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1.
A nonenzymatic electrochemical sensor for glucose and fructose was fabricated that contained a glassy carbon electrode modified with a copper oxide (CuO)/multiwalled carbon nanotube (MWCNT) nanocomposite. The electrochemical properties of the CuO/MWCNT‐modified glassy carbon electrode were investigated. Two distinguishable anodic peaks were observed around 0.30 and 0.44 V corresponding to the oxidation of glucose and fructose, respectively, at the surface of the modified electrode. The detection limits for glucose and fructose were both 0.04 mmol/L. The sensor was used to simultaneously determine the concentrations of glucose and fructose in hydrolyzed sucrose samples, and to measure glucose in blood serum samples, demonstrating its potential as a nonenzymatic carbohydrate sensor.  相似文献   

2.
《Electroanalysis》2017,29(12):2839-2846
In this paper, a glassy carbon electrode (GCE) was modified with polyzincon. The modified electrode was used as a simple, inexpensive and highly sensitive electrochemical sensor for the determination of organophosphorus pesticide fenitrothion. To fabricate the electrochemical sensor, GCE was immersed in 0.10 mmol L−1 zincon solutions at pH 7.0 and then successively scanned between −1.00 to 2.20 V (vs . Ag/AgCl) at a scan rate of 70 mV s−1 for six cycles. The morphology and structure of the polyzincon were studied with atomic force microscopy and scanning electron microscopy. A comparison of the electrochemical behavior of fenitrothion on the unmodified and polyzincon modified‐GCE showed that in the modified electrode not only the oxidation peak current increased, but also the overpotential shifted to lower one. The experimental conditions such as sample solution pH, accumulation potential, and time were optimized. The differential pulse voltammetric responses of fenitrothion at potential about −0.60 V was used for the determination of fenitrothion. The peak current increased with increasing the concentration of fenitrothion in the range of 5 to 8600 nmol L−1 with a detection limit of 1.5 nmol L−1. Finally, the electrochemical sensor was used for the analysis of fenitrothion in water and fruit samples.  相似文献   

3.
In this work, Ni@Pt core‐shell nanoparticles with diameter of 3–4 nm and thin Pt shell was synthesized by a successive reduction approach using carbon as support to develop high‐performance non‐enzymatic glucose sensor. The resulting electrochemical sensor displayed good catalytic activity toward glucose oxidation, presenting a high current density of 66.9 µA mM?1 cm?2 at an applied potential of ?0.1 V. It showed a wide linear range of 0.1–30.1 mM and the limit of detection was down to 30 µM (S/N=3). Notably, it was found that the proposed sensor exhibited good selectivity to avoid the interference from ascorbic acid, uric acid, fructose and acetamidophenol. Furthermore, the feasibility of the as‐prepared non‐enzymatic glucose sensor in the determination of glucose in serum samples was successfully implemented.  相似文献   

4.
In this work, a glassy carbon electrode (GCE) was modified with multiwall carbon nanotubes/ionic liquid/graphene quantum dots (MWCNTs/IL/GQDs) nanocomposite. Then, the nanocomposite was decorated with nickel‐cobalt nanoparticles (Ni?Co NPs), and it was used as a non‐enzymatic glucose sensor. Field emission scanning electron microscopy, X‐ray diffraction spectroscopy, and energy dispersive spectroscopy were employed to prove the electrodeposition of the Ni?Co NPs on the surface of MWCNTs/IL/GQDs/GCE. Also, cyclic voltammetric and amperometric methods were utilized for the investigation of the electrochemical behaviour of the Ni?Co NPs/MWCNTs/IL/GQDs/GCE for glucose oxidation. The novel amperometric sensor displayed two linear ranges from 1.0 to 190.0 μmol L?1 and 190.0 to 4910 μmol L?1 with a low detection limit of 0.3 μmol L?1 as well as fast response time (2 s) and high stability. Also, the sensor showed good selectivity for glucose determination in the presence of ascorbic acid, citric acid, dopamine, uric acid, fructose, and sucrose, as potential interference species. Finally, the performance of the proposed sensor was investigated for the glucose determination in real samples. Ni?Co NPs/MWCNTs/IL/GQDs/GCE showed good sensitivity and excellent selectivity.  相似文献   

