8-aminoquinoline functionalized graphene oxide for simultaneous determination of guanine and adenine

The nanocomposite graphene oxide/8-aminoquinoline (GAQ) was prepared as modified electrode material for simultaneous determination of guanine and adenine. The prepared GAQ was characterized by SEM, TEM, FTIR, Raman, and UV-vis, which confirmed that the 8-aminoquinoline had been functionalized by covalent modification. The differential pulse voltammetry (DPV) proved the electrochemical properties of the GAQ, which exhibited good electrocatalytic activity and prominent synergistic effect for sensitive determination of guanine and adenine. The guanine and adenine both were detection by DPV showed good linearity with linear range covering 0.1–160 μM, and the detection limits (LOD) (S/N = 3) both were estimated to be 0.033 μM for guanine and adenine, respectively.     

Novel DNA sensor for guanine content

The bifunctional complex [Ru(TAP)(2)POQ-Nmet](2+), 1, formed with a [Ru(TAP)(2)Phen](2+) metallic unit linked to a quinoline moiety, and [Ru(TAP)(2)Phen](2+), 2, as reference, have been tested as photoprobes of DNA. Interestingly, 1 exhibits an emission enhancement of a factor of 16-17 upon binding to calf thymus DNA. Moreover, this emission is modulated by the nucleic base content of the polynucleotide. It varies by almost an order of magnitude from a polynucleotide containing 100% of G-C to a guanine-free nucleic acid where the excited-state lifetime reaches about 2 micros. The origins of these interesting properties are analyzed by comparing 1 with reference 2 in the presence of different polynucleotides.     

氧化石墨烯修饰碳离子液体电极同时测定鸟嘌呤和腺嘌呤

以离子液体1-丁基-3-甲基咪唑六氟磷酸盐为粘合剂制备了碳糊电极,然后将氧化石墨烯滴涂到碳糊电极表面制成了一种新型的氧化石墨烯修饰碳离子液体电极。研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为。实验结果表明,在0.1 mol/L醋酸盐缓冲溶液中(pH4.5),鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为,在2.0×10-7～1.5×10-5mol/L浓度范围内鸟嘌呤和腺嘌呤的浓度在该电极上与电化学响应信号呈良好的线性关系,相关系数分别为为0.992和0.996。信噪比为3时,检出限为1.0×10-8mol/L。     

A glassy carbon electrode modified with graphene quantum dots and silver nanoparticles for simultaneous determination of guanine and adenine

Microchimica Acta - A glassy carbon electrode (GCE) was modified with graphene quantum dots (GQDs) carrying silver nanoparticles. The modified GCE displays excellent performance in the...     

Label-free electrochemical impedance sensing of DNA hybridization based on functionalized graphene sheets

Negative-charge change and conformation transition upon DNA immobilization and hybridization on functionalized graphene sheets were monitored by the EIS technique and adopted as the signal for label-free electrochemical DNA hybridization detection.     

基于羟基化酞菁锌-石墨烯纳米材料的和厚朴酚电化学传感器的构建及其应用

通过非共价作用制备了可溶性四羟基酞菁锌-石墨烯纳米复合材料,并将其应用于构建新型高灵敏度和厚朴酚电化学传感器.由于水溶性四羟基酞菁锌和石墨烯的协同作用,显著提高了纳米复合材料的比表面积和导电性,增强了和厚朴酚的电化学响应.在最优实验条件下测定,和厚朴酚在0.01～1.0μmol/L和1.0～100 μmol/L范围内呈...     

Zeolite A functionalized with copper nanoparticles and graphene oxide for simultaneous electrochemical determination of dopamine and ascorbic acid

A novel Cu-zeolite A/graphene modified glassy carbon electrode for the simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA) has been described. The Cu-zeolite A/graphene composites were prepared using Cu²⁺ functionalized zeolite A and graphene oxide as the precursor, and subsequently reduced by chemical agents. The composites were characterized by X-ray diffraction, Fourier transform infrared spectra and scanning electron microscopy. Based on the Cu-zeolite A/graphene-modified electrode, the potential difference between the oxidation peaks of DA and AA was over 200 mV, which was adequate for the simultaneous electrochemical determination of DA and AA. Also the proposed Cu-zeolite/graphene-modified electrode showed higher electrocatalytic performance than zeolite/graphene electrode or graphene-modified electrode. The electrocatalytic oxidation currents of DA and AA were linearly related to the corresponding concentration in the range of 1.0 × 10⁻⁷–1.9 × 10⁻⁵ M for DA and 2.0 × 10⁻⁵–2.0 × 10⁻⁴ M for AA. Detection limits (<!-- no-mfc -->S/N<!-- /no-mfc --> = 3) were estimated to be 4.1 × 10⁻⁸ M for DA and 1.1 × 10⁻⁵ M for AA, respectively.     

