Behavior Of Bovine Serum Albumin Research Articles

Detection of green fluorescence in serum albumin upon excitation with 375 nm light: revealing new fluorescent properties

The novel data on the fluorescence behavior of bovine serum albumin and human serum albumin under 375 nm excitation are presented, introducing a distinctive fluorescence phenomenon that holds promising implications for protein research. Extensive studies of these proteins are conducted to understand their intrinsic fluorescence properties, typically observed upon excitation with light in the range of 280–300 nm, resulting in fluorescence emission around 345 nm.

Different behavior of Ferguson plot between agarose and polyacrylamide gels

In this study, we conducted Ferguson plot analyses using both agarose and polyacrylamide gels in native electrophoresis and SDS-PAGE. The results revealed intriguing differences in the behavior of bovine serum albumin (BSA) and other model proteins. Specifically, BSA exhibited Ferguson plot slopes that were dependent on the oligomer size in agarose native gel electrophoresis, while such size-dependent behavior was not observed in native-PAGE or SDS-PAGE. These findings suggest that Ferguson plot analysis is a suitable approach when using agarose gel under the electrophoretic conditions employed in this study. Furthermore, our investigation extended to model proteins with acidic isoelectric points and larger molecular weights, namely Ferritin and caseinolytic peptidase B (ClpB). Notably, these proteins displayed distinct Ferguson plot slopes when subjected to agarose gel electrophoresis. Intriguingly, when polyacrylamide gel was employed, ClpB exhibited multiple bands, each with its unique Ferguson plot slope, deviating from the expected behavior based on molecular size. This divergence in Ferguson plot characteristics between agarose and polyacrylamide gels points to an interesting and complex interplay between protein properties and gel electrophoresis conditions.

Protein Adsorption on Mixed Self-Assembled Monolayers: Influence of Chain Length and Terminal Group.

Mixed self-assembled monolayers (SAMs) are often used as highly tunable substrates for biomedical and biosensing applications. It is well documented, however, that mixed SAMs can be highly disordered at the molecular level and do not pack as closely or homogeneously as single-component SAMs, particularly when the chain lengths and head groups of the SAM thiol components are significantly different. In this study, we explore the impact of SAM structure and mixing ratio (-OH and -CH3 termini) on the weak physisorption behavior of bovine serum albumin (BSA), which adsorbs more readily to hydrophobic, methyl-terminated SAMs. Our results suggest that once the mixture includes 50% or more of the methyl terminus, the mixing ratio alone is a relatively good predictor of adsorption, regardless of the relative chain lengths of the thiols used in the mixture. This trend persists at any mixing ratio for SAMs where methyl- and hydroxyl-terminated groups are the same length or where the hydroxyl-terminated thiol is longer. The only variance observed is at low mixing ratios (<50% methyl-terminated) for a mixed SAM where the methyl-terminated component has a longer chain length. Relative protein adsorption increases on these mixtures, perhaps due to the disordered exposure of the excess alkane backbone. Taken together, however, we do not find significant evidence that varying chain lengths for mixed SAMs prepared on polycrystalline substrates and analyzed in air have an outsized influence on nanoscopic adsorption behavior, despite molecular-level disorder in the SAM itself.

Instant formation of nanopores on flexible polymer membranes using intense pulsed light and nanoparticle templates

ABSTRACT The development of simple and high-throughput approaches to yield solid-state nanopores on large surface membranes may facilitate the prevalence of nanopore analysis technology and in-vitro diagnosis using portable devices. However, solid-state nanopores are typically realized by complex and high-end nanofabrication equipments. Here, we present a method to achieve nanopores on polymer membranes using silver nanoparticles (AgNPs) as templates and intense pulsed light (IPL) as a heating source. The density and size of nanopores are controllable by adjusting the spin coating rate, the concentration of nanoparticle suspension, and the size of nanoparticles (NPs). The temperature of the AgNPs can rapidly reach 1132 K under instant heating of photothermal effect through light irradiation in 2 ms, resulting in localized melting and decomposition of an underneath polycarbonate (PC) membrane to yield nanopores with sizes ranging from 10 to 270 nm. After removing the nanoparticle residues, the flexible membrane with nanopores can be integrated into a flow cell to achieve a nanopore sensor that has been used to measure the translocation behaviors of bovine serum albumin (BSA). The results have demonstrated the capability of the sensor in protein denaturation identification. This low-cost and high-throughput technique to fabricate solid-state nanopores on flexible polymeric membranes may facilitate the development of more nanopore-based flexible sensors that can be integrated with other flexible components for wearable diagnosis.

