Between Bovine Serum Albumin Research Articles

Binding mechanism of five typical sweeteners with bovine serum albumin

In this work, the interactions between bovine serum albumin (BSA) and five sweeteners including aspartame (APM), acesulfame (AK), sucralose (TGS), sodium cyclamate (SC), and rebaudioside-A (REB-A) have been studied by multispectroscopic techniques, and molecular simulation in order to provide much useful information for the application of new and safer artificial sweeteners. Fluorescence quenching assays indicated that the formation of complexes between sweeteners and BSA mainly induced the fluorescence quenching of protein and the binding site number were about 1 indicting that there is one mainly binding site of APM, AK, TGS, SC, or REB-A in domain of BSA with relatively weak interactions. Molecular modeling results indicated that hydrogen bonding interactions were the mainly binding forces of sweeteners with BSA. Circular dichroism spectra indicated that APM and REB-A obviously induced the secondary structure changes of BSA. The presence of APM increased the fraction of α–Helix of BSA from 65.4% to 73.8%, while the presence of REB-A resulted in decreasing the fraction of α–helix of BSA from 65.4% to 51.2%. The melting temperature studies showed that these five sweeteners except REB-A act as stabilizers to increase the thermal stability of BSA during the thermal denaturation process. In addition, AK, TGS, and SC obviously increased the esterase-like activity of BSA, and such loss of activity of BSA induced by APM and REB-A.

Measuring the Interactions between Protein-Coated Microspheres and Polymer Brushes in Aqueous Solutions.

Hydrophilic or zwitterionic polymer-functionalized surfaces have become attractive biomaterials in bioscience and technology due to their excellent protein-resistant ability. Understanding the fundamental interactions between proteins and polymers plays an essential role in the surface design of biomaterials. In this work, we studied the interactions between bovine serum albumin (BSA) and two sorts of polymer brushes including zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and hydrophilic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in NaCl aqueous solutions directly with a self-established total internal reflection microscope (TIRM) to provide a better understanding of the underlying nonfouling mechanism of polymers. Our results indicate that both the surface charge and brushes length can affect protein adsorption through electrostatic and steric repulsions, respectively. Both PCBMA- and POEGMA-coated surfaces display negative charge properties due to incomplete coverage and ionic adsorption. As a result, strong electrostatic repulsions between proteins and negatively charged polymer-coated surfaces could contribute to the resistance of protein-coated particles in solutions with low ionic strength (0.1, 0.5, and 1 mM) and disappear in solutions with high ionic strength (10 mM). The measured interaction profiles demonstrate that PCBMA brushes could provide apparent steric forces only at high ionic strength (10 mM), where zwitterionic brushes exhibit a relatively extended conformation with a lack of electrostatic forces between intra- and interpolymers. In contrast, the steric repulsion between proteins and POEGMA brushes appears when particles diffuse at low positions in all salt concentrations (0.1-10 mM) with similar steric decay lengths, which results from the unresponsiveness of POEGMA brushes to the salt stimulus.

Adsorptive Voltammetry for the Determination of Ochratoxin A Using Enrichment Effect by Cationic Surfactants

AbstractA rapid and simple electrochemical method was utilized for the determination of the presence of classic fungal metabolite ochratoxin A (OTA) based on differential pulse adsorptive voltammetry, using the carbon nanotube paste (CNTP) electrode. OTA showed a clear oxidation peak, and the CNTP electrode exhibited a more sensitive response to OTA oxidation than the glassy carbon, the plastic formed carbon, and the carbon paste electrodes. The addition of long‐chain cationic surfactants, such as benzethonium chloride, cetyltrimethylammonium bromide, and benzyldimethyltetradecylammonium chloride (zephiramine), enhanced the electrochemical response of OTA. Under optimized experimental conditions, the calibration plots are linear in the 5×10−6−5×10−5 M OTA concentration range, and the limit of detection is 1.1×10−6 M. In order to improve the selectivity for OTA determination, we attempted to combine this adsorptive stripping voltammetric technique with “sequestration electrochemistry,” based on the specific interaction occurring between bovine serum albumin (BSA) and OTA. The peak current of OTA oxidation decreased substantially as a result of OTA‐BSA binding. Furthermore, it was demonstrated that the application of this proposed method of hydrodynamic adsorptive voltammetry, using a micro‐droplet and a rotating disk electrode, improves the approach's sensitivity and reduces the time and sample volume required for the analysis.

