Spectroscopic studies on the interaction between troxerutin and bovine serum albumin

Influence of protein configuration on aggregation kinetics of nanoplastics in aquatic environment

Aggregation kinetics of nanoplastics in aquatic environment are influenced by their interactions with proteins having different structures and properties. This study employed time-resolved dynamic light scattering (TR-DLS) to investigate the effects of 5 proteins (bovine hemoglobin (BHb), bovine (BSA) and human serum albumin (HSA), collagen type I (Col I), and bovine casein (CS)) on aggregation kinetics of polystyrene nanoplastics (PSNPs) under natural water conditions, which were simulated using various ionic strength (1-1000 mM NaCl and 0.01-100 mM CaCl₂), pH (3-9), and protein concentration (1-5 mg/L of total organic carbon). The results indicated that the interactions between proteins and PSNPs strongly depended on electrostatic properties, protein structures, and solution chemistries, which induced distinct aggregation behaviors in NaCl and CaCl₂ solutions. Electrostatic repulsion and steric hindrance dominated their interactions in NaCl solution by stabilizing PSNPs with the order of spherical BSA and disordered CS > heart-shaped HSA > fibrillar Col I; whereas positively charged BHb destabilized PSNPs with aggregation rate of 1.71 nm/s at 300 mM NaCl. In contrast, at CaCl₂ concentration below 20 mM, proteins destabilized PSNPs following the sequence of HSA > BHb > Col I > BSA depending on counterbalance among double layer compression, cation bridging, and steric hindrance; whereas CS stabilized PSNPs by precipitating Ca²⁺ that inhibited charge screening effect. Both protein concentration and solution pH affected protein corona formation, surface charge, and protein structure that altered stability of PSNPs. Characterizations using fluorescence spectroscopy, circular dichroism, and two-dimensional correlation analysis spectroscopy showed fluorescence quenching and ellipticity reduction of proteins, indicating strong adsorption affinity between PSNPs and proteins. The study provides insight to how protein configuration and water chemistry affect fate and transport of nanoplastics in aquatic environment.

Novel fluorene-based fluorescent probe with excellent stability for selective detection of SCN- and its applications in paper-based sensing and bioimaging

SCN- is one of the most important anions in metabolic processes. However, the investigation of SCN- in living systems is restricted by the lack of stable functional molecular tools. Herein, the first fluorene-based polymer fluorescent probe V1 was synthesized through rational design. Compared with small molecule fluorescent probes, V1 exhibited excellent fluorescence stability in bovine serum albumin (BSA) solution. Furthermore, the V1-based paper sensor was highly selective toward SCN- in aqueous solution. Significantly, these merits of the probe V1 enable the detection of SCN- in different living cell lines and zebrafish.

A label-free “turn-on” fluorescence platform for glucose based on AuNCs@MnO2 nanocomposites

The principle of sensitive detection of glucose in human serum using Bro-AuNCs @MnO₂ nanocomposites as a fluorescent sensor.

Design, synthesis and DNA-binding study of some novel morpholine linked thiazolidinone derivatives

The emergence of multiple drug resistance amongst bacterial strains resulted in many clinical drugs to be ineffective. Being vulnerable to bacterial infections any lack in the development of new antimicrobial drugs could pose a serious threat to public health. Here we report design and synthesis of a novel class of morpholine linked thiazolidinone hybrid molecules. The compounds were characterized by FT-IR, NMR and HRMS techniques. Susceptibility tests showed that most of the synthesized molecules were highly active against multiple bacterial strains. Compound 3f displayed MIC values which were better than the standard drug for most of the tested strains. DNA being a well defined target for many antimicrobial drugs was probed as possible target for these synthetic molecules. DNA-binding study of 3f with sm-DNA was probed through UV-vis absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. The studies revealed that compound 3f has strong affinity towards DNA and binds at the minor groove. The docking studies revealed that the compound 3f shows preferential binding towards A/T residues.

Study on the interaction between 21-(Ph-NN)-NCTPP and bovine serum albumin by spectroscopic techniques

The interaction between 21-(Ph-NN)-NCTPP and bovine serum albumin (BSA) was investigated by fluorescence and ultraviolet-visible (UV-Vis) spectroscopy under imitated physiological conditions. The results showed that the intrinsic fluorescence of BSA was quenched strongly by 21-(Ph-NN)-NCTPP. The binding constants (Ka) and the binding sites (n) were obtained at three different temperatures (298, 304, and 310K). The thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated, the results indicated that the binding process was spontaneous and the hydrophobic interaction played a major role in [21-(Ph-NN)-NCTPP]-BSA binding process. Based on the Förster non-radiation energy transfer theory, the binding distance from 21-(Ph-NN)-NCTPP to BSA was estimated to be about 3.51nm. What's more, the synchronous fluorescence spectra indicated that the conformation of BSA has not been changed.