5.
《Electroanalysis》2018,30(2):353-360
A label‐free electrochemical immunosensor based on the liquid crystal (E)‐1‐decyl‐4‐[(4‐decyloxyphenyl)diazenyl]pyridinium bromide (Br−Py), together with heparin‐stabilized gold nanoparticles (AuNP‐Hep) and Nafion is proposed for the determination of prostate‐specific antigen (PSA). The Br−Py liquid crystal presented redox properties and good film‐forming abilities on the electrode surface, and thus it is a suitable alternative as a redox probe for a label‐free electrochemical immunosensor, which could simplify the analysis methodology. The stepwise construction of the immunosensor and the incubation process (immunocomplex formation) were characterized by voltammetry and electrochemical impedance spectroscopy. The proposed immunosensor could directly detect PSA concentrations in the incubation samples, based on the suppression of the Br−Py redox peak (‘base peak’) current. After optimization, the immunosensor exhibited a linear response to PSA concentrations in the range of 0.1 to 50 ng mL−1, with a calculated detection limit of 0.08 ng mL−1. The reproducibility (coefficient of variance less than 3.0 %), selectivity and accuracy of the methodology were adequate. The immunosensor was satisfactorily applied in the quantification of PSA in human blood plasma samples.  相似文献   

6.
《Electroanalysis》2018,30(5):819-827
Microcystins are potent hepatotoxins produced by cyanobacteria, which proliferate in wastewaters with high nutrient content. Due to their high toxicity and potential risk to human health, even at low concentrations, the development of a sensitive and rapid method for the monitoring of microcystin‐LR (MC‐LR) in water samples is of great importance. In this context, a new direct electrochemical nano‐immunosensor for MC‐LR detection using the liquid crystal (E)‐1‐decyl‐4‐[(4‐decyloxyphenyl)diazenyl]pyridinium bromide (Br‐Py) as a redox probe and gold nanoparticles stabilized in bovine serum albumin (AuNP‐BSA) is described herein. The microcystin‐LR antibody (anti‐MC‐LR) was covalently immobilized using N‐(3‐dimethylaminopropyl)‐N‐ethylcarbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS) on an AuNP‐BSA/BrPy film. The proposed sensor response is based on the inhibition of the Br‐Py electrochemical signal after the specific interaction of MC‐LR with immobilized anti‐MC‐LR on the electrode surface. The electrochemical behavior of the immunosensor was studied by square‐wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, using SWV and an incubation time of 15 min, the immunosensor exhibits a linear response to MC‐LR concentrations of 0.05 to 500.0 ng mL−1 with a detection limit of 0.05 ng mL−1. The anti‐MC‐LR/AuNP‐BSA/Br‐Py/GCE was successfully applied in the determination of MC‐LR in spiked seawater samples.  相似文献   

7.
An electrochemical sensor based on electropolymerizing o‐phenylenediamine (o‐PD) on a glassy carbon electrode (GCE) was developed for determination of reducing sugars. The molecular imprinted sensor was tested by differential pulse voltammetry (DPV) to verify the changes in peak currents of hexacyanoferrate. Under the optimum analytical conditions, the current change was linear to the logarithm of glucose and fructose concentration from 0.25 to 25 µM. The detection limit of glucose and fructose were 0.185 µM and 0.173 µM, respectively. Besides, the applicability of the sensitive sensor has been successfully evaluated by determining reducing sugars in the samples from sugarcane industries.  相似文献   

