Desorption Of Bovine Serum Albumin Research Articles

A Multiple-Stimuli-Responsive Amphiphilic Copolymer for Antifouling and Antibacterial Functionality via a "Resistance-Kill-Release" Mechanism.

In recent years, polymers with stimuli-responsive properties have been increasingly reported on due to their diverse applications. However, most of the studies have only focused on the performance of polymers under specific scenarios. The laws of changes in the properties in response to various external stimuli have been less systematically and quantitatively studied. In this paper, we prepared an amphiphilic polymer (PadaMX and PAdaM3QA−X) with temperature-, pH-, ion-, and β-cyclodextrin (β-CD)-responsive properties. According to the cloud point tested by the UV-Vis method, the lower critical soluble temperature (LCST) of PAdaM3QA−10% was more sensitive to a change in pH and less sensitive to a change in ions compared with PadaM3 due to quaternized side chains with a stronger intramolecular mutual repulsion. We then fabricated the coatings with responsive properties by immobilizing the adamantyl groups on β-CD-modified surfaces. The hydrophilicity of the coatings was improved after quaternization, as proven by the water contact angle (WCA) measurement. The antifouling and antibacterial performance was further evaluated via the fluorescence intensity of bovine serum albumin (BSA) adsorbed on the surfaces and the spread plate method. A 78.4% BSA desorption rate and a 96.8% sterilization rate were achieved by the PAdaM3QA−10% coating. In summary, this work prepared a multiple-stimuli-responsive amphiphilic copolymer for antifouling and antibacterial functionality via a “resistance–kill–release” mechanism.

Molecular imprinting of bovine serum albumin and lysozyme within the matrix of polyampholyte hydrogels based on acrylamide, sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid and (3-acrylamidopropyl)trimethyl ammonium chloride

Molecularly-imprinted polyampholyte (MIP) hydrogels based on nonionic monomer – acrylamide (AAm), anionic monomer – sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and cationic monomer – (3-acrylamidopropyl)trimethyl ammonium chloride (APTAC) were obtained by immobilization of bovine serum albumin (BSA) and lysozyme in situ polymerization conditions. It was found that the best amphoteric hydrogel for sorption of BSA is APTAC-75H while for sorption of lysozyme is AMPS-75H. The sorption capacity of APTAC-75H and AMPS-75H with respect to BSA and lysozyme is 305.7 and 64.1-74.8 mg per 1 g of hydrogel respectively. Desorption of BSA and lysozyme from MIP template performed by aqueous solution of 1M NaCl is equal to 82-88%. Separation of BSA and lysozyme from their mixture was performed on MIP templates. The results of adsorption-desorption cycles of BSA on adjusted to BSA polyampholyte hydrogel APTAC-75H and of lysozyme on adjusted to lysozyme polyampholyte hydrogel AMPS-75H show that the mixture of BSA and lysozyme can be selectively separated with the help of MIP hydrogels.

Effect of proteins on the oxidase-like activity of CeO2 nanozymes for immunoassays.

Having the benefits of low cost, excellent stability and tolerance to extreme conditions, nanozymes are a potential alternative of horseradish peroxidase (HRP) or other enzymes for bioanalytical chemistry, especially immunoassays. CeO2 nanoparticles have oxidase-mimicking activity and can avoid the use of unstable H2O2. For robust assays, the effect of proteins on the activity of CeO2 needs to be carefully studied. Herein, we studied the adsorption and desorption of bovine serum albumin (BSA) from CeO2. The CeO2 nanoparticles exhibited a higher protein adsorption capacity compared to the other tested metal oxide nanoparticles. Although the oxidase-like activity of CeO2 was inhibited by BSA, low concentrations of phosphate and fluoride ions boosted the activity of protein-capped CeO2. CeO2 was still active under strong acidic conditions and at high temperature, while HRP lost its activity. For immunoassay development, we covered CeO2 with an amine-modified silane for covalent conjugation to antibodies. A one-step indirect competitive ELISA for fenitrothion was developed, and an IC50 value of 35.6 ng mL-1 and a limit of detection of 2.1 ng mL-1 were obtained.

