reduction. Electrochemical analysis revealed that the maximum turnover frequency for CO2 to CO conversion reached to 1,460,000 s-1 at an...

Chemical and Electrochemical Properties of Bamboo Activated Carbon Activate Using Potassium Hydroxide Assisted by Microwave-Ultrasonic Irradiation

This paper presents the utilization of bamboo residue from the chopstick industry as modified carbon (AC) for supercapacitor application. Bamboo activated carbon (BAC) was activated using Potassium hydroxide (KOH) and assisted with microwave ultrasonic (Mw-U) irradiation to enhance the properties of bamboo activated carbon (BAC). Different microwave (Mw) power intensities of 100 W, 300 W, and 500 W at 30 minutes of retention time have been applied on activation and the carbonization process was conducted at temperature 800°C. The BAC was analyzed for the morphology using a scanning electron microscope and proximate and ultimate analysis. Then BAC with the higher surface area was subjected to the electrochemical analysis to determine the electrochemical properties. The study indicated Mw-U irradiation improved the morphology of the BAC, eliminated the impurity of the sample, and gave higher carbon content of BAC. The findings show that lower Mw-U irradiation power provided a higher surface area of BAC. The surface area of 646.87 m2/g and total pore volume of 2.8x10-1 cm3/g was obtained with a power intensity of Mw-U activation at 100 W. While, electrochemical properties, the specific capacitance (Cs) of BAC was 77 Fg-1 at 25 mVs-1 in 1 mol/L KOH of electrolyte for cyclic voltammetry (CV) which indicates the ability of the prepared BAC to be used as an electrode in supercapacitor application. This study determined that Mw-U irradiation can improve the properties of the bamboo during chemical activation and formed BAC that consists of supercapacitor properties.

Synthesis and Characterization of Nickel Oxide Nanostructures for Electrochemical Analysis of Methotrexate

Metal oxide nanoparticles have found numerous applications in different fields. In this paper, the preparation of nickel oxide nanostructures is given. The nanostructures were synthesized by using the hydrothermal method. The characterization was done with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The newly synthesized nanostructures were utilized as a modifier of the working electrode, i.e., glassy carbon electrode (GCE). The modified GCE exhibited an excellent response towards methotrexate (MTX) anticancer drug. The modified GCE, as compared to bare GCE, showed an increased response towards MTX. In this study, BrittonRobinson buffer (BRB) was selected as a supporting electrolyte having pH 5. By using electrochemical impedance spectroscopy (EIS), the method was found linear in the range of 5-40 µM with a limit of detection and quantification values of 2.4 µM and 7.28 µM, respectively. The method developed by this way was successfully applied for the analysis of MTX from injection formulations. The interference studies were also carried out to check the method's selectivity.