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•Au@Fe3O4 magnetic nanoparticles were constructed to detect dopamine.•The electrocatalytic redox activity of dopamine was investigated in detail.•The sensing platform had detection ...limit of 2.7 nM for dopamine.•The proposed sensor showed rapid response within 3 s.•The sensor was successfully applied for detection of dopamine in human urine samples.
Substantially, noble metals are important for the development of low-cost, sensitive, selective, superior performance, and portable electrochemical sensors. Herein, we describe gold (Au) nanoparticles (NPs) systematically decorated with magnetic Fe3O4 nanocomposites on the fabrication of sensitive dopamine sensor is described. Magnetic Au@Fe3O4 nanocomposites were prepared by reducing HAuCl4 on the surfaces of Fe3O4 nanoparticles. The surface morphology of Au@Fe3O4 nanocomposites was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical behaviour of the modified electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometric techniques, in which it was shown to be highly sensitive and selective towards DA. The amperometric detection of dopamine sensor, using this sensing element, exhibits a wide linear response of 0-0.8 μM with a low detection limit of 2.7 nM. In addition, the fabricated electrode showed an excellent stability and good reproducibility. The proposed analytical method was successfully applied to determine the concentration of dopamine in human urine samples and the unknown concentration of DA in human urine samples No. 1, 2 and 3 were determined as 0.056 ± 0.82 × 10−3, 0.037 ± 0.87 × 10−3 and 0.020 ± 0.94 × 10−3 μM, respectively, with recoveries ranging from 97.2% to 103.4%, suggesting that the fabricated electrode can effectively detect DA in human urine samples.
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•Au@Fe3O4@rGO nanocomposite sensor was fabricated to detect acetaminophen (AP).•The material was synthesised by simple co-precipitation method.•Au@Fe3O4@rGO shows high sensitivity and ...catalytic activity towards the oxidation AP.•The nanocomposite shows the detection limit of 5 nM for AP.•The sensor was successfully used to trace the quantity of AP in human urine sample.
In this work, the decoration of a GCE with an Au@Fe3O4@rGO nanocomposite material and its benefit as a sensor for the detection of acetaminophen (AP) in a phosphate buffer solution (PBS) with (pH = 7) are analysed. The nanocomposite mixture was prepared by a simple co-precipitation method and characterized by different surface analytical techniques. The electrochemical characteristics of the modified nanocomposite electrode were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. The Au@Fe3O4@rGO/GCE nanocomposite showed good electrochemical sensitivity and performance towards AP. The peak current obtained by amperometry gradually increased with an increase in the AP concentration in the hiatus ranging from 0.01 to 0.28 μM (R2 = 0.99) with a calculated low limit of detection (LOD) and good sensitivity of 5 nM and 0.11 μA μM−1 respectively revealing a good rapid response. The proposed sensor was assessed for the determination of AP in human urine sample and in the unknown concentration of AP with good recoveries suggesting that the modified electrode can effectively sense AP in human urine sample.
The alkaline oxygen evolution reaction (OER) remains a bottleneck in green hydrogen production owing to its slow reaction kinetics and low catalytic efficiencies of earth abundant electrocatalysts in ...the alkaline OER reaction. This study investigates the OER performance of hierarchically porous cobalt electrocatalysts synthesized using the dynamic hydrogen bubble templating (DHBT) method. Characterization studies revealed that electrocatalysts synthesized under optimized conditions using the DHBT method consisted of cobalt nanosheets, and hierarchical porosity with macropores distributed in a honeycomb network and mesopores distributed between cobalt nanosheets. Moreover, X-ray photoelectron spectroscopy studies revealed the presence of Co(OH)2 as the predominant surface cobalt species while Raman studies revealed the presence of the cubic Co3O4 phase in the synthesized electrocatalysts. The best performing electrocatalyst required only 360 mV of overpotential to initiate a current density of 10 mA cm−2, exhibited a Tafel slope of 37 mV dec−1, and stable OER activity over 24 h. The DHBT method offers a facile, low cost and rapid synthesis approach for preparation for highly efficient cobalt electrocatalysts.
