Electrochemical characteristics of gatifloxacin and its interaction with DNA.

The electrochemical behavior of gatifloxacin (GTFX) and its interaction with natural calf thymus DNA (ctDNA) is investigated by differential pulse voltammetry (DPV) on a carbon paraffined electrode. According to the suggested electrochemical equation, a binding constant of 1.7058 x 10(5) (mol L(-1))(-1) and binding sizes s = 3.09 (base pairs) of GTFX with ctDNA are obtained by nonlinear fit analysis of electrochemical data. The results demonstrate that GTFX has the properties of an intercalative binder.     

Electrochemical oxidation of morin and interaction with DNA

A poly (tetrafluroethylene)-deoxyribonucleate acid (PTFE-DNA) film-modified glassy carbon electrode (GCE) has been fabricated. The electrochemical oxidation behaviors of morin as well as its interaction with DNA have been studied at PTFE-DNA film-modified GCE and bare GCE by electrochemical methods. This modified electrode shows an enhanced effectiveness towards the oxidation of morin. Importantly, as to the interaction between morin and DNA in solution, characteristic parameters such as the binding stoichiometry and association equilibrium constant according to the Hill model for cooperative binding have been determined on the basis of linear sweep voltammetry and chronocoulometry.     

Electrochemical studies of NiTMpyP and interaction with DNA

In this paper, cyclic voltammetry, linear sweep voltammetry and chronocoulometry in connection with the hang mercury drop electrode were used to study NiTMpyP and its mixture with DNA. The reduction of NiTMpyP in our experimental conditions involves in 4e reduction of TMpyP. NiTMpyP interacting with DNA forms electrochemically non-active complex DNA-2NiTMpyP, which can not be reduced on the Hg electrode. The peak potential of NiTMpyP does not shift and its electrochemical kinetic parameters indicate no significant change in the presence of DNA. However, the reduction current of NiTMpyP decreases obviously due to the formation of DNA-2NiTMpyP, which implies its equilibrium concentration decreases when DNA was mixed. The decrease of peak current is proportional to DNA concentration, which can be applied to estimate DNA concentration.     

Electrochemical and spectroscopic studies of the interaction of proflavine with DNA.

The interaction of proflavine with herring sperm DNA has been investigated by cyclic voltammetry and UV-Vis spectroscopy as well as viscosity measurements. Shifts in the peak potentials in cyclic voltammetry, spectral changes in UV absorption titration, an increase in viscosity of DNA and the results of the effect of ionic strength on the binding constant strongly support the intercalation of proflavine into the DNA double helix. The binding constant for the interaction between proflavine and DNA was K = 2.32 (+/- 0.41) x 10(4) M(-1) and the binding site size was 2.07 (+/- 0.1) base pairs, estimated in voltammetric measurements. The value of the binding site size was determined to be closer to that expected for a planar intercalating agent. The standard Gibbs free-energy change is ca. -24.90 kJ/mol at 25 degrees C, indicating the spontaneity of the binding interaction. The binding constant determined by UV absorption measurements was K = 2.20 (+/- 0.48) x 10(4) M(-1), which is very close to the value determined by cyclic voltammetry assuming that the binding equilibrium is static.     

Electrochemical studies of the interaction of Basic Brown G with DNA and determination of DNA

A new method of electrochemical probe has been proposed for the determination of Herring Sperm DNA (DNA) based on its interaction with Basic Brown G (BBG). The electrochemical behavior of interaction of BBG with DNA was investigated on Hg electrode. In 0.1 mol L⁻¹ NH₃-NH₄Cl buffer solution (pH 8.0), BBG can be reduced on Hg electrode with a well-defined voltammetric peak at −0.67 V (versus SCE). In the presence of DNA, the reduction peak current of BBG decreases and the peak potential shifts to a more positive potential without the appearance of new peak. The study shows that a new BBG-DNA complex is formed by linear sweep voltammetry (LSV) and spectrophotometry. The decrease of the second order derivative of reductive peak current (Δi^″p) of BBG is proportional to the concentration of DNA in the range of 0.10-36 μg mL⁻¹. Limit of detection of DNA is 0.04 μg mL⁻¹. DNA of Hepatitis B Virus in serum samples was determined satisfactorily. Additionally, the binding mechanism was preliminarily discussed. The mode of interaction between BBG and DNA was found to be intercalation binding.     