8.
《Electroanalysis》2018,30(8):1774-1780
This study presents a new approach for an electrochemical immunoassay using gold nanoparticle (AuNP)‐labeled antibodies and pre‐oxidation and reduction processes, followed by open circuit potential (OCP) measurement. Detection of the pregnancy marker, human chorionic gonadotropin hormone (hCG), was used as a model. After preparation of a sandwich‐type immunosystem, the pre‐oxidation and reduction processes were applied, followed by OCP detection. The applied potential and time period were studied for the optimization of pre‐oxidation and reduction processes. We observed that the pre‐oxidation potential of 1.2 V for 60 s and reduction potential of −0.2 V for 30 s provided the highest OCP signal. The detection limit was 79 pg/mL using the optimal conditions. This system could be applied to a simplified and miniaturized diagnostic system for integration in compact analytical devices.  相似文献   

9.
A mixed‐valence cluster of cobalt(II) hexacyanoferrate and fullerene C60‐enzyme‐based electrochemical glucose sensor was developed. A water insoluble fullerene C60‐glucose oxidase (C60‐GOD) was prepared and applied as an immobilized enzyme on a glassy carbon electrode with cobalt(II) hexacyanoferrate for analysis of glucose. The glucose in 0.1 M KCl/phosphate buffer solution at pH = 6 was measured with an applied electrode potential at 0.0 mV (vs Ag/AgCl reference electrode). The C60‐GOD‐based electrochemical glucose sensor exhibited efficient electro‐catalytic activity toward the liberated hydrogen peroxide and allowed cathodic detection of glucose. The C60‐GOD electrochemical glucose sensor also showed quite good selectivity to glucose with no interference from easily oxidizable biospecies, e.g. uric acid, ascorbic acid, cysteine, tyrosine, acetaminophen and galactose. The current of H2O2 reduced by cobalt(II) hexacyanoferrate was found to be proportional to the concentration of glucose in aqueous solutions. The immobilized C60‐GOD enzyme‐based glucose sensor exhibited a good linear response up to 8 mM glucose with a sensitivity of 5.60 × 102 nA/mM and a quite short response time of 5 sec. The C60‐GOD‐based glucose sensor also showed a good sensitivity with a detection limit of 1.6 × 10‐6 M and a high reproducibility with a relative standard deviation (RSD) of 4.26%. Effects of pH and temperature on the responses of the immobilized C60‐GOD/cobalt(II) hexacyanoferrate‐based electrochemical glucose sensor were also studied and discussed.  相似文献   

10.
Mediator free enzyme sensor has been fabricated by covalently immobilizing cholesterol oxidase (ChOx) onto 11‐mercaptoundecanoic acid functionalized gold nanoparticles (MUDA‐AuNPs) – octadecylamine (ODA) hybrid Langmuir–Blodgett film. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies reveal that MUDA‐AuNP/ODA LB film has good affinity for ChOx and provides favorable microenvironment for direct electron transfer between enzyme and electrode. Interference free estimation of cholesterol has been realized at 0.3 V with linear range from 25 to 500 mg/dL, detection limit of 23.38 mg/dL, sensitivity of 1.085 μA mM?1 and response time of 20 s at pH 7.0.  相似文献   

11.
《Electroanalysis》2018,30(8):1811-1819
Novel copper‐palladium nanoparticles modified glassy carbon electrodes (Cu−Pd/GC) with enhanced nonenzymatic sensing for glucose were facilely prepared by one‐step electrodeposition. The structure and composition of the prepared nanoparticles were characterized by XRD, SEM, TEM and EDS, respectively. The electrode modified process was characterized by electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometric experiments were used to evaluate the electrocatalytic activities of the electrodes toward glucose. The surface morphology and the electrocatalytic activities of Cu−Pd/GC was compared to Pd and Cu nanoparticles modified glassy carbon electrodes (Pd/GC and Cu/GC), respectively. Thanks to homogeneous distribution of Cu−Pd nanoparticles and the synergistic effect of Cu and Pd atoms, Cu−Pd/GC exhibited the highest sensitivity (298 μA mM−1 cm−2) and the widest linear amperometric response (0.01 mM to 9.6 mM, R2=0.996) toward glucose compared to Pd/GC and Cu/GC. The detection limit of Cu−Pd/GC was 0.32 μM (S/N=3). In addition, the as‐prepared Cu−Pd/GC glucose sensor also exhibited exceptional capabilities of anti‐interference, reproducibility and long‐term stability. The as‐prepared sensor was also evaluated for determination of glucose concentration in human blood serum samples, which exhibited high reliability and accuracy, having great potential in clinical application.  相似文献   

