Binding elucidation of azo dyes with human serum albumin via spectroscopic approaches and molecular docking techniques.

The large number of synthesized azo dyes is widely applied in the food, pharmaceutical, cosmetic, textile, and leather industries. In this study, the binding mechanism of two synthesized dyes with human serum albumin (HSA); as the most abundant protein in plasma; was elucidated by fluorescence spectroscopy, Fourier-transform infrared spectroscopy and molecular modeling methods. The fluorescence quenching measurements showed that each dye can quench the intrinsic fluorescence of HSA via a dynamic quenching mechanism with an increase in concentration. From the thermodynamic data observations, revealed that the binding process is a spontaneous molecular force for each dye with HSA due to hydrophobic interactions and hydrogen bonding. FT-IR spectra showed that the secondary structure of the protein changes due to interaction of each dye with HSA. Furthermore, docking simulation demonstrated that the probable binding location of both dyes is subdomain IIA of HSA (Sudlow site I) and that complex formed is stabilized by hydrophobic interactions and hydrogen bonding.Communicated by Ramaswamy H. Sarma.

Investigation on intermolecular interaction of synthesized azo dyes with bovine serum albumin.

This research was performed using spectroscopic techniques and molecular docking to elucidate the mechanisms of interaction between bovine serum albumin (BSA) and two novel synthesized azo dyes. The titration of dyes into BSA solution results in quenching of fluorescence emission by complex formation. The UV-Vis spectroscopy confirms that formation of complex in ground state between both dyes and BSA induces conformational and micro environmental changes of the protein. Based on the calculation of the thermodynamic parameters, it can be concluded that both dyes spontaneously bind onto BSA, and van der Waals force and hydrogen bonding interaction played a predominant roles in the process of spontaneous bonding. The average binding distance (r) between protein and both dyes was calculated by Förster energy transfer measurements and revealed both dyes bind to the BSA residues of tryptophan over short distances. The results of molecular docking studies indicated that the probable binding location of both dyes is subdomain IB of BSA via hydrophobic interaction and hydrogen bond. Furthermore, as shown by synchronous fluorescence and Fourier transform infrared spectroscopy, both dyes can lead to conformational changes of BSA, which alter its biological functions.Communicated by Ramaswamy H. Sarma.

Investigation of binding interaction between human serum albumin with zirconium complex of curcumin and curcumin.

The current study investigates the binding process of Zr(CUR) as a novel six-coordinate complex of zirconium with curcumin ligand and curcumin (CUR); as the main pharmacologically active ingredient of turmeric to human serum albumin (HSA); using fluorescence spectroscopy, infrared spectroscopy and molecular docking techniques. The fluorimetric results revealed that Zr(CUR) and CUR could effectively quench the endogenous fluorescence of HSA, formed a 1:1 complex, with a static quenching mechanism. The distance between donor (HSA) and acceptor (Zr(CUR) and CUR) were determined to be 3.15 nm for Zr(CUR) and 2.95 nm for CUR on the basis of the Forester's theory of non-radiative energy transfer. Results of the infrared absorption spectrum show that the secondary structure of HSA changes for both types. Molecular docking results indicated that for structure with minimum binding energy Zr(CUR) and CUR are in the position between IIA and IIIA. Also, a docking study showed that Zr(CUR) and CUR have several hydrogen bonds and Van der Waals contact with HSA.Communicated by Ramaswamy H. Sarma.

Multi technique investigation on interaction between 5-(2-thiazolylazo)-2,4,6-triaminopyrimidine and HSA and BSA.

In research laboratories and in various industries, azo compounds are among the most effective and commonly used organic dyes. The association between human (HSA) and bovine (BSA) serum albumins with 5-(2-thiazolylazo)-2,4,6-triaminopyrimidine (TTP) was investigated in this research using spectroscopy methods and molecular modeling study. The fluorescence quenching results showed that the quenching mechanisms were static and dynamic processes for HSA and BSA, respectively. From the thermodynamic observations, it is clear that the binding process is a spontaneous molecular interaction, in which van der Waals and hydrogen bonding interactions for HSA and hydrophobic interaction for BSA play the major roles. According to Förster energy transfer, non-radiative energy transferred from HSA and BSA to TTP, is provided by close distance (r0) between TTP and Trp residues of HSA and BSA. The synchronous fluorescence spectroscopy, FT-IR findings and UV-Vis absorption data confirm that TTP can induce conformational and micro environmental changes in both the proteins. Furthermore, docking results predicted the probable binding site of TTP in subdomain IIA of HSA and BSA molecules where Trp residues are located. Types of amino acid residues surrounding the TTP molecule supported that van der Waals forces, hydrophobic forces and electrostatic forces play important roles in stabilization of drug-protein complexes formed.Communicated by Ramaswamy H. Sarma.

