Tumor cell membrane-coated continuous electrochemical sensor for GLUT1 inhibitor screening / 药物分析学报

Glucose transporter 1(GLUT1)overexpression in tumor cells is a potential target for drug therapy,but few studies have reported screening GLUT1 inhibitors from natural or synthetic compounds.With cur-rent analysis techniques,it is difficult to accurately monitor the GLUT1 inhibitory effect of drug molecules in real-time.We developed a cell membrane-based glucose sensor(CMGS)that integrated a hydrogel electrode with tumor cell membranes to monitor GLUT1 transmembrane transport and screen for GLUT1 inhibitors in traditional Chinese medicines(TCMs).CMGS is compatible with cell membranes of various origins,including different types of tumors and cell lines with GLUT1 expression knocked down by small interfering RNA or small molecules.Based on CMGS continuous monitoring technique,we inves-tigated the glucose transport kinetics of cell membranes with varying levels of GLUT1 expression.We used CMGS to determine the GLUT1-inhibitory effects of drug monomers with similar structures from Scutellaria baicalensis and catechins families.Results were consistent with those of the cellular glucose uptake test and molecular-docking simulation.CMGS could accurately screen drug molecules in TCMs that inhibit GLUT1,providing a new strategy for studying transmembrane protein-receptor interactions.

A descrição teórica da determinação eletroquímica do fármaco perilartina, assistida pelo oxihidróxido de cobalto, emparelhado com o seu dióxido

Introdução: perilartina é um adoçante natural potente, considerado 2000 vezes mais doce que o açúcar comum. Ela pode ser alérgica para algumas pessoas. Além disso, ela se usa apenas no Japão, o que pressupõe a possibilidade de adulterar produtos japoneses sem o seu uso. Assim, o desenvolvimento de um método eficiente da sua determinação qualificativa e quantificação é realmente atual. Metodologia: um modelo matemático de um processo anódico foi desenvolvido e analisado mediante a teoria de estabilidade linear e análise de bifurcações. O modelo inclui os cenários mais prováveis do andamento do processo eletroanalítico. Resultados: a perilartina é oxidada no meio básico, formando o poliol e o sal do "pseudoácido" correspondente, o que contribui fortemente para a força iônica da dupla camada elétrica. Isto pode ser responsável pela aparição das instabilidades oscilatória e monotônica no processo eletroanalítico. Conclusão: malgrado o supracitado, o compósito é um modificador eficiente para a determinação eletroquímica da perilartina no meio básico.

Introducción: perilartina es un edulcorante natural potente, considerado 2000 veces más dulce que el azúcar común. Esta puede causar alergia a algunas personas. Además, ella solo se usa en Japón, lo que presupone la posibilidad de falsificar productos japoneses sin su uso. Así, el desarrollo de un método eficiente de su determinación cuantitativa y cualitativa es realmente actual. Metodología: un modelo matemático de un proceso anódico fue desarrollado y analizado mediante la teoría de estabilidad lineal e análisis de bifurcaciones. El modelo incluye los escenarios más probables del curso del proceso electroanalítico. Resultados: la perilartinase oxida en el medio básico, formando el poliol y la sal del "pseudoácido" correspondiente, lo que contribuye fuertemente para la fuerza iónica de la doble capa eléctrica. Esto puede ser responsable por la aparición de las inestabilidades oscilatoria y monotónica en el proceso electroanalítico. Conclusión: a pesar de lo mencionado, el compuesto es un modificador eficaz para la determinación electroquímica de la perilartina en el medio básico.

SUMMARY Introduction: Perillartine is a strong natural sweetener, considered 2000 as sweet as a common sugar. It may be allergic to some people. Also, it is used only in Japan, which may presuppose the possibility of falsify Japanese products without its use. Thus the development of an eficiente method of its quantitative and qualitative determination is really actual. Methodology: A mathematical model of an anodic process has been developed and analyzed by means of linear stability theory and bifurcation analysis. The model includes the most probable scenarios of the course of the electroanalytical process. Results: Perillartine is oxidized in basic media, yielding the polyol and the correspondent pseudoacid salt, which strongly contributes to the double electric layer ionic force. This may be responsible for the oscillatory and monotonic instabilities appearance in the electroanalytical process. Conclusion: Despite of the above mentioned statements, the composite is na efficient modifier for the electrochemical determination of perillartine in basic media.

