Spectroscopic analysis on the binding interaction of biologically active pyrimidine derivative with bovine serum albumin

A biologically active antibacterial reagent, 2-amino-6-hydroxy-4-（4-N, N-dimethylaminophenyl）-pyr- imidine-5-carbonitrile （AHDMAPPC）, was synthesized. It was employed to investigate the binding in- teraction with the bovine serum albumin （BSA） in detail using different spectroscopic methods. It ex- hibited antibacterial activity against Escherichia cali and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites （n ≈ 1） were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change （AH）, free energy （AG） and entropy change （AS） for the reaction were calculated to be 15.15 kJ/mol, -36.11 kJ/mol and 51.26J/mol K according to van＇t Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Forster＇s theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV-visible, synchronous fluorescence, circular dichroism （CD） and three-dimensional fluorescence spectra. All these results in- dicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.

Immobilization of Bovine Serum Albumin on Poly(ether ether ketone) for Surface Biocompatibility Improvement

UV-induced graft polymerization of acrylic acid（AA） on poly（ether ether ketone）（PEEK） films was carried out to introduce ―COOH for the subsequent immobilization of bovine serum albumin（BSA）.BSA was introduced on PEEK surface based on the condensation reaction between ―NH 2 and ―COOH.The modified surface（PEEK-BSA） was characterized by energy-disperse spectrometry（EDS）,X-ray photoelectron spectroscopy（XPS）,water contact angle measurement and UV spectrum analysis.The contact angle was found to decrease from 104° for the virgin PEEK films to 63° for the BSA-immobilized PEEK films,demonstrating a significant improvement of surface hydrophilicity.Moreover,the appearance of nitrogen on PEEK film confirmed by XPS and EDS indicates the immobilization of BSA on PEEK surface.

Sonocatalytic Damage of Bovine Serum Albumin (BSA) in the Presence of Nanometer Titanium Dioxide (TiO_2) Catalyst

The sonocatalytic damage of bovine serum albumin （BSA） was studied in the presence of nanometer titanium dioxide （TiO2） powders by low frequency （80 kHz） ultrasound. The destruction of secondary structure and change of α-helical structure of BSA were reflected by ultraviolet （UV） and circular dichroism （CD） spectroscopies.

Synthesis of Metal Porphyrins Tailed with Salicylic Acid and their Interaction with Bovine Serum Albumin

A synthetic method of porphyrins tailed with salicylic substituents is described. Reaction of bromoalkoxyphenyl porphyrin 1 with salicylic acid gave porphyrins 2~5. These new compounds were confirmed by 1H NMR, IR, UV-vis, MS and elemental analysis, and observed their interaction with bovine serum albumin (BSA) in fluorescence spectrum.

Determination of Enantiomeric Compositions of Tryptophan by Chemometric Analysis of the Fluorescence Spectra of Bovine Serum Albumin Receptor-ligand Mixtures

In this work, a novel method was constructed to determine the enantiomeric composition of tryptophan （Trp） by bovine serum albumin （BSA） based on the fluorescence spectra of the receptor-ligand mixtures coupled with partial least squares （PLS-1） analysis. As a result the enantiomeric composition of Trp was accurately determined.

Characterization of Interaction Between Raltitrexed and Bovine Serum Albumin by Optical Spectroscopic Techniques

The interaction of raltitrexed（RTX） with bovine serum albumin（BSA） was investigated by steady state/lifetime fluorescence spectroscopy and circular dichroism（CD） spectroscopy under the simulative physiological conditions.The results of fluorescence titration reveal that RTX could strongly quench the intrinsic fluorescence of BSA via a static quenching procedure.The obtained binding constant K A of RTX with BSA was 478630 and 44259 L/mol at 298 and 310 K,respectively.According to van＇t Hoff equation,the thermodynamic parameters ΔH,ΔG and ΔS were calculated,indicating that hydrophobic forces were the predominant intermolecular forces in stabilizing the complex.The binding process was a spontaneous process,in which Gibbs free energy change was negative.According to F rster＇s non-radioactive energy transfer theory,the distance r between donor（BSA） and acceptor（RTX） was 3.82 nm,suggesting that the energy transfer from BSA to RTX occurred with high probability.Displacement experiment and the number of binding sites calculation confirmed that RTX could bind to the site-I of BSA.Furthermore,the effects of pH and some metal ions on the interaction of RTX with BSA were also investigated.The results of synchronous fluorescence and CD spectra show that the RTX-BSA binding induced conformational changes in BSA.

Morphological characterization of metal porphyrin tailed with aspirin interacting with bovine serum albumin congeries

The porphyrins tailed with acetylsalicylic acid （ASA） and Zn （or Cu） complexes were prepared. Meanwhile, morphological images, such as shape and size of porphyrins-BSA congeries were observed by using atomic force microscopy （AFM）. The result showed the interaction of BSA and prepared porphyrins led to obvious change of shape and size of BSA congeries.