Surface modification of super paramagnetic iron oxide nanoparticles via milk casein for potential use in biomedical areas.

Super paramagnetic iron oxide nanoparticles (SPIONs) have proved that they have tremendous potential to use in various biomedical applications. But the surface of pure iron oxide nanoparticles so fast oxidized, that is a major drawback for biomedical applications. Covered SPIONs have good surface activity. Therefore, the first goal was to synthesize the naked SPIONs. Then we modified with 3-Aminopropyltriethoxysilane (APTES) and trichlorotriazine (TCT). Several techniques measurements were used for characterization the size and special features of naked SPIONs and TCT modified SPIONs. These results show that the SPIONs were synthesized. After that the SPIONs are coated with casein and indicate that there is an interaction between them. Moreover, we have investigated magnetic properties and anticancer effects of casein-coated SPIONs. Therefore, we showed casein could be used to increase the biocompatibility of the surface of SPIONs. At the end, we show that bonding of dipyridamole (DIP) to the surface of casein-coated SPIONs have good magnetite properties for targeted drug delivery. We find that the release of DIP by casein-coated SPIONs-DIP was sensitive to pH. Both release curves in pH 5.5 and 7.4 showed the release of DIP by ß-casein coated SPIONs-DIP better than α-casein coated SPIONs-DIP. The cell culture studies of the casein-coated SPIONs-DIP provide good anticancer effects against both breast and prostate cancer cell lines. Here, we propose a simple and inexpensive chemical method for preparation of highly biocompatible core-shell SPIONs and binding of drug for using in targeted drug delivery system. Communicated by Ramaswamy H. Sarma.

Spectroscopic and molecular docking studies on interaction of two Schiff base complexes with bovine serum albumin.

This study was designed to examine interaction of two ternary copper (II) Schiff base complexes with bovine serum albumin (BSA), using spectroscopic and molecular docking techniques. The fluorescence quenching measurements revealed that the quenching mechanism was static and the binding site of both Schiff bases to BSA was singular. Förster energy transfer measurements, synchronous fluorescence spectroscopy, and docking study showed both Schiff bases bind to the Trp residues of BSA in short distances. Docking study showed that both Schiff base molecules bind with BSA by forming several hydrogen and van der Waals bonds. In addition, molecular docking study indicated that Schiff base A and Schiff base B were located within the binding pocket of subdomain IB and subdomain IIA of BSA, respectively. Results of Fourier transform-infrared spectroscopy demonstrated that bovine serum albumin interacts with both Schiff bases and the secondary structure of BSA was changed.Communicated by Ramaswamy H. Sarma.

Spectrophotometric-chemometrics study of the effect of solvent composition and temperature on the spectral shape and shift of copper and nickel phthalocyanines in different aqueous-nonaqueous mixed solvents.

Phthalocyanines (Pcs) are green-blue colored aromatic macrocyclic compounds used extensively in the dyeing industry. The assembly phenomenon for dye molecules is directly traceable by most of the spectroscopic methods. In this investigation, the monomer-dimer equilibria of copper and nickel phthalocyanines tetra sulfonic acid tetrasodium salts (CuPcTS, NiPcTS) have been investigated by spectrophotometric and chemometrics methods in binary mixtures of H2O-DMSO and H2O-CH3CN. The dimerization constants, (KD), enthalpies and entropies of CuPcTS and NiPcTS have been calculated by studying the UV-Vis spectra at different concentrations of dyes (10-6 to 10-4molL) and in the temperature range 298-343 K and in some samples up to 353 K by multivariate curve resolution (mcr) methods. By increasing the temperature, the value of KD decreases. The inverse temperature dependence of KD (van't Hoff equation) was used for determination of ΔH 0 and ΔS 0and following that ΔG 0of the dimerization reactions. As a result, upon aggregation, an increase in the intensity of the new shoulder at (~600 nm) and the Q-band at (662-670 nm) and concomitant decrease of the dimer band at (630-624 nm) are observed for all of the samples in different solvents composition. Therefore, the H-dimer type of these pigments was notable, in studied binary solvents. The effect of the solvent composition, concentration dye, and temperature on the spectral responses, the exciton parameters and concentration distribution diagrams of the two pigments were studied and discussed. The density functional theory (DFT) calculations were done in the aqueous and gas phase that they were included the HOMO-LUMO energies and the simulated UV-Vis spectrum. These calculations were beneficial for studying the UV-Vis spectrum of it in the aqueous phase for checking experimental data.