Understanding Protein and Polysaccharide Fouling with Silicon Dioxide and Aluminum Oxide in Low-Pressure Membranes.

Humic, protein, and polysaccharide substances have been recognized as significant types of foulants in membrane systems. Despite the remarkable amount of research that has been performed on the interaction of these foulants, particularly humic and polysaccharide substances, with inorganic colloids in RO systems, little attention has been paid to the fouling and cleaning behavior of proteins with inorganic colloids in UF membranes. This research examined the fouling and cleaning behavior of bovine serum albumin (BSA) and sodium alginate (SA) with silicon dioxide (SiO2) and α-aluminum oxide (Al2O3) in individual and combined solutions during dead-end UF filtration. The results showed that the presence of SiO2 or Al2O3 in water alone did not cause significant fouling or a flux decline in the UF system. However, the combination of BSA and SA with inorganics was observed to have a synergistic effect on membrane fouling, in which the combined foulants caused higher irreversibility than individual foulants. Analysis of blocking laws demonstrated that the fouling mechanism shifted from cake filtration to complete pore blocking when the combined organics and inorganics were present in water, which resulted in higher BSA and SA fouling irreversibility. The results suggest that membrane backwash needs to be carefully designed and adjusted for better control of BSA and SA fouling with SiO2 and Al2O3.

Thermo-Resistive Phase Behavior of Trivalent Ion-Induced Microscopic Protein-Rich Phases: Correlating with Ion-Specific Protein Hydration

Proteins, in the presence of trivalent cations, exhibit intriguing phase behavior which is contrasting compared to mono- and divalent cations. At room temperature (RT), trivalent cations induce microscopic liquid-liquid phase separation (LLPS) in which a protein-rich phase coexists with a dilute phase. The critical solution temperature related phenomena in these complex fluids are well studied; however, such studies have mostly been restricted below the denaturation temperature (TM) of the protein(s) involved. Here, we probe the phase behavior of bovine serum albumin (BSA) incubated at 70 °C (>TM) in the presence of Na+, Mg2+, La3+, Y3+, and Ho3+ ions. BSA in the presence of mono- and bivalent ions forms an intense gel phase at 70 °C; however, the trivalent salts offer remarkable thermal resistivity and retain the fluid LLPS phase. We determine the microscopic phase behavior using differential interference contrast optical microscopy, which shows that the LLPS droplet structures in the M3+ ion-containing protein solutions prevail upon heating, whereas Mg2+ forms composed cross-linking gelation upon thermal incubation. We probe the interior environment of the protein aggregates by ps-resolved fluorescence anisotropy measurements using 8-anilino-1-naphthalenesulfonic acid (ANS) as an extrinsic fluorophore. It reveals that while the LLPS phase retains the rotational time constants upon heating, in the case of gelation, the immediate environment of ANS gets significantly perturbed. We investigate the explicit protein hydration at RT as well as at T > TM using the ATR THz-FTIR (1.5-22.5 THz) spectroscopy technique and found that hydration shows strong ion specificity and correlates the phase transition behavior.

