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The effect of quercetin flavonoid (QUE), on the binding interaction of antihypertensive drug, amiloride (AMI) with bovine serum albumin (BSA) was investigated in this study. Spectroscopic methods such as steady‐state, synchronous, three‐dimensional fluorescence, and circular dichroism spectroscopy were employed to study the interaction. Fluorescence data were analyzed using the Stern–Volmer equation and a static quenching process was found to be involved in the formation of AMI–BSA and QUE–BSA complexes and were in good agreement with the thermodynamic study. The thermodynamic parameters illustrated that the process is spontaneous and enthalpy driven. Hydrophobicity is acting as the primary force in the binding interaction. Fluorescence spectral data were resolved using a multivariate curve resolution‐alternating least squares method (MCR–ALS). Site marker and molecular docking studies confirmed the binding site of AMI on BSA, i.e. site II. The binding distance between amino acid of BSA and AMI was calculated and found to be 2.18 nm which indicated that energy transfer has occurred from an amino acid of BSA to AMI. The binding affinity of AMI to BSA was found to be reduced in the presence of QUE, which may lead to the poor distribution of AMI at the desired site. [ABSTRACT FROM AUTHOR]

Three series of isomeric 2-pyridyl 4-aryl thiazoles have been synthesized by reacting 2/3/4-pyridine thioamides derived from the corresponding nitriles with various 4-substituted phenacyl bromides using Hantzsch thiazole synthesis. Amongst the three isomeric series, 2-pyridyl and 4-pyridyl isomers are found to exhibit better photophysical properties than 3-pyridyl series. 4-Pyridyl isomer with methoxy substituent on phenyl ring is found to exhibit high luminescence quantum yield. The relationship between the structure and the photophysical properties have been studied using DFT calculations. [ABSTRACT FROM AUTHOR]

Controlled drug delivery is one of the probable answers to different problems associated with conventional dosing regimens. Ciprofloxacin (CFX) is an antibiotic, signifying second generation fluoroquinolone which is active against wide‐ranges of microbes. Due to low solubility and bioavailability, it requires a controlled release device for its delivery. An attempt has been made in the present work to develop gelatin grafted poly (vinyl alcohol) (GPVA) hydrogel nanoparticle and study the release behaviour of CFX when incorporated as β‐cyclodextrin CFX inclusion complex and pure CFX. GPVA hydrogel nanoparticles were prepared using two‐step desolvation method and characterized using FTIR, DLS, SEM, and XRD. The in‐vitrorelease at different physiological pH 1.2, 6.8 and 7.4 showed a controlled release of drug from the system when gelatin is grafted with PVA and when an inclusion complex of the drug is introduced in the polymer system. The release kinetic followed zero order with non Fickian Super case II transport mechanism. [ABSTRACT FROM AUTHOR]

This paper discusses multi‐spectroscopic and molecular docking analysis of the interaction between atenolol (ATN) and deoxyribose nucleic acid (DNA) using alizarin (ALZ) as a spectroscopic probe. ATN is a β1‐receptor antagonist belonging to the β‐blocker class of molecules. Experimental findings that were based on different spectroscopic analysis, melting studies, viscometric analysis, 1H nuclear magnetic resonance and circular dichroism studies revealed the presence of a grove‐binding mode. The effect of ionic strength was also studied, and observations suggested that electrostatic interaction also played a minor role during interaction. Molecular docking analysis suggested that the dominant force for the grove‐binding phenomenon was hydrogen bonding between the 24‐H residue of ATN and O of the 10‐G residue, and the 40‐H residue of ATN and N of the 17‐A base residue. Competitive binding study of the ALZ−DNA complex with ATN showed that, despite an increase in the amount of ATN in the ALZ−DNA complex, the overall absorbance remained unchanged. The decrease in fluorescence in the ALZ−DNA system may be due to new non‐fluorescent ATN−DNA−ALZ complex formation. [ABSTRACT FROM AUTHOR]

A fluorophore modulation with sodium dodecyl sulphate (SDS) assemblies for the selective and sensitive sensing of Fe3+ ions in aqueous solution is illustrated in this work. Emission spectral characteristics of fluorescent molecule, propranolol (PPH) was intact in presence of metal ions. While on modulation with SDS assemblies, PPH was transformed into a tuneable sensor for Fe3+ ions. This sensor ensemble was not only highly sensitive towards Fe3+ ions in aqueous solution with detection limits lower than 3 μM but also possess high discriminating efficiency in presence of other metal ions like Cu2+, Pb2+, Zn2+, Ni2+, Fe2+, Cd2+, Co2+, Al3+, Mg2+, Hg2+ and Mn2+. The electrostatic interaction of the anionic group of surfactants with the metal cations significantly increases the communication between metal ions and PPH moiety which results in the quenching of PPH fluorescence. We have employed fluorescence steady state and lifetime studies to understand the metal sensing behaviour of the PPH-SDS sensor system. Principal component analysis (PCA) was used to evaluate the discriminative ability of the developed sensor system towards Fe3+ ions. [ABSTRACT FROM AUTHOR]