Correction to: Toxicity of Copper Oxide (CuO) Nanoparticles on Human Blood Lymphocytes.

The original version of this article unfortunately contained mistakes. The name Hamid Degampanah is corrected to "Hamid Dezhampanah". Affiliation 1 is corrected to University of Guilan from Guilan University.

Toxicity of Fe2 O3 nanoparticles on human blood lymphocytes.

Magnetic nanoparticles (NPs) are used to a large extent in the targeted delivery of therapeutic agents. In this study, we aimed to investigate the possible toxicity of Fe2 O 3 NPs on human cells, including blood lymphocytes. We isolated blood lymphocytes from healthy humans using Ficoll polysaccharide and subsequently by gradient centrifugation. Then, the toxicity parameters, including cell viability, reactive oxygen species (ROS) formation, lipid peroxidation, cellular glutathione (GSH) level, mitochondrial and lysosomal damage, were measured in blood lymphocytes after exposure to Fe 2 O 3 NPs. Our results indicated that Fe 2 O 3 NPs significantly (dependent on concentration) reduced the cell viability, and the IC 50 was determined to be 1 mM. With increasing concentrations, we found that Fe 2 O 3 NPs-induced cell toxicity was associated with a significant increase in intracellular ROS and loss of mitochondrial membrane potential and lysosomal membrane leakiness. Consequently, these NPs at different concentrations affect GSH level and cause oxidative stress in human lymphocytes.

Milk caseins as useful vehicle for delivery of dipyridamole drug.

The interaction of bovine milk α- and ß-caseins as an efficient drug carrier system with Dipyridamole (DIP) was investigated using spectroscopy and molecular docking studies at different temperatures (20-37 °C). FTIR, CD, and fluorescence spectroscopy methods demonstrated that α- and ß-caseins interact with DIP molecule mainly via hydrophobic and hydrophilic interactions and change in secondary structure of α- and ß-caseins. DIP showed a higher quenching efficiency and binding constant of α-casein than ß-casein. There was only one binding site for DIP and it was located on the surface of the protein molecule. The thermodynamic parameters of calculation showed that the binding process occurs spontaneously and demonstrated that α- and ß-caseins provide very good binding and entrapment to DIP via hydrogen bonds, Van der Waals forces, and hydrophobic interactions. Fluorescence resonance energy transfer, synchronous fluorescence spectroscopy, and docking study showed that DIP binds to the Trp residues of α- and ß-casein molecules with short distances. Docking study showed that DIP molecule made several hydrogen bonds and van der Waals interactions with α- and ß-caseins. The study of cell culture and micellar solubility of DIP demonstrated α- and ß-caseins relatively the same helping in delivery of DIP. Milk α- and ß-caseins are considered as a useful vehicle for the solublization and stabilization of DIP in aqueous solution at natural pH.

Intermolecular interaction of nickel (ii) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin: A multi-technique study.

The interaction of nickel (II) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin (BSA) has been investigated by combination of fluorescence, UV-vis absorption, Fourier transform infrared (FT-IR), and circular dichorism (CD) spectroscopies as well as through molecular docking. Fluorescence quenching and absorption spectra were investigated as a mean for estimating the binding parameters. Analysis of fluorescence quenching data at different temperatures was performed in order to specify the thermodynamics parameters for interactions of phthalocyanine complex with BSA. According to experimental data it was suggested that phthalocyanine had a significant binding affinity to BSA and the process was entropy driven. Based on the results of molecular docking it was indicated that the main active binding site for this phthalocyanine complex is site I in subdomain IIA of BSA. The results provide useful information for understanding the binding mechanism of anticancer drug-albumin and gives insight into the biological activity and metabolism of the drug in blood.

An Investigation on intermolecular interaction between Bis(indolyl)methane and HSA and BSA using multi technique methods.

Bis(indolyl)methane (BIM) as one of the main active components of anticancer and antibacterial drugs is applied in medicinal and extensive area of chemistry. In this research, interaction of human and bovine serum albumins as drug carriers with BIM was investigated using spectroscopy methods and molecular modeling study. The fluorescence quenching measurements at the range of 293-310 K revealed that the quenching mechanisms for human and bovine serum albumins are static and dynamic processes, respectively. The results of quenching study were used to calculate thermodynamic parameters [Formula: see text] which indicated that the binding process occurs spontaneously and demonstrated that human and bovine serum albumins provide very good binding via hydrogen bonds, van der Waals forces, and hydrophobic interactions. Förster energy transfer measurements, synchronous fluorescence spectroscopy, and docking study showed BIM binds to the Trp residues of human and bovine serum albumin molecules in short distances. Docking study showed that BIM molecule has two hydrogen bonds and several van der Waals contacts with human and bovine serum albumins. Results of FT-IR and CD spectroscopy demonstrated that serum albumins interact with BIM molecule mainly via hydrophobic and hydrophilic interactions and the secondary structure of serum albumins are changed.

