Electrochemical Characteristics and Electrosensing of an Antiviral Drug,Entecavir via Synergic Effect of Graphene Oxide Nanoribbons and Ceria Nanorods

A sensitive electrochemical sensor was fabricated based on ceria‐graphene oxide nanoribbons composite (CeO₂‐GONRs) for an antiviral drug, entecavir (ETV). It was characterized by SEM, EDAX, AFM, IR and Raman spectroscopic techniques. The electrochemical behaviour of ETV was investigated by cyclic voltammetric, differential pulse voltammetric (DPV), linear sweep voltammetric (LSV) and square wave voltammetric (SWV) methods at CeO₂‐GONRs modified glassy carbon electrode. Good linearity was observed between the peak current and concentration of ETV in the range of 0.51 ‐ 100 μM with a detection limit of 0.042 μM in DPV method, 2.1 – 61.1 μM with a detection limit of 0.7 μM in LSV method and 0.1 ‐ 80 μM with a detection limit of 68.1 nM in SWV method. The proposed sensitive DPV method was successfully applied for the determination ETV in tablets and biological samples.     

Electrochemical reduced graphene oxide-poly(eriochrome black T)/gold nanoparticles modified glassy carbon electrode for simultaneous determination of ascorbic acid,dopamine and uric acid

This work reports on the preparation of electrochemically reduced graphene oxide (ERGO)-poly(eriochrome black T) (pEBT) assembled gold nanoparticles for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in PBS pH 6.0. Characterisations of the composite were carried out by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. As a result of the synergistic effect, the modified glassy carbon electrode (GCE) possessed an efficient electrochemical catalytic activity with a high selectivity and sensitivity in oxidising AA-DA and DA-UA as compared to the bare GCE. The peak separations of AA and DA, DA and UA were 183 mV and 150 mV, respectively. The linear response ranges for AA, DA and UA were 10–900 μM, 0.5–20 μM and 2–70 μM with detection limits of 0.53 μM, 0.009 μM and 0.046 μM (S/N = 3), respectively. The sensitivity of ERGO-pEBT/AuNPs was measured as 0.003 µA/μM, 0.164 µA/μM and 0.034 µA/μM for AA, DA, and UA, respectively. The modified electrochemical sensor was used in the determination of AA, DA, and UA in vitamin C tablets and urine sample with good recovery.     

Selective Detection of Dopamine in the Presence of Uric Acid Using NiO Nanoparticles Decorated on Graphene Nanosheets Modified Screen‐printed Electrodes

A convenient, low cost, and sensitive electrochemical method, based on a disposable graphene nanosheets (GR) and NiO nanoparticles modified carbon screen printed electrode (NiO/GR/SPE), is described for the simultaneous determination of dopamine (DA) and uric acid (UA). The modified electrode exhibited good electrocatalytic properties toward the oxidation of DA and UA. A peak potential difference of 150 mV between DA and UA was large enough to determine DA and UA individually and simultaneously. The anodic peak currents of DA were found to be linear in the concentration range of 1.0–500.0 μM with the detection limit of 3.14×10^?7 M.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid Based on Gold Nanoparticles‐PTCA‐Cys Composites Modified Electrodes

In this study, a nanocomposite of 3, 4, 9, 10‐perylenetetracarboxylic acid and L‐cysteine (PTCA‐Cys) with satisfactory water‐solubility and film‐forming ability was prepared and worked as substrate for modifying the glassy carbon electrode. Then, gold nanoparticles (AuNPs) were immobilized to achieve a PTCA‐Cys‐AuNPs modified electrode which provided more reaction positions on the sensor. Scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and different pulse voltammetry were employed to characterize the assembly process of the sensor. The constructed sensor displayed desirable sensitivity, selectivity and stability towards the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Under the optimal experimental conditions, the oxidation peaks of AA, DA and UA appeared at 64, 240 and 376 mV, respectively. The corresponding linear response ranges were 3.2–435, 0.04–100 and 0.80–297 μM, and the detection limits were 1.1, 0.010 and 0.27 μM (S/N=3), respectively.     

