博莱霉素与DNA在镍离子注入修饰电极上的相互作用 及其应用

博莱霉素(BLM)在0.1mol/LHOAc-NaOAc缓冲溶液(pH4.62)中,在Ni/GCE离子注入修饰电极上有一灵敏的还原峰,峰电位为-1.16V(vs.SCE),峰电流与BLM浓度有关。用线性扫描和循环伏安法研究体系的行为表明,体系为具有加速作用的不可逆过程,是注入的Ni加速BLM的还原。引入DNA后,BLM的峰电位为-1.15V(vs.SCE),与未加入DNA前几乎完全一致;只使峰电流降低,形成一种非电活性的结合物,求得该结合物的结合比为BLM：DNA=3：1,结合常数为β=3.16×10^16,用线性扫描和循环伏安法,并辅以紫外可见光谱法等手段研究表明,电极过程仍为不可逆过程,与未加入DNA时一样。加入DNA后,BLM的峰电流降低,可用于DNA的测定,回收率在96.8～103.9%之间.     

Electrochemical Studies of Adriamycin Interaction with Dna and Determination of Dna at a Ni/Gc Ion Implantation Modified Electrode

ABSTRACT

The electrochemical behavior of the reduction of adriamycin at Ni/GC modified electrode has been studied by linear sweep and cyclic voltammetry. The reaction of DNA with ADM formed an electrochemically nonactive complex, which resulted in a decrease in the ADM equilibrium concentration and its reduction current. The decrease in peak current was proportional to DNA concentration and can be used to determination DNA concentration. The experiments of AES and XPS showed that Ni is surely implanted into the surface of GCE and the depth distribution of Ni was in good agreement with Gooses normal distribution; the implanted Ni at GCE improved the electrocatalytic activity.     

镍离子注入修饰电极上米托蒽醌与DNA相互作用的电化学研究

研究了在镍离子注入修饰电极和0.05mol/LTris-0.5mol/LNaCl缓冲溶液(pH=7.1)中,米托蒽醌(MX)与DNA作用的电化学.在37℃恒温1.5h条件下,MX与DNA形成一种非电活性的结合物,使MX峰电流降低,其结合比n(MX):n(DNA)=2:1,结合常数为1.61×10¹²,电子转移系数为0.41,电极反应速率常数0.33s^-1.加入DNA后,MX峰电流降低,据此,可以测定DNA.     

Studies on the electrochemical behavior of cytochrome c and its interaction with DNA at a Co/GC ion implantation modified electrode

The electrochemical behavior of cytochrome c (cyt c) and its interaction with DNA at a Co/glassy carbon (GC) ion implantation modified electrode were studied by linear sweep and cyclic voltammetry. In 0.005 mol dm(-3) Tris-0.05 mol dm(-3) NaCl buffer solution (pH = 7.10), a sensitive reduction derivative peak of cyt c was obtained by linear sweep voltammetry. The peak potential was 0.032 V (SCE). The peak current was proportional to the concentration of cyt c. The electrode process was quasi-reversible with adsorption. The electrode reaction rate constant k and the electron transfer coefficient a of cyt c were 4.42 s(-1) and 0.47, respectively. AES and XPS experiments showed that Co was implanted into the surface of the GC electrode (GCE). The implanted Co formed Co-C, which catalyzed the reduction of cyt c. The reaction of DNA with cyt c led to an electrochemically active complex, which resulted in an increase in the reduction current of cyt c. After adding DNA into the solution containing cyt c, the electrode process was still quasi-reversible with adsorption.     

Electrochemical and Spectroscopic Study of the Interaction of Indirubin with DNA

The interaction of indirubin with DNA was studied by differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) at the bare or DNA‐modified electrode and UV‐vis or IR spectra. As a result of intercalating of this drug into the double helical structure of DNA, the DPV of indirubin shows that peak potentials shift and peak currents decrease with the addition of DNA. UV‐vis spectra exhibits that the absorption intensity of indirubin at 538.7 nm^?1 decreases, which indicates that the anticancer herbal drug indirubin binds DNA. In addition, IR‐spectra of DNA and DNA‐indirubin adduct imply indirubin interacts with the phosphate groups of DNA by hydrogen bond or electrostatic interaction. Under our experiment conditions, the decrease of peak current is proportional to DNA concentration, which can be applied to estimate DNA concentration. The results indicate that the herbal drug indirubin can interfere with the DNA by intercalating into the double helix of DNA and interacting with the phosphate groups of DNA.     

