A novel nanozyme doped ZnO/r-GO-based sensor for highly sensitive electrochemical determination of muscle-relaxant drug: cyclobenzaprine HCl.

A nanocomposite of Ce-doped ZnO/r-GO was synthesized using a conventional hydrothermal method. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of cyclobenzaprine hydrochloride (CBP). The properties of the composite were extensively analyzed, including its morphology, structure, and electrochemical behavior. This study investigates the application of a modified glassy carbon electrode for the detection of CBP, a muscle relaxant used to treat musculoskeletal diseases that cause muscle spasms. The electrode is modified with Ce-doped ZnO/r-GO. Various detection methods, such as cyclic voltammetric and square wave techniques (SWV), were utilized. The composite material showed high effectiveness as an electron transfer mediator in the oxidation of CBP. The electrode showed a good response for SWV evaluations in CBP identification, with a minimum detection limit of 1.6 × 10-8 M and a wide linear range from 10 × 10-6 M to 0.6 × 10-7 M, under ideal conditions. The rate constant for charge transfer (ks) and the estimation of the electrochemical active surface area were obtained. A developed sensor exhibited desirable selectivity, long-lasting stability, and remarkable reproducibility. A sensor was used to analyze water, human serum, and urine samples, resulting in positive recovery results.

Investigations of the Interaction Mechanism Between Orphenadrine Hydrochloride and Bovine Serum Albumin by Spectroscopic and Voltammetric Techniques.

The interaction of orphenadrine hydrochloride (ORD) with the model protein, bovine serum albumin (BSA), was investigated using a variety of spectroscopic techniques such as steady-state fluorescence, ultraviolet-visible, Fourier transform infrared, 3-D spectroscopy, and electrochemical methods under physiological conditions. Stern-Volmer plots were used to calculate fluorescence quenching at various temperatures. The findings point to a static quenching mechanism between ORD and BSA. At various reaction times, the binding sites (n) and binding constants (K) of ORD to BSA were recorded. Thermodynamic parameters ∆H0, ∆S0 and ∆G0 between ORD and BSA were calculated and reported. The average binding distance (r) between the donor (BSA) and acceptor (ORD) molecules was predicted using Förster's theory. Three-dimensional fluorescence spectra, Fourier transform infrared spectra, and synchronous fluorescence studies all supported the alternations in protein structure following the interaction with ORD. A displacement study using site probes such as warfarin, ibuprofen, and digitoxin confirmed ORD binding at Sudlow's site I of BSA. The effect of common metal ions such as Cu2+, Ni2+, Ca2+, Co2+, and Zn2+ on binding constant values was investigated and reported.

Highly sensitive electro-oxidative voltammetric determination of anthelmintic drug albendazole using porous graphitic carbon nitride sensor infused with cationic micellar solution.

A sensitive and novel electrochemical senser, acetyl trimethylammonium bromide (CTAB)-immobilized nitrogen rich g-C3N4 nanosheet modified carbon paste electrode was developed, for the electrochemical investigation of the anthelmintic drug Albendazole (ABZ) using voltammetric tools like cyclic and square wave voltammetry. The results showed that the modified carbon paste electrode exhibited remarkable electro-catalytic action towards the electrochemical oxidation of ABZ in a phosphate buffer solution at pH 3 compared to bare carbon paste electrode. The electrode material was characterized by CV, scanning electron microscopy (SEM), atomic force microscope (AFM), and electrochemical impedance spectroscopy (EIS). A highly sensitive square wave voltammetric technique was developed for the determination of ABZ, at a trace level with great precision and accuracy, good limit of detection (LOD) 0.01 µM and limit of quantification (LOQ) of 0.036 µM, in the concentration range of 0.2-10 µM. This approach can be used in pharmaceutical formulations for clinical diagnosis, quality assurance, and drug screening. In addition, this technique is also implemented for the assessment of ABZ in water samples and biological samples like urine and blood plasma.

Study on the interaction between anti-tuberculosis drug ethambutol and bovine serum albumin: multispectroscopic and cyclic voltammetric approaches.