Development of a Carbon Paste Electrode Modified with Reduced Graphene Oxide and an Imidazole Derivative for Simultaneous Determination of Biological Species of N‐acetyl‐L‐cysteine,Uric Acid and Dopamine

In this work, the modified carbon paste electrode (CPE) with an imidazole derivative 2‐(2,3 dihydroxy phenyl) 4‐methyl benzimidazole (DHPMB) and reduced graphene oxide (RGO) was used as an electrochemical sensor for electrocatalytic oxidation of N‐acetyl‐L‐cysteine (NAC). The electrocatalytic oxidation of N‐acetyl‐L‐cysteine on the modified electrode surface was then investigated, indicating a reduction in oxidative over voltage and an intensive increase in the current of analyte. The scan rate potential, the percentages of DHPMB and RGO, and the pH solution were optimized. Under the optimum conditions, some parameters such as the electron transfer coefficient (α) between electrode and modifier, and the electron transfer rate constant) k_s) in a 0.1 M phosphate buffer solution (pH=7.0) were obtained by cyclic voltammetry method. The diffusion coefficient of species (D) 3.96×10^?5 cm² s^?1 was calculated by chronoamperometeric technique and the Tafel plot was used to calculate α (0.46) for N‐ acetyl‐L‐cysteine. Also, by using differential pulse voltammetric (DPV) technique, two linear dynamic ranges of 2–18 µM and 18–1000 µM with the detection limit of 61.0 nM for N‐acetyl‐L‐cysteine (NAC) were achieved. In the co‐existence system of N‐acetyl‐L‐cysteine (NAC), uric acid (UA) and dopamine (DA), the linear response ranges for NAC, UA, and DA are 6.0–400.0 µM, 5.0–50.0 µM and 2.0–20.0 µM, respectively and the detection limits based on (C=3s_b/m) are 0.067 µM, 0.246 µM and 0.136 µM, respectively. The obtained results indicated that DHPMB/RGO/CPE is applicable to separate NAC, uric acid (UA) and dopamine (DA) oxidative peaks, simultaneously. For analytic performance, the mentioned modified electrode was used for determination of NAC in the drug samples with acceptable results, and the simultaneous determination of NAC, UA and DA oxidative peaks was investigated in the serum solutions, too.     

Amperometric Biosensors for Tyramine Determination Based on Graphene Oxide and Polyvinylferrocene Modified Screen‐printed Electrodes

A comparison of the analytical characteristics of two tyramine biosensors, based on graphene oxide (GRO) and polyvinylferrocene (PVF) modified screen‐printed carbon electrodes (SPCE), is reported. Diamine oxidase (DAOx) or monoamine oxidase (MAOx) was immobilized onto the PVF/GRO modified SPCE to fabricate the biosensors. Surface characteristics and electrochemical behaviour of the modified SPCEs were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammetry (CV). Electrode surface composition and experimental variables such as pH and working potential were optimized in order to ensure a high performance. Under optimum experimental conditions, both DAOx/PVF/GRO/SPCE and MAOx/PVF/GRO/SPCE biosensors exhibited wide linear dynamic ranges for tyramine from 9.9×10^?7 to 1.2×10^?4 M and from 9.9×10^?7 to 1.1×10^?4 M, respectively. MAOx/PVF/GRO/SPCE biosensor showed higher sensitivity (11.98 μA mM^?1) for tyramine determination than the DAOx/PVF/GRO/SPCE biosensor (7.99 μA mM^?1). The substrate specifity of the biosensors to other biogenic amines namely histamine, putrescine, spermine, spermidine, tryptamine, β‐phenylethylamine and cadaverine was also investigated. The developed biosensors were successfully used for tyramine determination in cheese sample.     

