Fluorescence Of Bovine Serum Albumin Research Articles

Magnetic microactuator embedded electrochemical sensing platform towards on-demand sensor cleaning

Reliable, time-resolved detection of biochemical markers is critical for providing actionable healthcare data. Biosensors can track various clinically relevant biomarkers to inform clinicians to make data-driven decisions. However, the notorious effects of complex fluids limit the lifetime of biosensors by fouling the active sensing sites, hindering their long-term functionality. Biomaterials with passive antifouling capabilities have been developed to minimize the effects of biofouling. However, these attempts can only delay the unavoidable outcome of fouling accumulation, which still limits long-term device functionality. Here, we present a novel class of biosensor capable of self-clearing their sensing surface that can avoid and actively remove biofoulants from the electrode surfaces. The active anti-biofouling modality consists of an electrochemical sensing platform embedded with magnetic microactuators previously proven to disrupt protein attachment and blood clot formation. In this study, we characterize the static and dynamic mechanical responses of the torsional thin-film magnetic microactuators. We confirm its protein-clearing capabilities using fluorescent bovine serum albumin. To quantify the advantages of magnetic actuation using electrochemical techniques, we conducted cyclic voltammetry and electrochemical impedance spectroscopy experiments. We believe this work presents a pivotal step towards enabling a truly longitudinal and continuous monitoring of multiple analytes in complex in vivo environment for a truly personalized medicine.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT computations and protein binding efficiency of a 1-D Ni(II) chain derived from a tridentate Schiff base ligand

A new Ni(II)-azido 1-D coordination polymer, [Ni2L2(μ1,1-N3)(μ1,3-N3)]n, was obtained through reaction of 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the perchlorate salt of nickel(II) in the presence of pseudohalide azide. X-ray crystallography and spectroscopic experiments (IR and UV-Vis) were used to describe this coordination polymer (CP). Single crystal X-ray studies revealed that the CP is a one-dimensional chain of Ni(II) in which the neighboring dimeric units (triply bridged by di-μ2-phenoxidoand µ1,1-N3) are further connected by μ1,3-azido bridges in a zig-zag fashion. The cooperative participation of N···H hydrogen bonding, π···π stacking and C-H···π interactions occur during crystal packing. A 2-D supramolecular architecture with star-shaped voids results from additional C–H···π stacking interactions. Hirshfeld surface analysis was used to look at the intermolecular interactions. DFT studies were carried out to calculate the HOMO-LUMO band gap of the ligand as well as the coordination polymer. Interaction of the CP with bovine serum albumin (BSA) protein was investigated spectroscopically by absorption and fluorescence titration methods. The result showed that the CP could quench the intrinsic fluorescence of BSA. Fluorescence resonance energy transfer (FRET) studies revealed that energy transfer takes place from BSA to the CP. Cyclic voltammetry of the CP indicated an irreversible cathodic redox couple assigned to Ni(II)/Ni(I).

Investigation of the molecular interaction between apraclonidine, an α2-adrenergic receptor agonist, and bovine serum albumin using fluorescence and molecular docking techniques

Apraclonidine (APR) is a potent and selective α2-adrenergic receptor agonist used in the diagnosis of Horner’s Syndrome, and the residuals of APR that accumulate in tissues of animals can cause central nervous and cardiovascular systems influences in humans. Therefore, to understand the influence of APR on human health, we examined the interaction of APR with the carrier protein in plasma, bovine serum albumin (BSA). The BSA fluorescence signal was quenched due to the APU–BSA complex formation and a weak binding affinity was estimated between APR and BSA. The inclusion of fluorescence, UV–vis absorption, molecular docking, and dynamics simulation techniques employed to broadly investigate the combination of APR with BSA at typical physiological conditions. The thermodynamic results revealed that enthalpy (ΔH0) and entropy (ΔS0) changes were computed as +11.14 kJ mol−1 and +97.56 J mol−1 K−1, respectively, which represented the binding is principally entropy-driven and the hydrophobic forces acting a significant role in the reaction. Analysis of synchronous and 3-D fluorescence signals revealed microenvironmental variations close to BSA’s Trp and Tyr residues upon APR addition. Both the competitive site marker as well as molecular docking results detected that APR exhibited a stronger binding affinity towards Drug Site 2 (DS2) compared to Drug Site 1 (DS1).