Descripción teórica del desempeño electroanalítico del material compuesto de oxihidróxido de vanadio con el colorante escuárico en la detección de la carfedona

Introducción: en este trabajo se evalúa desde el punto de vista mecanístico teórico el comportamiento electroanalítico del compuesto oxihidróxido de vanadio-colorante escuárico en la detección de la carfedona. El proceso electroanalítico incluye la formación de dos formas de vanadio tetravalente, incluyendo el dióxido de vanadio e ion vanadilo. Método: un mecanismo, capaz de describir el comportamiento del sensor, ha sido sugerido y un modelo matemático fue desarrollado y analizado mediante la teoría de estabilidad lineal y análisis de bifurcaciones. Resultados: el análisis del modelo ha probado que la dependencia lineal entre la concentración del fármaco y el parámetro electroquímico se mantiene firme en la ancha región topo-lógica de parámetros. Las inestabilidades oscilatoria y monotónica suelen realizarse cuando son causadas por influencias fuertes de las etapas química y electroquímica en la capacitancia de la doble capa eléctrica. Conclusiones: el compuesto de nano-partículas de oxihidróxido de vanadio (estabilizadas con el colorante escuárico) puede servir como un modificador eficiente de electrodo para la detección de la carfedona. El oxihidróxido de vanadio desempeña funciones de sustancia activa y el colorante, de la mediadora.

SUMMARY Introduction: In this work, the electroanalytical behavor of the vanadium oxyhydroxide-squaraine dye composite for the carfedon detection is evaluated. The electroanalytical process includes the formation of two tetravalent vanadium forms, including vanadium dioxide and vanadylion. Methods: A mechanism, capable to describe the sensor behavior, has been suggested, and the correspondent mathematical model has been developed and analyzed by means of the linear stability theory and bifurcation analysis. Results: The model analysis has proved that the linear dependence between the drug concentration and the concentration is firmly maintained in a wide topological parameter region. As for the oscillatory and monotonic instabilities, they may be realized, being caused by strong influences of the chemical and electrochemical stages on double electric layer capacitance. Conclusions: The vanadium oxyhydroxide composite with the squaraine dye may serve as an efficient electrode modifier for carfedone determination. The vanadium oxyhydroxide works as an active substance and the dye as a mediator.

Introdução: neste trabalho, avalia-se, do ponto de vista mecanístico teórico, o comportamento eletroanalítico do compósito oxihidróxido do vanádio-corante esquárico na detecção da carfedona. O processo eletroanalítico inclui a formação de duas formas do vanádio tetravalente, incluindo o dióxido de vanádio e íon vanadila. Método: um mecanismo, capaz de descrever o comportamento do sensor, tem sido sugerido e um modelo matemático correspondente, desenvolvido e analisado por meio da teoria de estabilidade linear e análise de bifurcações. Resultados: a análise do modelo tem provado que a dependência linear entre a concentração do fármaco e o parâmetro eletroquímico se mantém firme numa ampla região topológica de parâmetros. Já as instabilidades oscilatória e monotônica soem realizar-se, sendo causadas pelas influências fortes das etapas química e electroquímica na capacitância da dupla camada elétrica. Conclusões: o compósito de nanopartículas do oxihidróxido de vanádio, estabilizadas pelo corante esquárico, pode servir de um modificador eficaz para a detecção da carfedona. O oxihidróxido de vanádio desempenha as funções de substância ativa, e o corante, de mediador.

Nitrogen-doped carbon@TiO2 double-shelled hollow spheres as an electrochemical sensor for simultaneous determination of dopamine and paracetamol in human serum and saliva / 药物分析学报

As the most commonly used antipyretic and analgesic drug,paracetamol(PA)coexists with neuro-transmitter dopamine(DA)in real biological samples.Their simultaneous determination is extremely important for human health,but they also interfere with each other.In order to improve the conductivity,adsorption affinity,sensitivity,and selectivity of TiO2-based electrochemical sensor,N-doped carbon@-TiO2 double-shelled hollow sphere(H-C/N@TiO2)is designed and synthesized by simple alcoholic and hydrothermal method,using polystyrene sphere(PS)as a template.Meanwhile,TiO2 hollow spheres(H-TiO2)or N-doped carbon hollow spheres(H-C/N)are also prepared by the same method.H-C/N@TiO2 has good conductivity,charge separation,and the highly enhanced and stable current responses for the detection of PA and DA.The detection limit and linear range are 50.0 nmol/L and 0.3-50 μmol/L for PA,40.0 nmol/L and 0.3-50 μmol/L for DA,respectively,which are better than those of carbon-based sen-sors.Moreover,this electrochemical sensor,with high selectivity,strong anti-interference,high reli-ability,and long time durability,can be used for the simultaneous detection of PA and DA in human blood serum and saliva.The high electrochemical performance of H-C/N@TiO2 is attributed to the multi-functional combination of different layers,because of good conductivity,absorption and electrons transfer ability from in-situ N-doped carbon and electrocatalytic activity from TiO2.