Electrochemical Study on the Interaction Between Neutral Red and DNA

IntroductionDeoxyribonucleic acid( DNA) is the most im-portant germ plasma of most organisms.It playsan importantrole in the process ofstoring,copyingand transmitting germ messages.There have beenmany papers studying on the interaction betweensmall molecules and DNA since the1 960′s.Nowthe researches have become a field of common in-terest[1] .Those researches have contributed to theunderstanding of the way of the interaction be-tween DNA and protein.What is more,those re-searches are he…     

Electrochemical Study on the Interaction Betwwen Neutral Red and DNA

A voltammetric study of the interaction of neutral Red(NR) with DNA at a gold electrode in a phosphate buffer solution is described. After adding DNA in an NR solution, the reduction peak current of NR decreases. The binding mechahisms of NR to DNA in different pH ranges are different. The reduction peak potential of NR in a pH 7.0 phosphate buffer solution in the presence of DNA shifts positively, indicating that the binding of NR to DNA is intercalation action, but at pH=6.0 the reduction peak potential of NR shifts negatively, indicating that the binding of NR to DNA is electrostatic action. The formed complexes are DNA-NR when [NR]/[DNA]<0.18 and DNA-3NR when [NR]/[DNA]>0.35, respectively.     

Studies on Electrochemical Behavior of Bleomycin and Its Interaction with DNA at a Co／GC Ion Implantation Modified Electrode

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检测痕量Hg~(2+)的DNA电化学生物传感器

通过自组装方法将修饰有二茂铁基团的富T序列DNA分子(DNA-Fc)固定在金电极表面,得到了一种基于DNA修饰电极的电化学汞离子(Hg2+)传感器.当溶液中有Hg2+存在时,Hg2+可与修饰电极上DNA的T碱基发生较强的特异结合,形成T-Hg2+-T发卡结构,使DNA分子构象发生改变,其末端具有电化学活性的二茂铁基团远离电极表面,电化学响应随之发生变化.示差脉冲伏安法(DPV)结果显示:DNA末端二茂铁基团的还原峰在0.26V(vs饱和甘汞电极(SCE))附近,峰电流随溶液中Hg2+浓度的增加而降低;Hg2+浓度范围在0.1nmol·L-1-1μmol·L-1时,电流相对变化率与Hg2+浓度的对数呈现良好的线性关系.该修饰电极对Hg2+的检测限为0.1nmol·L-1,可作为痕量Hg2+检测的电化学生物传感器.干扰实验也表明,该传感器对Hg2+具有良好的特异性与灵敏度.     

Ultrasensitive Electrochemical Biosensor for HPV16 Oncogene Based on Y-shaped DNA Catalytic Hairpin Assembly and Template-free DNA Extension Reaction

An ultrasensitive electrochemical biosensor for HPV16 oncogene was explored. Hairpin DNA-1, which can specifically bind with HPV16 oncogene, was fixed on the surface of gold electrode. Two hairpin DNAs underwent catalytic hairpin assembling with hairpin DNA-1 to construct Y-shaped DNA nanostructure, liberating HPV16 oncogene for target recycling. The 3’ terminus of Y-shaped DNA nanostructure was prolonged under the catalysis of terminal deoxynucleotidyl transferase. Methylene blue was adsorbed onto DNA nanostructure to generate characteristic differential pulse voltammetry signal. This signal was increased with the concentration of HPV16 oncogene, and the detection limit of HPV16 oncogene was as low as 0.19 fM.     

二茂铁及其与DNA复合物的电化学行为

在Tris-NaCl(pH=7.2)缓冲溶液中, 应用循环伏安法、微分脉冲伏安法、旋转圆盘电极实验、电化学阻抗谱等技术研究了二茂铁在旋转碳纳米管(CNT)修饰电极上的电化学行为及其与小牛胸腺DNA的相互作用. 结果表明, 二茂铁及其与双链DNA的电活性产物在静止的CNT修饰电极上均呈现一对基本可逆的氧化还原峰；在旋转电极上呈现出明显的极限扩散电流, 电化学阻抗谱呈现一个压扁的半圆. 二茂铁与DNA的作用在扩散控制过程中表现为峰电流和极限扩散电流随DNA浓度增大而减小；电化学控制过程则表现为电化学反应电阻随DNA浓度增大而增大, 条件电位下的速度常数也有一定程度的减小.     

