Search Results (12)

In the current work, the MWCNTs/ZnO nanocomposite was successfully synthesized using simple method. Then, FE-SEM, XRD, and EDX techniques were applied for morphological and structural characterization. Afterward, a sensitive voltammetric sensor based on modification of a screen-printed carbon electrode (SPCE) using MWCNTs/ZnO nanocomposite was developed for the determination of doxorubicin in the presence of dacarbazine. To evaluate the electrochemical response of the MWCNTs/ZnO/SPCE towards doxorubicin, cyclic voltammetry (CV) was applied. The MWCNTs/ZnO nanocomposite showed a significant synergistic effect on the electrochemical response of the electrode for the redox reaction of doxorubicin. Also, the MWCNTs/ZnO/SPCE demonstrated an enhanced sensing platform for the quantification of doxorubicin, obtaining a detection limit (LOD) of 0.002 µM and a sensitivity of 0.0897 µA/µM, as determined by differential pulse voltammetry (DPV) within a linear range from 0.007 to 150.0 µM. Also, the MWCNTs/ZnO nanocomposite-modified SPCE showed high electrochemical activities towards the oxidation of doxorubicin and dacarbazine with peak-potential separation of 345 mV, which is sufficient for doxorubicin determination in the presence of dacarbazine. Also, the MWCNTs/ZnO nanocomposite-modified SPCE presented reproducible and stable responses to determine doxorubicin. Finally, the developed platform demonstrated a successful performance for doxorubicin and dacarbazine determination in real samples, with recovery in the range of 97.1% to 104.0% and relative standard deviation (RSD) from 1.8% to 3.5%. Full article

In this paper, the application of NiO nanosheets (NiO NSs) for the detection of methotrexate (MTX) is described. The NiO NSs were synthesized using a hydrothermal method. The electrocatalytic activity of two modifiers, ionic liquid (IL) and NiO NSs, was examined on a carbon paste electrode (CPE) in relation to MTX, utilizing voltammetry methods such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoamperometry at 0.1 M phosphate buffer solution (PBS) pH = 7.0. The anodic peak currents for MTX on the NiO NSs/IL/CPE were approximately 3.5 times greater than those on unmodified CPE. Based on DPV measurements, the electrochemical sensor demonstrated a linear response in the concentration range (LDR: 0.01 µM to 160.0 µM), with a limit of detection (LOD: 0.003 µM). Moreover, the NiO NSs/IL/CPE sensor demonstrated good stability, repeatability, reproducibility, and selectivity, which were of importance in the electroanalysis of compounds. Lastly, the practicality of the NiO NSs/IL/CPE sensor was assessed by analyzing MTX levels in urine samples and pharmaceutical formulation, yielding satisfactory recovery rates of 97.1% to 103.3%. Full article

Water pollution with phenolic compounds is a serious environmental issue that can pose a major threat to the water sources. This pollution can come from various agricultural and industrial activities. Phenolic compounds can have detrimental effects on both human health and the environment. Therefore, it is essential to develop and improve analytical methods for determination of these compounds in the water samples. In this work, the aim was to design and develop an electrochemical sensing platform for the determination of 2,4-dichlorophenol (2,4-DCP) in water samples. In this regard, a nanocomposite consisting of CoWO₄ nanoparticles (NPs) anchored on reduced graphene oxide nanosheets (rGO NSs) was prepared through a facile hydrothermal method. The formation of the CoWO₄/rGO nanocomposite was confirmed via different characterization techniques. Then, the prepared CoWO₄/rGO nanocomposite was used to modify the surface of a screen-printed carbon electrode (SPCE) for enhanced determination of 2,4-DCP. The good electrochemical response of the modified SPCE towards the oxidation of 2,4-DCP was observed by using cyclic voltammetry (CV) due to the good properties of CoWO₄ NPs and rGO NSs along with their synergistic effects. Under optimized conditions, the CoWO₄/rGO/SPCE sensor demonstrated a broad linear detection range (0.001 to 100.0 µM) and low limit of detection (LOD) (0.0007 µM) for 2,4-DCP determination. Also, the sensitivity of CoWO₄/rGO/SPCE for detecting 2,4-DCP was 0.3315 µA/µM. In addition, the good recoveries for determining spiked 2,4-DCP in the water samples at the surface of CoWO₄/rGO/SPCE showed its potential for determination of this compound in real samples. Full article