Synthesis and characterization of superabsorbent hydrogels based on carboxymethyl cellulose and agar: Agar for smart swelling and controllable delivery

The current study described a thorough analysis of the adsorption characteristics of a hydrogel that was chemically connected and built on agar and carboxymethyl cellulose (CMC). With regard to swelling %, the Agar-Agar/ECH/CMC hydrogel was created under ideal conditions. In order to achieve the highest percentage of swelling, different response parameters were changed. The structure and morphology of the hydrogels were characterized by FT-IR spectroscope, thermogravimetric analysis and scanning electron microscope. The results revealed that the CMC contributed to the enhanced size of pore, whereas Agar-Agar as a strong backbone in the hydrogel to support it for keeping its appearance. Their equilibrium swelling ratio in distilled water and different physiological fluids were evaluated, indicating the maximum swelling ratio in water reached an exciting level of 1000 as the hydrogels still keeping a steady appearance. Moreover, the hydrogels exhibited smart swelling and shrinking in NaCl or CaCl2 aqueous solution, as well as the release behavior of bovine serum albumin (BSA) that could be controlled by changing CMC content. The Agar-Agar -based hydrogels are promising for the applications in the biomaterials area.

Physico-chemical properties of the association of cetyltrimethylammonium bromide and bovine serum albumin mixture in aqueous-organic mixed solvents

Herein, we have investigated the association behavior of bovine serum albumin (BSA) and cetyltrimethylammonium bromide (CTAB) using the conductivity method in H2O and H2O + organic mixed solvents at different temperatures. The association phenomenon was detected from the deviation of the conductivity changes with enhancing the surfactant concentration and changes of numerous physico-chemical properties, such as CMC, α, β and thermodynamic variables (∆G0m, ∆H0m and ∆S0m). The values of CMC for the CTAB + BSA system in 10 % (v/v) solvents follow the trend: CMCwater < CMCwater+DMSO < CMCwater+AN < CMCwater+DX < CMCwater+DMF. The interaction of BSA with CTAB is notably influenced due to a change of temperature and extent of hydration of BSA and surfactant. The obtained values of –∆G0m manifest that the association of BSA and CTAB mixture is a spontaneous process, while the values of –∆G0m in presence of 10 % (v/v) aq. organic solvents come out in the given sequence: -∆Gmo (H2O + DMSO) > ∆Gmo (H2O + DMF) > -∆Gmo (H2O + DX) > -∆Gmo (H2O + AN). The H-bonding, ion-dipole, along with the hydrophobic interactions, are believed to be the binding interactions between BSA and CTAB in the study media.

Effect of Temperature on Re-entrant Condensation of Globular Protein in Presence of Tri-valent Ions.

Globular proteins play several essential roles in functioning different mechanisms of the living organisms, and the stability of such protein molecules in an aqueous solution is strongly affected by multivalent ions. In this article, we have systematically studied the effect of temperature (between 5 and 25ºC) on the re-entrant condensation behaviour of bovine serum albumin (BSA) in the presence of trivalent ions, Yttrium (Y3+), and Lanthanum (La3+). The effect of temperature is explained considering the optical properties of the protein, i.e., from the optical absorption and emission behaviours. The absorption in the visible region and the fluorescence emission of BSA becomes maximum at the lowest temperature. The decrement of mobility at lower temperature is responsible for fluorescence enhancement. Moreover, the activation energy of the turbid or viscus phase of the BSA protein under re-entrant condensation is enhanced in comparison with the transparent phase and the corresponding energy value is estimated from the fluorescence study.

Use of Microfluidic Capillary Electrophoresis for the Determination of Multi-Component Protein Adsorption Isotherms: Application to High-Throughput Analysis for Hydrophobic Interaction Chromatography.

Chromatography is a widely used separation process for purification of biopharmaceuticals that is able to obtain high purities and concentrations. The phenomena that occur during separation, mass transfer and adsorption are quite complex. To better understand these phenomena and their mechanisms, multi-component adsorption isotherms must be investigated. High-throughput methodologies are a very powerful tool to determine adsorption isotherms and they waste very small amounts of sample and chemicals, but the quantification of component concentrations is a real bottleneck in multi-component isotherm determination. The behavior of bovine serum albumin, Corynebacterium diphtheriae CRM197 protein and lysozyme, selected as model proteins in binary mixtures with hydrophobic resin, is investigated here. In this work we propose a new method for determining multi-component adsorption isotherms using high-throughput experiments with filter plates, by exploiting microfluidic capillary electrophoresis. The precision and accuracy of the microfluidic capillary electrophoresis platform were evaluated in order to assess the procedure; they were both found to be high and the procedure is thus reliable in determining adsorption isotherms for binary mixtures. Multi-component adsorption isotherms were determined with a totally high-throughput procedure that turned out to be a very fast and powerful tool. The same procedure can be applied to every kind of high-throughput screening.