A Diversified Spectrometric and Molecular Docking Technique to Biophysical Study of Interaction between Bovine Serum Albumin and Sodium Salt of Risedronic Acid, a Bisphosphonate for Skeletal Disorders.

The binding interaction between bovine serum albumin (BSA) and sodium salt of risedronic acid (RSN) was studied by using the FT-IR (Fourier transform infrared), UV-Vis (ultraviolet–visible), fluorescence (emission and synchronous), CD (circular dichroism) spectrometric, and computational (molecular docking) techniques at 289, 297, and 305 K temperatures with physiological buffer of pH 7.40. The conformational and secondary structural changes observed for BSA from CD spectra and by curve fitting procedure were applied to Fourier self-deconvolution in FT-IR spectra. The formation of a BSA-RSN complex was confirmed from UV-Vis spectroscopy. The static type of quenching shown for RSN to BSA was verified from Stern–Volmer and modified Stern–Volmer equations. The binding constant of order 105 was obtained to be confirming that there exists a strong binding interaction between BSA and RSN. Synchronous fluorescence shows that the microenvironment of tryptophan was altered, not tyrosine of BSA; in addition to this, the distance between tryptophan of BSA and RSN was found out from Forster's theory of nonradiation energy transfer. The interaction between BSA and RSN mainly occurred as a result of hydrogen bonds and van der Waals forces, the process is exothermic and spontaneous, and it was achieved through van 't Hoff equation. This interaction was affected by the presence of biologically active Fe2+, Ni2+, Ca2+, Mg2+, and Cd2+ ions and was also studied. The subdomain IIIA of BSA involved with RSN interaction was authenticated from molecular docking analysis.

Insights into the binding interaction between copper ferrite nanoparticles and bovine serum albumin: An effect on protein conformation and activity.

The binding affinity between bovine serum albumin (BSA) and copper ferrite (CuFe2 O4 ) nanoparticles in terms of conformation, stability and activity of protein was studied using various spectroscopic methods. The quenching involved in BSA-CuFe2 O4 NP interaction was static quenching as analysed by different techniques (steady-state and time-resolved fluorescence along with temperature-dependent fluorescence measurements). Among all types of possible interactions, it was revealed that the major binding forces were van der Waals interaction and hydrogen bonding, which were explored from negative values of enthalpy change (∆H=-193.85kJmol-1 ) and entropy change (∆S=-588.88Jmol-1 K-1 ). Additionally, synchronous, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy measurements confirmed the conformational changes in BSA upon the addition of CuFe2 O4 NP. Furthermore, thermal denaturation observations were consistent with the circular dichroism results. The interaction of CuFe2 O4 NP with BSA decreased the esterase activity in the BSA assay, revealing the affinity of copper ferrite towards the active site of BSA.

The interaction between BSA and DOTAP at the air-buffer interface

In this article, the interaction between bovine serum albumin (BSA) and the cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) at the air-buffer interface was investigated at different subphase’s pH values (pH = 3, 5 and 10). Surface pressure measurements (π − A) and penetration kinetics process (π − t) were carried out to reveal the interaction mechanism and the dynamical behavior. The data showed that π − A isotherms moved towards larger mean molecular area when the concentration of BSA ([BSA]) increased, the amount of BSA adsorbed onto DOTAP monolayer reached a threshold value at a [BSA] of 5 × 10−8 M, and BSA desorbed from the lipid monolayer as time goes by. The results revealed that the association of BSA with DOTAP at the air-buffer interface was affected by the subphase’s pH value. When pH = 10, the interaction mechanism between them was a combination of hydrophobic interaction and electrostatic attraction, so BSA molecules could be well separated and purified from complex mixtures. AFM images demonstrated that pH value and [BSA] could affect the morphology feature of DOTAP monolayer and the adsorption and desorption processes of BSA. So the study provides an important experimental basis and theoretical support for learning the interaction mechanism among biomolecules in separation and purification of biomolecules and biosensor.

