ABSTRACT
In this study, an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) for the first time. The decrease in the oxidation signals of deoxyguanosine (dGuo) and deoxy-adenosine (dAdo), measured by differential pulse voltammetry, upon incubation with different con-centrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA. The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0-10.0μg/mL. The limit of detection and limit of quantification for indinavir were 0.29 and 0.98μg/mL, respectively, based on the dGuo signal, and 0.23 and 0.78μg/mL, respectively, based on the dAdo signal. To gain further insights into the interaction mechanism between indinavir and ct-dsDNA, spectroscopic measurements and molecular docking simulations were performed. The binding constant (Kb) between indinavir and ct-dsDNA was calculated to be 1.64 × 108 M-1, based on spectrofluorometric measure-ments. The obtained results can offer insights into the inhibitory activity of indinavir, which could help to broaden its applications. That is, indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.
ABSTRACT
Objective: To establish an electrochemical method for the determination of phenol. Methods: An electrochemical workstation with three electrodes system was used with glassy carbon electrode as working electrode, Ag/AgCl as reference electrode and Pt as counter electrode. Cyclic voltammetry and differential pulse voltammetry were used for the determination of phenol. Results:Under the condition of 4% Na2SO4as the supporting electrolyte, phenol showed an obvious oxidation peak on the glassy carbon elec-trode. The peak current increased linearly with the concentration of phenol within the range of 0. 8 μg·ml-1-10. 2 μg·ml-1( r=0. 997 5). The lower limit of detection was 0. 20 μg·ml-1. The average recovery was 101. 2% (RSD=2. 2% , n=6). Conclusion:The method is simple and accurate, and can be used for the determination of phenol.
ABSTRACT
For the first time, sulfanilamide (SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode (GCE). The cyclic voltammetry (CV) experiments showed an irreversible oxidation peak at +1.06 V in 0.1 mol/L BRBS (pH = 2.0) at 50 mV/s. Different vol-tammetric scan rates (from 10 to 250 mV/s) suggested that the oxidation of SFD on the GCE was a diffusion-controlled process. Square-wave voltammetry (SWV) method under optimized conditions showed a linear response to SFD from 5.0 to 74.7μmol/L (R = 0.999) with detection and quantification limits of 0.92 and 3.10μmol/L, respectively. The developed SWV method showed better results for detection limit and linear range than the chronoamperometry method. It has been successfully applied to determine SFD concentration in pharmaceutical formulation, human urine and serum samples with recovery close to 100%.
ABSTRACT
A sensitive electrochemical sensor for the detection of semicarbazide ( SEM ) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube ( CMWCNTs ) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution ( pH 7 ) and scan rate of 0. 1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5. 0 × 10-6 mol/L-1. 09×10-3 mol/L, the linear regression equation was Ip(μA)=-0. 472+0. 0599C (μmol/L) with linear correlation coefficient of 0. 997. The detection limit was 1. 88×10-7 mol/L. At the same time, the recovery was from 92. 8% to 98. 0% in the test of pork liver samples.
ABSTRACT
A sensitive electrochemical sensor for the detection of semicarbazide ( SEM ) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube ( CMWCNTs ) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution ( pH 7 ) and scan rate of 0. 1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5. 0 × 10-6 mol/L-1. 09×10-3 mol/L, the linear regression equation was Ip(μA)=-0. 472+0. 0599C (μmol/L) with linear correlation coefficient of 0. 997. The detection limit was 1. 88×10-7 mol/L. At the same time, the recovery was from 92. 8% to 98. 0% in the test of pork liver samples.
ABSTRACT
The present study reports voltammetric reduction of nitazoxanide in Britton-Robinson (B-R) buffer by cyclic and square-wave voltammetry at glassy carbon electrode. A versatile fully validated voltammetric method for quantitative determination of nitazoxanide in pharmaceutical formulation has been proposed. A squrewave peak current was linear over the nitazoxanide concentration in the range of 20-140 mg/mL. The limit of detection (LOD) and limit of quantification (LOQ) was calculated to be 5.23μg/mL and 17.45μg/mL, respectively.
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A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate.The experimental results suggest that the phcniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response.Peak current response is linearly dependent on the concentration of pheniramine in the range 200-1500 μg/mL with correlation coefficient 0.9987.The limit of detection is 58.31 μg/m L.The modified electrode shows good sensitivity and repeatability.
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Redox behavior of midazolam was studied at a glassy carbon electrode in various buffer systems,supporting electrolytes and pH using differential paise,square-wave and cyclic voltammetry.Based on its reduction behavior,a direct differential pulse voltammetric method has been developed and validated for the determination of midazolam in parenteral dosage.Three welldefined peaks were observed in 0.1％ SLS,Britton-Robinson (BR) buffer of pH 2.5.The effect of surfaetants like sodium lauryl sulfate (SLS),cetyl trimethyl ammonium bromide (CTAB) and Tween 20 was studied.Among these surfactants SLS showed significant enhancement in reduction peak.The cathodic peak currents were directly proportional to the concentration of midazolam with correlation coetfficient of 0.99.
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The synthesis and characterization of aromatic alcohols such as 1-(4-bromo phenyl) ethanol, 1-(4-Hydroxy-3-methoxyphenyl) ethanol, (4-Hydroxy-3-methoxy-benzyl alcohol) employing biotransformation (using whole cells of Baker’s Yeast in their free as well as immobilized form in mixtures of glycerol and water) and Electrochemical technique are reported. The electrochemical behavior of 4-bromoacetophenone, 4-Hydroxy-3-methoxyacetophenone, and 4-Hydroxy-3- methoxybenzaldehyde was analyzed using cyclic voltammetry at glassy carbon electrode (GCE) and constant current electrolysis. Effect of scan rate and pH on the reduction peaks has been calculated. The kinetic parameters were also calculated and the process was found to be diffusion controlled. The products obtained were purified & then characterized by spectroscopic techniques. All the compounds have been tested in vitro against a number of microorganisms in order to assess their antimicrobial properties. Biocatalytic and Electrochemical procedures were found to be more effective, safe, economical, environmental friendly, easy to handle. These green methodologies over conventional chemical methods provide new and improved synthetic routes to many valuable compounds.
ABSTRACT
Incorporation of green methodology via biocatalytic and electrochemical steps using Baker’s Yeast and electrons as reducing agent respectively have been employed as a novel and efficient route to furnish relevent chiral building blocks for fine chemicals and pharmaceuticals. Reduction of selected ketones such as 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone and ethyl-2-oxocyclopentanecarboxylate have been carried out by biotransformation (using whole cells of Baker’s Yeast in their free as well as immobilized form in mixtures of glycerol and water) and via electrochemical method to the corresponding alcohols. Optimum conditions for electrochemical reduction like solvent, supporting electrolyte, reduction potential and pH were determined at glassy carbon electrode employing cyclic voltammetric technique. The effect of scan rate, pH were also studied. The electrochemical reduction was carried out at constant current using stainless steel (SS-316) electrodes. The products obtained were purified & then the results of both reduction routes (biocatalytic & electrochemical) were compared and then characterized by spectroscopic techniques.