12.
We report here a nonenzymatic sensor by using a nanoporous platinum electrode to detect glucose directly. The electrode was fabricated by electrochemical deposition and dissolution of PtZn alloy in zinc chloride‐1‐ethyl‐3‐methylimidazolium chloride (ZnCl2‐EMIC) ionic liquid. Both SEM and electrochemical studies showed the evidences for the nanoporous characteristics of the as‐prepared Pt electrodes. Amperometric measurements allow observation of the electrochemical oxidation of glucose at 0.4 V (vs. Ag/AgCl) in pH 7.4 phosphate buffer solution. The sensor also demonstrates significant reproducibility in glucose detection; the higher the roughness factor of the Pt electrode, the lower the detection limit of glucose. The interfering species such as ascorbic acid and p‐acetamidophenol can be avoided by using a Pt electrode with a high roughness factor of 151. Overall, the nanoporous Pt electrode is promising for enzymeless detection of glucose at physiological condition.  相似文献   

13.
《Electroanalysis》2017,29(10):2401-2409
Copper nanoparticles (nano‐Cu) were electrodeposited on the surface of glassy carbon electrode (GCE) potentiostatically at −0.6 V vs. Ag/AgCl for 60 s. The developed nano‐copper modified glassy carbon electrode (nano‐Cu/GCE) was optimized and utilized for electrochemical assay of chemical oxygen demand (COD) using glycine as a standard. The surface morphology and chemical composition of nano‐Cu/GCE were investigated using scanning electron microscope (SEM) and energy dispersive X‐ray spectrometer (EDX), respectively. The electrochemical behavior was investigated using linear sweep voltammetry (LSV) which is characterized by a remarkable anodic peak at ∼0.6 V, compared to bare GCE. This indicates that nano‐Cu enhances significantly the electrochemical oxidation of glycine. The effect of different deposition parameters, such as Cu2+ concentration, deposition potential, deposition time, pH, and scan rate on the response of the developed sensor were investigated. The optimized nano‐Cu/GCE based COD sensor exhibited a linear range of 15 to 629.3 ppm, and a lower limit of detection (LOD) of 1.7 ppm (S/N=3). This developed method exhibited high tolerance level to chloride ion (0.35 M chloride ion has minimal influence). The analytical utility of the prepared COD sensor was demonstrated by investigating the COD recovery (99.8±4.3) and the assay of COD in different water samples. The results obtained were verified using the standard dichromate method.  相似文献   

14.
《Electroanalysis》2017,29(12):2708-2718
An inexpensive stability−indicating anodic voltammetric method for rapid determination of two non‐classical β ‐lactam antibiotics; Meropenem (MP) and Ertapenem (EP) has been developed and validated. The method was based on the enhancement of voltammetric response at a disposable graphite pencil electrode (GPE). Differential pulse voltammetric (DPV) method was developed for quantification of both drugs in B−R buffer solution (pH 2.0) at GPE. The GPE displayed very good voltammetric behavior with significant enhancement of the peak current compared to glassy carbon electrode (GCE). Stress stability studies were performed using 0.5 M of either HCl or NaOH and H2O2. Mass and infrared spectroscopy were used for identification of degradants and their pathways were illustrated. Under optimal conditions, the peak currents showed a linear dependence with drug concentrations. The achieved limits of detection (LOD) were 1.23, 2.07 and 1.50 μM for MP and two waves of EP, respectively. The developed voltammetric method was successfully applied for direct determination of MP and EP in drug substances, pharmaceutical vials and in presence of either their corresponding hydrolytic, oxidative‐degradants or interfering substances with no potential interferences. The differential pulse voltammograms were highly advantageous and applicable in QC laboratories for rapid, selective micro‐determination of MP and EP.  相似文献   

