2D-titanium carbide (MXene) based selective electrochemical sensor for simultaneous detection of ascorbic acid,dopamine and uric acid

Two-dimensional (2D) titanium carbide (MXene) nanosheets exhibited excellent conductivity,flexibility,high volumetric capacity,hydrophilic surface,thermal stability,etc.So,it has been exploited in various applications.Herein,we report synthesis of mixed phase 2D MXene as a catalytic material for simultaneous detection of important biomolecules such as ascorbic acid (AA),dopamine (DA) and uric acid (UA),Crystalline structure,surface morphology and elemental composition of mixed phase titanium carbide (Ti-C-Tx) MXene (Tx =-F,-OH,or-O) nanosheets were confirmed by X-ray diffraction (XRD),Raman spectroscopy,high-resolution transmission electron microscopy (HR-TEM),high-resolution scanning electron microscopy (HR-SEM) and Energy-dispersive X-ray spectroscopy (EDS) mapping analysis.Furthermore,Ti-C-Tx modified glassy carbon electrode (GCE) was prepared and its electrochemical properties are studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).It was found that Ti-C-Tx modified GCE (Ti-C-Tx/GCE) showed excellent electrocatalytic activity and separated oxidation peaks of important biomolecules such as AA (at 0.01 V),DA (at 0.21 V) and UA (at 0.33 V).Also,Ti-C-Tx/GCE sensor is enabled their simultaneous detection in physiological pH from 100 to 1000 μM for AA,0.5-50 μM for DA and 0.5-4 μM & 100-1500 μM for UA.The limit ofdetection's (LOD) was estimated as 4.6 μM,0.06 μM and 0.075 μM for AA,DA and UA,respectively.Moreover,real sample analysis indicated that spiked AA,DA and UA can be determined accurately by Ti-C-Tx/GCE with the recovery ratio in the range between 100.5％-103％ in human urine samples.The proposed Ti-C-Tx modified electrode exhibited good stability,selectivity and reproducibility as an electrochemical sensor for the detection ofAA,DA and UA molecules.     

Nano‐biosensor based on reduced graphene oxide and gold nanoparticles,for detection of phenylketonuria‐associated DNA mutation

Phenylketonuria (PKU)‐associated DNA mutation in newborn children can be harmful to his health and early detection is the best way to inhibit consequences. A novel electrochemical nano‐biosensor was developed for PKU detection, based on signal amplification using nanomaterials, e.g. gold nanoparticles (AuNPs) decorated on the reduced graphene oxide sheet on the screen‐printed carbon electrode. The fabrication steps were checked by field emission scanning electron microscope imaging as well as cyclic voltammetry analysis. The specific alkanethiol single‐stranded DNA probes were attached by self‐assembly methodology on the AuNPs surface and Oracet blue was used as an intercalating electrochemical label. The results showed the detection limit of 21.3 fM and the dynamic range of 80–1200 fM. Moreover, the selectivity results represented a great specificity of the nano‐biosensor for its specific target DNA oligo versus other non‐specific sequences. The real sample simulation was performed successfully with almost no difference than a synthetic buffer solution environment.Inspec keywords: biosensors, nanosensors, nanoparticles, graphene compounds, gold, nanomedicine, DNA, molecular biophysics, biomedical equipment, electrochemical sensors, electrochemical electrodes, field emission scanning electron microscopy, voltammetry (chemical analysis), self‐assembly, biochemistryOther keywords: reduced graphene oxide, gold nanoparticles, phenylketonuria‐associated DNA mutation, newborn children, electrochemical nanobiosensor, signal amplification, nanomaterials, reduced graphene oxide sheet, screen‐printed carbon electrode, field emission scanning electron microscopy imaging, cyclic voltammetry, alkanethiol single‐stranded DNA probes, self‐assembly methodology, Oracet blue, intercalating electrochemical label, Au‐CO     

