Electrochemical Studies on the Interaction of Heparin with Phenosafranine and Its Analytical Application

The interaction of phenosafranine (PSF) with a glycosaminoglycan of heparin (Hep) in aqueous solution was characterized by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in this paper and further used for Hep detection. In pH 1.5 Britton‐Robinson (B‐R) buffer solution PSF had a well‐defined voltammetric reductive peak at ?0.256 V (vs SCE), and the electrochemical response was faded by the addition of Hep. Cyclic voltammetric experiments indicated that the electrochemical behaviors of free PSF didn't change no matter whether Hep was presented in PSF solution or not. Based on the decrease of the peak current, a second order derivative linear sweep voltammetry was used to establish a sensitive electroanalytical method for Hep. The peak current was proportional to the concentration of Hep in the range of 0.7～20.0 mg L^?1, demonstrating that this method was suitable for routine Hep detection. Under optimal conditions, the linear regression equation for the Hep determination was ΔIp”(nA) = 46.30 C (mg L^?1) + 343.31 (n = 11, γ = 0.991) with a detection limit of 0.08 mg L^?1 (3σ). The established method was further successfully applied to heparin sodium injection samples determination. The interaction mechanism was discussed based on the electrostatic attraction of the negatively charged Hep with the positively charged PSF, and the stoichiometry of Hep‐PSF was calculated by the voltammetric method.     

Voltammetric Determination of Heparin Based on Its Interaction with Brilliant Cresyl Blue

Introduction Heparinisapolysaccharideofglycosaminoglycan class,whichconsistsofrepeatingdisaccharideunitsof iduronic/glucuronicacidandglucosamineresidueswith manybiologicalfunctions[1,2].Manymethodshave beenproposedforthedetectionofheparin,including UV Vis…     

Studies on the Interaction of Beryllon Ш with Proteins by Voltammetric Technique and its Application

A new quantitative determination method of proteins using beryllon Ш by voltammetric technique was developed in this paper. In pH 3.5 Britton-Robinson (B-R) buffer solution, beryllon Ш can bind with human serum albumin (HSA) to form an electro-inactive supermolecular complex. Beryllon Ш has a well-defined voltammetric reduction peak at -0.38 V (vs. SCE) and the addition of protein in this solution can cause the decrease of the reductive peak current. Based on the decrease of the reduction peak current, a new electrochemical method for the determination of HSA was established with linear range of 1.0~40.0 mg/L and the detection limit of 1.0 mg/L. This method is further applied to the determination of real sample of healthy human serum.     

Voltammetric and Fluorimetric Studies of Dibenzoylmethane on Glassy Carbon Electrodes and Its Interaction with Tetrakis (3,5-Dicarboxyphenoxy) Cavitand Derivative

Due to the medical importance of dibenzoylmethane, one of the aims of the study was to find an appropriate packing material and a biologically friendly co-solvent to help its introduction into living systems. Accordingly, redox properties of dibenzoylmethane were investigated on glassy carbon electrodes in acetonitrile and in 1-propanol with cyclic voltammetry, and showed a diffusion-controlled process. In the anodic window, an oxidation peak appeared at around 1.9 V in both solvents. Cycling repeatedly between 0 and 2 V, the reproducibility of this peak was acceptable, but when extending the window to higher potentials, the electrode deactivated, obviously due to electrode material. The addition of the investigated tetrakis(3,5-dicarboxyphenoxy) cavitand did not significantly change the voltammograms. Further electrochemical experiments showed that the coexistence of water in acetonitrile and 1-propanol drastically reduces the solubility of dibenzoylmethane. Moreover, very rapid electrode deactivation occurred and this fact made the use of electrochemical methods complicated. Considering that both the cavitand and dibenzoylmethane are soluble in dimethyl sulfoxide, the interaction of these species was investigated and formation of stable complexes was detected. This observation was verified with fluorescence quenching studies. The mixture of water and dimethyl sulphoxide also dramatically improved the solubility of the cavitand–dibenzoylmethane complex at high excess of water. The addition of cavitand improved the solubility of dibenzoylmethane, a property which supports the application of dibenzoylmethane in therapy.     