Spectroscopy and Molecular Modeling Study on Binding of Nickel Phthalocyanine to Human Serum Albumin.

The interaction of nickel tetra sulfunated phthalocyanine( NiTSPc) with human serum albumin (HSA), in 20 mM phosphate buffer pH 7.4 was investigated using advanced techniques including fluorescence, synchronous fluorescence, Fourier transform infrared (FT-IR), circular dichroism (CD) spectroscopy and molecular docking. The fluorescence quenching measurements showed a single binding site on HSA for NiTSPc with the binding constant (K_b) value equals to 1.26×106 at 25°C. The results showed that quenching mechanism of HSA by NiTSPc was of dynamic type. The results from FTIR and CD spectroscopies demonstrated that NiTSPc binds to amino acid residues of the main polypeptide chain in protein destroying the hydrogen bonding network. The corresponding thermodynamic parameters were then calculated by analysis of fluorescence data using van't Hoff plot. These data indicated that driving force for interaction was mainly hydrophobic in nature and the process was entropy driven. The information obtained from CD, FT-IR and synchronous fluorescence spectroscopies revealed that both microenvironment and conformation of HSA was changed. Molecular docking study confirmed the binding mode obtained by experimental data.

Spectroscopic studies on the interaction of a water-soluble cationic porphyrin with bovine serum albumin.

The interaction of a water-soluble cationic porphyrin, Cobalt(III) 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin [Co(III)TMPyP], with bovine serum albumin (BSA) has been studied in 1 mM phosphate buffer pH 7.0 containing 5 mM NaCl by UV-vis absorption, resonance light scattering (RLS) and fluorescence spectroscopies at 25°C. The results of RLS studies represent no aggregate formation of porphyrin in the surface of BSA and low tendency of this porphyrin for aggregate formation. The binding of porphyrin complex to BSA quenches fluorescence emission of BSA via a dynamic mechanism and the quenching process obeys a linear Stern-Volmer relationship. The values of Stern-Volmer constants, KSV, was determined nearly 10(5) M(-1), that depend on BSA concentration. The average aggregation number of BSA calculated from the analysis of fluorescence quenching data indicates that absence of any porphyrin induced aggregation of BSA due to its interaction with porphyrin complex. The binding of Co(III) TMPyP had no obvious effect on the molecular conformation of the protein. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the protein.

Study on interaction of cationic porphyrazine with synthetic polynucleotides.

Interactions of cationic tetrakis (N, N', N″, N‴- tetramethyltetra-3, 4-pyridinoporphyrazinatozinc (II) (Zn (tmtppa)) with synthetic polynucleotides, poly (G-C) and poly (A-T), and calf thymus DNA have been characterized in 7.5 mM phosphate buffer of pH 7.2 by UV-Vis absorption and fluorescence spectroscopy. The appearance of hypochromicity more than 30% in UV-Vis spectra of porphyrazine due to interaction of both poly (G-C) and poly (A-T) indicates interaction similar to that of porphyrazine with DNA. The binding constants were determined from the changes in the Q-band maximum of the porphyrazine spectra at various poly (G-C) and DNA concentrations. The values of K were 2.5×106 M⁻¹, 2.5×106 M⁻¹ and 2.5×105 M⁻¹ for poly (G-C), poly (A-T) and DNA, respectively, at 25°C. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were calculated using the van't Hoff equation at various temperatures. The enthalpy and entropy changes were determined to be 41.14 kJ mol⁻¹ and 260.50 J mol⁻¹·K⁻¹ for poly (G-C) and 53.59 kJ mol⁻¹ and 285.46 J mol⁻¹·K⁻¹ for DNA at 25°C. The positive and large values of the entropy and enthalpy suggest that both hydrophobic and electrostatic interactions may play an important role in the stabilization of the complex formation. The binding of polynucleotides to porphyrazine quenches fluorescence emission of ethidium bromide (EB), and the quenching process obeys linear Stern-Volmer relationship. The results reviled groove-binding mode of porphyrazine for both AT- and GC-rich polynucleotides of DNA.