Different compositions of trimetallic
alloy containing silver,
copper, and nickel (Ag
x
Cu
y
Ni
z
) were electrodecorated
in a protic ionic liquid medium on glassy carbon electrodes in order
to ...investigate the suitability of the materials as catalysts for electrochemical
reduction of carbon dioxide (CO
2
). Surface characteristic
morphology obtained by scanning electron microscopy shows cauliflower
crystallites for the deposit of Ag, whereas materials of Cu and Ni
exhibit cubic grains and fine particles, respectively. Deposits of
trimetallic alloy containing Ag, Cu, and Ni exhibit the mixture of
the three characteristic features. Further, trimetallic alloy containing
a large amount of Ag provides high crystallinity, whereas predominance
of Cu as well as Ni results in porous structures, as revealed by X-ray
diffraction analysis. Atomic absorption spectroscopy () was used to
determine the compositions of different alloy materials. The suitability
of nanomaterials as cathodes for electroreduction of benzyl bromide
in CO
2
containing 0.1 M tetra-
n
-butylammonium
tetrafluoroborate (DMF/TBABF
4
)/
N
,
N
-dimethylformamide medium was explored. The linear sweep
voltammogram reveals that Ag
46
Cu
40
Ni
14
shows higher cathodic peak current and lower cathodic peak potential
than those of other deposited nanomaterials as well as alloys, indicating
its higher catalytic activity for such an electroreduction process,
whereas potentiostatic electrolysis confirms the abovementioned results.
A novel electrochemical sensing platform for the determination of bisphenol A (BPA) was constructed on a glassy carbon electrode adapted by employing carboxylic acid functionalized carbon ...black-multi-walled carbon nanotubes (CB/f-MWCNTs). The morphology of CB/f-MWCNTs composite was described by examining scanning electron microscopy (SEM), X-ray powder diffraction (XRD), high-resolution transmission microscopy (HR-TEM) and laser Raman spectra. The developed electrode was examined for the electrochemical oxidation of BPA using cyclic voltammetry (CV) and amperometric techniques in which, CB/f-MWCNTs composite was demonstrated to be highly sensitive and selective detection of towards BPA. Contrasted with a bare GCE electrode, the CB/f-MWCNTs electrode showed an increase of peak current of about 260 μA on the electro-oxidation of BPA. The instant detection of BPA was refined with amperometry under streamlined conditions. CB/f-MWCNTs composite modified GC electrode revealed an excellent sensitivity within the concentration varying from 0.1 to 130 μM with a lower detection limit of 0.08 μmol L−1 (S/N = 3, R2: 0.998). The projected strategy was effectively to utilise the recognition of BPA real samples (plastic drinking water bottles) with acceptable results and great recuperation.
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•CB/F-MWCNTs/GCE modified nanocomposite was fabricated to improve the performance of bis-phenol A (BPA) sensor.•CB/f-MWCNTs composite GC electrode exhibited an excellent sensitivity and catalytic activity toward the oxidation of BPA.•The proposed sensor was successfully used to determine BPA leached from real plastic mineral water bottle samples.
Substantially, noble metals are important for the development of low-cost, sensitive, selective, superior performance, and portable electrochemical sensors. Herein, we describe gold (Au) ...nanoparticles (NPs) systematically decorated with magnetic Fe
O
nanocomposites on the fabrication of sensitive dopamine sensor is described. Magnetic Au@Fe
O
nanocomposites were prepared by reducing HAuCl
on the surfaces of Fe
O
nanoparticles. The surface morphology of Au@Fe
O
nanocomposites was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical behaviour of the modified electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometric techniques, in which it was shown to be highly sensitive and selective towards DA. The amperometric detection of dopamine sensor, using this sensing element, exhibits a wide linear response of 0-0.8 μM with a low detection limit of 2.7 nM. In addition, the fabricated electrode showed an excellent stability and good reproducibility. The proposed analytical method was successfully applied to determine the concentration of dopamine in human urine samples and the unknown concentration of DA in human urine samples No. 1, 2 and 3 were determined as 0.056 ± 0.82 × 10
, 0.037 ± 0.87 × 10
and 0.020 ± 0.94 × 10
μM, respectively, with recoveries ranging from 97.2% to 103.4%, suggesting that the fabricated electrode can effectively detect DA in human urine samples.
A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by ...multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM−1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples.