A Biophysical Study of Molecular Interaction of Tucatinib with Bovine Serum Albumin

AbstractA profound understanding of the binding dynamics of drugs with plasma proteins is highly important as it determines its therapeutical potential. Herein, we have investigated the molecular interaction of Tucatinib (TUC), a novel, primitive and highly selective drug for treatment of HER2+ advanced unresectable breast cancer, with bovine serum albumin (BSA) using multi‐pronged spectroscopic techniques and molecular docking. TUC considerably quenched the intrinsic fluorescence of BSA via static quenching mechanism, and it binds to the hydrophobic cleft of subdomain IIA of BSA with a moderate binding affinity. The thermodynamic analysis revealed the major interplay of van der Waals forces and hydrogen bonding interactions in stabilising the binding. The Förster distance ‘r’ signifies feasible energy transfer between BSA and TUC. The conformational analyses indicate some alterations in the protein secondary structure as a consequence of some changes in the protein polar environment due to complex formation. The experimental results are supported by docking analyses.

Development of theaflavins-loaded albumin nanoparticles and in silico analysis of theaflavins: BSA interaction

Theaflavins (TFs), bioactive compounds present in black tea manufactured from Camellia sinensis leaves have potential health benefits. Due to their instability and low bioavailability, we have encapsulated TFs into albumin nanoparticles (Alb-TFs-NP) and characterized them using different techniques. The mean particle size of Alb-TFs-NP was 125.9 nm with a low (0.23) polydispersity index and Zeta potential of -76.8 mV. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) analysis revealed a spherical shape of Alb-TFs-NP with a smooth surface. The fluorescence of bovine serum albumin (BSA) and TFs was at 280 nm and 660 nm excitation and 690-700 nm emission respectively. The BSA-TFs complex interacts at distinct amino acid binding sites with good docking energy of TF1 (-10.5 kcal/mol-1), TF2 (-11.1 kcal/mol-1), TF2a (-11.2 kcal/mol-1) and TF3 (-10.4 kcal/mol-1) at the BSA active site. Primarily hydrogen bonding was involved in the BSA-TFs interaction. The study could further research the transport distribution and bioactivities of TFs in the human body.

Interaction mechanism of oseltamivir phosphate with bovine serum albumin: multispectroscopic and molecular docking study

Oseltamivir phosphate (OP) is an antiviral drug with potential risks to human health due to overuse, leading to serious consequences such as gastrointestinal disturbances, abnormal neuropsychiatric symptoms, and sudden death. Therefore, gaining an in-depth understanding of its interaction with proteins is crucial. We investigated the interaction between OP and bovine serum albumin (BSA) utilizing multispectral methods (i.e., fluorescence, ultraviolet absorption, circular dichroism) combined with molecular docking techniques. Fluorescence spectroscopy indicated that OP quenched BSA fluorescence by forming the OP-BSA complex. The Stern-Volmer constants (KSV) between OP and BSA were determined to be 3.06 × 103 L/mol, 2.36 × 103 L/mol, and 1.86 × 103 L/mol at 293 K, 298 K, and 303 K, respectively. OP occupies exclusively one binding site on BSA, and the fluorescent probe displacement measurements revealed that this is BSA site I. Thermodynamic data (∆H, ∆S, and ∆G) obtained by fitting the van’t Hoff equation were − 77.49 kJ/mol, -176.54 J/(mol∙K), and − 24.88 kJ/mol, respectively, suggesting that hydrogen bonding and van der Waals forces mainly participate in OP-BSA complex stabilization. Moreover, the reaction occurs spontaneously at room temperature. Synchronous fluorescence spectra indicated that OP interacts with tryptophan residue of BSA. The results of ultraviolet (UV) and 3D fluorescence spectroscopy indicated that the OP-BSA complex formation altered the microenvironment around amino acid residues. Circular dichroism spectra revealed that the addition of OP decreased the α-helix content of BSA by 7.13%. Docking analysis confirmed that OP binds to BSA site I through hydrogen bonding with amino acids VAL342, SER453, and ASP450. Finally, ADMET studies were conducted to explore the pharmacokinetics of OP as an antiviral drug.