Dynamic Behaviors and Morphology Change of Anionic Phospholipid DPPG Monolayer Caused by Bovine Serum Albumin at Air-Water Interface

The interaction between bovine serum albumin (BSA) and the anionic 1.2-dipalmitoyl-sn-glycero-3-(phospho-rac-(1-glycerol)) (sodium salt) (DPPG) phospholipid at different sub-phase pH values was investigated at air-water interface through surface pressure measurements and atomic force microscopy (AFM) observation. By analyzing surface pressure-mean molecular area (π-A) isotherms, the limiting molecular area in the closed packing state-the concentration of BSA (Alim-[BSA]) curves, the compressibility coefficient-surface pressure (C−1S-π) curves and the difference value of mean molecular area-the concentration of BSA (ΔA-[BSA]) curves, we obtained that the mean molecular area of DPPG monolayer became much larger when the concentration of BSA in the subphase increased at pH=3 and 5. But the isotherms had no significant change at different amount of BSA at pH=10. In addition, the amount of BSA molecules adsorbed onto the lipid monolayer reached a threshold value when [BSA]>5×10−8 mol/L for all pHs. From the surface pressure-time (π-t) data, we obtained that desorption and adsorption processes occurred at pH=3, however, there was only desorption process occurring at pH=5 and 10. These results showed that the interaction mechanism between DPPG and BSA molecules was affected by the pH of subphase. BSA molecules were adsorbed onto the DPPG monolayers mainly through the hydrophobic interaction at pH=3 and 5, and the strength of hydrophobic interaction at pH=3 was stronger than the case of pH=5. At pH=10, a weaker hydrophobic interaction and a stronger electrostatic repulsion existed between DPPG and BSA molecules. AFM images revealed that the pH of subphase and [BSA] could affect the morphology features of the monolayers, which was consistent with these curves. The study provides an important experimental basis and theoretical support to understand the interaction between lipid and BSA at the air-water interface.

Identification of peptide-binding sites within BSA using rapid, laser-induced covalent cross-linking combined with high-performance mass spectrometry.

We are developing a rapid, time-resolved method using laser-activated cross-linking to capture protein-peptide interactions as a means to interrogate the interaction of serum proteins as delivery systems for peptides and other molecules. A model system was established to investigate the interactions between bovine serum albumin (BSA) and 2 peptides, the tridecapeptide budding-yeast mating pheromone (α-factor) and the decapeptide human gonadotropin-releasing hormone (GnRH). Cross-linking of α-factor, using a biotinylated, photoactivatable p-benzoyl-L-phenylalanine (Bpa)-modified analog, was energy-dependent and achieved within seconds of laser irradiation. Protein blotting with an avidin probe was used to detect biotinylated species in the BSA-peptide complex. The cross-linked complex was trypsinized and then interrogated with nano-LC-MS/MS to identify the peptide cross-links. Cross-linking was greatly facilitated by Bpa in the peptide, but some cross-linking occurred at higher laser powers and high concentrations of a non-Bpa-modified α-factor. This was supported by experiments using GnRH, a peptide with sequence homology to α-factor, which was likewise found to be cross-linked to BSA by laser irradiation. Analysis of peptides in the mass spectra showed that the binding site for both α-factor and GnRH was in the BSA pocket defined previously as the site for fatty acid binding. This model system validates the use of laser-activation to facilitate cross-linking of Bpa-containing molecules to proteins. The rapid cross-linking procedure and high performance of MS/MS to identify cross-links provides a method to interrogate protein-peptide interactions in a living cell in a time-resolved manner.

Experimental and theoretical investigation of interaction between bovine serum albumin and the mixture of caffeic acid and salicylic acid as the antioxidants

In the present work, interaction between bovine serum albumin (BSA) with caffeic acid (CA), salicylic acid (SA) and the mixture of these components were studied by experimental and computational methods In the experimental measurements, differential pulse voltammetry (DPV) and UV–vis spectrophotometry (UV–Vis) were separately used to investigate the nature of interactions. Also, some of the thermodynamics parameters were obtained from these measurements. At the second step, the chemometric methods including multivariate curve resolution–alternating least squares (MCR–ALS) and parallel factor analysis (PARAFAC) were used since the results of the experimental measurements have a strongly overlapping signals. For this purpose, a three-way array was resolved by PARAFAC and a row- and column-wise augmented matrix, which built with DPV and UV–vis sub-matrices, were analyzed using MCR-ALS. The interesting results for stoichiometry and electrochemical behaviors of these components were obtained by using the proposed algorithms. Finally, molecular docking were applied to compare experimentally determined binding parameters with molecular modelling. According to the obtained results an excellent agreement was found between experimental and computational results.