Reduced graphene oxide-grafted bovine serum albumin/bredigite nanocomposites with high mechanical properties and excellent osteogenic bioactivity for bone tissue engineering

The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.

Synthesis of Zinc Oxide Nanoparticles with Good Photocatalytic Activities under Stabilization of Bovine Serum Albumin

Zinc oxide nanoparticles were synthesized using bovine serum albumin as stabilizers through a facile one-pot strategy in aqueous media. The morphology and crystal phase of the zinc oxide nanoparticles were determined by transmission electron microscopy, X-ray diffractograms, and Fourier transform infrared spectroscopy. The synthesized ZnO nanoparticles exhibited strong absorption and photoluminescence properties in the visible wavelength region based on the fluorescence and UV-visible spectroscopy. Based on the results, the zinc oxide nanoparticles could effectively degrade the organic dyes through the mediation of the hydroxyl radical under visible light irradiation. Furthermore, the zinc oxide nanoparticles show good recycling stability during the photocatalytic experiments. These results suggested that the as-prepared zinc oxide nanoparticles might be used as a potential photocatalyst to efficiently treat the organic pollutants.

Microwave Synthesis of CdTe/TGA Quantum Dots and Their Thermodynamic Interaction with Bovine Serum Albumin

The thioglycollic acid（TGA） as a capping agent, CdTe/TGA quantum dots（QDs） with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and p H are the crucial factors for properties of QDs. The QDs were characterized by UVvis absorption and fluorescence spectra, transmission electron microscopy and Fourier transform infrared spectroscopy. The experimental results show that when the p H value is 11.5 and molar ratio of TGA：Cd：Te is 1.2：1：0.4 at 100 ℃ heating for 15 min, the resulted QDs exhibit a high fluorescence quantum yield of 78%. The fluorescence full width at half maximum（FHMW） of QDs is around 23 nm. The products are spherical with average size of 3-5 nm. There is a strong coordination effect between TGA and Cd2＋. Moreover, the results of interaction between as-made QDs and bovine serum albumin（BSA） suggest that the QDs-BSA binding reaction is a static quenching. The negative values of free energy（△G〈0） suggest that the binding process is spontaneous, △H〈0 and △S〈0 show that hydrogen bonds and van der Waals interactions play a major role in the binding reaction between QDs and BSA.

Effects of urea,metal ions and surfactants on the binding of baicalein with bovine serum albumin

The interaction of baicalein with bovine serum albumin（BSA） was investigated with the help of spectroscopic and molecular docking studies.The binding affinity of baicalein towards BSA was estimated to be in order of 10~5 M^（-1） from fluorescence quenching studies.Negative ΔH°（-5.66 ＋ 0.14 kJ/mol） and positive（ΔS°）（＋ 79.96 ＋ 0.65J/mol K） indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positive ΔS°.The hydrophobic association of baicalein with BSA diminishes in the presence of sodium dodecyl sulfate（SDS） due to probable hydrophobic association of baicalein with SDS,resulting in a negative ΔS°（-40.65 ＋ 0.87 J/mol K）.Matrix-assisted laser desorption ionization/time of flight（MALDI-TOF） experiments indicate a 1：1 complexation between baicalein and BSA.The unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime measurements.It was observed that the presence of urea ruptured the non-covalent interaction between baicalein and BSA.The presence of metal ions（Ag~＋,Mg^（2＋）,Ni^（2＋）,Mn^（2＋）,Co^（2＋） and Zn^（2＋）） increased the binding affinity of ligand towards BSA.The changes in conformational aspects of BSA after ligand binding were also investigated using circular dichroism（CD） and Fourier transform infrared（FT-IR） spectroscopic techniques.Site selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1（subdomain MA） of BSA.

STUDIES ON THE COMPETITION FOR CADMIUM ION BETWEEN CHELATING AGENTS AND BOVINE SERUM ALBUMIN

Eleven chelating agents were studied for their capabilities to mobilize the cadmium bound tp bovine serum albumin(BSA).The parameter F,which is defined as the ratio between the percentages of cadmium bound to BSA in the presence and absence of chelating agents,can be used as the criterion to evaluate the mobilizing capability of chelating agent.The F values determined experimentally lead to a mobilizing capability order:DTPA>EDTA>EGTA>NTA>TR1EN>PEN>CYS>HIS>SAThe polyaminopolycarboxylate type chelators mobilize cadmium effectively.A linear relationship was found between 1gF and lg k'CdL (conditional stability constant of the cadmium chelate).

Study on the interaction between clarithromycin and bovine serum albumin in the imitated physiology solution

The interaction between clarithromycin (CAM) and bovine serum albumin (BSA) was investigated using linear-sweep voltammetry in pH 7.4 phosphate buffer solution where CAM caused two irreversible reduction waves P2 and P3 on mercury electrode. The study showed that the formation constant and formation ratio for the interaction between CAM and BSA were 1.51 × 10(12) and 3:1 for P2, 4.53 × 10(5) and 1:1 for P3, respectively. The ion strength enhanced the hydrophobic interaction between CAM and BSA.