Proteolysis of Iron Oxide-Associated Bovine Serum Albumin.

Proteins are a substantial nitrogen source in soils provided that they can be hydrolyzed into bioavailable small peptides or amino acids. However, the strong associations between proteins and soil minerals restrict such proteolytic reactions. This study focused on how an extracellular fungal protease (Rhizopus sp.) hydrolyzed iron oxide-associated bovine serum albumin (BSA) and the factors that affected the proteolysis. We combined batch experiments with size-exclusion and reversed phase liquid chromatography and in situ infrared spectroscopic measurements to monitor the generation of proteolytic products in solution as well as the real-time changes of the adsorbed BSA during 24 h. Results showed that protease hydrolyzed the iron oxide-associated BSA directly at the surface without an initial desorption of BSA. Concurrently, the protease was adsorbed to vacant surface sites at the iron oxides, which significantly slowed down the rate of proteolysis. This inhibiting effect was counteracted by the presence of preadsorbed phosphate or by increasing the BSA coverage, which prevented protease adsorption. Fast initial rates of iron oxide-associated BSA proteolysis, comparable to proteolysis of BSA in solution, and very slow rates at prolonged proteolysis suggest a large variability in mineral-associated proteins as a nitrogen source in soils and that only a fraction of the protein is bioavailable.

Reaction-Mediated Desorption of Macromolecules: Novel Phenomenon Enabling Simultaneous Reaction and Separation.

Combining chemical reaction with separation offers several advantages. In this work possibility to induce spontaneous desorption of adsorbed macromolecules, once being PEGylated, through adjustment of the reagent composition is investigated. Bovine serum albumin (BSA) and activated oligonucleotide, 9T, are used as the test molecules and 20 kDa linear activated PEG is used for their PEGylation. BSA solid-phase PEGylation is performed on Q Sepharose HP. Distribution coefficient of BSA and PEG-BSA as a function of NaCl is determined using linear gradient elution (LGE) experiments and Yamamoto model. According to the distribution coefficient the selectivity between BSA and PEG - BSA of around 15 is adjusted by using NaCl. Spontaneous desorption of PEG - BSA is detected with no presence of BSA. However, due to a rather low selectivity, also desorption of BSA occurred at high elution volume. A similar procedure is applied for activated 9T oligonucleotide, this time using monolithic CIM QA disk monolithic column for adsorption. Selectivity of over 2000 is obtained by proper adjustment of PEG reagent composition. High selectivity enables spontaneous desorption of PEG-9T without any desorption of activated 9T. Both experiments demonstrates that reaction-mediated desorption of macromolecules is possible when the reaction conditions are properly tuned.

The Effect of Nano-ZnO Surface Wettability on Modulating Protein Adsorption

Although surface wettability plays a major role in regulating protein adsorption and nanostructured ZnO has shown great potential in various biomedical fields, few reports have examined the influence of nano-ZnO surface wettability on protein adsorption. Herein, we explored the adsorption behavior of bovine serum albumin (BSA) on the superhydrophilic, hydrophilic, hydrophobic and superhydrophobic nano-ZnO surfaces. The adsorption amount of BSA increased with increase of hydrophilicity because of increased adsorption sites on the hydrophilic surface. The protein adsorption was proved to occur along with the desorption and conformational changes by well-fitted kinetic adsorption curves with the Spreading Particle Model and Fourier transformation infrared spectral analysis. The rates of BSA adsorption and desorption increased with hydrophobicity of the ZnO surfaces, which was considered to be related with the energy barrier created by water bound to the ZnO surfaces via hydrogen bonding. The rate of conformational change varied in a complex way, which might be influenced by the surface wettability of ZnO and some other factors. The present work may open up a new avenue to design nano-bio interfacial materials for advanced biological study and clinical applications.