Unraveling the interaction mechanism between orphan drug Nitisinone and bovine serum albumin through spectroscopic and in silico approaches

The interaction between Nitisinone (NTBC) and bovine serum albumin (BSA) as the transport protein in a circulating system was investigated for the first time utilizing various analytical (UV–Vis spectrophotometry, fluorescence spectroscopy, dynamic light scattering, and differential scanning calorimetry) and computational (molecular docking and molecular dynamics simulations) methods. The BSA fluorescence intensity was quenched upon interaction with NTBC, and the quenching mechanism was observed as static. The interaction between NTBC and BSA was examined at 288 K, 298 K, and 308 K where the binding constants were found to be 1.44 × 105 ± 0.22 M−1, 5.18 × 104 ± 0.20 M−1, and 3.02 × 104 ± 0.22 M−1 respectively, suggesting an intermediate binding affinity between NTBC and BSA. Changes in the microenvironment surrounding tryptophan and tyrosine residues of BSA were elucidated using 3-D fluorescence spectroscopy. Thermodynamic studies revealed the calculated values of ΔH = − 54.34 ± 5 kJ/mol and ΔS = − 0.0908 ± 0.24 kJ/mol K−1, indicating the involvement of van der Waals forces and hydrogen bonds in the interaction between NTBC and BSA. Moreover, the interaction’s spontaneous nature was evidenced by negative ΔG values across all temperatures. Using dynamic light scattering, it was observed that higher NTBC concentrations led to a gradual rise in hydrodynamic diameter and notable aggregation of the NTBC-BSA complex. Moreover, changing signal values and shifted peaks of BSA, NTBC, and complex in differential scanning calorimetry curves, meant there were molecular interactions between the NTBC and BSA. In silico approaches also elucidated how NTBC binds to active sites on BSA, further supporting other findings. Moreover, molecular docking studies offer a more profound insight into the changing dynamics of hydrophobic, hydrogen, and halogen bonding involved in stabilizing the NTBC-BSA complex.

Interactions of three berberine mid-chain fatty acid salts with bovine serum albumin (BSA): Spectroscopic analysis and molecular docking

In this paper, the interaction of three berberine mid-chain fatty acid salts ([BBR][FAs]), viz. berberine caproate ([BBR][CAP]), berberine heptylate ([BBR][HEP]) and berberine octoate ([BBR][OCT]), with bovine serum albumin (BSA) was studied by means of UV–visible absorption spectroscopy, fluorescence spectroscopy, fourier transform infrared spectroscopy (FT-IR) and molecular docking techniques. Fluorescence experiments revealed that three berberine salts quench the fluorescence of BSA by static quenching mechanism resulted from a stable [BBR][FAs]-BSA complex formation. The stoichiometric numbers of [BBR][FAs]-BSA complexes were found to be 1:1. Synchronous and three-dimensional fluorescence spectra as well as FT-IR demonstrated that the binding of [BBR][FAs] altered the microenvironment and conformation of BSA. The binding average distance from [BBR][FAs] to BSA (3.2–3.5 nm) was determined according to Förster energy transfer theory. Site probe investigation showed that [BBR][FAs] bound to BSA active site I (sub-domain IIA). The binding promotes the esterase-like activity of BSA. The molecular docking results confirmed the fluorescence competition findings and provided the type of binding forces. Furthermore, the relationship between the anionic chain length of [BBR][FAs] and the interaction was explored, and the positive correlation was found.

Investigation on the binding behaviors of two dihydrochalcones to bovine serum albumin and their anti-glycation activities

The interactions of two dihydrochalcones (naringin dihydrochalcone (NGDC) and neohesperidin dihydrochalcone (NHDC)) with bovine serum albumin (BSA) and their anti-glycation effects were studied utilizing multiple spectral methods and molecular simulation technique. The findings proved that NGDC/NHDC could use a static quenching mechanism to reduce the intrinsic fluorescence of BSA, and the interaction between NGDC/NHDC and BSA was a spontaneous behavior with the binding constant ranging from 104 to 105M−1. Furthermore, NGDC and NHDC mainly interacted with the site I (subdomain IIA) of BSA via hydrophobic interactions and hydrogen bonds, endorsed by molecular docking study. A conjoint analysis of circular dichroism, three-dimensional fluorescence, dynamic light scattering, and UV-vis absorption spectra confirmed that NGDC/NHDC could induce some alterations in the spatial conformation and microenvironment of BSA. Additionally, NGDC and NHDC inhibited the non-enzymatic glycation of BSA by decreasing the contents of advanced glycation end products (AGEs), trapping methylglyoxal/glyoxal and maintaining the stability of the natural conformation of the protein. Overall, these findings were highly beneficial in disclosing the interaction mechanisms between dihydrochalcones and BSA and providing valuable information for the application of dihydrochalcones as functional food ingredients.