Electrochemical study of oxygen interaction with lapachol and its radical anions

Cyclovoltammetric studies were performed with lapachol [2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone], in the absence and presence of oxygen, which aimed to investigate possible oxygen interaction with lapachol and its radical anion. The obtained results clearly indicate the consumption of the semiquinone anion-radicals by oxygen in an EC type reaction, generating the deprotonated form of lapachol and HOO*. The observed generation of reactive oxygen species (ROS) after electron transfer can be related to the mechanism of biological action of lapachol.     

电化学方法研究DNA与不可逆靶向分子的相互作用

用循环伏安法、示差脉冲伏安法、计时库仑法、整体电解法和扫描电化学显微镜研究了具有抗癌活性的双苯并咪唑衍生物(BBID)不可逆电化学行为及BBID与DNA的相互作用,推导了适用于研究不可逆电活性分子与DNA相互作用的电化学公式,该公式可以简便、快速地测定靶向分子与DNA的结合常数和结合位点数。实验发现,BBID与天然鱼精DNA的结合以结构作用为主,同时,由于求得的结合常数(K)值较大,因此其中可能还存在序列作用的因素。结合方式主要为包含4个碱基对的紧密小沟结合。     

Electrochemical investigation on the interaction of diclofenac with DNA and its application to the construction of a graphene-based biosensor

We have investigated the interaction between diclofenac and deoxyribonucleic acid (DNA) by the electrochemical method. On glassy carbon electrode, the voltammetric curve of diclofenac showed an oxidation peak, which was obviously influenced by the addition of DNA. Accordingly, a series of electrochemical experiments were carried out to elucidate the interaction between diclofenac and DNA. Based on the diclofenac–DNA interaction, a biosensor for diclofenac was developed. When a film of DNA was immobilized on the electrode surface, DNA showed an oxidation signal promoted by graphene oxide. Due to the diclofenac–DNA interaction, the peak current of DNA decreased and the peak potential shifted positively with increasing the concentration of diclofenac. The response of the biosensor was linear to the concentration of diclofenac in the range of 1 to 130?μM. Using such a biosensor, the photodegradation of diclofenac was successfully monitored.     

电化学方法研究β-环糊精-硫堇包合物与DNA的相互作用

用电化学方法研究了β-环糊精-硫堇包合物与DNA的相互作用。结果表明,在pH7.2的PBS缓冲液中,β-环糊精以1:1包合硫堇,其包合常数为458L mol-1。β-环糊精-硫堇包合物以嵌入方式与DNA形成一种非电活性超分子化合物,包合物与DNA的结合比是1:1,结合常数为6.25×104L mol-1。     

Electrochemical determination of nonylphenol based on ionic liquid-functionalized graphene nanosheet modified glassy carbon electrode and its interaction with DNA

Nonylphenol (NP) was determined using electrochemical method based on ionic liquid-functionalized graphene nanosheet modified electrode. The fabricated electrode was characterized by electrochemical impedance spectroscopy. The different influence parameters, such as pH value, scan rate, accumulation potential, and time, were investigated. Under the optimum conditions, the linear relationship between peak current value and concentration of NP was obtained with differential pulse voltammetry in two ranges from 0.5 to 30 μM and 30 to 200 μM with the detection limit of 0.058 μM (S/N?=?3). Moreover, this modified electrode was applied to NP determination in water and soil samples with the recoveries from 94.8 to 104 %, which showed the method could be applied to determine NP in environment. In addition, to explore the damage to DNA, the interaction between NP and DNA was investigated with the association constant (β) of 0.4867 and the Hill coefficient (m) of 3.75?×?10⁵ M^?1, respectively.     