The binding of bovine serum albumin (BSA) to ethambutol (EMB) was investigated using spectroscopic methods, viz., fluorescence, Fourier transform infrared (FTIR), ultraviolet (UV)/vis absorption and cyclic voltammetry techniques. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of serum albumin by EMB is static, which was also confirmed by lifetime measurements. The number of binding sites, n, and binding constant, K, were obtained at various temperatures. The distance, r, between EMB and the protein was evaluated according to the Förster energy transfer theory. Based on displacement experiments using site probes, viz., warfarin, ibuprofen and digitoxin, the site of binding of EMB in BSA was proposed to be Sudlow's site I. The effect of EMB on the conformation of BSA was analyzed by using synchronous fluorescence spectra (SFS) and 3D fluorescence spectra. The results of fluorescence, UV/vis absorption and FTIR spectra showed that the conformation of BSA was changed in the presence of EMB. The thermodynamic parameters including enthalpy change (ΔH0 ), entropy change (ΔS0 ) and free energy change (ΔG0 ) for BSA-EMB were calculated according to the van't Hoff equation and are discussed.

Investigation of binding behaviour of procainamide hydrochloride with human serum albumin using synchronous, 3D fluorescence and circular dichroism.

Interaction of procainamide hydrochloride (PAH) with human serum albumin (HSA) is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp-214 was estimated employing the Förster's theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA (Sudlow's site I). The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra (SFS), 3D fluorescence spectra and circular dichroism (CD) results indicated the conformational changes in the structure of HSA.

Multi-spectroscopic characterization of bovine serum albumin upon interaction with atomoxetine.

The quenching interaction of atomoxetine (ATX) with bovine serum albumin (BSA) was studied in vitro under optimal physiological condition (pH=7.4) by multi-spectroscopic techniques. The mechanism of ATX-BSA system was a dynamic quenching process and was confirmed by the fluorescence spectra and lifetime measurements. The number of binding sites, binding constants and other binding characteristics were computed. Thermodynamic parameters ∆H° and ∆S° indicated that intermolecular hydrophobic forces predominantly stabilized the drug-protein system. The average binding distance between BSA and ATX was studied by Försters theory. UV-absorption, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD), synchronous spectra and three-dimensional (3D) fluorescence spectral results revealed the changes in micro-environment of secondary structure of protein upon the interaction with ATX. Displacement of site probes and the effects of some common metal ions on the binding of ATX with BSA interaction were also studied.

Binding of fexofenadine hydrochloride to bovine serum albumin: structural considerations by spectroscopic techniques and molecular docking.

The binding interaction of peripheral H1 receptor antagonist drug, fexofenadine hydrochloride to bovine serum albumin (BSA) is investigated by fluorescence spectroscopy in combination with UV-absorption spectroscopy under physiological conditions. The Stern-Volmer plots at different temperatures and the steady state fluorescence suggested a static type of interaction between fexofenadine and BSA. Binding constants were determined to provide a measure of the binding affinity between fexofenadine and BSA. It was found that BSA has one binding site for fexofenadine. On the basis of the competitive site marker experiments and thermodynamic results, it was considered that fexofenadine was primarily bound to the site I of BSA mainly by hydrogen bond and van der Waals force. Utilising Förster resonance energy transfer the distance, r between the donor, BSA and acceptor fexofenadine was obtained. Furthermore, the results of circular dichroism and synchronous fluorescence spectrum indicated that the secondary structure of BSA was changed in the presence of fexofenadine. Molecular docking was applied to further define the interaction of fexofenadine with BSA.

Spectroscopic exploration and thermodynamic characterization of desvenlafaxine interacting with fluorescent bovine serum albumin.