Exploring the interaction of a potent anti-cancer drug Selumetinib with bovine serum albumin: Spectral and computational attributes.

The binding of drugs to plasma proteins determines its fate within the physiological system, hence profound understanding of its interaction within the bloodstream is important to understand its pharmacodynamics and pharmacokinetics and thereby its therapeutic potential. In this regard, our work delineates the mechanism of interaction of Selumetinib (SEL), a potent anti-cancer drug showing excellent effect against multiple solid tumors, with plasma protein bovine serum albumin (BSA), using methods such as absorption, steady-state fluorescence, time-resolved, fluorescence resonance energy transfer, Fourier transform infrared spectra (FTIR), circular dichroism (CD), synchronous and 3D-fluorescence, salt fluorescence, molecular docking and molecular dynamic simulations. The BSA fluorescence intensity was quenched with increasing concentration of SEL which indicates interactions of SEL with BSA. Stern-Volmer quenching analysis and lifetime studies indicate the involvement of dynamic quenching. However, some contributions from the static quenching mechanism could not be ruled out unambiguously. The association constant was found to be 5.34 × 105 M-1 and it has a single binding site. The Förster distance (r) indicated probable energy transmission between the BSA and SEL. The positive entropy changes and enthalpy change indicate that the main interacting forces are hydrophobic forces, also evidenced by the results of molecular modeling studies. Conformation change in protein framework was revealed from FTIR, synchronous and 3D fluorescence and CD studies. Competitive binding experiments as well as docking studies suggest that SEL attaches itself to site I (subdomain IIA) of BSA where warfarin binds. Molecular dynamic simulations indicate the stability of the SEL-BSA complex. The association energy between BSA and SEL is affected in the presence of different metals differently.

Probing berberine syringate-bovine serum albumin interactions by multi-spectroscopic, conductimetric, volumetric and molecular docking methods

In this paper, a new berberine-based salt berberine syringate ([BBR][SA]) was synthesized and [BBR][SA]-bovine serum albumin (BSA) interactions were investigated by various techniques like UV–visible absorption, fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), volumetry and conductimetry. Using the experimental values of density and conductivity, the specific volume of BSA and the critical aggregation concentration of [BBR][SA] were derived. From the variation trends of specific volume for BSA with [BBR][SA] concentrations, it was observed the predominate ionic interaction/dehydration effect at small [BBR][SA] concentration and the non-polar interaction/hydration phenomenon at higher [BBR][SA] concentration for the binding of [BBR][SA] with BSA, as well as hydration shell structure changes at different temperatures in the medium with different pH values. Aggregation of [BBR][SA] is slowed by increasing concentration of BSA and temperature. The thermodynamic parameters of aggregation process have been exploited to gain more information on the interaction of [BBR][SA] with BSA. UV–vis absorption, multiple fluorescence spectroscopy (steady-state spectroscopy, synchronous fluorescence, three-dimensional fluorescence), and FT-IR have been utilized to understand the interaction mechanisms and binding strength between the two molecules. [BBR][SA] quenches the fluorescence of BSA through static quenching mechanism. The 1:1 complex between [BBR][SA] and BSA with a strong affinity was formed. The changes in microenvironment and conformation of BSA caused by [BBR][SA] were revealed by synchronous fluorescence spectra, 3D fluorescence maps and FT-IR. The binding average distance from [BBR][SA] to BSA (2.83 nm) was obtained based on the theory of Förster energy transfer. Competitive binding experiment confirms [BBR][SA] binding to Sudlow site I (sub-domain IIA) of BSA. In addition, molecular docking was generated to provide valuable information about the available binding sites of [BBR][SA] on BSA and the types of binding forces.