15.
An electrochemically treated graphite pencil electrode (PGPE) has been simply prepared for trace level determination of α‐naphthol. The pretreatment of GPE surfaces is conducted in 0.8 M NaOH by cycling the potential between +1.3 and +1.9 V for 50 CV segments at a scan rate of 100 mV s?1. The influence of the pretreatment is studied extensively, and optimum conditions are obtained. Linear sweep anodic stripping voltammetry (LSASV) is used for the determination of α‐naphthol. Based on the constructed calibration curve, a linear range of 0.01 μM to 2.0 μM with a detection limit of 1.5 nM (S/N=3) is obtained. The results reveal that the electrochemical treatment of the GPE surface improves its electrochemical catalytic activity with reference to surfaces of the non‐treated GPE. The present method is applied for the determination of trace α‐naphthol in real water samples.  相似文献   

16.
《Electroanalysis》2017,29(10):2307-2315
A disposable sandwich‐type electrochemical sensor for selective detection of glucose was established. The primary receptor, 3‐aminophenylboronic acid was grafted covalently onto the surface of screen‐printed carbon electrodes through an in situ‐generated diazo‐reaction. Glucose was first captured by boronic acid group on the electrode, followed by captureing an electroactive ferroceneboronic acid (FcBA) as the secondary receptor to form bidentate glucose‐boronic complex. Electrochemical impedance spectroscopy was applied to characterize the construction of sandwich‐type disposable sensor. In the sandwich assay, current response of captured FcBA on the electrode was dependent on the concentration of glucose. The sandwich assay showed higher selectivity for glucose than that for fructose, mannose, galactose and other electroactive interferences including uric acid, ascorbic acid and dopamine, and exhibited a dynamic concentration range of glucose from 0.5 to 20.0 mmol L−1. The disposable sensor demonstrated a good reproducibility with 2.2 % relative standard deviation (RSD). In addition, the disposable glucose sensor was used in detection of the trace glucose in the clinical urine samples.  相似文献   

17.
Selective glucose measurement in serum and blood and rapid glucose measurement using nicotinamide adenine dinucleotide (NAD)‐dependent glucose dehydrogenase (NAD‐GDH) are still very challenging. Here, we report a selective and rapid glucose sensor, based on electrochemical‐enzymatic‐enzymatic (ENN) redox cycling involving bis(2,2‐bipyridyl)dichloroosmium(II) [Os(bpy)2Cl2], diaphorase (DI), NAD+, NAD‐GDH, and glucose. DI and Os(bpy)2Cl2 are used to obtain fast mediated oxidation of NADH that is generated as a result of glucose oxidation by NAD‐GDH. DI and NAD‐GDH are co‐immobilized via affinity binding on an avidin‐modified indium tin oxide electrode to obtain fast and stable ENN redox cycling. Two enzymes (DI and NAD‐GDH) and two electron mediators [Os(bpy)2Cl2 and NAD+] are insensitive to oxygen. The applied potential (0.0 V vs Ag/AgCl) is low enough to minimize interfering electrochemical reactions, and the redox reactions of Os(bpy)2Cl2 with interfering species are slow. NAD‐GDH is much less reactive to problematic monosaccharides such as xylose, fructose, galactose, and mannose than glucose. Artificial serum containing 5 % (w/v) human serum albumin shows a similar electrochemical background level in serum. All results enable us to obtain selective and reproducible glucose detection. The fast ENN redox cycling allows sensitive glucose detection with a wide range of concentrations in artificial serum with a short measuring time (5 s) without an incubation period.  相似文献   