Construction and performance analysis of a microbial electrochemical sensor for monitoring heavy metals in water environment / 生物工程学报

A microbial fuel cell (MFC)-based microbial electrochemical sensor was developed for real-time on-line monitoring of heavy metals in water environment. The microbial electrochemical sensor was constructed with staggered flow distribution method to optimize the parameters such as external resistance value and external circulation rate. The inhibition of concentration of simulated heavy metal wastewater on voltage under optimal parameters was analyzed. The results showed that the best performance of MFC electrochemical sensor was achieved when the external resistance value was 130 Ω and the external circulation rate was 1.0 mL/min. In this case, the microbial electrochemical sensors were responsive to 1-10 mg/L Cu2+, 0.25-1.25 mg/L Cd2+, 0.25-1.25 mg/L Cr6+ and 0.25-1.00 mg/L Hg2+ within 60 minutes. The maximum rejection rates of the output voltage were 92.95%, 73.11%, 82.76% and 75.80%, respectively, and the linear correlation coefficients were all greater than 0.95. In addition, the microbial electrochemical sensor showed a good biological reproducibility. The good performance for detecting heavy metals by the newly developed microbial electrochemical sensor may facilitate the real-time on-line monitoring of heavy metals in water environment.

A descrição matemática da detecção eletroquímica da ergina, assistida pelos novos derivados triazólicos, dopados pelo íon amavadina / The mathematical description for the ergin electrochemical detection, assisted by amavadin ion doped triazolic derivatives / Descripción matemática de la detección electroquímica de ergina, asistida por los nuevos derivados de triazol, dopados por el ión amavadina

RESUMO Introdução: Pela primeira vez, o processo eletroanalítico da detecção da ergina (LSA) sobre um elétrodo, modificado por um derivado triazólico, dopado pelo íon amavadina, tem sido descrito teoricamente. Métodos: O modelo matemático, correspondente ao desempenho do sensor, tem sido desenvolvido e analisado do ponto de vista da teoria de estabilidade linear. Foi mostrado que a amavadina pode servir de modificador eficiente para a detecção eletroanalítica da ergina. Outrossim, a presença de um material orgânico no modificador reforça a capacidade da ergina de polimerizar-se, formando um compósito polimérico. Resultados: Os comportamentos oscilatório e monotô-nico são mais prováveis que no caso mais comum, haja vista a formação-deformação de compostos iônicos aquando da detecção eletroanalítica.

SUMMARY Introduction: For the first time, the electroanalytical process of ergin (LSA) determination over an electrode, modified by triazolic derivative, doped by an amavadin-ion, has been theoretically described. Methods: The mathematical model, correspondent to the sensor function, has been developed and analyzed by means of linear stability theory. It has been shown that the amavadin may serve as an efficient electrode modifier for the electroanalytical detection of ergin. Moreover, the presence of an organic material as electrode modifier reinforces the possibility of ergin polymerization, yielding a polymer composite. Results: The oscillatory and monotonic behavior is more probable than in the common case, considering the formation and destruction of the ionic compounds during the electroanalytical detection.

RESUMEN Introducción: Por primera vez se ha descrito teóricamente el proceso eletroanalítico de detección de ergina (LSA) en un electrodo, modificado por un derivado triazólico, dopado por el ión amavadina. Métodos: El modelo matemático, correspondiente al rendimiento del sensor, ha sido desarrollado y analizado desde el punto de vista de la teoría de la estabilidad lineal. Se ha demostrado que la amavadina puede servir como un modificador eficaz para la detección eletroanalítica de ergina. Además, la presencia de un material orgánico en el modificador refuerza la capacidad de la ergina para polimerizar, formando un compuesto polimérico. Resultados: Los comportamientos oscilatorios y monótonos son más probables que en el caso más común, dada la formación-deformación de compuestos iónicos durante la detección eletroanalítica.