Multiple spectroscopic and computational studies on binding interaction of 2-phenylamino-4-phenoxyquinoline derivatives with bovine serum albumin

Binding characteristics of potent non-nucleoside HIV-1 reverse transcriptase inhibitors, 4-(2′,6′-dimethyl-4′-formylphenoxy)-2-(5″-cyanopyridin-2″ylamino) quinoline (1) and 4-(2′,6′-dimethyl-4′-cyanophenoxy)-2-(5″-cyanopyridin-2″ylamino) quinoline (2), to bovine serum albumin (BSA) under simulative physiological conditions were investigated by multiple spectroscopic and computational methods. The experimental results demonstrated that (1) and (2) bound to BSA at site III (subdomain IB), and quenched BSA fluorescence through a static quenching process. The binding interaction of (1) or (2) to BSA forms stable complexes with the binding constants (Kb) at the level of 104 L/mol and the number of binding site was determined to be 1 for both systems, indicating that new synthesized compounds occupied one site in BSA with moderate binding affinities. Based on the analysis of the thermodynamic parameters, it can be indicated that the main binding forces for interaction between BSA and both compounds were hydrogen bonding and van der Waals force. Synchronous fluorescence results revealed that the interaction of two compounds with BSA led to modifications in the microenvironment surrounding tryptophan residue of BSA. Circular dichroism spectra demonstrated alterations in the secondary structure of BSA induced by (1) and (2). Moreover, the experimental data of molecular docking and molecular dynamics (MD) simulations supported the results obtained from multiple spectroscopic techniques, confirming the binding interactions between both compounds and BSA.

Exploration of the intermolecular isoproturon–bovine serum albumin combination: Biophysical and computational prospects

Isoproturon (IPU), a selective systemic herbicide that is frequently applied to eradicate large-leaved weeds and annual grasses in agricultural fields. However, the accumulation of IPU residues during food production might negatively affect on human and animal health. To comprehend the impact of IPU on the mankind and environment, the interaction analysis of IPU with plasma protein is crucial. This work used a variety of techniques, including fluorescence, UV–vis absorption, computational docking and dynamics simulation to extensively examine the combination of IPU with bovine serum albumin (BSA) under typical physiological settings. IPU quenched the BSA fluorescence and form the IPU–BSA complex through a static process. A weak binding affinity was anticipated (binding constant = 4.68–2.48 × 103 M−1) for IPU–BSA interaction. Thermodynamic results revealed that the IPU–BSA binding reaction was a spontaneous process, predominantly governed by hydrogen bonds, van der Waals and hydrophobic forces, which was well supported by molecular docking analysis. Synchronous and three-dimensional fluorescence spectral results exhibited microenvironmental fluctuations near the protein’s Trp and Tyr residues with added IPU, but inclusion of IPU to BSA was observed to enhance the protein’s thermal constancy. Site marker displacement results demonstrated that IPU desirably binds to BSA at site II. An in silico findings also unveiled the primary binding arrangement of IPU was placed at site II of BSA and surrounded by hydrophobic and polar residues. Molecular dynamics simulation results suggested the IPU–BSA complex persisted compact and stable.

Molecular docking and multi-spectroscopic approaches to unravel the mechanism of the interaction between thiocolchicoside and bovine serum albumin

A popular muscle relaxant for the treatment of severe, painful muscular spasms is thiocolchicoside (TCS). Although the precise mechanism underlying its ability to relax muscles is unknown, it demonstrates a specific affinity for the inhibitory gamma-aminobutyric acid and glycinergic receptors. This study used a variety of spectroscopic methods and molecular docking to examine the interaction of TCS with bovine serum albumin (BSA). UV absorption and fluorescence spectroscopic titration analysis supported the conclusion that TCS suppressed BSA's fluorescence through a blend of static and dynamic mechanisms. The thermodynamical constraints revealed that the interaction between BSA and TCS is spontaneous and that van der Waals and hydrogen bonding forces play key roles in stabilising the complex. TCS binds to the site III on BSA, as demonstrated by competitive binding assays utilising site-specific markers and molecular docking studies. By binding TCS, BSA exhibits minor microenvironmental modifications near the tryptophan amino acid residue, according to a structural study employing synchronous fluorescent.