On the aggregation of bovine serum albumin

In an attempt to elucidate the aggregation behaviour of bovine serum albumin and its modulation by salt ions, size-exclusion high-performance liquid chromatography was used and complemented by dynamic light scattering. The influence of the protein concentration, and type and concentration of inorganic salt on the aggregation of albumin in solution have been analyzed. Based on the observations herein reported an aggregation mechanism is proposed, according to which (i) some functional groups of albumin dissociate in solution forming macromolecular ions; (ii) the macromolecular ions bind with each other into large aggregates; and (iii) the salt ions establish chemical equilibria with the charges of opposing character present in the macromolecular ions’ backbone, promoting or preventing the aggregation. The present work shows that the aggregation behaviour of bovine serum albumin in solution and its modulation by salt ions can be explained by chemical concepts, with chemical equilibrium playing an essential role.

Comparative scrutinize of BSA and HEWL in the vicinity of metallo-catanionic aggregates derived from single chain metallosurfactant and anionic surfactant

In recent times, protein-surfactant interactions have been extensively explored due to their stimulating applications in different fields. These systems have efficaciously addressed the economic, environmental, and ecological issues. Sensing their prominence, through this report, we investigate and compare the interactional behavior of Bovine Serum Albumin (BSA) and Hen Egg White Lysozyme (HEWL) with metallo-catanionic aggregate mixtures. Attempts have been made to synthesize the metallo-catanionic aggregates from single-chain metallosurfactant (FeCTAC I) and anionic surfactant (SDS) i.e., FeCTAC I:SDS. Before proceeding towards the interactional studies of metallo-catanionic aggregates with model proteins, the morphology of formed aggregates was elucidated. Here, out of different possible molar ratios of FeCTAC I:SDS, two ratios i.e 70:30 and 30:70 were opted. The aggregates were examined through conductivity, Dynamic Light Scattering (DLS), Field Emission Scanning Electron Microscopy (FESEM), Confocal Laser Scanning Microscopy (CLSM), Small Angle X-Ray Scattering (SAXS), Zeta Potential, and Vibrating Sample Magnetometer (VSM) techniques. Interestingly, the SAXS analysis demonstrated the micellar behavior of 70:30 and vesicular behavior of 30:70 aggregates mixture, due to the difference of overall charge on them. The interactional study of BSA and HEWL with FeCTAC I:SDS was carried out through SDS-PAGE, absorption, emission, and circular dichroism (CD) spectroscopy. The effect of FeCTAC I:SDS on the linear polypeptide chain of BSA and HEWL was observed to be different, however, the secondary and tertiary structures were affected similarly. To elucidate the exact locality of FeCTAC I:SDS aggregates on the BSA, a site marker experiment was carried out. The pyrene extrinsic fluorescence experiment was performed to verify the type of interactions among HEWL and metallo-catanionic aggregates. From, the comparative studies, we concluded that the overall system was controlled by the type of forces playing between the protein and aggregate mixture that emerged from the total charge on the protein as well as on the aggregates. These types of metallo-catanionic aggregates that are flexible to shape are considered as the new alternatives for nano-vehicle applications.