Multicenter uric acid biosensor based on tetrapod-shaped ZnO nanostructures

In this work, we developed a tetrapod-shaped ZnO nanostructure (T-ZnO) biosensor to determine uric acid (UA), which is the primary end product of purine metabolism. The as-fabricated UA sensor presents a higher performance than that of the reported biosensors based on ZnO nanorods and ZnS quantum dots, etc. High-quality ZnO nanotetrapods were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectra (EDX), X-ray diffraction (XRD) and Raman spectroscopy, respectively. A high affinity of uricase/ZnO to UA was revealed by cyclic voltammograms. The biosensor performance has been systematically investigated by amperometric response measurements. A fast current response time is within 9 s. It was also found that the uricase/T-ZnO biosensor presented a high and reproducible sensitivity of 80.0 microA cm(-2) mM(-1) and an experiment limit of detection of 0.8 microM. This study provides an insight utilizing the unique ZnO nanostructure to develop the highly sensitive and rapidly responsive nano-bio devices.     

Synthesis of composite material of cobalt oxide (Co3O4) with hydroxide functionalized multi-walled carbon nanotubes (MWCNTs) for electrochemical determination of uric acid

The gout is mainly found due to accumulation of uric acid crystals into the joints which produces the inflammatory symptoms. Thus, it is highly demanded to detect uric acid from our body. Herein, we prepare a composite material of cobalt oxide (Co₃O₄) with hydroxide functionalized multi-walled carbon nanotubes (MWCNTs) by hydrothermal method. The composite material is used for the modification of glassy carbon electrode (GCE) and investigated for the electrochemical determination of uric acid (UA). The analytical techniques such as scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Fourier Infra-red spectroscopy (FTIR) are used to characterize the composite material. The Co₃O₄ exhibits a dendrite morphology and very well chemically coupled with MWCNTs. The elemental analysis confirms the presence of cobalt (Co), oxygen (O) and carbon (C) as main constituent of the composite material. The Co₃O₄ exhibitsa cubic unit cell crystallography in the composite system. The FTIR study reveals the characteristic bands of Co–O bands in the composite material. The cyclic voltammetry isused to study the electrochemical properties of prepared materials. The composite sample with highest percentage of MWCNTs shows an excellent electrochemical activity towards the oxidation of uric acid in phosphate buffer solution pH 7.3. The enzyme free uric acid sensor possesses a linear range of 0.1 mM to 3 mM with a quantified limit of detection of 0.005?±?0.0023 mM. The modified electrode is stable, selective, and very sensitive towards uric acid, therefore it may be used for the monitoring of uric acid from clinical samples. The proposed composite material can be of great interest for energy and biomedical fields.

     

Facile synthesis of gold nanoparticles using carbon dots for electrochemical detection of neurotransmitter,dopamine in human serum and as a chemocatalyst for nitroaromatic reduction

Herein, the authors reported a carbon dots mediated synthesis of gold nanoparticles (AuNPs) at room temperature. Transmission electron microscopy revealed that the AuNPs are spherical in shape with a size of 10 nm. As‐prepared AuNPs was immobilised on carbon paste electrode and subjected to electrochemical sensing of an important neurotransmitter dopamine. Differential pulse voltammetry studies revealed sensitive and selective determination of dopamine in the presence of commonly interfering ascorbic acid and uric acid. The linear detection range was 10–600 μM and the limit of detection was 0.7 ± 0.18 μM. The practical application was demonstrated by measuring dopamine in human blood serum and urine samples. The catalytic activity of AuNPs was evaluated by sodium borohydride mediated reduction of nitroaromatic compounds. The reduction kinetics was found to be pseudo‐first‐order kinetics. All the tested nitroaromatics reduced to corresponding amines in <10 min.Inspec keywords: voltammetry (chemical analysis), electrochemical sensors, biosensors, nanosensors, reduction (chemical), organic compounds, nanofabrication, gold, catalysis, transmission electron microscopy, electrochemical electrodes, blood, nanoparticles, carbon, chemical variables measurement, catalysts, particle sizeOther keywords: nitroaromatic compounds, reduction kinetics, gold nanoparticles, chemocatalyst, nitroaromatic reduction, carbon dots mediated synthesis, room temperature, transmission electron microscopy, carbon paste electrode, electrochemical sensing, ascorbic acid, uric acid, linear detection range, human blood serum, urine samples, sodium borohydride mediated reduction, neurotransmitter dopamine, differential pulse voltammetry, catalytic activity, pseudofirst‐order kinetics, amines, temperature 293 K to 298 K, C‐Au     