Voltammetric, Potentiometric and Spectrophotometric Studies of Some Hydrazones and Their Metal Complexes in Ethanolic-Aqueous Buffered Solutions

Summary. The electrochemical behavior of some hydrazones derived from 6-chloro-2-hydrazinopyridine in the Britton-Robinson universal buffer of pH 2–11 containing 35% ethanol was investigated at the mercury electrode using dc-polarography, controlled-potential coulometry, and cyclic voltammetry techniques. The examined hydrazones were reduced in solutions of pH < 9 in a single 4-electron diffusion-controlled irreversible step corresponding to both the saturation of –N=C< double bond and cleavage of the –HN–NH– single bond of the hydrazone molecule via the consumption of two electrons for each center. Whereas the starting compound, 6-chloro-2-hydrazinopyridine, was reduced in a single 2-electron diffusion-controlled irreversible step corresponding to cleavage of its –NH–NH₂ single bond. The mechanistic pathway of the electrode reaction of the studied compounds was elucidated and discussed. The pK_a values of the examined hydrazones and the stoichiometry of their complexes in solution with some transition metal ions were determined spectrophotometrically. The dissociation constants and the thermodynamic parameters of the investigated hydrazones, and the stability constants of their metal complexes in solution were determined potentiometrically.     

以酚藏花红为指示剂催化荧光法测定痕量亚硝酸根的研究

基于稀磷酸介质中，亚硝酸根对溴酸钾氧化酚藏花红反应的催化作用，建立了催化荧光法测定痕量亚硝酸根的新方法。反应在５５℃水浴中进行８ｍｉｎ，线性范围为０．２７～７．３μｇ／Ｌ，其回归方程为ΔＦ＝０．４０＋１０．９３ｃ，ｒ＝０．９９９４。用于水样中痕量亚硝酸根的测定，结果良好。     

酚藏花红与DNA作用的共振光散射特征及微量DNA的光散射测定

研究了酚藏花红与脱氧核糖核酸在近中性条件下作用中的共振光散射特征，并以此建立起纳克级核酸的分析方法。考察了影响因素和最佳反映条件，建立了用ＲＬＳ光谱测定纳克级ＤＮＡ的新方法。     

Spectrophotometric Study on the Interaction between Arsenazo M and Proteins

Dye binding protein assays are commonly used in biochemical and clinical laboratories, and the reaction mechanism is still under investigation1-2. In this paper, the interaction of Arsenazo M with serum proteins was studied. Procedure In most experiments, 1.20 mL of Arsenazo M (5.0010-4 mol/L), 2.0 mL of C-L buffer solution, 3.0 mL alcohol and certain amount of protein standard solutions or samples were added to 10 mL volumetric flasks, then diluted to mark with water, and mixed thor…     

Studies on the Erythromycin-Modified Glassy Carbon Electrod and Interaction with DNA

ERMbelongingtotetradecabasicmacrolideisoneoftheantibioticsobtainedfromthefermentationliquorofStreptomyceserythreus.ItismainlyusedfortheinfectionsofGrain-PositivebacleriaandGram-negativecoccus',andhasimportantusageinclinicalpractice=.Inthebody,ERMpreventstheproteinsofgermsfromsynthesisforithasstrongeraffinitytothebacterialnucleoprotein'.Itwasalsoreported'thatERMboundtightlywithDNA.Untiltoday,ERMisstilloneoftheantibioticsthatismostwidelyusedinclinicalpracticeforitslowtoxicity.However,lit…     

Voltammetric Studies of the Interaction of Tris (1,10-phenanthroline) Cobalt (III) with Bovine Serum Albumin

Recently, the studies on the interaction of DNA with small molecules have been attracting much interest1-6. These researches not only gave the important information about thermodynamics and kinetics, but also can prompt the combination between the electrode substances and biomacromolecule with super catalysis and sensor character. It is of great significance in understanding energy conversion and metabolism in live body, biomolecular structure, various physical and chemical characters for e…     