In this work, UiO-66-NH₂/GO nanocomposite was prepared using a simple solvothermal technique, and its structure and morphology were characterized using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). An enhanced electrochemical sensor for the detection of epirubicin (EP) was proposed, which utilized a UiO-66-NH₂/GO nanocomposite-modified screen-printed graphite electrode (UiO-66-NH₂/GO/SPGE). The prepared UiO-66-NH₂/GO nanocomposite improved the electrochemical performance of the SPGE towards the redox reaction of EP. Under optimized experimental conditions, this sensor demonstrates a remarkable limit of detection (LOD) of 0.003 µM and a linear dynamic range from 0.008 to 200.0 µM, providing a highly capable platform for sensing EP. Furthermore, the simultaneous electro-catalytic oxidation of EP and topotecan (TP) was investigated at the UiO-66-NH₂/GO/SPGE surface utilizing differential pulse voltammetry (DPV). DPV measurements revealed the presence of two distinct oxidation peaks of EP and TP, with a peak potential separation of 200 mV. Finally, the UiO-66-NH₂/GO/SPGE sensor was successfully utilized for the quantitative analysis of EP and TP in pharmaceutical injection, yielding highly satisfactory results. Full article

Food colorants are important in food selection because they improve the gastronomic appeal of foods by improving their aesthetic appeal. However, after prolonged use, many colorants turn toxic and cause medical problems. A synthetic azo-class dye called carmoisine gives meals a red color. Therefore, the carmoisine determination in food samples is of great importance from the human health control. The current work was developed to synthesis ZnO hollow quasi-spheres (ZnO HQSs) to prepare a new electrochemical carmoisine sensor that is sensitive. Field emission-scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to analyze the properties of prepared ZnO HQSs. A screen-printed graphite electrode (SPGE) surface was modified with ZnO HQSs to prepare the ZnO HQSs-SPGE sensor. For carmoisine detection, the ZnO HQSs-SPGE demonstrated an appropriate response and notable electrocatalytic activities. The carmoisine electro-oxidation signal was significantly stronger on the ZnO HQSs-SPGE surface compared to the bare SPGE. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and differential pulse voltammetry (DPV) have been utilized to investigate the suggested protocol. The DPV results revealed an extensive linear association between variable carmoisine concentrations and peak current that ranged from 0.08 to 190.0 µM, with a limit of detection (LOD) as narrow as 0.02 µM. The ZnO HQSs-SPGE’s ability to detect carmoisine in real samples proved the sensor’s practical application. Full article

In this work, we prepared a novel electrochemical sensor for the detection of tramadol based on a UiO-66-NH₂ metal–organic framework (UiO-66-NH₂ MOF)/third-generation poly(amidoamine) dendrimer (G3-PAMAM dendrimer) nanocomposite drop-cast onto a glassy carbon electrode (GCE) surface. After the synthesis of the nanocomposite, the functionalization of the UiO-66-NH₂ MOF by G3-PAMAM was confirmed by various techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and Fourier transform infrared (FT-IR) spectroscopy. The UiO-66-NH₂ MOF/PAMAM-modified GCE exhibited commendable electrocatalytic performance toward the tramadol oxidation owing to the integration of the UiO-66-NH₂ MOF with the PAMAM dendrimer. According to differential pulse voltammetry (DPV), it was possible to detect tramadol under optimized circumstances in a broad concentration range (0.5 μM–500.0 μM) and a narrow limit of detection (0.2 μM). In addition, the stability, repeatability, and reproducibility of the presented UiO-66-NH₂ MOF/PAMAM/GCE sensor were also studied. The sensor also possessed an acceptable catalytic behavior for the tramadol determination in the co-existence of acetaminophen, with the separated oxidation potential of ΔE = 410 mV. Finally, the UiO-66-NH₂ MOF/PAMAM-modified GCE exhibited satisfactory practical ability in pharmaceutical formulations (tramadol tablets and acetaminophen tablets). Full article

In this paper, a simple strategy was proposed for the analysis of catechol by a carbon paste electrode (CPE) modified with graphene oxide–third generation of poly(amidoamine) dendrimer (GO/G3–PAMAM) nanocomposite and ionic liquid (IL). The synthesis of GO–PAMAM nanocomposite was confirmed using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. The prepared modified electrode (GO–PAMAM/ILCPE) exhibited good performance to detect catechol with a notable decrease in overpotential and increase in current compared with an unmodified CPE. Under optimum experimental conditions, GO–PAMAM/ILCPE electrochemical sensors indicated a lower limit of detection (LOD) of 0.034 μM and a linear response in the concentration range of 0.1 to 200.0 µM for the quantitative measurement of catechol in aqueous solutions. In addition, GO–PAMAM/ILCPE sensor exhibited an ability to simultaneously determine catechol and resorcinol. It can be found that catechol and resorcinol could be completely separated on the GO–PAMAM/ILCPE with the differential pulse voltammetry (DPV) technique. Finally, a GO–PAMAM/ILCPE sensor was utilized to detect catechol and resorcinol in water samples with recoveries of 96.2% to 103.3% and relative standard deviations (RSDs) of less than 1.7%. Full article