The mechanism of the interaction between bovine serum albumin (BSA) and desvenlafaxine was studied using fluorescence, ultraviolet absorption, 3-dimensional fluorescence spectroscopy, circular dichroism, synchronous fluorescence spectroscopy, cyclic voltametry, differential scanning calorimetry, and attenuated total reflection-Fourier transform infrared spectroscopic techniques under physiological condition at pH 7.4. Stern-Volmer calculations authenticate the fluorescence of BSA that was quenched by desvenlafaxine in a collision quenching mode. The fluorescence quenching method was used to evaluate number of binding sites "n" and binding constant KA that were measured, and various thermodynamic parameters were evaluated at different temperatures by using the van't Hoff equation and differential scanning calorimetry technique, which indicated a spontaneous and hydrophobic interaction between BSA and desvenlafaxine. According to the Förster theory we calculate the distance between the donor, BSA and acceptor, desvenlafaxine molecules. Furthermore, circular dichroism and attenuated total reflection-Fourier transform infrared spectroscopy indicate nominal changes in the secondary structure of the protein.

Multi-spectroscopic and voltammetric evidences for binding, conformational changes of bovine serum albumin with thiamine.

The interaction between thiamine hydrochloride (TA) and bovine serum albumin (BSA) was investigated by fluorescence, FTIR, UV-vis spectroscopic and cyclic voltammetric techniques under optimised physiological condition. The fluorescence intensity of BSA is gradually decreased upon addition of TA due to the formation of a BSA-TA complex. The binding parameters were evaluated and their behaviour at different temperatures was analysed. The quenching constants (Ksv) obtained were 2.6 × 104, 2.2 × 104 and 2.0 × 104 L mol-1 at 288, 298 and 308 K, respectively. The binding mechanism was static-type quenching. The values of ΔH° and ΔS° were found to be 26.87 kJ mol-1 and 21.3 J K-1 mol-1, and indicated that electrostatic interaction was the principal intermolecular force. The changes in the secondary structure of BSA upon interaction with TA were confirmed by synchronous and 3-D spectral results. Site probe studies reveal that TA is located in site I of BSA. The effects of some common metal ions on binding of BSA-TA complex were also investigated.

Quenching of fluorescence by meclizine, a probe study for structural and conformational changes in human serum albumin.

The goal of this study was to investigate the interactions between meclizine (MEC) and human serum albumin (HSA) under physiological conditions by different spectroscopies and molecular modeling technique. The drug, MEC quenched the intrinsic fluorescence of HSA and the analysis of the results revealed that static quenching mechanism. The binding of MEC quenches the HSA fluorescence; stoichiometry was 1:1 interaction. Thermodynamic quantities were calculated at different temperatures suggested that hydrophobic and van der Waals interaction with HSA-MEC. The molecular distance, r, between donor and acceptor was estimated according to Forster's theory of non-radiation energy transfer. CD and FT-IR studies confirm changes of secondary structure of HSA. Molecular docking studies validate MEC molecule interact to HSA in sub domain IIA.

Electrochemical Determination of Albendazole at Glassy Carbon Electrode.

In this article, the electrochemical behavior on a glassy carbon electrode (GCE) was investigated and the electrochemical parameters of albendazole (ALB) were calculated. ALB effectively accumulated on the GCE surface and caused a pair of redox peaks at around 1.095 V and 1.028 V and an oxidation peak at 0.844 V (versus saturated calomel electrode) in 0.2 M phosphate buffer solution (pH 3.0). Under optimized conditions, the anodic peak current was linear to the ALB concentration the range of 1.5 × 10-7 M to 4.0 × 10-5 M. The regression equation was: Ipa (10-6 A) = 0.79 [ALB] (µM) + 0.84 (R2 = 0.982). The detection limit 6.08 × 10-8 M was obtained. The proposed method was successfully used to determine ALB content in tablet samples, with satisfactory results.

Biomolecular interaction study of hydralazine with bovine serum albumin and effect of ß-cyclodextrin on binding by fluorescence, 3D, synchronous, CD, and Raman spectroscopic methods.