Study on the interaction between Besifloxacin and bovine serum albumin by spectroscopic techniques

The interaction between Besifloxacin (BFLX) and bovine serum albumin (BSA) was investigated by spectroscopic (fluorescence, UV-Vis absorption and circular dichroism) techniques under imitated physiological conditions. The experiments were conducted at different temperatures (298, 304 and 310 K) and the results showed that the BFLX caused the fluorescence quenching of BSA through a static quenching procedure. The binding constant (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at different temperatures. The results revealed that the binding process was spontaneous and the acting force between BFLX and BSA were mainly electrostatic forces. According to Förster non-radiation energy transfer theory, the binding distance between BFLX and BSA was calculated to be 4.96 nm. What is more, both synchronous fluorescence and circular dichroism spectra confirmed conformational changes of BSA.

Investigations into the bovine serum albumin binding and fluorescence properties of Tb (III) complex of a novel 8-hydroxyquinoline ligand

A novel ligand, 2-methyl-6-(8-quinolinyl)-dicarboxylate pyridine (L), and its corresponding Tb (III) complex, Na4Tb(L)2Cl4·3H2O, were successfully prepared and characterized. The luminescence spectra showed that the ligand L was an efficient sensitizer for Tb (III) luminescence. The interaction of the complex with bovine serum albumin (BSA) was investigated through fluorescence spectroscopy under physiological conditions. The Stern-Volmer analysis indicated that the fluorescence quenching was resulted from static mechanism. The binding sites (n) approximated 1.0 and this meant that interaction of Na4Tb(L)2Cl4·3H2O with BSA had single binding site. The results showed van der Waals interactions and hydrogen bonds played major roles in the binding reaction. Furthermore, circular dichroism (CD) spectra indicated that the conformation of BSA was changed.

Study on the interaction between carbonyl-fused N-confused porphyrin and bovine serum albumin by spectroscopic techniques

The interaction between carbonyl-fused N-confused porphyrin (CF-NCP) and bovine serum albumin (BSA) was investigated by fluorescence and ultraviolet-visible (UV-Vis) spectroscopy. The results indicated that CF-NCP has strong ability to quench the intrinsic fluorescence of BSA by forming complexes. The binding constants (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at three different temperatures. The results revealed that the binding process is spontaneous, and the acting force between CF-NCP and BSA were mainly electrostatic forces. According to Förster non-radiation energy transfer theory, the binding distance between CF-NCP and BSA was calculated to be 4.37nm. What is more, the conformation of BSA was observed from synchronous fluorescence spectroscopy.

The investigation of the interaction between Tropicamide and bovine serum albumin by spectroscopic methods

The fluorescence and ultraviolet-visible (UV-Vis) spectroscopy were explored to study the interaction between Tropicamide (TA) and bovine serum albumin (BSA) at three different temperatures (292, 301 and 310K) under imitated physiological conditions. The experimental results showed that the fluorescence quenching mechanism between TA and BSA was static quenching procedure. The binding constant (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at different temperatures. The results revealed that the binding process is spontaneous, hydrogen binds and vander Waals were the main force to stabilize the complex. According to Förster non-radiation energy transfer theory, the binding distance between TA and BSA was calculated to be 4.90 nm. Synchronous fluorescence spectroscopy indicated the conformation of BSA changed in the presence of TA. Furthermore, the effect of some common metal ions (Mg(2+), Ca(2+), Cu(2+), and Ni(2+)) on the binding constants between TA and BSA were examined.

Spectroscopic analyses on interaction of Naphazoline hydrochloride with bovine serum albumin

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between Naphazoline hydrochloride (Naphcon) and bovine serum albumin (BSA) at three different temperatures (292, 301, and 310 K) under imitated physiological conditions. The quenching mechanism of BSA by Naphacon was interpreted using the Stern-Volmer mechanism, and a combined quenching (dynamic and static quenching). The binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) of the interaction system were calculated at different temperatures. According to Förster non-radiation energy transfer theory, the binding distance between BSA and Naphcon was found to be 4.71 nm. Synchronous fluorescence spectroscopy showed the conformation of BSA changed in the presence of Naphacon. In addition, the effect of some common metal ions (Mg(2+), Ca(2+), Ni(2+), Cu(2+), and Fe(2+)) on the binding constant between Naphcon and BSA was examined.