INFLUENCE OF CERTAIN D-METALS ON FORMATION OF ADVANCED GLYCATION END PRODUCTS, AGGREGATION AND AMYLOID TRANSFORMATION OF ALBUMIN IN GLYCATION REACTION

The aim of the research is to investigate the influence of the factor of the glycation behavior of bovine serum albumin (BSA) by glucose, and the factor of d-metal cations (nickel (II), cobalt (II), iron (II), iron (III), copper (II) or zinc (II)) presence, on the process of aggregation and the amyloid transformation of BSA and, therefore, to establish the effect of these cations on the rate of the formation of advanced glycation end products (AGEs), and the intensity of fluorescence of the amino acids tyrosine and tryptophan.Materials and methods. Reagents in the glycation are: glucose (at the final concentration of 0.36 M), BSA (at the final concentration of 1 mg/ml), deionized water, one of the d-metal cations, i. e. nickel (II), cobalt (II), iron (II), iron (III), copper (II) or zinc (II) (in the form of chloride, sulfate or nitrate salts, at the final concentration of 40 μM). The conditions for the glycation reaction are the incubation for 24 hours at the temperature of 60°C. The influence of two factors (the factor of the glycation reaction and the factor of a d-metal ion presence in the reaction medium) on the concentration of glycation end products (AGEs) formed during the glycation reaction, on the fluorescence intensity of the amino acids tryptophan and tyrosine, on the aggregation of BSA, and on the ability of BSA to the amyloid transformation under the described conditions, have been studied.Results. It was found out that the studied factors have a statistically significant effect on the considered parameters. The highest activity was found for the copper ion (II), which intensifies the formation of the AGEs in the samples where glycation occurs, reduces the fluorescence intensity of the amino acids’ tryptophan and tyrosine (independently and increasing the effect against the background of glycation). Besides, it independently causes the aggregation of BSA hereby intensifying the effect against the background of glycation, it independently causes the amyloid transformation of BSA enhancing the effect against the background of glycation. The above-listed effects were the least pronounced in the reaction media with the addition of nickel (II) or cobalt (II). These cations reduce the rate of the AGEs formation, do not cause the formation of protein aggregates. In the presence of glucose, nickel (II) weakly suppresses the fluorescence intensity of tryptophan and tyrosine, and slightly enhances the amyloid transformation of BSA. Cobalt (II) slightly inhibits the amyloid transformation of BSA. In terms of the severity and nature of the effects, the iron (II), iron (III) and zinc (II) cations occupy an intermediate position between copper (II), on the one hand, and nickel (II) and cobalt (II), on the other hand, combining the influence on the AGEs formation, the intensity of fluorescence of tryptophan and tyrosine, the aggregation and amyloid transformation of BSA. In the absence of glucose, the ability of zinc (II) to induce the formation of protein aggregates turned out to be the highest, and its ability to stimulate the amyloid transformation of BSA corresponded to that of copper (II).Conclusion. The presence of d-metal cations affects the rate of the AGEs formation in the glycation reaction, affects the rate of the BSA amyloid transformation and the protein aggregates formation. Among such ions as nickel (II), cobalt (II), iron (II), iron (III), copper (II) and zinc (II), copper (II) ions turned out to be the most active in their ability to accelerate the AGEs formation, suppress the fluorescence of tryptophan and tyrosine, enhance the aggregation and amyloid transformation of BSA in the glycation reaction. The least manifestation of these properties is observed for nickel (II) and cobalt (II) ions.

Bulk phase behaviour vs interface adsorption: Effects of anions and isotopes on β-lactoglobulin (BLG) interactions

HypothesisProtein adsorption is highly relevant in numerous applications ranging from food processing to medical implants. In this context, it is important to gain a deeper understanding of protein-protein and protein-surface interactions. Thus, the focus of this investigation is on the interplay of bulk properties and surface properties on protein adsorption. It was hypothesised that the type of solvent and ions in solution should significantly influence the protein’s bulk and interface behaviour, which has been observed in literature and previous work for other net negatively charged, globular proteins such as bovine serum albumin (BSA). ExperimentsThe phase behaviour of β-lactoglobulin (BLG) with lanthanum chloride (LaCl3) and iodide (LaI3) in normal water H2O(l) and heavy water (D2O(l)) was established via optical microscopy and ultraviolet-visible spectroscopy. The formation of an adsorption layer and its properties such as thickness, density, structure, and hydration was investigated via neutron reflectivity, quartz-crystal microbalance with dissipation, and infra-red measurements. Findingsβ-lactoglobulin does not show significant anion-induced or isotope-induced effects - neither in bulk nor at the solid-liquid interface, which deviates strongly from the behaviour of bovine serum albumin. We also provide a comprehensive discussion and comparison of protein-specific bulk and interface behaviour between bovine serum albumin and β-lactoglobulin dependent on anion, cation, solvent, and substrate properties. These findings pave the way for understanding the transition from adsorption to crystallisation.