硫氮共掺杂石墨烯修饰电极的制备及电化学性能研究

以天然鳞片石墨为原料,采用改进的Hummers法制备了氧化石墨(GO),以GO和硫氰酸铵为前驱体,采用一步水热法制备了硫氮共掺杂石墨烯(SNG)。X射线衍射、扫描电子显微镜和拉曼光谱分析结果显示,硫和氮成功掺入石墨烯晶格中,SNG表面褶皱明显且形成了三维孔道结构。通过交流阻抗、循环伏安法和差分脉冲伏安法考察了对苯二酚(HQ)、邻苯二酚(CC)和间苯二酚(RC)在修饰玻碳电极(SNG-180/GCE)上的电化学行为。结果表明:硫氮共掺杂能有效改善石墨烯的电化学性能,修饰电极实现了对HQ、CC和RC的同时检测,线性范围在5.5~43.06μmol/L和90.91~245.28μmol/L之间,检出限为1.83μmol/L(信噪比为3)。     

Uricase-catalyzed oxidation of uric acid using an artificial electron acceptor and fabrication of amperometric uric acid sensors with use of a redox ladder polymer.

Electrochemical oxidation of uric acid catalyzed by uricase (uric acid oxidase, UOx; EC 1.7.3.3) was studied using several redox compounds including 5-methylphenazinium (MP) and 1-methoxy-5-methylphenazinium (MMP) as electron acceptors for UOx, which does not contain any redox cofactor. It was found that MP and MMP were useful to mediate electrons from UOx to an electrode in the enzymatic oxidation of uric acid. A novel redox polymer, poly(N-methyl-o-phenylenediamine)(poly-MPD), containing the MP units was also found to possess the mediation ability for UOx, and poly-MPD was immobilized together with UOx onto an electrode substrate covered with a self-assembled monolayer of 2-aminoethanethiolate with use of glutaraldehyde as a binding agent. The resulting electrode (poly-MPD/UOx/Au) exhibited amperometric responses to uric acid with very fast response of approximately 30 s, allowing reagentless amperometric determination in a concentration range covering that in the blood of a healthy human being. Kinetic parameters of the apparent Michaelis constant and the maximum current response obtained at the poly-MPD/UOx/Au suggested that electrochemical oxidation of uric acid was controlled by diffusion of uric acid into the enzyme film and that the redox polymer worked well in mediating between active sites of UOx molecules and the electrode substrate.     

A reduced graphene oxide based electrochemical biosensor for tyrosine detection

In this paper, a 'green' and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5?×?10(-7)?M to 2?×?10(-5)?M with a detection limitation of 7.5?×?10(-8)?M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.     

Conducting polymer‐coated, palladium‐functionalized multi‐walled carbon nanotubes for the electrochemical sensing of hydroxylamine

Electrochemical sensors of hydroxylamine were fabricated on glassy carbon electrodes (GCEs) by the electropolymerization of 3,4‐ethylenedioxypyrrole (EDOP) and 3,4‐ethylenedioxythiophene (EDOT) on palladium (Pd) nanoparticles attached to thiolated multi‐walled carbon nanotubes (MWCNTs), denoted as PEDOP/MWCNT‐Pd/GCE and PEDOT/MWCNT‐Pd/GCE. The sensors were characterized by field emission scanning electron microscopy and electrochemical impedance spectroscopy. They showed strong catalytic activity toward the oxidation of hydroxylamine. Cyclic voltammetry and amperometry were used to characterize the sensors' performances. The detection limits of hydroxylamine by PEDOP/MWCNT‐Pd/GCE and PEDOT/MWCNT‐Pd/GCE were 0.22 and 0.24 μM (S/N = 3), respectively. The sensors' sensitivity, selectivity, and stability were also investigated.     