A non‐covalent functionalization of copper tetraphenylporphyrin/chemically reduced graphene oxide nanocomposite for the selective determination of dopamine

A non‐covalent functionalization based on a copper tetraphenylporphyrin/chemically reduced graphene oxide (Cu‐TPP/CRGO) nanocomposite is demonstrated for selective determination of dopamine (DA) in pharmaceutical and biological samples. A homogeneous electron‐rich environment can be created on the graphene surface by Cu‐TPP due to the π–π non‐covalent stacking interaction. The synthesized Cu‐TPP/CRGO nanocomposite was characterized using scanning electron microscopy NMR, ultraviolet–visible and electrochemical impedance spectroscopies. The electrocatalytic activity of DA was evaluated using cyclic voltammetry and differential pulse voltammetry. The oxidation peak current (I_pa) of DA increased linearly with increasing concentration of DA in the range 2–200 μM. The detection limit was calculated as 0.76 μM with a high sensitivity of 2.46 μA μM^?1 cm ^{? 2}. The practicality of the proposed DA sensor was evaluated in DA hydrochloride injection, human urine and saliva, and showed satisfactory recovery results for the detection of DA. In addition, the Cu‐TPP/CRGO nanocomposite‐modified electrode showed excellent stability, repeatability and reproducibility towards the detection of DA. Copyright © 2015 John Wiley & Sons, Ltd.     

Sensitive electrochemical sensing for polycyclic aromatic amines based on a novel core–shell multiwalled carbon nanotubes@ graphene oxide nanoribbons heterostructure

Being awfully harmful to the environment and human health, the qualitative and quantitative determinations of polycyclic aromatic amines (PAAs) are of great significance. In this paper, a novel core–shell heterostructure of multiwalled carbon nanotubes (MWCNTs) as the core and graphene oxide nanoribbons (GONRs) as the shell (MWCNTs@GONRs) was produced from longitudinal partially unzipping of MWCNTs side walls using a simple wet chemical strategy and applied for electrochemical determination of three kinds of PAAs (1-aminopyrene (1-AP), 1-aminonaphthalene and 3,3′-diaminobiphenyl). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and electrochemical methods were used to characterize the as-prepared MWCNTs@GONRs. Due to the synergistic effects from MWCNTs and GONRs, the oxidation currents of PAAs at the MWCNTs@GONRs modified glassy carbon (GC) electrode are much higher than that at the MWCNTs/GC, graphene/GC and bare GC electrodes. 1-AP was used as the representative analyte to demonstrate the sensing performance of the MWCNTs@GONRs/GC electrode, and the proposed modified electrode has a linear response range of 8.0–500.0 nM with a detection limit of 1.5 nM towards 1-AP.     

Simultaneous Detection of Dopamine and Uric Acid on Indium Tin Oxides Modified with Cost‐effective Gas‐phase Synthesized Single Walled Carbon Nanotubes

Cost‐effective gas‐phase synthesized single walled carbon nanotubes (SWCNTs) were first employed for the surface modification of indium tin oxides (ITO) via electrostatic coating of poly‐l‐lysine (PLL). Compared with control substrates of bare ITO and SWCNT‐PLL‐slide glasses, SWCNT‐PLL‐ITO, with high catalytic properties associated with large surface areas, showed significant improvement of electro catalytic activity toward the oxidation of dopamine (DA) and uric acid (UA). The cyclic voltammetric (CV) peak separation of oxidation for both DA and UA was estimated to be ∼ 0.13 V, which renders them capable of simultaneously detecting DA and UA in a mixed solution. The differential pulse voltammetry (DPV) technique was further performed to obtain a linear detection range of DA from 1.0 μM to 100 μM, and a detection limit of 1.0 μM was confirmed in the mixed solution. Furthermore, the practical analytical ability of the method was finally confirmed by selective detection of both DA and UA in human urine samples without any preliminary treatment, implying the feasibility of applying bio‐sensors in a low‐cost manner.     

One‐pot Electro‐polymerized SDPAS/PPy/CNTs Modified Electrode for Selective Detection of Dopamine

To improve the performance of dopamine (DA) detection in the presence of ascorbic acid (AA) and uric acid (UA), sodium diphenylamine sulfonate/polypyrrole/multi‐walled carbon nanotubes (SDPAS/PPy/CNTs) film was fabricated on the surface of gold electrode through one‐pot polymerization initiated by electrochemical oxidation. SDPAS were covalently embedded into the backbone of PPy to endow the resultant film with numerous negative‐charged terminals, resulting in selective pre‐adsorption of protonated DA⁺ on the electrode and switching the following anodic reaction to be an adsorption‐controlled process. The detection of DA in the presence of AA and UA by square wave voltammetry method showed an outstanding repeatability with the relative standard deviation of 0.45 %. A good linear relationship was observed between the oxidative peak current and the concentration of DA in the range of 0.827–104 μM (R²=0.993), and the limit of detection (LOD) was calculated to be 0.105 μM (S/N=3).     