Preliminary study of adsorption behavior of bovine serum albumin (BSA) protein and its effect on antibacterial and corrosion property of Ti-3Cu alloy

The adsorption behavior, antibacterial, and corrosion properties of a Ti-3Cu alloy were studied in a phosphate-buffered saline solution containing 0, 1, 3, and 6 g L−1 bovine serum albumin protein at 37 °C and pH = 7.4 (±0.2). The protein adsorption behavior was examined via cyclic voltammetry, secondary ions mass spectroscopy (SIMS), and angle-resolved X-ray photoelectron spectroscopy (ARXPS). The corrosion property was analyzed by the open circuit potential (OCP), potentiodynamic polarization (PD), and electrochemical impedance spectroscopy (EIS) examinations. The antibacterial test was conducted according to the GB/T 21510 China Standard. It was observed that the surface charge density (QADS) was directly proportional to the amount of the adsorbed BSA protein, signifying that the protein adsorption was accompanied by the charge transfer, pointing to chemisorptions phenomena. BSA amino groups and other organic species were observed in the surface analysis examinations. It was shown that the formation of barrier complexes between the TiO2 oxide-layer and PBS solution resulted in decreasing the release of Cu-ions, which consequently reduced the antibacterial activity. On the other hand, these barrier complexes improved the corrosion resistance by increasing the charge transfer resistance and double-layer capacitance of the Ti-3Cu alloy.

Different behavior of bovine serum albumin as foaming agent in foam enrichment of Rhodamine 6G and Evans blue

As a classic foaming agent, bovine serum albumin (BSA), can be adsorbed on gas–liquid interface to generate stable foam. In the present study, the foam disappeared when Evans Blue (EB) interacted with BSA. Therefore, this phenomenon was used to separate the non-defoaming Rhodamine 6G (R6G) from the defoaming EB. After optimizing the parameters such as BSA concentration, pH and gas flow rate, R6G was enriched with spilled foam. The enrichment ratio and recovery of R6G were 5.32 and 88.29%, respectively, in pH 7 solution at a gas flow rate of 0.25 mL/min using 0.20% BSA as foaming agent. The present strategy provides an effective method for foam separation and dye recycling.

Synthesis and characterization of sulphonic acid ligand immobilized Aminopropyl silanetriol copolymer and evaluation of its Bovine serum albumin adsorption efficiency

Abstract An adsorbent Stearyl Alcohol (SA) - grafted- epichlorohydrin (E) -grafted- aminoproypyl silanetriol (APST) was synthesized, functionalized with sulfonic acid by sulfonation process [(SA-g-E)-g-APST/ SO3H]. The characterization of the adsorbent material was done using FTIR, XRD, SEM and TGA analyses. Adsorption behaviour of bovine serum albumin (BSA) was investigated using batch adsorption experiments. Adsorption efficiency was found to be extreme at pH 4.5. Kinetic studies revealed the suitability of pseudo-second-order model and adsorption equilibrium was attained within 3 h. On studying the rate limiting step, film diffusion process proved to be the best fit. Considering different isotherms, Sips isotherm model proved to be the best acceptable with a maximum adsorption capacity of 35.12 mg/g at 303 K. The favorability of the adsorption process was studied by calculating the separation factor (RL) and the results were found to be positive. Thermodynamic studies pronounce the spontaneous nature of adsorption, having maximum entropy in the system. Revival studies were done using 0.1 M Na2CO3 as the desorbing agent. The desorption experiment was carried out for over six cycles - showed the repeatability and regeneration capability of the adsorbent.

Unraveling How Ethanol-Induced Conformational Changes Affect BSA Protein Adsorption onto Silica Surfaces.