Semiconductor nanoparticles surface modified with organic molecules capable of visible light absorption and effectively transferring the electrons to the catalytic sites have the potential to be good photocatalysts. ZnO nanoparticles of size ∼3 nm are grafted with two azonaphthols, one conjugated and the other non-conjugated. The photophysical properties of modified ZnO indicate an effective electron transfer from the conjugated azonaphthol to ZnO but not in the case of the non-conjugated molecule. It is also observed from lifetime studies that the conjugated molecule stabilises the defect sites on ZnO nanoparticles. It is possible that excited electrons from the conjugated molecule are transferred to specific defect sites in ZnO. This apparently does not occur in the non-conjugated molecule, bringing to focus the importance of the photophysical characteristics of organic modifiers in designing visible light active photocatalysts. [ABSTRACT FROM AUTHOR]

Highly pH sensitive hydrogels, based on agarose and acrylamide were synthesized and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimeter, and scanning electron microscopy. The release of dipyridamole from the hydrogel matrix was monitored using fluorescence spectroscopy. Since the solubility of the drug gets enhanced by cationic surfactant, an inclusion complex was prepared using cetyl trimethylammonium bromide and the release of inclusion complex from the polymer matrix was also studied. Swelling behavior of the prepared hydrogels in different pH media were studied at room temperature and maximum swelling was observed at basic pH. [ABSTRACT FROM PUBLISHER]

Lysozyme (LYZ) is a model protein frequently employed to study interaction with drugs and to understand the crystallization process of protein due to its small size and rapid crystallization behavior. Studies related to drug interaction and complexation with proteins will be significantly benefited if a suitable drug-lysozyme crystal is available. This can further aid in the understanding of the mechanism of nucleation, growth and the formation of drug-lysozyme complex. In the present study, amlodipine (AMLD) complexation with LYZ has been monitored, along with its effect on lysozyme crystallization. Different spectroscopic methods have been employed to monitor the nature of complexation, binding mode and changes in helix after interaction with AMLD. The absorbance and fluorescence spectroscopic measurement indicated the probability of a ground state complex between LYZ and AMLD. Further, the temperature dependent fluorescence studies showed an increase in binding constant with temperature, suggesting the static quenching mechanism involved in complex formation due to hydrophobic interactions. CD, FTIR, DLS and DSC techniques confirm the probability of changes in the tertiary structure of protein. Molecular docking was applied to investigate the interaction of amino acid residues of LYZ with AMLD. It was found that the complex formation is spontaneous and the ΔG value obtained (-21. 76 kJ/mol) very well matched with temperature dependent fluorescence study (-24.91 kJ/mol). Crystallization of LYZ was performed with different concentration ranges of AMLD to get a clear picture of its interference on the process. The time required for crystallization of AMLD-LYZ complex and the observed structure of crystal indicates that AMLD influences lysozyme crystallization process by changing the nature of nucleation and rate of crystal growth. Image 1 • Amlodipine complexation with lysozyme is studied using spectroscopic methods. • Molecular docking is applied to investigate the interaction of amino acid residue of lysozyme with amlodipine. • Effect of amlodipine on lysozyme crystallization is monitored. • Complexation of amlodipine with lysozyme changes the rate of nucleation and crystal growth. [ABSTRACT FROM AUTHOR]

The effect of quercetin flavonoid (QUE), on the binding interaction of antihypertensive drug, amiloride (AMI) with bovine serum albumin (BSA) was investigated in this study. Spectroscopic methods such as steady-state, synchronous, three-dimensional fluorescence, and circular dichroism spectroscopy were employed to study the interaction. Fluorescence data were analyzed using the Stern-Volmer equation and a static quenching process was found to be involved in the formation of AMI-BSA and QUE-BSA complexes and were in good agreement with the thermodynamic study. The thermodynamic parameters illustrated that the process is spontaneous and enthalpy driven. Hydrophobicity is acting as the primary force in the binding interaction. Fluorescence spectral data were resolved using a multivariate curve resolution-alternating least squares method (MCR-ALS). Site marker and molecular docking studies confirmed the binding site of AMI on BSA, i.e. site II. The binding distance between amino acid of BSA and AMI was calculated and found to be 2.18 nm which indicated that energy transfer has occurred from an amino acid of BSA to AMI. The binding affinity of AMI to BSA was found to be reduced in the presence of QUE, which may lead to the poor distribution of AMI at the desired site., (© 2020 John Wiley & Sons, Ltd.)

This paper discusses multi-spectroscopic and molecular docking analysis of the interaction between atenolol (ATN) and deoxyribose nucleic acid (DNA) using alizarin (ALZ) as a spectroscopic probe. ATN is a β 1 -receptor antagonist belonging to the β-blocker class of molecules. Experimental findings that were based on different spectroscopic analysis, melting studies, viscometric analysis, 1 H nuclear magnetic resonance and circular dichroism studies revealed the presence of a grove-binding mode. The effect of ionic strength was also studied, and observations suggested that electrostatic interaction also played a minor role during interaction. Molecular docking analysis suggested that the dominant force for the grove-binding phenomenon was hydrogen bonding between the 24-H residue of ATN and O of the 10-G residue, and the 40-H residue of ATN and N of the 17-A base residue. Competitive binding study of the ALZ-DNA complex with ATN showed that, despite an increase in the amount of ATN in the ALZ-DNA complex, the overall absorbance remained unchanged. The decrease in fluorescence in the ALZ-DNA system may be due to new non-fluorescent ATN-DNA-ALZ complex formation., (© 2018 John Wiley & Sons, Ltd.)