Effect of protein molecules and MgCl2 in the water phase on the dilational rheology of polyglycerol polyricinoleate molecules adsorbed at the soy oil-water interface

The objective of this study was to investigate the effect of inorganic salt and protein in the aqueous phase on the dilational rheology properties of interfacial film stabilized by the hydrophobic emulsifier polyglycerol polyricinoleate (PGPR). The interfacial behavior was investigated using the oscillating drop method. With increased PGPR concentration, the interfacial tension tended to decrease and reached an equilibrium value of 3.3 mN m−1, at 1.0% (w/w) PGPR. With 0.01% (w/w) PGPR in the oil phase, the presence of whey protein isolate (WPI) increased the dilational elasticity modulus of PGPR, but the addition of bovine serum albumin (BSA) decreased the elasticity modulus. This was likely due to competitive adsorption of BSA and PGPR at the soy oil/water interface, resulting in the desorption of BSA from the interface. At 1.0% (w/w) PGPR, both WPI and BSA increased the interfacial dilational elastic modulus and the reason might be that the presence of protein could suppress the diffusion-exchange process of PGPR between bulk phase and interface. The addition of MgCl2 may enhance the adsorption of PGPR molecules at the interface and therefore increased the dilational modulus.

Forced Desorption of Bovine Serum Albumin and Lysozyme from Graphite: Insights from Molecular Dynamics Simulation.

We use molecular dynamics (MD) simulation to study the adsorption and desorption of two widely different proteins, bovine serum albumin (BSA) and lysozyme, on a graphite surface. The adsorption is modeled using accelerated MD to allow the proteins to find optimum conformations on the surface. Our results demonstrate that the "hard protein" lysozyme retains much of its secondary structure during adsorption, whereas BSA loses it almost completely. BSA has a considerably larger adsorption energy compared to that of lysozyme, which does not scale with chain length. Desorption simulations are carried out using classical steered MD. The BSA molecule becomes fully unzipped during pull-off, whereas several helices survive this process in lysozyme. The unzipping process shows up in the force-distance curve of BSA as a series of peaks, whereas only a single or few, depending on protein orientation, force peaks occur for lysozyme. The maximum desorption force is larger for BSA than for lysozyme, but only by a factor of about 2.3.

Biomimetic synthesis of hybrid hydroxyapatite nanoparticles using nanogel template for controlled release of bovine serum albumin

A biomimetic method was used to prepare hybrid hydroxyapatite (HAP) nanoparticles with chitosan/polyacrylic acid (CS-PAA) nanogel. The morphology, structure, crystallinity, thermal properties and biocompatibility of the obtained hybrid nanogel-HAP nanoparticles have been characterized. In addition, bovine serum albumin (BSA) was used as a model protein to study the loading and release behaviors of the hybrid nanogel-HAP nanoparticles. The results indicated that the obtained HAP nanoparticles were agglomerated and the nanogel could regulate the formation of HAP. When the nanogel concentration decreased, different HAP crystal shapes and agglomerate structures were obtained. The loading amount of BSA reached 67.6mg/g for the hybrid nanoparticles when the mineral content was 90.4%, which decreased when the nanogel concentration increased. The release profile of BSA was sustained in neutral buffer. Meanwhile, an initial burst release was found at pH4.5 due to the desorption of BSA from the surface, followed by a slow release. The hemolysis percentage of the hybrid nanoparticles was close to the negative control, and these particles were non-toxic to bone marrow stromal stem cells. The results suggest that these hybrid nanogel-HAP nanoparticles are promising candidate materials for biocompatible drug delivery systems.

Investigation of Bovine Serum Albumin (BSA) Attachment onto Self-Assembled Monolayers (SAMs) Using Combinatorial Quartz Crystal Microbalance with Dissipation (QCM-D) and Spectroscopic Ellipsometry (SE).