Design of Azomethine based Metalloorganic Complexes and their Binding Interactions with Nucleic Acid and Protein

Mononuclear nickel, copper, and zinc complexes based on salen type (ONNO) donor acting as a tetradentate ligand obtained by the condensation of 4-methyl-o-phenylenediamine and 5-fluoro salicylaldehyde in 1:2 ratios. The compounds are characterized using UV-visible, FT-IR, 1H, 13C-NMR, HR-MS, Elemental (CHN) analyses ESR spectral techniques, and single crystal X-ray diffraction studies (SC-XRD). The binding interactions of the metal complexes with deoxyribonucleic acid (DNA) and bovine serum albumin (BSA) are monitored using UV absorption titration and tryptophan emission quenching techniques, respectively. The complexes possess strong binding propensities with DNA and prefer groove binding, as indicated by the hyperchromic effect. The complexes quench the intrinsic fluorescence of BSA with increasing amounts of the complex concentration in a dose-dependent manner. The gel electrophoresis was carried out against pBR322 to analyze the cleaving ability of the complexes. The results of the NBO (natural bond orbitals) analysis performed in combination with the Time-dependent Density Functional Theory (TD-DFT) calculations provided a good explanation of their electronic and structural characteristics. Further, the predictions of molecular docking studies support the experimental observations. The Gel electrophoresis study reveals the cleaving ability of the complexes by their interactions with DNA. In addition, the cell viability of the complexes is assessed based on MTT assay and the results indicate that they have a good antiproliferative activity only on liver cancer cell-line HepG-2 and does not show cytotoxic effect on normal vero cell lines with 90% viability.

Potential toxic effects of perfluorobutanesulfonyl fluoride analysis based on multiple-spectroscopy techniques and molecular modelling analysis

Perfluorobutanesulfonyl fluoride (PBSF) has been used in the manufacture of fluorochemicals. Since PBSF is not biodegradable, the predicted environmental levels of PBSF are also expected to rise over time. In recent years, there has been a rise in the levels of PBSF in humans. In order to clarify the impact of PBSF on the accumulation of substances in the human body, we examined the interaction mechanism between PBSF and bovine serum albumin (BSA). To investigate the interaction mechanism between PBSF and BSA, we utilized a range of methods including UV–visible spectrophotometry, fluorescence spectroscopy, circular dichroism, molecular docking simulation, and molecular dynamics (MD) simulation. The inherent fluorescence of BSA was effectively suppressed by PBSF through fluorescence quenching analysis, using a static mechanism. The Ka value of 1.34 × 105 mol−1 L indicated a strong binding between PBSF and BSA. Further analysis of the interaction between PBSF and BSA involved examining thermodynamic parameters, fluorescence resonance energy transfer, and conducting other theoretical calculations. These investigations produced results that were in strong accordance with the experimental observations. The participation of hydrophobic interactions between BSA and PBSF was uncovered through molecular docking and MD simulation investigations. Furthermore, this investigation explored the impact of copper ions (Cu2+) and calcium ions (Ca2+) on the interaction between PBSF and BSA, establishing a vital basis for comprehending the mechanism by which PBSF affects proteins in the human surroundings.

Binding studies of potential amyloid-β inhibiting chalcone derivative with bovine serum albumin

Chalcones (α-phenyl-β-benzoylethylene) and their natural-source derivatives have been investigated for their remarkable biological activities, like neuroprotective, anti-inflammatory, and anti-tumor properties. A triazole chalcone ligand (E)-3-(4-(dimethylamino)phenyl)-1-(4-((1-(2-(4-((E)-3-(4(dimethylamino)phenyl)acryloyl)phenoxy)ethyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)prop-2-en-1-one (L1) was synthesized by Cu(I)- catalysed click reaction. The mechanistic properties of L1 for therapy were evaluated by analyzing the binding interactions between L1 and bovine serum albumin (BSA) through photophysical and computational studies. The structural elucidation of ligand L1 was carried out by NMR and mass spectrometry. The Aβ inhibitory activity of L1 was studied by thioflavin T assay and transmission electron microscopy. The biomolecular interaction of L1 with bovine serum albumin was examined through multi-spectroscopic techniques in combination with in silico studies. UV–Visible absorption, fluorescence spectroscopy, circular dichroism, Förster resonance energy transfer, and three-dimensional fluorescence studies confirmed the formation of a BSA-L1 complex. The potential binding sites, mechanism of interactions, and variations in the environment of tyrosine and tryptophan amino acid residues of BSA were assessed at different temperatures. The binding constant for the Static quenching mechanism of intrinsic fluorescence of BSA was of the order of 105 M−1. The esterase enzyme activity assay in the presence of L1 revealed an increase in the protein enzyme activity. Molecular docking studies suggested L1 was predominantly bound to BSA by hydrogen bonds and Van der Waals forces.

Spectroscopic aspects on the interaction of nisin with serum albumin: thermodynamic and kinetic studies.