Effect of albumin on the fluorescence quantum yield of porphyrin -based agents for fluorescent diagnostics

BackgroundAmong modern methods of tumor diagnosis, fluorescent methods are considered one of the most prospective. Diagnostic agents (DAs) spread throughout the body by the bloodstream, so, the DA molecules are often transported by albumins and can be affected by these proteins. In our study we evaluate the effect of complex formation between bovine serum albumin (BSA) and three fluorescence DA’s (Photolon, Photoditazin and Dimegin) on their fluorescent quantum yields. MethodsElectron absorption spectroscopy and fluorescence spectroscopy were carried out to calculate fluorescence quantum yields of the DAs using Rhodamine 6G as a standard fluorescent dye. ResultsFor all three DA’s dissolved in phosphate buffer with pH 7.5 (close to that of blood) the addition of albumin resulted in bathochromic shift of the Soret band as well as change of amplitudes of absorption bands. Similar changes were observed for fluorescence spectra of all DAs that are connected with complex formation between DA and albumin. The presence of isobestic point suggests that DA can present in the solution only in two states, free and BSA-bound. Chlorine-based DA’s demonstrate about 1.5-times higher fluorescence quantum yield in PBS than Dimegin. Nevertheless, the addition of BSA to the solutions of all DA’s decreases sharply their fluorescence quantum yield to approximately equal values. ConclusionThe complex formation between DA and albumin equalize fluorescence efficacies of all studied DAs, so the results of photodymanic diagnostics using the specific DA will depend on other factors.

Study of the Interactions of Bovine Serum Albumin with the New Anti-Inflammatory Agent 4-(1,3-Dioxo-1,3-dihydro-2H-isoindol-2-yl)-N'-[(4-ethoxy-phenyl)methylidene]benzohydrazide Using a Multi-Spectroscopic Approach and Molecular Docking.

The lipophilic derivative of thalidomide (4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N′-[(4-ethoxyphenyl)methylidene]benzohydrazide, 6P) was synthesized to enhance its characteristics and efficacy. Earlier studies have proved the immunomodulatory and anti-inflammatory effects of 6P. In this study the interaction between bovine serum albumin (BSA) and 6P was studied using a multi-spectroscopic approach which included UV spectrophotometry, spectrofluorimetry and three dimensional spectrofluorometric and molecular docking studies. Static quenching was involved in quenching the fluorescence of BSA by 6P, because a complex formation occurred between the 6P and BSA. The binding constant decreased with higher temperature and was in the range of 2.5 × 105–4.8 × 103 L mol−1 suggesting an unstable complex at higher temperatures. A single binding site was observed and the the site probe experiments showed site II (sub-domain IIIA) of BSA as the binding site for 6P. The negative values of ∆G0, ∆H0 and ∆S0 at (298/303/308 K) indicated spontaneous binding between 6P and BSA as well as the interaction was enthalpy driven and van der Waals forces and hydrogen bonding were involved in the interaction. The docking results and the results from the experimental studies are complimentary to each other and confirm that 6P binds at site II (sub-domain IIIA) of BSA.

Fabrication of a cost-effective polymer nanograting as a disposable plasmonic biosensor using nanoimprint lithography

A simple and cost-effective flexible plasmonic sensor is developed using a gold-coated polymer nanograting structure prepared via soft UV nanoimprint lithography. The sub-wavelength nanograting patterns of digital versatile discs were used as a template to prepare the polydimethylsiloxane stamp. The plasmonic sensing substrate was achieved after coating a gold thin film on top of the imprinted nanograting sample. The surface plasmon resonance (SPR) modes excited on the gold-coated nanograting structure appeared as a dip in the reflectance spectrum measured at normal incidence under white light illumination in the ambient air medium. Electromagnetic simulation based on the finite element method was carried out to analyze the excited SPR modes. The simulated result shows very close agreement with the experimental data. The performance of the sensor with respect to changing the surrounding dielectric medium yields a bulk refractive index sensitivity of 788 ± 21 nm per refractive index unit. Further, label-free detection of proteins using a plasmonic sensing substrate was demonstrated by monitoring specific interactions between bovine serum albumin (BSA) and anti-BSA proteins, which gave a detection limit of 123 pg mm−2 with respect to target anti-BSA protein binding. Thus, our proposed plasmonic sensor has potential for the development of an economical and highly sensitive label-free optical biosensing device for biomedical applications.