Descripción matemática de la determinación electroanalítica del fármaco salvarsano y su ciclooligómeros, asistida por un compuesto del colorante escuárico y oxihidróxido de cobalto / The mathematical description of the electroanalytical determination of salvarsan drug and its cyclooligomers, assisted by the composite of squaraine dye with cobalt oxyhydroxide / A descrição matemática da determinação eletroanalítica do fármaco salvarsan e seus ciclo-oligômeros, auxiliada pela composição do corante esquaraína com oxihidróxido de cobalto

RESUMEN Objetivo: En este trabajo se realiza, por primera vez, la evaluación teórica de la posibilidad de la detección electroanalítica de salvarsano, fármaco antisifilítico. El oxihidróxido de cobalto, en su compuesto con el colorante escuárico, se usa como modificador de electrodo. Metodología: Mediante el análisis de estabilidad, se ha confirmado su eficiencia en los procesos de detección de salvarsano. La linearidad de dependencia entre el parámetro electroquímico y la concentración del fármaco se obtiene y se mantiene fácilmente. Conclusión: Las inestabilidades oscilatoria y monotónica se realizan en el sistema, causadas por las influencias de las etapas electroquímicas a las capacitancias de la doble capa eléctrica (DCE).

SUMMARY Aim: In this work, the theoretical evaluation of the electroanalytical detection of antisyphilitic drug salvarsan is given for the first time. Cobalt oxyhydroxide in a composite with the squaraine dye is used as electrode modifier. Methodology: By means of the stability analysis the efficiency of the salvarsan determination is confirmed. The linearity of the dependence between the electrochemical parameter and drug concentration is easily obtained and maintained. Conclusion: The oscillatory and monotonic instabilities are realized in this system, being caused by the electrochemical stages' influences to the double electric layer (DEL).

RESUMO Objetivo: neste trabalho, a avaliação teórica da detecção eletroanalítica do antissifilítico salvarsan é feita pela primeira vez. O oxihidróxido de cobalto em um composto com o corante esquaraína é usado como modificador de eletrodo. Metodologia: por meio da análise de estabilidade é confirmada a eficiência da determinação de salvarsan. A linearidade da dependência entre o parâmetro eletroquímico e a concentração do fármaco é facilmente obtida e mantida. Conclusão: as instabilidades osci-latórias e monotônicas são percebidas neste sistema, sendo causadas pelas influências dos estágios eletroquímicos sobre a dupla camada elétrica (DEL).

Detection of Rutin in Sophorae Immaturus Flos with Electrochemical Sensor Assembled with Gold Nanoparticles/Nafion/Multi-wall Carbon Nanotube / 中国实验方剂学杂志

Objective::A new-type electrochemical sensor was developed by electrodepositing gold nanoparticle on the surface of glassy carbon electrode (GCE) modified by Nafion-multi-wall carbon nanotube (MWNTs) by the potentiostatic method, and used for the detection of rutin in practical samples. Method::The electrochemical properties of the sensor in potassium ferricyanide-potassium ferrocyanide system were studied by electrochemical impedance spectroscopy and cyclic voltammetric method, in order to explore the electrochemical performance of the sensor. The electrochemical behavior of rutin on the surface of the sensor was studied by the cyclic voltammetric method, and the factors affecting the performance of the sensor were optimized. The content of rutin was determined by differential pulse voltammetric methods. Result::The optimized conditions were -0.25 V of the deposition potential of gold nanoparticle, 20 s of the deposition time, pH 3.0, and 6 μL of 1 g·L-1 carbon nanotube. Under the conditions, a good linear relationship between reduction peak current and rutin concentration was obtained from 5.0 ×10-9 to 7.0 ×10-7 mol·L-1, and the detection limit was 3.6×10-9 mol·L-1. Conclusion::The developed sensor has a good electrical conductivity and stability, and is highly sensitive and simple for the detection of rutin, with a low detection limit. It has been successfully applied to the detection of rutin in Sophorae Immaturus Flos with the recoveries between 97.6%and 104.4%, which provides a new method for the determination of rutin and a new idea for the quality control of Chinese medicinal materials.