18.
《Electroanalysis》2017,29(10):2340-2347
This paper proposes the use of the boron‐doped diamond electrode (BDDE) in flow and batch injection analysis (FIA and BIA) systems with multiple‐pulse amperometric (MPA) detection for the determination of warfarin (WA) in pharmaceutical formulations. The electrochemical behavior of WA obtained by cyclic voltammetry (CV) in 0.1 mol L−1 phosphate buffer shows an irreversible oxidation process at +1.0 V (vs Ag/AgCl). The MPA was based on the application of two sequential potential pulses as a function of time on BDDE: (1) for WA detection at +1.2 V/100 ms and; (2) for electrode surface cleaning at −0.2 V/200 ms. Both hydrodynamic systems (FIA‐MPA and BIA‐MPA) used for WA determination achieved high precision (with relative standard deviations around 2 %, n =10), wide linear range (2.0−400.0 μmol L−1), low limits of detection (0.5 μmol L−1) and good analytical frequency (94 h−1 for FIA and 130 h−1 for BIA). The WA determination made by the proposed methods was compared to the official spectrophotometric method. The FIA‐MPA and BIA‐MPA methods are simple and fast, being an attractive option for WA routine analysis in pharmaceutical industries.  相似文献   

19.
《Electroanalysis》2018,30(8):1880-1885
This work presents a simple and low‐cost method for fast and selective determination of Verapamil (VP) in tablets and human urine samples using a boron‐doped diamond working electrode (BDD) coupled to a flow injection analysis system with multiple pulse amperometric detection (FIA‐MPA). The electrochemical behaviour of VP in 0.1 mol L−1 sulfuric acid showed three merged oxidation peaks at around +1.4 V and upon reverse scan, one reduction peak at 0.0 V (vs. Ag/AgCl). The MPA detection was performed applying a sequence of three potential pulses on BDD electrode: (1) at +1.6 V for VP oxidation, (2) at +0.2 V for reduction of the oxidized product and (3) at +0.1 V for cleaning of the working electrode surface. The FIA system was optimized with injection volume of 150 μL and flow rate of 3.5 mL min−1. The method showed a linear range from 0.8 to 40.0 μmol L−1 (R>0.99) with a low limit of detection of 0.16 μmol L−1, good repeatability (RSD<2.2 %; n=10) and sample throughput (45 h−1). Selective determination of VP in urine was performed at+0.2 V due to absence of interference from ascorbic and uric acids in this potential. The addition‐recovery tests in both samples were close to 100 % and the results were similar to an official method.  相似文献   

20.
《Electroanalysis》2018,30(3):474-478
A non‐enzymatic electrochemical glucose sensor based on a Cu‐based metal‐organic framework (Cu‐MOF) modified electrode was developed. The Cu‐MOF was prepared by a simple ionothermal synthesis, and the characterizations of the Cu‐MOF were studied by Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), single‐crystal X‐ray powder diffraction (SCXRD), and X‐ray powder diffraction (XRD). Electrochemical behaviors of the Cu‐MOF modified electrode to glucose were measured by differential pulse voltammetry (DPV). The electrochemical results showed that the Cu‐MOF modified electrode exhibited an excellent electro‐catalytic oxidation towards glucose in the range of 0.06 μM to 5 mM with a sensitivity of 89 μA/mM cm2 and a detection limit of 10.5 nM. Moreover, the fabricated sensor showed a high selectivity to the oxidation of glucose in coexistence with other interferences. The sensor was satisfactorily applied to the determination of glucose in urine samples. With the significant electrochemical performances, MOFs may provide a suitable platform in the construction of kinds of electrochemical sensors and/or biosensors and hold a great promise for sensing applications.  相似文献   

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