Bisphenol A (BPA), an endocrine disrupting chemical, had been used worldwide as a raw material in water bottles and food packages. It leaches into food products and water sources and hence, it should ...be monitored effectively. Herein, an electrochemical sensing platform based on Cu-MOF@Pd-500 modified glassy carbon (GC) electrode was fabricated for the sensing of BPA. The material was synthesized by a simple solvothermal method, carbonized at 500 ⁰C, and characterized by various surface analytical techniques. Cyclic voltammetric (CV) analysis reveals that the Cu-MOF@Pd-500 modified GCE exhibits 1.5 folds hike in peak current and a considerable shift in peak potential towards the anodic side when compared to Cu-MOF@ 500, suggesting the higher electrocatalytic activity of the former than that of the later. The electrochemical oxidation of BPA provides an irreversible diffusion-controlled process involving two electrons and two protons. Differential pulse voltammetric (DPV) analysis reveals that the constructed sensor material provides a linear response over BPA concentration of 1 − 150 µM with a low detection limit (LOD) of 0.06 µM, (S/N = 3) and amperometric studies deliver a linear range of 1–22 µM with a LOD of 0.025 µM in 0.1 M PBS at a pH 7.0. Additionally, the Cu-MOF@Pd-500 delivers good repeatability, stability, and anti-interference capabilities. The results obtained also support the effectiveness of Cu-MOF@Pd-500 for quantifying and identifying BPA in real sample analysis (plastic water bottles) with an average recovery of the ratio of 101.93 having a relative standard deviation (RSD) of 0.42%.
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•Cu-MOF/Pd derived oxide nanoparticles were synthesized and characterised.•Catalysis of MOFs on the electrooxidation of bisphenol was studied.•The sensor shows wide linearity with good repeatability and reproducibility.•Detection of BPA on Cu-MOF@Pd-500 was as low as 25 nM.•Real analysis was done with water bottles exposed on sunlight.
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•Presents the latest advancements in wearable biosensors for cardiovascular monitoring.•Discusses the use of hydrogel-based biosensors for biomarkers sensing in biofluids.•Explores ...the use of flexible electronics-based sensors for continuous health monitoring.•Reviews polymer-based wearable sensors for personalized healthcare applications.
This review provides a comprehensive overview of the latest advancements in wearable biosensors, emphasizing their applications in cardiovascular disease monitoring. Initially, the key sensing signals and biomarkers crucial for cardiovascular health, such as electrocardiogram, phonocardiography, pulse wave velocity, blood pressure, and specific biomarkers, are highlighted. Following this, advanced sensing techniques for cardiovascular disease monitoring are examined, including wearable electrophysiology devices, optical fibers, electrochemical sensors, and implantable cardiac devices. The review also delves into hydrogel-based wearable electrochemical biosensors, which detect biomarkers in sweat, interstitial fluids, saliva, and tears. Further attention is given to flexible electronics-based biosensors, including resistive, capacitive, and piezoelectric force sensors, as well as resistive and pyroelectric temperature sensors, flexible biochemical sensors, and sensor arrays. Moreover, the discussion extends to polymer-based wearable sensors, focusing on innovations in contact lens, textile-type, patch-type, and tattoo-type sensors. Finally, the review addresses the challenges associated with recent wearable biosensing technologies and explores future perspectives, highlighting potential groundbreaking avenues for transforming wearable sensing devices into advanced diagnostic tools with multifunctional capabilities for cardiovascular disease monitoring and other healthcare applications.
A o-tolidine based triazine (TTP) covalent organic framework was prepared, and successful formation of the porous polymer network was confirmed by solid state 13C and 15N CP-MAS NMR spectra, XRD, and ...other morphological techniques. The synthesized TTP was decorated with transition metal/metal oxide nanoparticles (Cu, Ni, and Cu–Ni). The presence of CuO and NiO nanoparticles on the TTP matrix were confirmed by Raman spectroscopy and the PXRD analysis and different morphologies with modest changes in particle size and porosity were confirmed by FE-SEM and HR-TEM studies. As evidenced by onset potential and current density, the Cu-TTP sample exhibited excellent electrocatalytic activity for the electrochemical carboxylation of propylene oxide in the presence of CO2 and HER, whereas the Ni-TTP sample displayed excellent OER activity. The presence of pyridinic, pyrrolic, and quaternary nitrogen was attributed to the excellent catalytic activity of Cu-TTP for electrocarboxylation and HER activity, whereas secondary amine bonds and a combination of mechanisms were responsible for the increased OER activity of Ni-TTP the sample, as evidenced by XPS.
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•o-tolidine based triazine POP modified with transition metal oxide NPs were prepared.•Cu@Cu2O composite shows large surface-to-volume ratio and abundant active sites.•Cu-TTP showed excellent electrocatalytic activity towards CO2RR and HER.•Presence of secondary amine in Ni-TTP provided low overpotential towards OER.