Descripción teórica de la posibilidad de la detección electroquímica de la gabapentina, asistida por CoO(OH) / The theoretical description for CoO(OH)-assisted gabapentine electrochemical determination

RESUMEN La posibilidad de usar el oxihidróxido del cobalto en la detección electroquímica de la gabapentina ha sido evaluada, y se sugirió un mecanismo del desempeño del analito y del modificador. Este fue desarrollado y analizado (mediante la teoría de estabilidad lineal y análisis de bifurcaciones) un modelo matemático basado en este mecanismo. La evaluación teórica confirma que el oxihidróxido de cobalto puede ser un modificador eficiente para la detección de la gabapentina, a pesar de la hibridez de su mecanismo de oxidación. La posibilidad y las causas de los comportamientos oscilatorio y monotónico también han sido investigadas.

SUMMARY The possibility for the use of cobalt (III) oxyhydroxide in gabapentine electrochemical determination has been evaluated. A mechanism for analyte and modifier function has been suggested. A mathematical model based in this mechanism has been developed and analyzed (by means of linear stability theory and bifurcation analysis). The theoretical evaluation confirms that the cobalt (III) oxyhydroxide may be an efficient modifier for gabapentine electrochemical determination, despite of the hybridity of its oxidation mechanism. The possibility and the causes for oscillatory and monotonic instabilities have also been investigated.

Highly sensitive simultaneous electrochemical determination of myricetin and rutin via solid phase extraction on a ternary Pt@r-GO@MWCNTs nanocomposite / 药物分析学报

The simultaneous electrochemical determination of myricetin and rutin remains a challenge due to their indistinguishable potentials. To solve this problem, we constructed a ternary platinum nanoparticle, reduced graphene oxide, multi-walled carbon nanotubes (Pt@r-GO@MWCNTs) nanocomposite via a facile one-pot synthetic method. Under the optimized conditions, the ternary Pt@r-GO@MWCNTs nanocomposite exhibited good electrocatalytic activity toward myricetin and rutin via solid phase extraction and excellent performance for the simultaneous determination of myricetin and rutin. The oxidation peak current of myricetin was proportional to its concentrations in the range of 0.05-50μM with a detection limit of 0.01μM (S/N = 3). The linear range for rutin was 0.05-50μM with a detection limit of 0.005μM (S/N = 3). The ternary nanocomposite sensor also exhibited good reproducibility and stability, and was successfully used for the simultaneous determination of myricetin and rutin in real orange juice samples with recoveries ranging between 100.57％and 108.46％.

Molecularly Imprinted Polymer Electrochemical Sensor Based on Fe3O4/MnO2 Doped Graphene Composites for Determination of 17β-Estradiol in Aquatic Environment / 分析化学

In this paper, Fe3O4/MnO2doped graphene molecularly imprinted hybrid material ( Fe3O4/MnO2-MIP@ RGO ) was successfully synthesized via reversible addition fragmentation chain transfer ( RAFT ) molecularly imprinting technique by using methacrylic acid as functional monomer, divinylbenzene as cross-linker, Fe3O4/MnO2@ RGO as carrier, and 17β-estradiol ( 17β-E2 ) as template molecule. A novel molecularly imprinting electrochemical sensor by using Fe3O4/MnO2-MIP@ RGO modified electrode was constructed to specifically detect trace 17β-E2 in water. The experimental results showed that the Fe3O4/MnO2-MIP@ RGO electrochemical sensor exhibited rapid and linear current response to 17β-E2 in water samples with a linear range of 4 nmol/L to 0. 8 μmol/L ( R=0. 9852) , the detection limit was 47. 2 pmol/L (3σ) and the relative standard deviation (RSD) was from 2. 1% to 2. 5% . This study provides a simple and efficient, economical and reliable method for the monitoring of 17β-estradiol in the complex water environment.

Flexible Graphene Platform-based Electrochemical Sensor for Sensitive Determination of Dopamine / 分析化学

The chemical vapor deposition grown graphene was transferred onto flexible polyethylene terephthalate surface to fabricate a graphene platform electrode ( GPE) , and gold nanoparticles ( AuNPs) were electrodeposited on GPE to form an AuNPs modified GPE ( AuNPs/GPE ) . The formation of AuNPs was confirmed by scanning electron microscopy ( SEM) , energy dispersive spectrometer ( EDS) , high-resolution transmission electron microscope ( HR-TEM) , X-ray diffraction ( XRD) and Raman spectra. On AuNPs/GPE, dopamine ( DA ) displayed a pair of well-defined redox peaks with highly enhanced peak currents compared with those on GPE. At detection potential of 0. 20 V, AuNPs/GPE sensor presented a wide linear range of 0. 1 μmol/L to 400. 0 μmol/L of DA with a detection limit of 3. 9 nmol/L (S/N=3). In addition, the proposed sensor allowed highly selective and sensitive, stable and fast amperometric sensing of DA.