Synthesis, luminescence properties of Eu(III) and Tb(III) complexes with a novel aromatic carboxylic acid and their interactions with bovine serum albumin

A novel aromatic carboxylic acid ligand (L) was synthesized and its corresponding Eu(III) and Tb(III) complexes, Na(3)EuLCl(3)·2H(2)O (EuL) and Na(3)TbLCl(3)·3H(2)O (TbL), were successfully prepared. L and its corresponding complexes were characterized by means of MS, elemental analysis, IR, (1)H NMR and TG. The luminescence spectra of Eu(III) and Tb(III) complexes were investigated and the results showed that L was an efficient sensitizer for Eu(III) and Tb(III) luminescence. The interactions of L, EuL and TbL with bovine serum albumin (BSA) have been investigated through fluorescence spectroscopy under physiological conditions. The Stern-Volmer analysis indicated that the fluorescence quenching of BSA by L, EuL and TbL was resulted from static mechanism, and the binding constants (K(a)) were 2.22×10(4), 1.33×10(5) and 4.27×10(5) at 300 K, respectively. The binding sites (n) and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. According to the theoretical and experimental results, van der Waals interactions and hydrogen bonds were found to play major roles in the binding reaction. Furthermore, UV-Vis absorption spectroscopy and synchronous fluorescence spectra indicated that the conformation of BSA was changed. The results obtained in the work can help understand the action mode between L and its corresponding Eu(III) and Tb(III) complexes with BSA, and they are also expected to provide important information of designs of new inspired drugs based on Eu and Tb.

Spectroscopic analysis of the interaction between thiazolo[2,3-b]pyrimidine analogues and bovine serum albumin

The interaction between thiazolo[2,3-b]pyrimidine (TZPM) analogues and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and UV-Vis spectroscopy at two different temperatures (299 and 307K) under imitated physiological conditions. The results indicate that both static quenching and dynamic quenching contribute to the fluorescence quenching of BSA by TZPM. The binding constant (K(a)) and binding sites (n) were calculated from the obtained spectra. Based on the Förster non-radiation energy transfer theory, the average binding distance between BSA and TZPM was estimated. The synchronous fluorescence spectra indicate that the conformation of BSA has been changed. The comparison of binding potency of TZPM and BSA suggests that the substituents on the benzene ring enhance the binding affinity of TZPM and BSA. We investigated the possible sub-domains on BSA that bind TZPM by displacement experiments. Furthermore, to explore the effect of molecular structure on the binding, a study on quantitative structure-property relationship (QSPR) was performed, the quantitative relationship equation of R(0), r and K(a) were obtained. We observed that R(0), r and K(a) between BSA and TZPM is connected with the margin of the highest and the lowest occupied orbital energy (ΔE), dipole moment (μ), Molar Volume (V(m)), Mole Mass (M).

Interaction of pyrrolizine derivatives with bovine serum albumin by fluorescence and UV-Vis spectroscopy

The interaction between pyrrolizine derivatives (PD) and bovine serum albumin (BSA) under imitated physiological conditions was analyzed by fluorescence and ultraviolet spectra. The experiments were conducted at three different temperatures (302, 306 and 310 K) and the results showed that PD caused the fluorescence quenching of BSA through a combined quenching procedure. The binding constant (K(a)), binding-site number (n) between PD and BSA at different temperatures were obtained. According to Förster non-radiation energy transfer theory, the binding distance (r) between BSA and PD was calculated. The corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were also obtained. The comparison of binding potency of PD and BSA suggested that the substituent on the benzene ring could enhance the binding affinity of PD and BSA. Finally, we investigated the possible sub-domain on BSA where bind PD by displacement experiments.

Study on the interaction between novel spiro pyrrolidine and bovine serum albumin by spectroscopic techniques

Spiro pyrrolidines, which were proved with diverse and potent biological activities and they were discovered widespread in nature. In this paper, using fluorescence and ultraviolet spectroscopy, we investigated the interactions between novel spiro pyrrolidine (NSP) and bovine serum albumin (BSA) under the imitated physiological condition. The results show that the NSP binds to BSA molecules. Static quenching and non-radiation energy transfer are the main reasons for fluorescence quenching. We calculated the binding constant (K(a)) and binding sites (n) at different temperatures and obtained the binding distance between the tryptophan residue in BSA and the NSP based on the Förster theory of non-radiation energy transfer. In addition, using synchronous fluorescence spectra, we demonstrated conformation changes of BSA caused by NSP. The comparison of binding potency of NSP and BSA suggests that the substituent on the benzene ring influences the binding ability of NSP and BSA.

Study on the interaction between NCP-(4-hydroxycoumarins) and bovine serum albumin by spectroscopic techniques

The interaction between N-confused porphyrins-(4-hydroxycoumarins) diad (NCP-(4-hydroxycoumarins)) and bovine serum albumin (BSA) was studied using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by NCP-(4-hydroxycoumarins) through a combined quenching procedure. The binding constants, binding sites and corresponding thermodynamic parameters between NCP-(4-hydroxycoumarins) and BSA at different temperatures were obtained. According to Förster non-radiation energy transfer theory, the binding distance between BSA and NCP-(4-hydroxycoumarins) was calculated to be about 2.1 nm. The effect of NCP-(4-hydroxycoumarins) on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu(2+), Ca(2+), Mg(2+), and Ni(2+) on the binding constant between NCP-(4-hydroxycoumarins) and BSA was examined.