抗坏血酸与DNA相互作用的电化学研究

脱氧核糖酸(DNA)贮存着生物体生命活动的所有信息,这些信息指导着细胞生长、分化、代谢、遗传和变异等重要的生命活动。DNA结构与功能的改变可引起细胞生物学行为的显著改变。DNA与抗癌药物相互作用的研究的报道较多[1,2],而与维生素类药物研究报道相对较少[3]。抗坏血酸(AA)即     

6-取代嘌呤的电化学行为及与DNA的相互作用

应用循环伏安法和微分脉冲伏安法研究了6-糠氨基嘌呤(6-KT)和6-巯基嘌呤(6-MP)在汞电极上的电化学行为及与小牛胸腺DNA的相互作用.结果发现,6-KT和6-MP的循环伏安曲线均显示两对分别表征为扩散控制和吸附控制的氧化还原波.扩散控制波的氧化峰电流随6-取代嘌呤浓度在0.1~50.0μmol.L-1范围内呈现良好的线性关系.依据预吸附时间和溶液pH值对吸附控制波的还原峰电位和峰电流的影响,讨论了6-KT和6-MP在汞电极上的吸附机理.作者认为,6-KT乃通过部分插入作用与DNA结合,而6-MP与DNA间的相互作用为静电模式.     

鲱鱼精DNA的电化学氧化及与组蛋白的相互作用

应用循环伏安法、微分脉冲伏安法和荧光光谱法研究了鲱鱼精DNA的电化学氧化及其与组蛋白的相互作用.结果发现,在0.20~1.25 V电位区间内,DNA在酸性溶液中呈现一个明显的不可逆氧化峰,在中性及碱性溶液中呈现两个不可逆氧化峰.氧化峰电位随溶液pH值增大而负移,变化幅度为-57 mV.pH-1.氧化峰电流与DNA浓度(0.45~8.20 mmol.L-1)成线性关系.DNA能与组蛋白结合,导致氧化电位正移,氧化电流减小,并减弱钌配合物指示剂和DNA相互作用的荧光强度以及减少DNA的氧化损伤.     

Electrochemical determination of allopurinol based on its interaction with xanthine oxidase

Allopurinol was determined in the range 0.20–50 μM utilizing xanthine oxidase immobilized onto a carbon paste electrode. Alternative assay methods relying on either inhibition of enzymatic activity or direct formation of a product are evaluated. Regeneration of xanthine oxidase activity under various conditions is also surveyed.     

Electrochemical investigation on the interaction of benzene sulfonyl 5-fluorouracil derivatives with double-stranded DNA and G-quadruplex DNA

The interaction of double-stranded(ds) and G-quadruplex(G4) DNA with sulfonyl 5-fluorouracil derivatives(5-fluoro-1-(arylsulfonyl) pyrimidine-2,4(1H,3H)-diones) was investigated in this research,in which Au electrodes modified with ds-DNA or G4-DNAs were used as a working electrode.The investigation showed that the binding affinity with G4-DNA was significantly increased when 5-fluorouracil(5-FU) was modified with arylsulfonyl groups.The presence of strong electron-withdrawing groups on benzene sulfonyl 5-FU greatly enhanced the binding selectivity(k G4-DNA /k ds-DNA).Such results provided new insights into the potential connections between the chemical structure of drug candidates and their anticancer activities.     

电化学法研究苯磺酰类5-氟尿嘧啶衍生物与双链和G-四链DNA的相互作用

本文以自组装法制得的双链DNA（ds．DNA）和G-四链体DNA（G4-DNA）修饰的金电极为工作电极,以Fe（CN）63-／4-为电活性指示剂,采用循环伏安法和微分脉冲伏安法研究了非电活性苯磺酰类5-氟尿嘧啶衍生物与ds-DNA和G4．DNA的相互作用．实验结果表明：苯磺酰类5-氟尿嘧啶与ds-DNA或G4．DNA的结合常数与苯环上邻、对位取代基的得失电子能力密切相关,强吸电子基团取代有利于苯磺酰类5-氟尿嘧啶选择性结合G-四链体DNA．     

磺胺二甲嘧啶的基本电化学性质及其与DNA的相互作用

研究了磺胺二甲嘧啶在多壁碳纳米管修饰电极上的电化学行为,优化了实验参数,在此基础上建立了一种直接测定磺胺二甲嘧啶的电分析方法.并用循环伏安法和紫外光谱法对磺胺二甲嘧啶与DNA的相互作用进行了研究,结果表明,磺胺二甲嘧啶与DNA的作用模式是静电作用.     