Understanding protein adsorption kinetics to surfaces is of importance for various environmental and biomedical applications. Adsorption of bovine serum albumin to various self-assembled monolayer surfaces including neutral and charged hydrophilic and hydrophobic surfaces was investigated using in-situ combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry. Adsorption of bovine serum albumin varied as a function of surface properties, bovine serum albumin concentration and pH value. Charged surfaces exhibited a greater quantity of bovine serum albumin adsorption, a larger bovine serum albumin layer thickness, and increased density of bovine serum albumin protein compared to neutral surfaces at neutral pH value. The quantity of adsorbed bovine serum albumin protein increased with increasing bovine serum albumin concentration. After equilibrium sorption was reached at pH 7.0, desorption of bovine serum albumin occurred when pH was lowered to 2.0, which is below the isoelectric point of bovine serum albumin. Our data provide further evidence that combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry is a sensitive analytical tool to evaluate attachment and detachment of adsorbed proteins in systems with environmental implications.

Selective Desorption of Intercalated Bovine Serum Albumin and Lysozyme by Organically Modified Montmorillonite

AbstractThe organically modified montmorillonite (M‐Mt) was applied as an adsorbent for the purification of bovine serum albumin (BSA). In order to differentiate the selectivity and perform the purification of BSA, two kinds of proteins, BSA and lysozyme (LYZ) were mixed together and prepared at different pH, which could change the electrical charges on the surfaces of the proteins. BSA and LYZ can be adsorbed at the lower pH into the organically modified montmorillonite, which could be confirmed by powder X‐ray diffraction (XRD) in the d‐value increased after the adsorption of proteins. However, there is only BSA desorption was observed, approved by the method of Sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis (PAGE), from this adsorbed protein mixture when the pH of the solution was adjusted and optimized. These results indicate that there is electrostatic interaction between a suitably modified montmorillonite and proteins BSA and LYZ to perform the selective desorption from BSA in the mixture of these proteins.

Preparation of Hierarchically Structured Layered Double Hydroxide Microspheres and Their Application in BSA Separation

Hierarchically structured layered double hydroxides (LDHs) are being actively investigated due to their potential applications in adsorption and catalysis that result from their special surface structures and positively charged nanosheets. However, a control over the structure and morphology of LDHs is essential to achieve the diverse structures and desirable properties. In this work, hierarchically porous LDH microspheres are successfully fabricated in a large scale by combining the hydrothermal method and in situ growth method, and the calcined LDH microspheres are further applied to separate bovine serum albumin (BSA) from solution. The prepared LDH microspheres are characterized by scanning electron microscopy (SEM), transmission electron microscopy, powder x-ray diffraction, and surface area analyzer. The SEM results demonstrate that microspheres have a coral-like hierarchical architecture comprised of oriented LDH nanoplatelets. The high specific surface areas (143.82 m2/g) of calcined LDH microspheres are demonstrated to be beneficial for the adsorption of BSA. To obtain better insights into the separation processes, the adsorption and desorption of BSA on LDH microspheres are investigated by solution temperature and BSA concentration. The results indicated that the adsorption process of BSA is an exothermic process and desorption process of BSA is endothermic process.

Fabrication and BSA adsorption/desorption properties of titania/silica composite films modified with silane coupling agents.

In this study, we successfully prepared titania/silica composite films modified with silane coupling agents having amino groups and investigated their bovine serum albumin (BSA) adsorption/desorption behavior under light irradiation. XRD patterns and ATR/FT-IR spectra of the films revealed the formation of titania/silica composite films modified with silane coupling agents. In these films, the adsorption and desorption of BSA could be controlled by light irradiation, through the locally photoinduced superhydrophilic titania surface.