The fluorescence spectroscopic study on the interaction between imidazo[2,1-b]thiazole analogues and bovine serum albumin

The interaction between imidazo[2,1-b]thiazole (IMTZ) and bovine serum albumin (BSA) was analyzed by fluorescence and ultraviolet spectroscopy at 302 and 310 K under simulative physiological conditions. The results show that IMTZ can effectively quench the intrinsic fluorescence of BSA via static and dynamic quenching. The binding constant, binding sites of IMTZ with BSA were calculated. According to the Förster non-radiation energy transfer theory, the average binding distance between IMTZ and BSA was obtained. What's more, the synchronous fluorescence spectra indicated that the conformation of BSA has been changed. The results provided the information for the binding of IMTZ to BSA, and the influences of substituent group on the interaction were also discussed.

The investigation of the interaction between NCP-EDA and bovine serum albumin by spectroscopic approaches

The fluorescence and ultraviolet spectroscopies were explored to study the interaction between N-confused porphyrins-edaravone diad (NCP-EDA) and bovine serum albumin (BSA) under simulative physiological condition at different temperatures. The experimental results show that the fluorescence quenching mechanism between NCP-EDA and BSA is a combined quenching (dynamic and static quenching). The binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) of the interaction system were calculated at different temperatures. According to Förster non-radiation energy transfer theory, the binding distance between NCP-EDA and BSA was calculated to be 3.63 nm. In addition, the effect of NCP-EDA on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.

Interaction of sodium benzoate with trypsin by spectroscopic techniques

The toxicity of sodium benzoate to trypsin was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-visible absorption spectroscopy and circular dichroism (CD) spectroscopy under mimic physiological conditions. Sodium benzoate could unfold trypsin by decreasing the β-sheet structure, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The results of spectroscopic measurements indicated that sodium benzoate changed the internal microenvironment of trypsin and induced the alteration of the whole molecule, which were performed toxic effects on the organism. Trypsin and sodium benzoate interacted with each other to produce a substance by van der Waals forces and hydrogen bond, the model of which was shown by AutoDock software.

Study on the interaction between salvianic acid A sodium and bovine serum albumin by spectroscopic methods

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by SAS through a static quenching procedure. The binding constants of SAS with BSA were 2.03, 1.17 and 0.71×10(5) L mol(-1) at 291, 298 and 305 K, respectively. Negative values of ΔG, ΔH, and ΔS indicate that the interaction between SAS and BSA is driven by hydrogen bonds and van der Waals forces. According to Förster non-radiation energy transfer theory, the binding distance between BSA and SAS was calculated to be about 2.92 nm. The effect of SAS on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu(2+), Ca(2+), Mg(2+), and Zn(2+) on the binding constant between SAS and BSA was examined.

Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between N-confused porphyrins (NCP) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results indicated that the fluorescence quenching mechanism between BSA and NCP was static quenching procedure at low NCP concentration at 293 and 305 K or a combined quenching (static and dynamic) procedure at higher NCP concentration at 305 K. The binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. The comparison of binding potency of the three NCP to BSA showed that the substituting groups in benzene ring could enhance the binding affinity. From the thermodynamic parameters, we concluded that the action force was mainly hydrophobic interaction. The binding distances between NCP and BSA were calculated using Förster non-radiation energy transfer theory. In addition, the effect of NCP on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.

Interaction of alpinetin with bovine serum albumin: Probing of the mechanism and binding site by spectroscopic methods

The binding interaction between alpinetin and bovine serum albumin (BSA) in physiological buffer solution (pH 7.4) was investigated by fluorescence, UV-vis spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. It was proved from fluorescence spectra that the fluorescence quenching of BSA by alpinetin was probably a result of the formation of BSA-alpinetin complexes, and the binding constant (K(a)) were determined according to the modified Stern-Volmer equation. The thermodynamic parameters, enthalpy change (DeltaH) and entropy change (DeltaS), were calculated to be 22.10kJmol(-1) and 166.04Jmol(-1)K(-1), respectively, which indicated that the interaction between alpinetin and BSA was driven mainly by hydrophobic interaction. Moreover, the competitive experiments of site markers suggested that the binding site of alpinetin to BSA was located in the region of subdomain IIA (sudlow site I). The binding distance (r) between the donor (BSA) and the acceptor (alpinetin) was 3.32nm based on the Förster theory of non-radioactive energy transfer. In addition, the results of synchronous fluorescence and FT-IR spectra demonstrated that the microenvironment and the secondary structure of BSA were changed in the presence of alpinetin.