The current work was performed to construct a novel electrochemical sensing system for determination of sunset yellow via the modification of screen-printed graphite electrode modified with hierarchical flower-like NiCo₂O₄ nanoplates (NiCo₂O₄/SPGE). The prepared material (hierarchical flower-like NiCo₂O₄ nanoplates) was analyzed by diverse microscopic and spectroscopic approaches for the crystallinity, composition, and morphology. Chronoamperometry, differential pulse voltammetry, linear sweep voltammetry, and cyclic voltammetry were used for determination of the electrochemical behavior of sunset yellow. The as-fabricated sensor had appreciable electro-catalytic performance and current sensitivity in detecting the sunset yellow. There were some advantages for NiCo₂O₄/SPGE under the optimized circumstances of sunset yellow determination, including a broad dynamic linear between 0.02 and 145.0 µM, high sensitivity of 0.67 μA/(μM.cm²), and a narrow limit of detection of 0.008 μM. The practical applicability of the proposed sensor was verified by determining the sunset yellow in real matrices, with satisfactory recoveries. Full article

Amaranth is one of the synthetic azo colorants used to improve the appearance and to increase the appeal of some foods and soft drinks. The excessive consumption of amaranth can be associated with health side effects, emphasizing the need to monitor this food dye. Accordingly, the present study aimed to introduce an electrochemical sensor of glassy carbon electrode (GCE) modified with N-doped reduced graphene oxide (N-rGO), N-rGO/GCE, to detect the amaranth sensitively and rapidly. Several electrochemical techniques such as differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and cyclic voltammetry (CV) are exploited for the evaluation of the efficiency of the developed electrode for the detection of amaranth. We found that N-rGO/GCE enhanced amaranth oxidation, thus significantly elevating the current signal. Amaranth showed that calibration curves ranged from 0.1 to 600.0 µM, and the limit of detection (LOD) (S/N = 3) was 0.03 μM. Finally, the developed sensor was effectively applied for real samples (tap water, apple juice, and orange juice) with acceptable recovery values from 96.0 to 104.3%. Full article

Many studies have addressed electrochemical biosensors because of their simple synthesis process, adjustability, simplification, manipulation of materials’ compositions and features, and wide ranges of detection of different kinds of biomedical analytes. Performant electrochemical biosensors can be achieved by selecting materials that enable faster electron transfer, larger surface areas, very good electrocatalytic activities, and numerous sites for bioconjugation. Several studies have been conducted on the metal–organic frameworks (MOFs) as electrode modifiers for electrochemical biosensing applications because of their respective acceptable properties and effectiveness. Nonetheless, researchers face challenges in designing and preparing MOFs that exhibit higher stability, sensitivity, and selectivity to detect biomedical analytes. The present review explains the synthesis and description of MOFs, and their relative uses as biosensors in the healthcare sector by dealing with the biosensors for drugs, biomolecules, as well as biomarkers with smaller molecular weight, proteins, and infectious disease. Full article

We used MoS₂ nanosheets (MoS₂ NSs) for surface modification of screen-printed electrode (MoS₂NSs-SPE) aimed at detecting isoniazid (INZ) in the presence of acetaminophen (AC). According to analysis, an impressive catalytic performance was found for INZ and AC electro-oxidation, resulting in an appreciable peak resolution (~320 mV) for both analytes. Chronoamperometry, differential pulse voltammetry (DPV), linear sweep voltammogram (LSV), and cyclic voltammetry (CV) were employed to characterize the electrochemical behaviors of the modified electrode for the INZ detection. Under the optimal circumstances, there was a linear relationship between the peak current of oxidation and the various levels of INZ (0.035–390.0 µM), with a narrow limit of detection (10.0 nM). The applicability of the as-developed sensor was confirmed by determining the INZ and AC in tablets and urine specimens, with acceptable recoveries. Full article

In recent years, several studies have focused on environmental pollutants. Bisphenol A (BPA) is one prominent industrial raw material, and its extensive utilization and release into the environment constitute an environmental hazard. BPA is considered as to be an endocrine disruptor which mimics hormones, and has a direct relationship to the development and growth of animal and human reproductive systems. Moreover, intensive exposure to the compound is related to prostate and breast cancer, infertility, obesity, and diabetes. Hence, accurate and reliable determination techniques are crucial for preventing human exposure to BPA. Experts in the field have published general electrochemical procedures for detecting BPA. The present timely review critically evaluates diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA. Additionally, the essential contributions of these substances for the design of electrochemical sensors are presented. It has been predicted that chemically modified electrode-based sensing systems will be possible options for the monitoring of detrimental pollutants. Full article