Electrochemical Dopamine Sensor Based on Multi-Walled Carbon Nanotubes-Tungsten Oxide Nanocomposites / 分析化学

Multi-walled carbon nanotubes-tungsten oxide (MWCNTs-WOx) nanocomposites were fabricated on glassy carbon electrode (GCE) through a simple electrodeposition method,in which WOx were fabricated on MWCNTs. The morphology and constitution were characterized by field emission scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). Electrochemical characterization of modified electrode was done by electrochemical impedance spectroscopy (EIS). The cyclic voltammogram (CV)method was adopted to investigate the electrochemical behavior of dopamine (DA) on MWCNTs-WOx-modified glassy carbon electrode, and a new detection method for DA was developed by differential pulse voltammetry (DPV). The results showed that MWCNTs-WOx nanocomposites had obvious electrocatalytic effect on DA in phosphate buffer solution (pH=6.5). Under the optimized experimental conditions, the DA peak current demonstrated a good linear relationship with concentration in the range of 0.05-1.00 mmol/L, and the detection limit was 17 μmol/L(S/N=3). Effects of different experimental parameters on the response current of the modified electrode were investigated,and it was found that the prepared electrochemical sensor displayed good reproducibility,high selectivity and strong anti-interference ability. UA did not interfere with the detection of DA. A new electrochemical method for the quantitative determination of DA was established and successfully applied to the determination of dopamine hydrochloride injection samples.

Determination of Trace ZnⅡ, CdⅡ and PbⅡ Metal Ions Using In-situ Bismuth-modified Boron Doped Diamond Electrode / 分析化学

Bismuth modified boron doped diamond (BDD) film electrode was employed for simultaneous determination of trace ZnⅡ,CdⅡand PbⅡby anodic stripping voltammetry.BiⅢwas simultaneously in-situ deposited on bismuth modified boron doped diamond electrode with ZnⅡ,CdⅡ and PbⅡ by pre-concentration.In the presence of BiⅢ,the sensitivity for determination of ZnⅡ,CdⅡ and PbⅡ was remarkably enhanced.Influence factors such as bismuth concentration,boron doped concentrations of BDD electrode,pH,preconcentration potential were investigated and optimized.Under the optimal conditions,the stripping peak currents increased linearly with the increasing concentration of ZnⅡ,CdⅡ and PbⅡ in the range of 10-300 μg/L.The limit of detection was 0.56 μg/L for ZnⅡ,0.32 μg/L for CdⅡand 0.75 μg/L for PbⅡ (S/N=3),respectively.The interference experiments showed that common ions had little influence on the determination except CuⅡ.In addition,the developed electrode displayed a good repeatability.The method was successfully applied to determination of ZnⅡ,CdⅡ and PbⅡ in real water samples with the standard addition recoveries of 92.0%-114.0%.

Research Progress on Nitrite Electrochemical Sensor / 分析化学

Nitrite has been widely used in industrial and agricultural production,and is commonly found in food,drinking water,biology sample and environment.However,nitrite is a toxic inorganic pollutant that is very harmful to the health of human.A variety of strategies have been proposed for nitrite detection in recent years.Electrochemical approaches have gained more and more attention owing to simplicity,rapidity,sensitivity,low cost,etc.The research progresses of nanocomposite material sensor for electrochemical detection of nitrite based on carbon material,metal material,metal organic frameworks,and conducting polymer and enzyme in recent years are introduced from the perspective of composite electrode modification layer.The construction approaches and sensing performances of modified electrode are put special emphasis.At last,future trends of nitrite electrochemical sensor are also discussed.