Development of bovine serum albumin-water partition coefficients predictive models for ionogenic organic chemicals based on chemical form adjusted descriptors

The partition coefficients between bovine serum albumin (BSA) and water (KBSA/w) for ionogenic organic chemicals (IOCs) were different greatly from those of neutral organic chemicals (NOCs). For NOCs, several excellent models were developed to predict their logKBSA/w. However, it was found that the conventional descriptors are inappropriate for modeling logKBSA/w of IOCs. Thus, alternative approaches are urgently needed to develop predictive models for KBSA/w of IOCs. In this study, molecular descriptors that can be used to characterize the ionization effects (e.g. chemical form adjusted descriptors) were calculated and used to develop predictive models for logKBSA/w of IOCs. The models developed had high goodness-of-fit, robustness, and predictive ability. The predictor variables selected to construct the models included the chemical form adjusted averages of the negative potentials on the molecular surface (Vs−adj−), the chemical form adjusted molecular dipole moment (dipolemomentadj), the logarithm of the n-octanol/water distribution coefficient (logD). As these molecular descriptors can be calculated from their molecular structures directly, the developed model can be easily used to fill the logKBSA/w data gap for other IOCs within the applicability domain. Furthermore, the chemical form adjusted descriptors calculated in this study also could be used to construct predictive models on other endpoints of IOCs.

Affinity study on bovine serum albumin’s peptides to amphiphilic gold nanoparticles: A test of epitopes and non-epitopes

It is an inevitable event that nanoparticles (NPs) will encounter proteins/peptides in nano-medicine, so it has been significant to know their interaction mechanism before in vivo applications. Previously, a 105-amino-acid sequence had been reported as the binding site between bovine serum albumin (BSA) and amphiphilic polymer coated gold nanoparticles (AP-AuNPs) along with a mortise-tenon joint hypothesis. This article tested the affinity difference between two epitope peptide sequences such as: LGEYGFQNALIVR (S1), DAFLGSFLYEYSR (S2) and one non-epitope peptide sequence as: FDEHVKLVNELTEF (S3). With the photoluminescent amino acid residues, the fluorescence quenching method based on the nanometal surface energy transfer (NSET) principle was able to study the thermodynamics of the current binding system. The binding constants (Ka) were determined and followed the order as: Ka-S1>Ka-S2>>Ka-S3. Moreover, Hill constants indicated that cooperativity only presented in the interactions of AP-AuNP with either S1 or S2, but not for S3. Moreover, gel electrophoresis, surface plasmon resonance, atomic force microscopy and three dimensional fluorescence microscopy were all also used to comprehensively analyse the binding interaction mechanism. These results further provided useful information to better understand the mortise-tenon joint, which might find applications to nanofabrication and biomedicine.

Detailed investigation of effects of Zn2 +, Fe2 + and Cu2 + metal ions on the binding interaction between eletriptan hydrochloride an anti-migraine headache drug and bovine serum albumin by various spectrometric techniques and molecular docking studies

Bovine serum albumin acts as storage and a transport of endogenous and exogenous compounds with protein in the blood. Eletriptan hydrochloride is an anti-migraine headache drug and binding of this drug to albumin is necessary in pharmacokinetic and pharmacodynamics. Many metal ions are present in blood plasma, therefore, the study on the effects of metal ions on the interaction between drugs and plasma proteins are essential. In this study, the effects of metal ions Zn2+, Fe2+ and Cu2+ on the interaction between bovine serum albumin (BSA) and eletriptan hydrochloride (ELT) were investigated by employing emission fluorescence, synchronous fluorescence, ultraviolet–visible (UV–Vis) absorption, Fourier transform infrared (FT-IR) spectroscopic and molecular docking studies at physiological buffer conditions (pH7.4). Results show that static quenching, spontaneous process, hydrogen bonds and vander Waals interactions and the values of Ka, n,Kb, R0,r and thermodynamic parameters were obtained at different temperatures; then the binding sites for ELT in BSA present in sub-domains IIA, IIIA and IB. The entire outcome indicates that the metal ions decrease the binding efficacy of ELT on BSA. The study of binding phenomena is important in providing basic information on the pharmacological actions, biotransformation and bio-distribution, and this would be useful in pharmaceutical industry, life sciences and clinical medicine.

Luminescence Studies of the Ligand Exchange Between Two Phenanthroline Complexes and Bovine Serum Albumin

The interactions between bovine serum albumin (BSA) and two Cu(II) phenanthroline complexes were studied by fluorescence and UV-visible absorption spectroscopy. The obtained results confirm that the phen ligand (phen = 1,10-phenanthroline) is dissociated from the two complexes and moves into the hydrophobic cavity of BSA and that the M–L complexes (M = Co2+, Cu2+; L = Hlact, imda; Hlact = lactic acid, H2imda = iminodiacetic acid) coordinate with the amino acids on the surface of the peptide in the solution. This mode of action significantly inhibits the denaturation of BSA. The calculated distance between the BSA and the two complexes suggests that the energy transfer from the excited state of BSA to a complex occurs with high efficiency.