阴离子表面活性剂与酚藏红花的作用及其在核酸荧光法测定中的应用

阴离子表面活性剂与酚藏红花的作用及其在核酸荧光法测定中的应用;荧光分析法     

Electrochemical Studies of Paclitaxel Interaction with Tubulin

Paclitaxel can stabilize microtubules and induce microtubule assembly, so people areinterested in the interaction of paclitaxel with tubulin. This interaction has been studiedby fluorometry'. but the electrochemical method has not been adopted to study it so far.Pig-brain tubulin was purified by temperature-depen4ent assemly(disassemblyprocedure=, protein concentrations were estimated by Bradford method and its purity wasdetermined by SDS-polyacrylamide gel electrophoresis (295 % purity). A …     

Spectrophotometric Study on the Interaction of Water with Chloranilic Acid and its Analytical Application

The reaction between chloranilic acid and water in alcohol was studied spectrophotometrically. The conditions of reaction were investigated in detail. The stable purple complex with an absorption wavelength at 530 nm was produced from the reaction between chloranilic acid and water. As a method for determination of H2O, Beer‘s law was obeyed in range of 0-6.0 % or 0-8.0 % (V/V) with the detection limit of 0.13 %. The relative standard deviation (RSD) was less than 2 %. The proposed method has been applied to determination of tracea mount of water in ethanol, flour and food flavoring, respectively. The recoveries of water in samples were 97～102%.     

Voltammetric and Spectrophotometric Determination of Nizatidi ne in Pharmaceutical Formulations

 Two methods are described for quantitative determination of nizatidine. The first is a cathodic stripping voltammetric method which is based on the accumulation of the compound at the hanging mercury drop electrode. The adsorptive stripping response was evaluated with respect of accumulation time, potential, concentration, pH and other variables. A linear calibration graph was obtained over the range 3.0×10⁻⁸–1.0×10⁻⁶ M with a detection limit 3.0×10⁻⁸ M after a 20s accumulation time at −0.2 V accumulation potential. On the other hand, it was found that the detection limit could be lowered to 1.0×10⁻⁸ M after 180s accumulation time at −0.2 V accumulation potential. The relative standard deviation was in the range 1.2−2.0% for six measurements. The tolerance amounts of the common excipients have also been reported. The second is a spectrophotometric method which is based on the formation and extraction of the ion-pair complex formed between nizatidine and either bromocresol green or bromothymol blue. The extracted colored ion-pair complexes absorb at 416 nm. The effect of different factors such as: type of organic solvent, pH, reagent concentration, number of extraction times, shaking time, temperature and the tolerance amount of the common excipients have been reported. The calibration graph was linear in the range 6.0×10⁻⁷–1.8×10⁻⁵ M with a detection limit of 6.0×10⁻⁷ M and molar absorptivity of 2.1×10⁴ lċmol⁻¹ċcm⁻¹ when using bromocresol green, while the calibration graph was linear in the range 3.0×10⁻⁷–1.1×10⁻⁵ M with a detection limit of 3.0×10⁻⁷ M and molar absorptivity of 3.2×10⁴ lċmol⁻¹ċcm⁻¹ when using bromothymol blue. The spectrophotometric methods offer alternative methods with reasonable sensitivity, selectivity and accuracy with relative standard deviation in the range 2.1−6.0% and 1.2−4.7% (for six measurements) when using bromothymol blue and bromocresol green, respectively. The proposed two methods were applied for the determination of nizatidine in commercially available dosage forms. A comparison between the voltammetric and the extraction-spectrophotometric methods was also reported. Received April 19, 1999. Revision August 30, 1999.     

Voltammetric and Impedimetric Detection of Interaction Between Dacarbazine and Nucleic Acids

Dacarbazine (DTIC) is a chemotherapy drug that is used for the treatment of Hodgkin's lymphoma, malignant melanoma, childhood solid tumors and soft tissue sarcoma. The surface confined interaction between DTIC and nucleic acids was investigated for the first time in this study by using both differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) in combination with disposable pencil graphite electrodes. The oxidation signals of DTIC and guanine were measured before and after interaction process using DPV technique. The interaction of DTIC with nucleic acids; poly[A], poly[G], or double stranded of poly[A]‐poly[T] and poly[G]‐poly[C] was also examined using DPV. Furthermore, EIS technique was utilized for detection of the interaction between DTIC and nucleic acids; ssDNA/dsDNA, poly[A], poly[G], or double stranded poly[A]‐poly[T] and poly[G]‐poly[C].     