A sensitive porphyrin/reduced graphene oxide electrode for simultaneous detection of guanine and adenine

Journal of Solid State Electrochemistry - In this study, we prepared the porphyrin/reduced graphene oxide (porphyrin/RGO) nanocomposite which combined the excellent electrical conductivity and high...     

An electrochemical sensor based on CuO nanoparticle for simultaneous determination of hydrazine and bisphenol A

In the present research, the direct electrochemical oxidation of hydrazine in the presence of bisphenol A was investigated at a copper oxide nanoparticles/ionic liquid/carbon paste electrode (CuO NPs/IL/CPE). The combination of the good conductive 1-hexyl-3-methylimidazolium hexafluorophosphate and CuO nanoparticles resulted in an electrode with attractive properties for the determination of hydrazine in the presence of bisphenol A. The linear dynamic ranges were obtained in the ranges of 0.05–150 and 0.2–175 µM with the detection limits (3sb/m) 0.03 and 0.1 µM for HY and BPA, respectively. High stability, sensitivity, selectivity and reproducibility, fast response, the ease of preparation, and surface renewal made the sensor well suitable for the determination of hydrazine in the presence of bisphenol A, which are important pollutants in the environment. Finally, this new sensor was used for the determination of HY and BPA in some water samples such as river water and wastewater.     

A rapid and sensitive electrochemical sensor for hydroxyl free radicals based on self-assembled monolayers of carboxyl functionalized graphene

Journal of Solid State Electrochemistry - In this work, carboxyl-functionalized graphene (CFG) was immobilized on glassy carbon electrode (GCE) by self-assembled monolayers (SAMs) based on covalent...     

聚硫堇/石墨烯复合材料修饰电极对NADH的电催化氧化研究

采用循环伏安法将硫堇在石墨烯修饰的玻碳电极表面聚合,得到了一种新的聚硫堇/石墨烯修饰电极,此电极兼备了石墨烯和聚硫堇的特性.实验表明:该修饰电极能有效降低NADH的过电位;对NADH的检测范围为2.4×10~(-6)~4.89×10~(-3) mol·L~(-1);检出限为6.826×10~(-7) mol·L~(-1);对尿酸和抗坏血酸的干扰有很好的消除作用;此电极稳定性、重现性较好,有很高的实际应用价值.     

Fabrication of poly(2,6-pyridinedicarboxylic acid)/MWNTs modified electrode for simultaneous determination of guanine and adenine in DNA

The fabrication of poly(2,6-pyridinedicarboxylic acid)/MWNTs modified glass electrode(PPDA/MWNTs/GCE) was proposed and used for individual or simultaneous determination of guanine and adenine.The performances of the PPDA/MWNTs/GCE were characterized with cyclic voltammetry(CV).The modified electrode exhibited enhanced electrocatalytic behavior and good stability for the detection of guanine and adenine.Differential pulse voltammetry(DPV) was used to determine the concentration of guanine,adenine.The detection limit(S/N = 3) for guanine and adenine was 0.045μmol/L and 0.05μmol/L,respectively.The electrochemical method for the measurement of guanine and adenine in calf thymus DNA was also developed with this modified electrode and the result was satisfactory.     

A highly sensitive electrochemical sensor for simultaneous determination of hydroquinone and bisphenol A based on the ultrafine Pd nanoparticle@TiO2 functionalized SiC

A titanium dioxide–silicon carbide nanohybrid (TiO₂–SiC) with enhanced electrochemical performance was successfully prepared through a facile generic in situ growth strategy. Monodispersed ultrafine palladium nanoparticles (Pd NPs) with a uniform size of ∼2.3 nm were successfully obtained on the TiO₂–SiC surface via a chemical reduction method. The Pd-loaded TiO₂–SiC nanohybrid (Pd@TiO₂–SiC) was characterized by transmission electron microscopy and X-ray diffractometry. A method for the simultaneous electrochemical determination of hydroquinone (HQ) and bisphenol A (BPA) using a Pd@TiO₂–SiC nanocomposite-modified glassy carbon electrode was established. Utilizing the favorable properties of Pd NPs, the Pd@TiO₂–SiC nanohybrid-modified glassy carbon electrode exhibited electrochemical performance superior to those of TiO₂–SiC and SiC. Differential pulse voltammetry was successfully used to simultaneously quantify HQ and BPA within the concentration range of 0.01–200 μM under optimal conditions. The detection limits (S/N = 3) of the Pd@TiO₂–SiC nanohybrid electrode for HQ and BPA were 5.5 and 4.3 nM, respectively. The selectivity of the electrochemical sensor was improved by introducing 10% ethanol to the buffer medium. The practical application of the modified electrode was demonstrated by the simultaneous detection of HQ and BPA in tap water and wastewater samples. The simple and straightforward strategy presented in this paper are important for the facile fabrication of ultrafine metal NPs@metal oxide–SiC hybrids with high electrochemical performance and catalytic activity.     