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 the Interaction Mechanism of Proflavine (PF) with DNA Using Carbon Paste (CPE) and Hanging Mercury Drop (HMDE) Electrode

Abstract

Proflavine binds with DNA in a complicated manner. This work involves the electrochemical study of this interaction using differential pulse voltammetry at a carbon paste electrode (CPE) and alternating current voltammetry at a hanging mercury drop electrode (HMDE). At the CPE the peak current intensity at 1.0 V (corresponding to the oxidation of the guanine residues) decreased by increasing the concentration of proflavine. At the HMDE, a decrease in the current intensity of the DNA peak at ? 1.2 V (corresponding to segmental desorption) was also observed by increasing the concentration of proflavine. These results confirmed, electrochemically, that proflavine intercalates within the DNA double helix and changes its conformation.     

Electrochemical behaviour of tilmicosin at the hanging mercury drop electrode

The electrochemical behaviour of tilmicosin (TIM) was investigated using cyclic voltammetry and square-wave voltammetry in Britton-Robinson buffers (pH 2–12). The voltammograms of TIM showed one-irreversible peak which attributed to reduction of the >C=C< group in the entire pH values. However, an additional peak was shown over the pH range 2.00 to 4.00. Its peak potential is more positive potential from that of >C=C< group, and its potential was not practically dependent on the pH. On the other hand, the peak potential of >C=C< group was shifted to the more negative values with increasing pH. According to the obtained voltammetric data, the probable reaction mechanism for the reduction of TIM was proposed. Moreover, the adsorption of TIM on the mercury electrode surface by means of square-wave adsorptive stripping voltammetry measurements is studied at different pH values. The peak current variations with the deposition time and TIM concentration were observed.     

Electroanalytical study of SYBR Green I and ethidium bromide intercalation in methylated and unmethylated amplicons

This work involves the electrochemical study of the interaction of SYBR Green I (SG) with native DNA using differential pulse voltammetry at a carbon paste electrode (CPE) and alternating current voltammetry at a hanging mercury drop electrode (HMDE). At the CPE the peak current intensity at 1.0 V decreased by increasing the concentration of SG. At the HMDE, a decrease in the current intensity of the DNA peak at −1.2 V was also observed by increasing the concentration of SG. These results electrochemically confirmed that SG intercalates within the DNA double helix and changes its conformation. Through the present work the differentiation of differently methylated analytes was achieved by application of alternative current and differential pulse voltammetric techniques. Amplicons (PCR products) corresponding to the GC-rich p53 exon 5 containing cytosine and its methylated analogue, synthesized by substituting 60% of cytosine by 5-methyl-cytosine, were amplified and investigated electrochemically in the presence of SG and ethidium bromide (EtBr) by differential pulse voltammetry. Considerable peak current differences were observed in the presence of SG and EtBr for unmethylated exon 5 vs. methylated. Therefore, both SG and EtBr could serve as electrochemical probes for identifying different DNA conformations.     

Multiple DNA binding modes of a metallointercalator revealed by DNA film voltammetry

Binding and the redox reaction of the metallointercalator Ru(bpy)2(dppz)2+ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine) with DNA was investigated by DNA film voltammetry. Calf-thymus DNA (CT-DNA) was assembled on a tin-doped indium oxide electrode by layer-by-layer electrostatic adsorption. Voltammetry of Ru(bpy)2(dppz)2+ (Ru-dppz) bound to the DNA film was measured in a redox-free electrolyte and showed strong dependence on the concentration of the metallointercalator. At low Ru-dppz concentrations, a single oxidation peak was observed, the potential of which shifted from 1.25 to 1.1 V with increasing Ru-dppz concentration (peak 1). At high metal chelate concentrations, an additional oxidation peak emerged with a potential of 1.25 V which was unaffected by the Ru-dppz concentration (peak 2). Three experiments were performed to investigate the mechanism and structural basis of the multiple peaks. First, voltammetry of Os(bpy)2(dppz)2+ bound to the CT-DNA film displayed only one peak at its oxidation potential of about 0.75 V. Second, the concentration dependence of Ru-dppz bound to a poly-(AU) film (which does not contain any guanine bases) exhibited only one oxidation peak at about 1.22 V that was independent of the Ru-dppz concentration. Third, when the guanine concentration in a mixed film of CT-DNA and poly-(AU) was changed and the bound Ru-dppz was kept constant, a pre-peak emerged and shifted to 1.1 V with increasing guanines. Based on these results, the appearance of two peaks in the voltammetric measurements of CT-DNA was rationalized by invoking two different DNA binding modes for the Ru-dppz complex: intercalation and electrostatic association. Peak 2 arises from slow oxidation of guanines catalyzed by Ru-dppz electrostatically associated with the DNA film, since the addition of Mg2+ decreases the magnitude of peak 2. Peak 1 was not affected by Mg2+ ions, leading us to conclude that it is due to intercalated Ru-dppz. The intercalation positions the metal complex in close contact with the guanines inside DNA resulting in fast electrocatalytic reaction, giving rise to a catalytic pre-peak.     