Peanut skin extract mediated synthesis of gold nanoparticles,silver nanoparticles and gold–silver bionanocomposites for electrochemical Sudan IV sensing

Sustainable methods are needed for rapid and efficient detection of environmental and food pollutants. The Sudan group of dyes has been used extensively as adulterants in food and also are found to be polluting the soil and water bodies. There have been several methods for detection of Sudan dyes, but most of them are not practical enough for common use. In this study, the electrochemical detection efficiency and stability of gold nanoparticle (AuNPs), silver NPs and Au–Ag bionanocomposites, synthesised by peanut skin extract, modified glassy carbon electrode has been investigated. The synthesised nanomaterial samples were characterised, for their quality and quantity, using ultra–visible spectroscopy, inductive coupled plasma mass spectrophotometer, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, high‐resolution transmission electron microscope and field emission scanning electron microscope. The nanomaterial hybrid electrodes showed great efficiency and stability in the detection of Sudan IV compared with the other previous electrodes. The peak current of the Sudan IV oxidation and reduction was found to be proportional to its concentration, in the range of 10–80 µM, with a detection limit of 4 µM. The hybrid electrodes showed 90% stability in detection for 20 cycles.Inspec keywords: gold, silver, nanoparticles, nanocomposites, biomedical materials, electrochemical sensors, dyes, nanofabrication, ultraviolet spectra, visible spectra, spectrophotometry, Fourier transform infrared spectra, X‐ray chemical analysis, transmission electron microscopy, scanning electron microscopy, field emission electron microscopyOther keywords: peanut skin extract mediated synthesis, gold nanoparticles, silver nanoparticles, gold–silver bionanocomposites, electrochemical Sudan IV sensing, electrochemical detection efficiency, modified glassy carbon electrode, ultra–visible spectroscopy, inductive coupled plasma mass spectrophotometer, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, high‐resolution transmission electron microscope, field emission scanning electron microscope, oxidation, reduction, detection limit, Au, Ag, Au‐Ag     

Development of a modified electrode with amine-functionalized TiO2/multi-walled carbon nanotubes nanocomposite for electrochemical sensing of the atypical neuroleptic drug olanzapine

In this work, using of amine-functionalized TiO₂/multi-walled carbon nanotubes (NH₂-TiO₂-MWCNTs) nanocomposite for modification of glassy carbon electrode (GCE) was investigated. The nanocomposite was characterized by Fourier transformed infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The efficiency of modified electrode for electrocatalytic the oxidation of olanzapine was studied by cyclic voltammetry, square wave voltammetry and chronoamperometry. The electrochemical measurements were carried out in phosphate-buffered solution (PBS, pH 5.0). The NH₂-TiO₂-MWCNTs/GCE provided high surface area and more sensitive performance. The charge transfer coefficient (α) and the apparent charge transfer rate constant (k_s) were calculated to be equal to 0.42 and 0.173 s^? 1, respectively. The square wave voltammetry exhibited two linear dynamic ranges and a detection limit of 0.09 μM of olanzapine. In addition, the modified electrode was employed for the determination of olanzapine in pharmaceutical and human blood serum samples in order to illustrate the applicability of proposed method.     

Impedance spectroscopy and affinity measurement of specific antibody–antigen interaction

We use impedance spectroscopy technique to develop a rapid and sensitive antigen biosensor. The biosensor is based on the immobilization of antibodies onto an 11-Mercaptoundecanoic acid self-assembled monolayer. The high insulating properties of the thiol can be measured with cyclic voltammetry and impedance spectroscopy with a redox couple. The, the modified gold electrode is activated with 1-ethyl-3 (3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) ester for antibody immobilisation. The affinity interaction of the antigen–antibody can be measured with quartz crystal microbalance technique. Dissociation and association constant are determined by applying a Fortran program fitting for the experimental data.     