Spectrofluoremetric technique was employed to study the binding behavior of hydralazine with bovine serum albumin (BSA) at different temperatures. Binding study of bovine serum albumin with hydralazine has been studied by ultraviolet-visible spectroscopy, fluorescence spectroscopy and confirmed by three-dimensional, synchronous, circular dichroism, and Raman spectroscopic methods. Effect of ß-cyclodextrin on binding was studied. The experimental results showed a static quenching mechanism in the interaction of hydralazine with bovine serum albumin. The binding constant and the number of binding sites are calculated according to Stern-Volmer equation. The thermodynamic parameters ∆H(o) , ∆G(o) , ∆S(o) at different temperatures were calculated. These indicated that the hydrogen bonding and weak van der Waals forces played an important role in the interaction. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (hydralazine) was evaluated and found to be 3.95 nm. Spectral results showed that the binding of hydralazine to BSA induced conformational changes in BSA. The effect of common ions on the binding of hydralazine to BSA was also examined. Copyright © 2016 John Wiley & Sons, Ltd.

Fluorescent bovine serum albumin interacting with the antitussive quencher dextromethorphan: a spectroscopic insight.

The interaction of dextromethorphan hydrobromide (DXM) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV-vis absorption, synchronous fluorescence spectra (SFS), 3D fluorescence spectra, Fourier transform infrared (FTIR) spectroscopy and circular dichroism under simulated physiological conditions. DXM effectively quenched the intrinsic fluorescence of BSA. Values of the binding constant, K(A), are 7.159 × 10(3), 9.398 × 10(3) and 16.101 × 10(3) L/mol; the number of binding sites, n, and the corresponding thermodynamic parameters ΔG°, ΔH° and ΔS° between DXM and BSA were calculated at different temperatures. The interaction between DXM and BSA occurs through dynamic quenching and the effect of DXM on the conformation of BSA was analyzed using SFS. The average binding distance, r, between the donor (BSA) and acceptor (DXM) was determined based on Förster's theory. The results of fluorescence spectra, UV-vis absorption spectra and SFS show that the secondary structure of the protein has been changed in the presence of DXM.

Evaluation of the binding interaction between bovine serum albumin and dimethyl fumarate, an anti-inflammatory drug by multispectroscopic methods.

The information of the quenching reaction of bovine serum albumin with dimethyl fumarate is obtained by multi-spectroscopic methods. The number of binding sites, n and binding constants, KA were determined at different temperatures. The effect of increasing temperature on Stern-Volmer quenching constants (KD) indicates that a dynamic quenching mechanism is involved in the interaction. The analysis of thermodynamic quantities namely, ∆H° and ∆S° suggested hydrophobic forces playing a major role in the interaction between dimethyl fumarate and bovine serum albumin. The binding site of dimethyl fumarate on bovine serum albumin was determined by displacement studies, using the site probes viz., warfarin, ibuprofen and digitoxin. The determination of magnitude of the distance of approach for molecular interactions between dimethyl fumarate and bovine serum albumin is calculated according to the theory of Förster energy transfer. The CD, 3D fluorescence spectra, synchronous fluorescence measurements and FT-IR spectral results were indicative of the change in secondary structure of the protein. The influence of some of the metal ions on the binding interaction was also studied.

Investigation into the interaction of methylparaben and erythromycin with human serum albumin using multispectroscopic methods.

In this paper, the interaction of methylparaben and erythromycin with human serum albumin (HSA) was studied for the first time using spectroscopic methods including Fourier transform infrared (FTIR) spectroscopy and UV absorption spectroscopy in combination with fluorescence quenching under physiological conditions. The binding parameters were evaluated using a fluorescence quenching method. Based on Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (HSA) and the acceptor (methylparaben and erythromycin) was evaluated. UV/vis absorption, FTIR, synchronous and 3D spectral results showed that the conformation of HSA was changed in the presence of methylparaben and erythromycin. The thermodynamic parameters were calculated according to the van't Hoff equation and are discussed. The effect of some biological metal ions and site probes on the binding of methylparaben and erythromycin to HSA were further examined.

Study of fluorescence interaction and conformational changes of bovine serum albumin with histamine H1 -receptor--drug epinastine hydrochloride by spectroscopic and time-resolved fluorescence methods.