Electrochemical Studies of Pirarubicin and Its Interaction with DNA at a Co／GC Ion Implantation Modified Electrode

IntroductionIon implantation is a new material surfacemodification technique.It has been also applied tostudying the electrochemical behaviors of organicdrugs and biological materials as well as their de-terminations. This method offers good stability,reproductivity and catalytic activity[1] .Pirarubicin( THP) is an active highly effective and new antitu-moral anthracycline antibiotic,which has gainedwidespread clinical use in the chemotherapeutictreatment of a variety of human cancers.The d…     

Application of a Single-Wall Carbon Nano-Tube Film Electrode to the Determination of Trace Amounts of Folic Acid

Single-wall carbon nano-tubes were used to modify the surface of a glassy carbon electrode (GC) and applied in the determination of folic acid with voltammetry. The experiments demonstrated that the presence of a carbon nano-tube film on the electrode greatly increased the reduction peak current of folic acid. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used in a comparative investigation of the electrochemical reduction of folic acid with the film electrode. Effects of pH on the peak current and the peak potential were studied in the pH range of 4.0–8.0 with Britton-Robinson buffer solution. The reduction peak current was found to be linearly related to folic acid concentration over the range of 1 × 10⁻⁸ to 1 × 10⁻⁴ mol L⁻¹ with a detection limit of 1 × 10⁻⁹ mol L⁻¹ after 5 min accumulation. The film electrode provides an efficient way for eliminating interferences from some inorganic and organic species in the solution. The high sensitivity, selectivity and stability of the film electrode demonstrate its practical application from a simple and rapid determination of folic acid in tablets.     

Electrochemical measurement of phenothiazine-interacted DNA

The amount of DNA was measured by using thioridazine, which would be attached to the DNA, as an electrochemical indicator. An indicator (thioridazine) solution, a test solution (DNA solution), and a poly-l-lysine solution were successively placed on a glassy carbon electrode, and the electrode was allowed to dry; DNA was immobilized on an electrode surface by the electrostatic binding between DNA and poly-l-lysine. The electrode was immersed into a buffer solution for 15 min, and then differential pulse voltammetry (DPV) was carried out: the oxidation current peak of thioridazine was observed, and its magnitude depended on the amount of DNA in the solution which was used for preparing the electrode. It could be estimated between 0.2 microg DNA (corresponds to 630 pmol nucleotides) to 20 microg DNA (63 nmol nucleotides) from the oxidation peak current of DPV.     

The influence of cetyltrimethyl ammonium bromide on electrochemical properties of thyroxine reduction at carbon nanotubes modified electrode

The effect of cetyltrimethyl ammonium bromide (CTAB) on the electrochemical behaviors of thyroxine at a glassy carbon electrode (GCE) modified with single-walled carbon nanotubes (SWNTs) was investigated. At the SWNTs film-coated GCE, a well-defined oxidation peak of thyroxine at 0.78 V was obtained, but the reduction peak of thyroxine was indiscernible. When trace CTAB was added to the working solution, the reduction current could be greatly enhanced and the oxidation current remained stable. The reaction mechanisms for the reduction of thyroxine were explored by chronocoulometry. Thyroxine might form particular ion complex with CTAB via the interaction between iodine atoms on thyroxine and bromide ions in CTAB, which made the concentration of thyroxine at the surface of the modified electrode increased and the electron transfer rate enhanced. The proper mechanisms for the enhanced reduction of thyroxine in the present of CTAB were explored by several electrochemical techniques including cycle voltammetry linear sweep voltammetry and others. It was concluded that the special interactions between the thyroxine CTAB and SWNTs resulted in the increase of the reduction peak current. All results indicated that two iodine atoms on the thyroxine and four electrons were involved the reduction process which was irreversible and two iodine ions produced. In this system, the sensitive reduction peak of thyroxine at 0.3 V was employed to determine thyroxine and a low detection limit of 2x10(-8) mol/L was obtained for 2 min accumulation at 0.9 V. The SWNTs coated GCE had good stability and reproducibility.