Nisin is a bacteriocin produced by Streptococcus and Lactococcus species and has antimicrobial activity against other bacteria. Nisin omits the need to use chemical preservatives in food due to its biological preserving properties. In the present in vitro study, we investigated nisin interaction with bovine serum albumin (BSA) using fluorescence spectroscopy and surface plasmon resonance (SPR) analysis to obtain information about the mechanisms of BSA complex formation with nisin. The BSA fluorescence intensity values gradually diminished with rising nisin concentration. The BSA fluorescence quenching analysis indicated that a combined quenching mechanism plays the main role. Finally, the Kb values were reduced with increasing temperature, which is demonstrative of nisin-BSA complex stability decrease at high temperatures. The negative values of ΔH° and ΔS° showed that hydrogen bonds and van der Waals forces are the foremost binding force between BSA and nisin. Meanwhile, the negative values of ΔG° demonstrated the exothermic and random nature of the reaction process. The results of the SPR verified the gained results through the fluorescence spectroscopy investigation, which denoted that the BSA affinity to nisin diminished upon increasing temperature. Overall, fluorescence spectroscopy and SPR results showed that the BSA interaction with nisin decreased with rising temperatures.

Interaction between potassium iodide and bovine serum albumin, ovalbumin and lysozyme under different temperature induction

In this study, the interaction between potassium iodide and protein molecules under different temperature induction was studied, taking potassium iodide (KI) and protein molecules as a model system. The effects of KI on protein conformation, size, surface charge, binding constant, and binding site were analyzed by fluorescence spectrum, infrared spectrum, and diffusing wave spectroscopy. The results revealed that bovine serum albumin (BSA)/ovalbumin (OVA) and I−1 formed the 1: 1 complex and significantly affected the hydrodynamic radius and spatial structure. This could be attributed to the exposure of tyrosine residues inside the proteins to the polar conditions under increased temperature. The unfolding of protein structures induced the interaction between KI/KCl and proteins. As for BSA and OVA, the particle size and surface charge of the complex increased significantly in the presence of KI/KCl. KI had a strong static quenching effect on the fluorescence of BSA and OVA. Overall, these results provide insights into the physiological effects of iodine ions.

Dopamine-Based Copolymer Bottlebrushes for Functional Adhesives: Synthesis, Characterization, and Applications in Surface Engineering of Antifouling Polyethylene.

Nonpolar materials like polyolefins are notoriously challenging substrates for surface modification. However, this challenge is not observed in nature. Barnacle shells and mussels, for example, utilize catechol-based chemistry to fasten themselves onto all kinds of materials, such as boat hulls or plastic waste. Here, a design is proposed, synthesized, and demonstrated for a class of catechol-containing copolymers (terpolymers) for surface functionalization of polyolefins. Dopamine methacrylamide (DOMA), a catechol-containing monomer, is incorporated into a polymer chain together with methyl methacrylate (MMA) and 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM). DOMA serves as adhesion points, BIEM provides functional sites for subsequent "grafting from" reactions, and MMA provides the possibility for concentration and conformation adjustment. First, the adhesive capabilities of DOMA are demonstrated by varying its content in the copolymer. Then, terpolymers are spin-coated on model Si substrates. Subsequently, the atom transfer initiator (ATRP) initiating group is used to graft a poly(methyl methacrylate) (PMMA) layer from the copolymers, with 40% DOMA content providing a coherent PMMA film. To demonstrate functionalization on a polyolefin substrate, the copolymer is spin-coated on high-density polyethylene (HDPE) substrates. A POEGMA layer is grafted from the ATRP initiator sites on the terpolymer chain on the HDPE films to provide antifouling characteristics. Static contact angle values and Fourier transform infrared (FTIR) spectra confirm the presence of POEGMA on the HDPE substrate. Finally, the anticipated antifouling functionality of grafted POEGMA is demonstrated by observing the inhibition of nonspecific adsorption of the fluorescein-modified bovine serum albumin (BSA) protein. The poly(oligoethylene glycol methacrylate) POEGMA layers grafted on 30% DOMA-containing copolymers on HDPE show optimal antifouling performance exhibiting a 95% reduction of BSA fluorescence compared to nonfunctionalized and surface-fouled polyethylene. These results demonstrate the successful utilization of catechol-based materials for functionalizing polyolefin surfaces.