Study on the Interaction between CdSe Quantum Dots and Bovine Serum Albumin with Ultraviolet Visible Absorption Spectroscopy

The interaction of CdSe quantum dots （QDs） with bovine serum albumin （BSA） has been investigated with ultraviolet visible absorption spectroscopy （UVAS）. It was found that the absorption intensity of CdSe QDs significantly decreased after adding BSA solution, showing that CdSe QDs were bonded to BSA. The binding molar ratio was 1：1 and the binding constant was 9.7 × 10^6 L mol^-1.

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

The voltammetric methods were used to prove the interaction of metal complex Co(phen)(3)(3+) with bovine serum albumin (BSA). The interaction of BSA with Co(phen)(3)(3+) molecules using BSA-modified electrode is described. Information of the binding ratio and interaction mode can be obtained from their electrochemical behavior and electrochemical data. Furthermore, attenuated total reflection infrared experiment was performed to prove the interaction between complexes and BSA.

Investigation of the topological shape of bovine serum albumin in solution by small-angle x-ray scattering at Beijing synchrotron radiation facility

This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radia- tion Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2~=t=0.25 ~_ （11=0.1 nm） which is co- incident with other ones＇ results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed.

Competitive Adsorption between Bovine Serum Albumin and Collagen Observed by Atomic Force Microscope

Atomic force microscopy (AFM) was used to study the competitive adsorption betweenbovine serum albumin (BSA) and type Ⅰ collagen on hydrophilic and hydrophobic silicon wafers.BSA showed a grain shape and the type Ⅰ collagen displayed fibril-like molecules with relativelyhomogeneous height and width, characterized with clear twisting (helical formation). These AFMimages illustrated that quite a lot of type Ⅰ collagen appeared in the adsorption layer on hydrophilicsurface in a competitive adsorption state, but the adsorption of BSA was more preponderant than thatof type Ⅰ collagen on hydrophobic silicon wafer surface. The experiments showed that theinfluence of BSA on type Ⅰ collagen adsorption on hydrophilic surface was less than that onhydrophobic surface.

Bovine Serum Albumin Loaded Solid Lipid Nanoparticles Prepared by Double Emulsion Method

Solid lipid nanoparticles loaded with bovine serum albumin（BSA） were prepared by a double emulsion method. As the mass fraction of the model drug BSA increased from 0 to 15%, the particle size gradually increased. The physical stability of the nanoparticles was investigated by zeta potential measurement and they were shown to be quite stable. Fluorescence spectroscopy confirmed that the loaded position of BSA was on the interface between the inner aqueous phase and the solid lipid phase. Both Fourier-transform infrared spectroscopy and circular dichroism spectra indicate that BSA in the nanoparticles was not destroyed, but the secondary structure was disrupted slightly.

Interaction of Mixed Porphyrin-polypyridyl Ru(II) Complex with Bovine Serum Albumin

The interactions of mixed porphyrin-polypyridyl Ru（Ⅱ） complexes [m（Py-3＇）TPP-Ru（phen）2Cl]^＋（1） and its derivatives [Nim（Py-3＇）TPP-Ru（phen）2Cl]＋（2） and [Cum（Py-3＇）TPP-Ru（phen）2Cl]^＋（3）（phen=1,10-phenanthroline; m（Py-3＇）TPP=5-（3＇-pyridyl）-10,15,20-triphenylporphyrin） with bovine serum albumin（BSA） were investigated by fluorescence, UV-Vis and circular dichroism（CD） spectroscopies. The UV-Vis and CD spectral experiments indicated that the secondary structures of the protein were perturbed in the presence of the porphyrin Ru（Ⅱ） complex and the perturbation was enhanced under the irradiation with ultra-violet light. The fluorescence quenching mechanism of BSA by the three complexes was determined to be a static process, and the apparent binding constant K values for complexes 1, 2 and 3 measured by fluorescence quenching method were （3.86±0.03）×10^3 L/mol（n=0.94±0.04）, （5.69±0.04）× 103 L/mol（n=1.03±0.06）, and （6.54±0.02）× 10^3 L/mol（n=1.03±0.05）, respectively.

The electrochemical behavior of N-n-undecy1-N＇-（sodium-p- amino-benzenesulfonate） thiourea and its interaction with bovine serum albumin

In pH 5.5 phosphate buffer solution, N-n-undecyl-N＇-（sodium-p-amino-benzenesulfonate） thiourea （UPT） produced a pair of redox peaks on the bare glassy carbon electrode. At the multi-walled carbon nanotube （MWNT） modified electrode, the electrochemical behavior of UPT enhanced greatly. In the presence of bovine serum albumin （BSA）, the peak currents of UPT decreased linearly due to the formation of a super-molecular complex. This method was successfully applied to the determination of BSA in a bovine serum sample.