Electrochemical behaviors of guanosine on carbon ionic liquid electrode and its determination

The electrochemical behaviors of guanosine on the ionic liquid of N-butylpyridinium hexafluorophosphate (BPPF₆) modified carbon paste electrode (CPE) was studied in this paper and further used for guanosine detection. Guanosine showed an adsorption irreversible oxidation process on the carbon ionic liquid electrode (CILE) with the oxidation peak potential located at 1.12 V (vs. SCE) in a pH 4.5 Britton-Robinson (B-R) buffer solution. Compared with that on the traditional carbon paste electrode, small shift of the oxidation peak potentials appeared but with a great increment of the oxidation peak current on the CILE, which was due to the presence of ionic liquid in the modified electrode adsorbed the guanosine on the surface and promoted the electrochemical response. The electrochemical parameters such as the electron transfer coefficient (α), the electron transfer number (n), and the electrode reaction standard rate constant (k_s) were calculated as 0.74, 1.9 and 1.26 × 10⁻⁴ s⁻¹, respectively. Under the optimal conditions the oxidation peak current showed a good linear relationship with the guanosine concentration in the range from 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol/L by cyclic voltammetry with the detection limit of 2.61 × 10⁻⁷ mol/L (3σ). The common coexisting substances showed no interferences to the guanosine oxidation. The CILE showed good ability to distinguish the electrochemical response of guanosine and guanine in the mixture solution. The urine samples were further detected by the proposed method with satisfactory results.     

Electrochemical studies on the interaction of heparin with crystal violet and its analytical application

In this paper, crystal violet (CV) was used to determine heparin concentration by linear sweep voltammetry on a dropping mercury electrode (DME). In Britton-Robinson (B-R) buffer solution, pH 3.0, CV had a well-defined second-order derivative linear sweep voltammetric reductive wave at −0.74 V (vs. SCE). After the addition of heparin to the CV solution, the reductive peak current decreased greatly with the positive movement of the peak potential and without appearance of new peaks in the scanning potential range. Based on the decrease in the reductive peak current, a new voltammetric method for the determination of heparin was established. The conditions for the interaction and the electrochemical detection were optimized, and interfering substances were investigated. Under the optimal conditions, the decrease in reductive peak currents of CV was proportional to heparin concentration in the range 0.1–8.0 mg/L with the linear regression equation Δip″(nA) = 400.42 + 1563.11c (mg/L), (n = 14, γ = 0.993). The detection limit was 0.092 mg/L. This new method was further successfully applied to the determination of heparin content in heparin sodium injection samples with satisfactory results. The binding ratio and binding mechanism were also studied by the electrochemical method. The text was submitted by the authors in English.     

Electrochemical genosensor for the detection of interaction between methylene blue and DNA

Described here are the chronocoulometric and voltammetric parameters for methylene blue [3,7-bis(dimethylamino)phenothiazin-5-ium chloride, MB] on binding to DNA at carbon paste electrode (CPE) surface. MB, which interacts with the immobilized calf thymus DNA was detected by using single stranded DNA modified CPE (ssDNA modified CPE), bare CPE and double stranded DNA modified CPE (dsDNA modified CPE) in combination with chronocoulometry and differential pulse voltammetry (DPV) techniques. The effect of ionic strength to the behavior of MB with dsDNA and ssDNA was also studied by means of voltammetry. These results demonstrated that MB could be used as an effective electroactive hybridization indicator for DNA biosensors. Performance characteristics of the sensor are described, along with future prospects.