Highly dispersive Ag nanoparticles on functionalized graphene for an excellent electrochemical sensor of nitroaromatic compounds

A facile carbon radical reaction procedure and a chemical reduction method were proposed to synthesize Ag nanoparticles on functionalized graphene with uniform, high dispersion and excellent stability. The resultant material showed excellent electrocatalytic activity to nitroaromatic compounds and high sensitivity to the detection of nitroaromatic compounds.     

石墨烯基电化学传感器检测盐酸洛美沙星

利用滴涂法在玻碳电极表面修饰Nafion–石墨烯复合膜,制备电化学传感器,并利用差分脉冲溶出伏安技术间接测定盐酸洛美沙星的含量.对酸化的样品离子缔合物进行沉淀、离心分离,在支持电解质0.7 mol/L HSCN–KSCN中于–3.50 V下搅拌富集3 min,然后进行阳极极化扫描,可获得灵敏的阳极溶出峰,利用此法测定盐...     

Fabrication of a nanostructure-based electrochemical sensor for simultaneous determination of N-acetylcysteine and acetaminophen

A carbon-paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one (2,7-BF) and carbon nanotubes (CNTs) was used for the sensitive and selective voltammetric determination of N-acetylcysteine (NAC). The mediated oxidation of NAC at the modified electrode was investigated by cyclic voltammetry (CV). Also, the values of catalytic rate constant (k), and diffusion coefficient (D) for NAC were calculated. Differential pulse voltammetry (DPV) of NAC at the modified electrode exhibited two linear dynamic ranges with a detection limit (3σ) of 52.0 nmol L⁻¹. DPV was used for simultaneous determination of NAC and acetaminophen (AC) at the modified electrode, and quantitation of NAC and AC in some real samples by the standard addition method.     

Simultaneous determination of guanine,adenine, thymine and cytosine with a simple electrochemical method

A simple method for simultaneous detection of guanine, adenine, thymine and cytosine was set up by using a bare glassy carbon electrode in acetate buffer solution of pH 4.5. The peak current responses of these four DNA bases in this supporting electrolyte were significantly increased comparing with those in phosphate buffer solution and Tris-HCl, moreover, the peak current values were linearly dependent on the concentration of four DNA bases, respectively. Individual and simultaneous determinations of four bases were performed by controlling certain experimental conditions, and broad linear ranges and low detection limits (S/N = 3) were obtained. The assay processes do not need any separation or pretreatment steps. In addition, this method showed good selectivity, reproducibility, and stability and can be used for determination of the four bases content in real DNA sample.     

Simultaneous determination of guanine and adenine in DNA using an electrochemically pretreated glassy carbon electrode

A simple and reliable method based on adsorptive stripping at an electrochemically pretreated glassy carbon electrode (GCE) was proposed for simultaneous or individual determination of guanine and adenine in DNA. The detection sensitivity of guanine and adenine was improved greatly by activating the GCE electrochemically. After accumulation on pretreated GCE at open circuit for 5 min or at the potential of +0.3 V for 120 s, guanine and adenine produced well-defined oxidation peaks at about +0.8 and +1.1 V, respectively in pH 5 phosphate buffer. The detection limit for individual measurement of guanine and adenine was 4.5 ng ml⁻¹ (3×10⁻⁸ mol l⁻¹) and 4 ng ml⁻¹ (3×10⁻⁸ mol l⁻¹), respectively. Acid-denatured DNA showed two oxidation peaks corresponding to guanine and adenine residues in the same buffer. The proposed method can be used to estimate the guanine and adenine contents in DNA with good selectivity in a linear range of 0.25-5 μg ml⁻¹.     

Electrochemical biosensor for sensitively simultaneous determination of dopamine, uric acid, guanine, and adenine based on poly-melamine and nano Ag hybridized film-modified electrode

An electrochemical sensor for simultaneous determination of dopamine (DA), uric acid (UA), guanine (G), and adenine (A) has been constructed by copolymerizing melamine monomer and Ag ions on a glassy carbon electrode (GCE) with cyclic voltammetry. The poly-melamine and nano Ag formed a hybridized film on the surface of the GCE. The morphology of the film was characterized by scanning electron microscope. The electrochemical and electrocatalytic properties of this film were characterized by cyclic voltammetry, linear sweep voltammetry, and square wave voltammetry (SWV). In 0.1 M phosphate buffer solution (pH 4.5), the modified electrode resolved the electrochemical response of DA, UA, G, and A into four well-defined voltammetric oxidation peaks by SWV; the oxidation peak current of DA, UA, G, and A increased 13-, 6-, 7-, and 9-fold, respectively, compared with those at the bare GCE and the SWV peak currents of DA, UA, G, and A with linear concentrations in the ranges of 0.1–50, 0.1–50, 0.1–50, and 0.1–60 μM, respectively. Based on this, a method for simultaneous determination of these species in mixture was setup. The detection limits were 10 nM for DA, 100 nM for UA, 8 nM for G, and 8 nM for A.