Fluorescent amino‐substituted squaraine probes for bovine serum albumin

The synthesis and spectroscopic properties of fluorescent amino‐substituted squaraine dyes have been presented. The interaction between bovine serum albumin (BSA) and fluorescence probes derived from squaric acid was studied by UV‐vis and fluorescence spectroscopies. The Benesi–Hildebrand, Lehrer, and Stern–Volmer equations were used to present the influence of BSA concentration on the binding constant for the process of association with squaraine dyes, as well as the effect of the concentration of fluorescence probes on the quenching process. It was also shown that the interaction between BSA and squaraine dyes is spontaneous. The number of binding sites to bovine serum albumin for a series of squaraine dyes has also been calculated.

Protein interactions with silver nanoparticles: Green synthesis, and biophysical approach

Silver nanoparticles (AgNPs) with an average particle size of 20nm were synthesized by using aromatic amino acid fluorescence active, tryptophan as a reducing agent. This study aims to investigate the interaction between Bovine Serum Albumin (BSA) and AgNPs as a function of particle size and shape. UV–vis analysis implies the formation of the ground state complex between BSA and AgNPs through electrostatic interactions. The fluorescence spectra indicated that the AgNPs have a potent ability to quench the intrinsic fluorescence of BSA by static quenching mechanisms. The different parameters (the apparent association constant (Kapp=2.6×104mol−1dm3), Stern–Volmer quenching constant (KSV=3.5×104mol−1dm3), number of binding sites (n=1.3) and bimolecular rate constant of the quenching reaction (kq=6.1×1012mol−1dm3s−1)) were calculated by using the UV–vis and fluorescence spectra and discussed. The indole moieties of tryptophan residues of BSA were responsible to the complex formation with AgNPs in ground and excited states via electrostatic, van der Waals, hydrogen bonding, hydrophobic and hydrophilic interactions. Adsorption of AgNPs into the core of BSA changes the tryptophan environment from hydrophobic to hydrophilic (from folding to partially folded and/or unfolded). Circular dichroism results suggested that the helicity of BSA decreased from 67.68% to 60.25% and 67.68% to 45.42% with [AgNPs] and temperature, respectively.

The Oxidative Activity of Ellagitannins Dictates Their Tendency To Form Highly Stabilized Complexes with Bovine Serum Albumin at Increased pH

Many food and forage plants contain tannins, high molecular weight polyphenols that characteristically interact strongly with protein, forming complexes that affect taste, nutritional quality, and the health of the consumer. In the present study, the interaction between bovine serum albumin (BSA) and each of seven hydrolyzable tannins or epigallocatechin gallate was examined. The objective was to define the effect of tannin oxidation, measured as oxidative activity (browning) or as oxidizability (degradation monitored by HPLC), on the formation on highly stabilized tannin-protein complexes and to determine how the reaction depended on the pH conditions. Gel electrophoresis and MALDI-TOF-MS were used to assess the formation of tannin-protein complexes. The results showed that tannin oxidizability was directly correlated with the tendency of the tannins to form highly stabilized complexes with BSA at increased pH (7.6). However, at slightly lower pH (6.7), other tannin features, such as the size and flexibility of the tannin, appeared to dictate the formation of highly stabilized tannin-protein complexes.

Real-timely monitoring the interaction between bovine serum albumin and drugs in aqueous with terahertz metamaterial biosensor

In this paper, a metamaterial (MM) resonator used as a sensitive biosensor is designed and fabricated for monitoring the interaction between bovine serum albumin (BSA) solution and four kinds of drug solutions in real time. The transmission spectra of the resonator are simulated and measured with terahertz time-domain spectroscopy system where the distinct resonance frequency shifts are observed. The experimental results indicate that the interactions between BSA and every kind of solution are violent before the reaction reaches equilibrium, and the reaction solutions manifest varying permittivity. Moreover, different reaction solutions show different frequency shifts and reaction times. The MM resonator worked as an effective biosensor achieves to monitor the interaction between BSA and drug solutions in real time, which is very useful for the development of novel drugs and other biomedical applications.