Synthesis and characterization of α-Fe2O3/polyaniline nanotube composite as electrochemical sensor for uric acid detection

We report the synthesis of α-Fe₂O₃/polyaniline nanotube (PAn NTs) composite as an electrochemical sensor for uric acid (UA) detection. Field emission scanning electron microscopy (FESEM) indicates a hexagonal shape of the α-Fe₂O₃ while a nanotube morphology of the PAn. Impedance spectroscopy results confirm a significant decrease in the charge transfer resistance of the glassy carbon electrode (GCE) modified with α-Fe₂O₃/PAn NTs due to the presence of PAn NTs. The results show that the increase in the conductivity of α-Fe₂O₃ in the presence of PAnNTs could improve the catalytic performance of α-Fe₂O₃/PAn NTs composite, compared to the pure α-Fe₂O₃ nanoparticles. From differential pulse voltammetry, a linear working range for the concentration of UA between 0.01?µM and 5?µM, with a LOD of 0.038?µM (S/N?=?3) was obtained. The sensitivity of the linear segment is 0.433?μA?µM^?1. The reliability of the modified electrode towards the detection of UA was investigated in the presence of interfering acids such as ascorbic acid, citric acid and succinic acid.     

Electrochemical studies of cystine modified self-assembled monolayer for Escherichia coli detection

An electrochemical DNA biosensor based on cystine modified self-assembled monolayer (cys-SAM) onto gold electrode (AuE) has been fabricated for Escherichia coli (E. coli) detection. This biosensing electrode has been characterized using scanning electron microscopy (SEM), FT-IR spectroscopy, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, this DNA biosensor can be used to detect complementary target DNA concentration in the range of 1 × 10^− 6 M to 1 × 10^− 20 M within 60 s of hybridization time at 25 °C and has been found to be stable for about four months when stored at 4 °C.     

{H3[PMo12O40]/Pt/PAMAM}复合膜的制备及对甲醇的电催化氧化

采用循环伏安法在玻碳电极上制备了{H3[PMo12O40]/Pt/PAMAM}复合膜,用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、电子能谱技术(EDS)、原子力显微镜(AFM)和循环伏安法(CV)研究了膜的组成、形貌及其对甲醇的电催化氧化活性。结果表明,Pt纳米粒子在PAMAM基底上分散均匀;最外层沉积H3[PMo12O40]后,与相同条件下制备的Pt/PAMAM膜相比,{H3[PMo12O40]/Pt/PAMAM}复合膜修饰电极对甲醇的氧化有更强的电催化活性。     

Simultaneous determination of 3,4-dihydroxyphenylacetic acid, uric acid and ascorbic acid by poly(L-arginine)/multi-walled carbon nanotubes composite film

The poly(L-Arginine)(PArg)-multiwalled carbon nanotubes (MWCNTs) composite film was used to modify glassy carbon electrode (GCE) to fabricate PArg/MWCNTs/GCE through electropolymerization of L-Arginine on MWCNTs/GCE. The PArg/MWCNTs/GCE exhibited high electro-catalytic activities towards the oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC), uric acid (UA), and ascorbic acid (AA), and could be sensitively used for simultaneous determination of DOPAC, AA, and UA in pH 7.4 phosphate-buffered solution (PBS).The linear ranges were 7 microM to 2.7 mM for DOPAC, 3 microM to 1.2 mM for UA, and 70 microM to 1.4 mM for AA. The detection limits were 1.3 microM for DOPAC, 0.7 microM for UA and 20 microM for AA.     

Electrochemical sensor to detect neurotransmitter using gold nano-island coated ITO electrode

Parkinson disease is a chronic neurodegenerative disorder characterized by the loss of dopamine, which is a neurotransmitter in the substantia nigra. In this study, a simple, rapid and inexpensive method to fabricate gold nano-island film (GNIF) coated ITO electrode has been developed based on electrochemical deposition of Au onto ITO substrate. The nanostructured film surface was characterized by scanning electron microscopy (SEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to evaluate the electrochemical behavior of induvidul dopamine and uric acid solution were studied. Moreover, GNIF/ITO electrode was applied to detecte DA in the presence of Bovine Serum Albumin (50 microM) as an interference. These results demonstrate that, interfering component has no effect on the determination of DA at GNIF electrode, hence this GNIF electrode is suitable for the determination of DA with high sensitivity and selectivity. Then, GNIF coated ITO electrode was applied to monitor the electrochemical simultaneous detection of dopamine and uric acid mixtures based on CV and DPV with high sensitivity. GNIF-modified ITO electrode showed a linear range for the determination of dopamine concentration from 0.1 microM to 40 microM in the presence of 50 microM of uric acid. Based on these results, the proposed technique can be a promising method to construct a highly sensitive biosensor as well as highly efficient protein chip.     