The Electrochemical Properties of Co(TPP), Tetraphenylborate Modified Glassy Carbon Electrode: Application to Dopamine and Uric Acid Analysis

We report the combination of the charge repelling property of tetraphenyl‐borate (TPB) anion and the electrooxidation catalytic effect of cobalt(II) tetrakisphenylporphyrin (CoTPP) embedded in a sol gel ceramic film to develop a modified glassy carbon electrode (CoTPP‐TPB‐SGGCE) for the simultaneous determination of dopamine (DA) and uric acid (UA). The optimized CoTPP‐TPB‐SGGCE shows excellent sensitivity and selectivity for the DA and UA analysis. As high as 2000 fold acceptable tolerance of ascorbic acid (AA) for the determination of trace DA and UA is reached. In the presence of 0.10 mM AA, the linear concentration range for DA is from 6.0×10^?8 to 2.5×10^?5 M, and the detection limit is 2.0×10^?8 M. For UA, the linear concentration range is from 1.0×10^?7 to 3.5×10^?5 M, and the detection limit is 7.0×10^?8 M. Our study has also demonstrated that the novel CoTPP‐TPB‐SGGCE shows high stability and reliability. For 6.00 μM DA and UA, a total of 12 measurements were taken in one week, and the relative standard deviation is 2.05% and 2.68% respectively. No obvious shift of peak current and peak potential is observed over a three‐month lifetime test. The response of the sensor is very quick and response time is approximately 1 s. Satisfactory results are also achieved when the CoTPP‐TPB‐SGGCEs being used to detect the DA and UA in human urine samples.     

A quadruplet electrochemical platform for ultrasensitive and simultaneous detection of ascorbic acid,dopamine, uric acid and acetaminophen based on a ferrocene derivative functional Au NPs/carbon dots nanocomposite and graphene

In this work, a new nanomaterial of thiol functional ferrocene derivative (Fc-SH) stabilized Au NPs/carbon dots nanocomposite (Au/C NC) coupling with graphene modified glassy carbon electrode (Fc-S-Au/C NC/graphene/GCE) was fabricated to serve as a quadruplet detection platform for ultrasensitive and simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and acetaminophen (AC). The Au/C NC was synthesized by adding HAuCl₄ into carbon nanodots solution without using any additional reductant and stabilizing agent. Then the Fc-SH was utilized as the protective and capping agent to modify the Au/C NC. Transmission electron microscopy (TEM), UV–Vis, Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) were adopted to characterize the morphology and electrochemical properties of the materials and the electrodes. The Fc-S-Au/C NC/graphene/GCE exhibits a synergistic catalytic and amplification effects towards oxidation of AA, DA, UA and AC owing to the existence of the nanomaterial and electron mediator. When simultaneous detection of AA, DA, UA and AC, the oxidation peak potentials of the four compounds on the electrode can be well separated and the peak currents were linearly dependent on their concentrations. The quadruplet detection platform shows excellent linear range and ultrasensitive response to the four components, the detection limits were estimated to be as low as 1.00, 0.05, 0.12 and 0.10 μM (S/N = 3), and the modified electrode exhibits excellent stability and reproducibility. The proposed electrode has been successfully applied to detect of these four analytes in real samples with satisfactory results.     

Electrochemical Formation of Nanostructured Gold Surfaces on Glassy Carbon for the Determination of Dopamine

Nanostructured gold surfaces were prepared by potentiostatic, potentiodynamic or galvanostatic Au electrodeposition on glassy carbon electrodes. The nanostructured gold electrodes (nsAu/GC) were used for the determination of dopamine (DA) in aqueous media. A directly proportional relationship was found between the peak current for DA (obtained by square wave voltammetry, SWV) and its concentration for all cases. However, the best performance for DA determination was attained with potentiodynamically electrodeposited surfaces. The SWV peak current was linearly dependent on DA concentration up to 10 μM, with a detection limit (3σ) of 0.57 μM, and a correlation coefficient (r) of 0.9966. A study on the effect of common interfering species such as ascorbic acid (AA) and uric acid (UA) on DA determination was also carried out. The use of a nanostructured surface gives rise to peaks for AA and UA that appear at 0.15–0.20 V above the peak potential for DA. The detection limit obtained for dopamine is below 1 μM in the presence of 0.1 mM AA and 0.1 mM UA. Thus, nanostructuring of glassy carbon surfaces with gold conveniently and easily improves the detection of DA in the presence of their principal interfering species.     