Electrochemical Detection of Heparin Based on Its Interaction with Light Green

The determination of heparin with linear sweep voltammetry has been developed in this paper based on its interaction with light green (LG). In pH 2.0 Britton–Robinson (B–R) buffer solution, LG has a sensitive linear sweep voltammetric reduction peak at ?0.41 V (vs. SCE) and heparin can react with LG to form an ion‐association electro‐active complex, which resulted in the decrease of the peak current of the reaction solution. Under the selected experimental conditions the decrease of peak current was directly proportional to the concentration of heparin in the range of 0.8–20.0 μg/mL with the linear regression equation as Δi (nA)=79.12 C?101.44 (n=14, γ =0.996) and the detection limit as 0.28 μg/mL (3σ). The effects of coexisting substances on the determination of heparin were investigated and the results showed that this method had good selectivity. The method was further applied to the determination of heparin content in heparin samples with satisfactory results and good recovery.     

Study on the Interaction of Vitamin B12 with DNA by Spectroscopy and Electrochemical Methods

The Interaction between vitamin B₁₂ (VB₁₂) and fish sperm DNA was investigated in physiological buffer (pH 7.4) using the methylene blue (MB) dye as a spectral probe by spetcrophotometery, viscosity measurements and cyclic voltammetry. The apparent binding constant of vitamin B₁₂ with DNA was found to be 3.2×10⁵ mol⁻¹·L. The voltammetric behavior of vitamin B₁₂ has been investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including ΔH⁰, ΔS⁰ and ΔG⁰ for the interaction between VB₁₂ and DNA have determined as −2.3×10⁴, 27.54 and −3.1×10⁴J·mol⁻¹·K⁻¹ respectively. One indication of DNA binding mode with VB₁₂ was the change in viscosity when a small molecule associates with DNA. The diffusion coefficients of VB₁₂ in the absence (D₀)_f and presence of DNA (D₀)_b was calculated as 5.04×10⁻⁶ and 1.13×10⁻⁶ cm²·s⁻¹ respectively. The results indicated that vitamin B₁₂ can bind to DNA and the major binding mode was intercalative binding.     

Molecular Spectroscopic Study on the Interaction between Heparin and Neutral Red

The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.     

Spectrophotometric and Thermodynamic Studies of Micellar Interaction of Surfactants with p-Nitrophenol

Interaction of p-nitrophenol (NPH) with various surfactants, viz., cetylpyridinium chloride (cationic), sodium dodecylsulphate (anionic) and Triton X-100 (nonionic) are studied spectrophotometrically, in aqueous-micellar medium. The interactions are of electrostatic as well as hydrophobic nature. The strength of interaction is represented in terms of the equilibrium constants and other thermodynamic quantities of formation of the p-nitrophenol-micelle donor-acceptor complexes in addition to a shift in the acid-base equilibrium of NPH. The interaction between NPH and CPC is much stronger that with Triton X-100 whereas the interaction with SDS is very weak. Formation of 1:1 charge transfer (or electron donor-acceptor) complex is evidenced from the results. The interaction of NPH is enthalpy driven with CPC and entropy driven with Triton X-100.     

氯磺酚S与蛋白质作用的分光光度研究

在ＰＨ２．４的Ｃｌａｒｋ－Ｌｕｂｓ缓冲介质中,氯磺酚Ｓ与蛋白质能形成复合物,最大吸收峰的波长为６３２ｎｍ,比试剂本身红移约８０ｎｍ,实验制定的几种蛋白质的工作曲线一范围较宽,灵敏度较高,用于人血清样品测定的准确度高、干扰少。本方法中试剂及反应体系稳定。分析手续简便经济。