Eco-friendly reduced graphene oxide for the determination of mycophenolate mofetil in pharmaceutical formulations / 药物分析学报

Graphene oxide (GO) was synthesized and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). GO was then electro-chemically reduced and used for electrochemical study of mycophenolate mofetil (MMF). The electro-chemically reduced graphene oxide (ERGO) film on glassy carbon electrode (GCE) showed enhanced peak current for electrooxidation of MMF. MMF exhibited two irreversible oxidation peaks at 0.84 V (peak a1) and 1.1 V (peak a2). Effects of accumulation time, pH and scan rate were studied and various electro-chemical parameters were calculated. A differential pulse voltammetric method was developed for the determination of MMF in bulk samples and pharmaceutical formulations. Linear relationship was ob-served between the peak current and concentration of MMF in the range of 40 nM―15μM with a limit of detection of 11.3 nM. The proposed method is simple, sensitive and inexpensive and, hence, could be readily adopted in clinical and quality control laboratories.

Ultrasensitive electrochemical determination of metronidazole based on polydopamine/carboxylic multi-walled carbon nanotubes nanocomposites modified GCE / 药物分析学报

An ultrasensitive electrochemical sensor based on polydopamine/carboxylic multi-walled carbon nano-tubes (MWCNTs-COOH) nanocomposites modified glassy carbon electrode (GCE) was presented in this work, which has been developed for highly selective and highly sensitive determination of an anti-microbial drug, metronidazole. The preparation of polydopamine/MWCNTs―COOH nanocomposites/GCE sensor is simple and possesses high reproducible, where polydopamine can be coated on the surface of MWCNTs―COOH via a simple electropolymerization process. Under optimized conditions, the proposed sensor showed ultrasensitive determination for metronidazole with a wide linear detection range from 5 to 5000μmol/dm3 and a low detection limit of 0.25μmol/dm3 (S/N = 3). Moreover, the proposed sensor has been successfully applied for the quantitative determination of metronidazole in real drug samples. This work may provide a novel and effective analytical platform for determination of me-tronidazole in application of real pharmaceutical and biological samples analysis.

An Integrated Air Monitoring Approach for Assessment of Formaldehyde in the Workplace

The aim of this study is to validate an integrated air monitoring approach for assessing airborne formaldehyde (FA) in the workplace. An active sampling by silica gel impregnated with 2,4-dinitrophenylhydrazine, a passive solid phase microextraction technique using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine as on-fiber derivatization reagent, an electrochemical direct-reading monitor, and an enzyme-based badge were evaluated and tested over a range of 0.020–5.12 ppm, using dynamically generated FA air concentrations. Simple linear regression analysis showed the four methods were suitable for evaluating airborne FA. Personal and area samplings in 12 anatomy pathology departments showed that the international occupational exposure limits in the GESTIS database were frequently exceeded. This monitoring approach would allow a fast, easy-to-use, and economical evaluation of both current work practices and eventual changes made to reduce FA vapor concentrations.

Poly(methylene blue)-modified electrode for indirect electrochemical sensing of OH radicals and radical scavengers

ABSTRACT A new modified electrode for indirect sensing of OH· and radical scavengers was described. The electrochemical polymerization of methylene blue in aqueous solutions and the properties of the resulting films on a glassy carbon electrode were carried out using cyclic voltammetry. A surface coverage of 1.11 × 109mol cm2 was obtained, revealing a complete surface coverage of the polymeric film on the electrode surface. OH· was able to destroy the poly(methylene blue) film by exposure to a Fenton solution. The loss of the electrochemical signal of the residual polymeric film attached to the electrode surface was related to the extent of its dissolution. The applicability of the sensor was demonstrated by evaluating the OH radical scavenging effect on different concentrations of ascorbic acid. The obtained radical scavenging capacity were 31.4%, 55.7%, 98.9% and 65.7% for the ascorbic acid concentrations of 5, 10, 30 and 50 mM, respectively.

Molecularly Imprinted Electrochemical Sensor for Determination of Cholesterol Based on Signal Amplification of Graphene / 分析化学

An electrochemical sensor was fabricated for determination of cholesterol ( ChO ) based on the molecularly imprinting and signal amplification of graphene. The sensor was prepared by electropolymerizing phenol on the surface of graphene modified glassy carbon electrode with ChO as template. The structure, properties and molecular imprinting effect of the imprinted membrane were studied by SEM, CV and DPV. The results showed that the sensor had good selectivity and high sensitivity to cholesterol. The calibration graph for the determination of cholesterol was linear in the range of 8. 0 × 10-8-2. 0 × 10-4 mol/L, with the detection limit (S/N=3) of 5. 6×10-8 mol/L. The sensor was applied to the determination of cholesterol in human serum samples with satisfactory results.