Electrochemical Sensor for Sensitive Determination of Capsaicin Using Pd Decorated Reduced Graphene Oxide

In this work, the reduced graphene oxide functionalized with poly dimethyl diallyl ammonium chloride (PDDA) modified palladium nanoparticles (PDDA‐rGO/Pd) had been facile synthesized and used as the sensing layer for sensitive determination of capsaicin. The prepared composite was characterized by transmission electron microscopy, UV‐visible absorption spectroscopy. The image demonstrated that Pd nanoparticles were uniformly distributed on the graphene surface. The electrochemical properties of the prepared sensor were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the nanocomposite exhibits attractive electrocatalytic activity towards the oxidation of capsaicin. This attributed to the synergistic action of the excellent properties of Pd nanoparticles and graphene nanosheets. Under optimized conditions, the electrochemical sensor possessed a dynamic linear range from 0.32 μM to 64 μM with a detection limit of 0.10 μM (S/N=3) for capsaicin detection. Moreover, the cost‐effective and simple fabrication procedure, good reproducibility and stability as well as acceptable accuracy for capsaicin determination in actual samples are also the main advantages of this method, which might have broad application in other amide alkaloid detection.     

Graphene Oxide Nanoribbons: Improved Synthesis and Application in MALDI Mass Spectrometry

Graphene nanoribbon is a novel variety of graphene with high length‐to‐width ratio and straight edges. Herein, we report an improved method for the synthesis of graphene oxide nanoribbons (GONRs) from longitudinal unraveling of multiwalled carbon nanotubes by means of a one‐step, one‐pot pressurized oxidation reaction. The obtained GONRs were characterized by different techniques. Furthermore, owing to their unique properties such as strong optical absorption and good water dispersibility, we show that GONRs can be used as an excellent matrix or probe in matrix‐assisted or surface‐enhanced laser desorption/ionization mass spectrometry (MALDI or SELDI MS) for the first time. In MALDI MS, GONRs generated significantly higher signals than conventional organic matrix and other graphene‐based matrices in the detection of low‐mass compounds. We also demonstrate the use of GONRs as a sensitive SELDI probe for simultaneous detection of multiple small molecules and profiling of small molecules in complex environmental samples, thus revealing its application potential in rapid screening of low‐mass pollutants in complex media.     

Electrochemical Oxidation and Sensitive Determination of Pyrogallol at Preanodized Screen‐Printed Carbon Electrodes

In this study, we report a simple, low‐cost and rapid electrochemical sensor based on the anodically pretreated screen‐printed carbon electrodes (SPCE*) for the determination of pyrogallol in pH 7.0 buffer solutions. Cyclic voltammetric studies show that SPCE* lowers overpotentials and improve electrochemical behaviour of pyrogallol, compared to untreated SPCE. All experimental parameters were optimized to improve voltammetric responses; excellent analytical features were achieved by flow‐injection amperometric methods. A linear calibration plot was obtained for 10‐1000 μM pyrogallol with a slope of 0.0562 μA/μM. The detection limit (S/N = 3) was 0.33 μM. Interferences from some inorganic salts and organic compounds were studied. The assay was applied to the determination of pyrogallol in tap water and lake water, respectively.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid,at a Graphene Paste Electrode Modified with Functionalized Graphene Sheets