Responsive membranes for hydrophobic interaction chromatography

Poly N-vinylcaprolactam (PVCL) chains were grown from the surface of regenerated cellulose membranes using atom transfer radical polymerization (ATRP). Modified membranes were characterized using scanning electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy and by measuring surface contact angles. The grafting degree of PVCL increases with increasing ATRP initiator immobilization time. PVCL is a thermo-responsive polymer with a lower critical solution temperature (LCST) that depends on the concentration of salt ions present in solution. The LCST decreases below room temperature in buffer containing 1.8M (NH3)2SO4 where the polymer adopts a more hydrophobic/collapsed conformation. At low ionic strength, the LCST remains above room temperature. Contact angles for PVCL in 20mM phosphate buffer with and without 1.8M (NH3)2SO4 were determined. Contact angles in the buffer with high ionic strength were higher than those in low ionic strength.Adsorption and desorption of bovine serum albumin (BSA) and immunoglobulin G (IgG) have been investigated. Loading was conducted in high ionic strength buffer. Elution was conducted in low ionic strength buffer. By using a responsive ligand that changes its conformation during loading and elution, high protein recoveries were obtained. Ligands that respond to solution ionic strength show promise for high performance hydrophobic interaction chromatography.

Tunable adsorption of bovine serum albumin by annealed cationic spherical polyelectrolyte brushes

By combining turbidimetric titration, dynamic light scattering (DLS), and zeta potential methods, we demonstrated that the adsorption of bovine serum albumin (BSA) in annealed cationic spherical polyelectrolyte brushes (SPB) can be controlled by modulating the pH, ionic strength, BSA concentration of the mixed solution, and SPB thickness. The SPB consist of a polystyrene core with a diameter around 80nm and a dense shell of poly (2-aminoethylmethacrylate hydrochloride) (PAEMH) with a thickness from 10 to 60nm covalently attached on the core surface. Results revealed the existence of three pH regions, corresponding to (1) adsorption of BSA in SPB, (2) aggregation of SPB induced by BSA adsorption, and (3) desorption of BSA from SPB. The extent of the pH regions can be modulated by ionic strength, BSA concentration, or SPB thickness. Adsorption measurements demonstrated that the adsorbed amount of BSA in SPB was affected by pH, ionic strength, and SPB thickness. These findings lay the foundation for protein separation by SPB.

Biomimetic fabrication of hierarchically structured LDHs/ZnO composites for the separation of bovine serum albumin

Hierarchically structured layered double hydroxides (LDHs), with special surface structural and positively charged layer, are of great interest due to their potential applications in bioseparation and catalysis. Herein this work presents a novel method for fabricating ZnAl LDHs/ZnO composites derived from cotton fibers, as well as its application in bovine serum albumin (BSA) separation. The morphology and structure of as-prepared samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. It is found that the fibrous morphologies are retained in inorganic replicas, and the surface of composites is composed of many small nanosheets. Batch adsorption results indicated that the prepared samples were very effective in adsorbing BSA. Effects of solution pH, adsorbent dose, adsorption time, and adsorption temperature were investigated in detail. The equilibrium data were found to be well described by Dubinin–Radushkevich model, while the kinetic data were well-fitted to the intraparticle diffusion model. Based on the mechanism of adsorption, the adsorption sites of composites can be easily occupied by adsorbed high negative charge anions through electrostatic interactions. The BSA desorption can be controlled via the addition of salt solution.

Effect of bovine serum albumin on the functionality and structure of catanionic surfactant at air–buffer interface

Interaction of bovine serum albumin (BSA) with the solvent spread monolayer of a catanionic surfactant, octadecyltrimethylammonium dodecylsulfate, (C18TA+DS−) at the air–buffer interface was investigated by measuring the surface pressure with time and change in surface area. Dipalmitoylphosphatidylcholine (DPPC) was used as reference. Kinetics of BSA desorption from the interface to the buffer subphase, that of C18TA+DS− and DPPC through their interaction with BSA, were also studied at different BSA concentrations (in the subphase) and surface pressures. Surface pressure (π)–area (A) isotherms (at pH=5.4, μ=0.01, T=298K) revealed that the coacervate/DPPC monolayer becomes expanded in the presence of BSA at low π while their protein bound species are released into the subphase at high π. Film morphology, studied by epifluorescence microscopy (EFM) and atomic force microscopy (AFM), reveals that the sizes of the domains of both DPPC and coacervate decrease in the presence of BSA. Presence of BSA in the coacervate and DPPC monolayer was supported from AFM data analysis.