A biomimetic phospholipid/alkanethiolate bilayer immobilizing uricase and an electron mediator on an Au electrode for amperometric determination of uric acid.

A biomimetic bilayer membrane immobilizing uricase (urate oxidase; EC 1.7.3.3) (UOx) and a redox agent of 1-methoxy-5-methylphenazinium (MMP) was fabricated on an Au electrode substrate with use of the Au substrate coated with a self-assembled monolayer of n-octanethiolate (OT/Au) and L-alpha-phosphatidylcholine beta-oleoyl-gamma-palmitoyl (PCOP). The preparation was carried out by successively immersing an Au electrode substrate in an ethanol solution of OT, an MMP aqueous solution, and a suspension of proteoliposome formed by PCOP containing UOx and MMP. The prepared electrode exhibited such fast steady amperometric responses to uric acid as to allow its determination within 20 s after injecting uric acid, indicating that UOx-catalyzed electrochemical oxidation of uric acid was accomplished with assistance of electron mediation by MMP between UOx and the Au substrate. An increase in the response currents with increasing concentration of uric acid was obtained in a concentration range of uric acid found in healthy human blood. Any interference in the current response that is caused by direct anodic oxidation of uric acid or ascorbic acid was not observed at the prepared sensor electrode because the densely packed bilayer effectively blocked the diffusion of these substrates toward the Au surface, making it possible to determine amperometrically uric acid at the electrode with high precision.     

Gold nanoparticles/graphene oxide composite for electrochemical sensing of hydroxylamine and hydrogen peroxide

It has been discovered that the complex formed by cetyltrimethyl ammonium bromide (CTAB) and graphene oxide (GO) is highly stable in aqueous solution and adhesive to the glassy carbon electrode (GCE) surface in our previous research. In this work, the film of CTAB/GO complex was directly formed on GCE and gold nanoparticles were facilely incorporated into the matrix of CTAB/GO complex at the same time. Scanning electron microscopic (SEM) investigation shows that gold nanoparticles were distributed uniformly on the sheets of graphene. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry were used to investigate the electrochemical behaviors of AuNP/CTAB/GO. The obtained AuNP/CTAB/GO presents excellent catalytic capabilities towards the oxidation of hydroxylamine (HA) and the reduction of H₂O₂. The oxidation current of HA and the reduction current of H₂O₂ are linear with their concentrations in the range of 10～1000 μM and 1.0～5000 μM, respectively. The detection limits for HA and H₂O₂ are 3.5 μM and 0.67 μM, respectively. The mechanism of the oxidation of HA on AuNP/CTAB/GO modified GCE was also studied.     

纳米TiO2/还原石墨烯复合修饰电极用于食品中 柠檬黄的检测

为了检测食品中柠檬黄的含量,利用滴涂法和电化学还原法制备纳米TiO_2/还原石墨烯复合修饰玻碳电极(TiO_2-Er GO/GCE)。采用透射电子显微镜和X射线粉末衍射仪对TiO_2和TiO_2-GO两种修饰电极材料进行表征;通过循环伏安法观察了柠檬黄在不同电极上的电化学行为,并对检测条件如p H值、富集电位、富集时间进行了优化。实验结果表明:TiO_2-Er GO/GCE增大了电极的电化学活性面积,提高了柠檬黄的电化学氧化响应;最优的检测条件为p H值为3.7、富集电位为-0.20 V、富集时间为180 s;在最优的检测条件下,采用线性扫描伏安法检测柠檬黄的线性范围为2.0×10-8~2.0×10-5 mol/L,检测限为8.0×10-9 mol/L(信噪比为3)。