The fluorescence, ultraviolet (UV) absorption, time resolved techniques, circular dichroism (CD), and infrared spectral methods were explored as tools to investigate the interaction between histamine H1 drug, epinastine hydrochloride (EPN), and bovine serum albumin (BSA) under simulated physiological conditions. The experimental results showed that the quenching of the BSA by EPN was static quenching mechanism and also confirmed by lifetime measurements. The value of n close to unity indicated that one molecule of EPN was bound to protein molecule. The binding constants (K) at three different temperatures were calculated (7.1 × 10(4), 5.5 × 10(4), and 3.9 × 10(4) M(-1)). Based on the thermodynamic parameters (ΔH(0), ΔG(0), and ΔS(0)), the nature of binding forces operating between drug and protein was proposed. The site of binding of EPN in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz, warfarin, ibuprofen, and digitoxin. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (EPN) was evaluated and found to be 4.48 nm. The UV-visible, synchronous fluorescence, CD, and three-dimensional fluorescence spectral results revealed the changes in secondary structure of the protein upon its interaction with EPN.

Non-covalent binding analysis of sulfamethoxazole to human serum albumin: Fluorescence spectroscopy, UV-vis, FT-IR, voltammetric and molecular modeling.

This study was designed to examine the interaction of sulfamethoxazole (SMZ) with human serum albumin(HSA). Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of human serum albumin by SMZ was static mechanism. The binding constant values for the SMZ-HSA system were obtained to be 22,500 L/mol at 288 K, 15,600 L/mol at 298 K, and 8500 L/mol at 308 K. The distance r between donor and acceptor was evaluated according to the theory of Föster energy transfer. The results of spectroscopic analysis and molecular modeling techniques showed that the conformation of human serum albumin had been changed in the presence of SMZ. The thermodynamic parameters, namely enthalpy change (∆H0) -36.0 kJ/mol, entropy change (∆S0) -41.3 J/mol K and free energy change (∆G0) -23.7 kJ/mol, were calculated by using van׳t Hoff equation. The effect of common ions on the binding of SMZ to HSA was tested.

Fabrication of multiwalled carbon nanotube-surfactant modified sensor for the direct determination of toxic drug 4-aminoantipyrine.

A multi-walled carbon nanotube (MWCNT)-cetyltrimethylammonium bromide (CTAB) surfactant composite modified glassy carbon electrode (GCE) was developed as a novel system for the determination of 4-aminoantipyrine(AAP). The oxidation process was irreversible over the pH range studied and exhibited a diffusion controlled behavior. All experimental parameters were optimized. The combination of MWCNT-CTAB endows the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. MWCNT-CTAB/GCE electrode gave a linear response for AAP from 5.0×10-9 to 4.0×10-8 M with a detection limit of 1.63×10-10 M. The modified electrode showed good selectivity against interfering species and also exhibited good reproducibility. The present electrochemical sensor based on the MWCNT-CTAB/GCE electrode was applied to the determination of AAP in real samples.

Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin.

The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters ΔG0, ΔH0 and ΔS0 were calculated at different temperatures according to the van't Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the Förster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies.

Elucidation of binding mechanism of hydroxyurea on serum albumins by different spectroscopic studies.

OBJECTIVES: The interaction of hydroxyurea (HU) with serum albumins (SAs) has not been investigated so far. However, it necessitates the interaction study of HU with SAs in phosphate buffer of pH 7.4. METHODS: The binding of HU on bovine serum albumin (BSA) and human serum albumin (HSA) was studied in vitro under simulated physiological conditions by spectroscopic methods viz., fluorescence, FT-IR, UV-vis absorption, synchronous fluorescence and three-dimensional fluorescence. RESULTS: The Stern-Volmer plot indicated the presence of dynamic quenching mechanism in the interaction of HU with SAs. The number of binding sites, n and binding constants, K were obtained at various temperatures according to the double logarithm regression curve. The result of FT-IR spectra, UV-vis absorption, synchronous fluorescence and three-dimensional fluorescence spectra showed that the conformation of SAs has been changed in the presence of HU. The thermodynamic parameters were calculated according to van't Hoff equation and discussed. CONCLUSION: This kind of study of interaction between BSA and HSA with HU would be useful in pharmaceutical industry, life sciences and clinical medicine.