Temperature-Swing Adsorption of Proteins in Water Using Cationic Copolymer-Grafted Silica Particles

We have prepared silica particles grafted with poly(N-isopropylacrylamide) (PNIPA) copolymers as adsorbent for the temperature-swing adsorption of bovine serum albumin (BSA) in water, where vinylbenzyl trimethylammonium chloride (VBTA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), or N,N-dimethylacrylamide (DMAA) was employed as a comonomer. The surface potentials of PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles in water at 298 and 313 K were negative, while those of P(NIPA-co-VBTA)-grafted silica particle were positive, because VBTA is a quaternary ammonium salt and positively charged in aqueous solutions. As for the P(NIPA-co-DMAEMA)-grafted silica particle, the surface potential changed from positive to near zero with increasing temperature from 298 K to 313 K. This may be because the coil-to-globule transition of grafted copolymers leads to the dehydration and deprotonation of DMAEMA group, which is a tertiary amine and can be positively charged only in the aqueous phase. Although PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles failed to adsorb BSA, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles adsorbed BSA, indicating that BSA is adsorbed by the electrostatic attraction between the negatively charged BSA and the positively charged copolymers on the silica surface. Moreover, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles repeatedly adsorbed BSA at 298 K and desorbed some of the preadsorbed BSA at 313 K via the temperature-swing operation. This BSA desorption may result from the decrease in the number of the positively charged groups accessible to BSA due to the coil-to-globule transition of the grafted copolymers with increasing temperature.

A Novel Method to Attenuate Protein Adsorption Using Combinations of Polyethylene Glycol (PEG) Grafts and Piezoelectric Actuation

An antifouling treatment based on the combined effects of grafted polyethylene glycol (PEG) polymers and the application of vibration is reported. A gold-coated lead zirconate titanate piezoelectric composite was grafted with PEG used as a model substrate. The PEG grafted surfaces were thoroughly characterized by attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. In vitro protein adsorption onto PEG coated surfaces was studied with and without the application of vibration. Bovine serum albumin (BSA) adsorption onto PEG grafted surfaces followed a similar pattern as reported in literature. However, when piezoelectric vibration was applied on the PEG grafted surface, BSA desorption was observed. At very low graft densities, the vibration significantly reduced the BSA adsorption compared with high PEG graft densities. Theoretical calculations showed that the thickness of PEG layer on the surface was affecting vibration induced protein desorption.

Zn- and Mg-doped hydroxyapatite nanoparticles for controlled release of protein.

Bovine serum albumin (BSA) protein incorporated with hydroxyapatite (HA) nanoparticles (NPs) were synthesized by an in situ precipitation process. 2 mol % Zn(2+) and Mg(2+) were used as dopants to synthesize Zn(2+)/Mg(2+)-doped HA-BSA NPs. In our study we used BSA as a model protein. The amount of BSA uptake by doped and undoped HA NPs and subsequent release of BSA from NPs were investigated. Zn-doped HA NPs showed the highest amount of BSA uptake, whereas the amount of BSA loaded in undoped HA NPs was the lowest. A two-stage BSA release profile from doped and undoped HA NPs was observed in phosphate buffer solution (PBS) at pH 7.2 +/- 0.2. The initial burst release was due to the desorption of BSA from the HA surface. The later stage of slow release was controlled by the dissolution of BSA incorporated HA NPs. The BSA release rate from Zn-doped HA NPs was found to be the highest, whereas undoped HA NPs released BSA at the slowest rate. Our study showed that the protein release rate from HA NPs can be controlled by the addition of suitable dopants, and doped HA-based NP systems can be used in bone growth factor and drug release study.