Protein adsorption at solid-liquid interfaces is highly relevant to a wide range of applications such as biosensors, drug delivery, and pharmaceuticals. Understanding how protein conformation in bulk solution impacts adsorption behavior is fundamentally important and could also lead to the development of improved protein-based coatings. To date, relevant studies have been conducted in aqueous solutions, while it remains largely unknown how organic solvents and more specifically solvent-induced conformational changes might influence protein adsorption. Herein, using the quartz crystal microbalance-dissipation (QCM-D) and localized surface plasmon resonance (LSPR) techniques, we systematically investigated the real-time adsorption behavior of bovine serum albumin (BSA) protein onto silica surfaces in different water-ethanol mixtures ranging from 0 to 60% (v/v) ethanol. The results showed that there was greater protein adsorption at higher ethanol fractions in the 10-30% range, while more complex adsorption profiles were observed in the 40-60% range. The combination of QCM-D and LSPR measurements led us to further identify specific cases in water-ethanol mixtures where washing steps caused densification of the adsorbed protein layer as opposed to typical desorption of weakly adsorbed molecules in aqueous conditions. We discuss mechanistic factors that drive these overall adsorption trends by taking into account how ethanol fraction affects BSA conformation in bulk solution. Together, our findings demonstrate that BSA proteins can adsorb onto silica surfaces across a wide range of water-ethanol mixture conditions, while specific adsorption profiles depended on the ethanol fraction in a manner closely linked to solution-phase conformational properties.

Associative interactions between pullulan and negatively charged bovine serum albumin in physiological saline solutions

In the present study, the behavior of bovine serum albumin (BSA) and pullulan (PULL) mixtures was investigated in physiological saline solution at 37 °C and pH = 7.4 (above the isoelectric point of BSA), by viscometry and membrane osmometry. The new Wolf approach was used for modeling the viscometric behavior of the PULL/BSA saline solutions. From the viscometric data, the contributions of binary, ternary and quaternary intersegmental contacts were determined. Osmotic pressure measurements were carried out as a function of PULL/BSA mixture concentration and composition. In dilute 0.15 M NaCl solutions, the electrostatic repulsion between the BSA molecules is partially screened and attractive PULL/protein interactions are mediated by Na ions. Thus, large deviations from ideal behavior were observed for BSA containing systems. This effect could be attributed to complexes formation as the protein content increases in the solution. The complexation was depicted as the adsorption protein molecules on the PULL chains through the electrolyte molecules. The results obtained by viscometry and osmometry were corroborated, allowing the prediction of the phase behavior of the mixtures. The reported experimental results provide useful information for the design of new biomaterials starting from pullulan and globular proteins.

Conformation Variation and Tunable Protein Adsorption through Combination of Poly(acrylic acid) and Antifouling Poly(N-(2-hydroxyethyl) acrylamide) Diblock on a Particle Surface.

Adsorption and desorption of proteins on biomaterial surfaces play a critical role in numerous biomedical applications. Spherical diblock polymer brushes (polystyrene with photoiniferter (PSV) as the core) with different block sequence, poly(acrylic acid)-b-poly(N-(2-hydroxyethyl) acrylamide) (PSV@PAA-b-PHEAA) and poly(N-(2-hydroxyethyl) acrylamide)-b-poly(acrylic acid) (PSV@PHEAA-b-PAA) were prepared via surface-initiated photoiniferter-mediated polymerization (SI-PIMP) and confirmed by a series of characterizations including TEM, Fourier transform infrared (FTIR) and elemental analysis. Both diblock polymer brushes show typical pH-dependent properties measured by dynamic light scattering (DLS) and Zeta potential. It is interesting to find out that conformation of PSV@PAA-b-PHEAA uniquely change with pH values, which is due to cooperation of electrostatic repulsion and steric hindrance. High-resolution turbidimetric titration was applied to explore the behavior of bovine serum albumin (BSA) binding to diblock polymer brushes, and the protein adsorption could be tuned by the existence of PHEAA as well as apparent PAA density. These studies laid a theoretical foundation for design of diblock polymer brushes and a possible application in biomedical fields.