The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH 7.0) using graphene paste electrode modified with functionalized graphene sheets (GPE‐MFGSs). The presence of FGS inhibited the adsorption of AA owing to the electrostatic repulsion, but was favorable for the affinity adsorption of DA and UA via the ion exchange and hydrogen bonding mechanisms, respectively. This led to the decrease in the oxidation potential of AA and the significantly enhanced oxidation peak currents of DA and UA at the GPE‐MFGSs. By cyclic voltammetry and differential pulse voltammetry, the oxidation potentials of AA, DA, and UA, at the GPE‐MFGSs in a ternary mixture were found to be well resolved so that their simultaneous determination could be achieved. Furthermore, the influence of some experimental variables such as graphene paste composition, working solution pH, scan rate and pulse amplitude was studied. In addition, by differential pulse voltammetry, the linear dependence of peak current on the concentration was obtained in the ranges of 0.05–9.0, 0.03–13, and 0.03–5.5 µM with the lowest detection limits of 0.02, 0.01, and 0.01 µM for AA, DAand UA, , respectively.     

2,2‐Bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane Modified Glassy Carbon Electrodes as Selective and Sensitive Voltammetric Sensors. Selective Detection of Dopamine and Uric Acid

2,2‐bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane (BAHHFP) was electro‐polymerized oxidatively on glassy carbon by cyclic voltammetry. The activity of the modified electrode towards ascorbic acid (AA), uric acid (UA) and dopamine (DA) was characterized with cyclic voltammetry and differential puls voltammetry (DPV). The findings showed that the electrode modification drastically suppresses the response of AA and shifts it towards more negative potentials. Simultaneously an enhancement of reaction reversibility is seen for DA and UA. Unusual, selective preconcentration features are observed for DA when the polymer‐modified electrode is polarized at negative potential. In a ternary mixture containing the three analytes studied, three baseline resolved peaks are observed in DPV mode. At physiological pH 7.4, after 5 min preconcentration at ?300 mV, peaks positions were ?0.073, 0.131 and 0.280 V (vs. Ag/AgCl) for AA, DA and UA, respectively. Relative selectivities DA/AA and UA/AA were over 4000 : 1 and 700 : 1, respectively. DA response was linear in the range 0.05–3 μM with sensitivity of 138 μA μM^?1 cm^?2 and detection limit (3σ) of 5 nM. Sensitive quantification of UA was possible in acidic solution (pH 1.8). Under such conditions a very sharp peak appeared at 630 mV (DPV). The response was linear in the range 0.5–100 μM with sensitivity of 4.67 μA μM^?1 cm^?2 and detection limit (3σ) of 0.1 μM. Practical utility was illustrated by selective determination of UA in human urine.     

Electrochemical co-deposition of reduced graphene oxide-gold nanocomposite on an ITO substrate and its application in the detection of dopamine

The simultaneous deposition of rGO and gold nano structures has been achieved by electrodeposition from mixed solutions containing graphene oxide(GO)and a gold precursor.Scanning electron microscope(SEM),Raman spectroscopy and atomic force microscopy(AFM)have been employed to reveal the morphology,uniformity and practical stability of the nanocomposite films on the indium tin oxide(ITO)substrate.The AFM data showed heights of tens of nanometers of the nanocomposite,suggesting that multilayers of rGO with gold nanoparticles had been formed as a result of the electrochemical co-deposition.Differential pulse voltammetry(DPV),as a widely used analytical technique,has been carried out on the rGO-Au/ITO electrode for the quantitative detection of dopamine(DA).The detection limit(S/N=3)for the determination of DA was evaluated as 0.6μM.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid at Pt Nanoparticles Decorated Multiwall Carbon Nanotubes Modified GCE

A modified electrode was fabricated by electrochemically deposition of Pt nanoparticles on the multiwall carbon nanotube covered glassy carbon electrode (Pt nanoparticles decorated MWCNT/GCE). A higher catalytic activity was obtained to electrocatalytic oxidation of ascorbic acid, dopamine, and uric acid due to the enhanced peak current and well‐defined peak separations compared with both, bare and MWCNT/GCE. The electrode surfaces were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). Individual and simultaneous determination of AA, DA, and UA were studied by differential pulse voltammetry. The detection limits were individually calculated for ascorbic acid, dopamine, and uric acid as being 1.9×10^?5 M, 2.78×10^?8 M, and 3.2×10^?8 M, respectively. In simultaneous determination, LODs were calculated for AA, DA, and UA, as of 2×10^?5 M, 4.83×10^?8 M, and 3.5×10^?7 M, respectively.