Adsorption Of Human Serum Albumin Research Articles

Adsorption of Human Serum Albumin on Graphene Oxide: Implications for Protein Corona Formation and Conformation.

The influence of solution chemistry on the adsorption of human serum albumin (HSA) proteins on graphene oxide (GO) was investigated through batch adsorption experiments and the use of a quartz crystal microbalance with dissipation (QCM-D). The conformation of HSA layers on GO was also examined with the QCM-D. Our results show that an increase in ionic strength under neutral pH conditions resulted in stronger binding between HSA and GO, as well as more compact HSA layers on GO, emphasizing the key role of electrostatic interactions in controlling HSA-GO interactions. Calcium ions also facilitated HSA adsorption likely through charge neutralization and bridging effect. At physiological ionic strength conditions (150 mM), maximum HSA adsorption was observed at the isoelectric point of HSA (4.7). Under acidic conditions, the adsorption of HSA on GO led to the formation of protein layers with a high degree of fluidity due to the extended conformation of HSA. Finally, the attachment of GO to a supported lipid bilayer that was composed of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine, a model for cell membranes, was reduced in the presence of protein coronas. This reduction in GO attachment was influenced by the conformation of the protein coronas on GO.

Co-adsorption of Albumin and Immunoglobulin G from Human Serum onto a cation exchanger mixed mode adsorbent

Binary mixture adsorption containing Human immunoglobulin (IgG) and Human serum albumin (HSA) on a new cation exchanger mixed mode adsorbent (MabDirect MM) is assessed by batch, fixed bed and expanded bed adsorption experiments. Competitive adsorption isotherm was measured by batch experiment at the binding condition of pH 5.0 without salt where it was found that increasing the IgG concentration present in the solution (0–3 g dm−3) the HSA adsorption capacity decreases significantly (from 29.32 to 3.17 mg gdry−1) as a result of IgG competitive adsorption with HSA on MabDirect MM. Fixed bed adsorption experiments with binary mixture of HSA and IgG were performed at two flowrates. There is no roll up in the adsorption breakthrough curves even when it was increased the experiment timescale (from 2 to 0.7 mL/min at adsorption stage) which suggests that they are both adsorbed also on different sites at the binding condition, 20 mM citrate buffer pH 5.0 with 0.4 M⋅NaCl. Adsorption capacity for both proteins are in agreement with their respective single adsorption isotherms. Displacement experiments were carried out and showed that some amount of protein is released when the other protein is being fed to the column. Expanded bed breakthrough experiment with binary mixture of HSA and IgG shows an adsorption capacity (14.2 mgHSA gdry−1 and 6.3 mgIgG gdry−1) in good agreement with single protein batch experiments and also fixed bed adsorption for similar conditions. Regarding HSA and IgG desorption, it was obtained a HSA recovery of 62% and an IgG recovery of 39%.

Interactions of bioactive molecules with thin dendritic glycopolymer layers.

The authors report on highly swellable, stable layers of spherical dendritic glycopolymers, composed of hyperbranched poly(ethylene imine) (PEI) as core and two different maltose shells (A = dense shell and B = open shell). These glycopolymers are cross-linked and attached with poly(ethylene-alt-maleic anhydride) (PEMA) or citric acid on SiOx substrates. The swelling and adsorption of biomolecules were analyzed by spectroscopic ellipsometry and quartz crystal microbalance with dissipation. The swelling degree and complexation with the drug molecule adenosine triphosphate (ATP) were found to be up to 10 times higher for dendritic glycopolymer layers cross-linked with PEMA than for layers cross-linked with citric acid. ATP complexation by electrostatic interaction with the PEI cores was confirmed by x-ray photoelectron spectroscopy analysis. Complexation led to partial collapsing, stiffening, and increase of polymer layer viscosity of the PEMA cross-linked layers. From modeling of ellipsometric data, it was deduced that ATP complexation preferably takes place at the polymer layer-solution interface. The size effect of the adsorbates was investigated by comparing ATP complexation with the adsorption of larger vitamin B12 and human serum albumin (HSA) protein. PEI-Mal A cross-linked with PEMA was found to be resistant toward B12 and HSA adsorption due to the diffusion barrier of the polymer layer. Thus, the authors present potentially biocompatible polymer surfaces for drug loading and their surface supported release.

Efficient adsorptive extraction materials by surface protein‐imprinted polymer over silica gel for selective recognition/separation of human serum albumin from urine

ABSTRACTIn this study, we report the development of adsorptive extraction materials by surface protein‐imprinted polymers (MIPs) over silica gel for selective recognition/separation of human serum albumin (HSA) from urine. The HSA‐imprinted polymers prepared on silica particle had at interface between the silica gel and different MIPs greatly produced enrichment for the binding of protein from the urine. The solid‐phase extraction of the optimized polymer layer was prepared by copolymerization of methacrylic acid (MAA), acrylamide (AAm), and dimethylaminoethylmethacrylate (DMAEMA) and a crosslinker methylenebisacrylamide (MBA) at the mole ratio of 1:158:88 (T:M:C) and showed moderate affinity (<104 order M−1) toward target protein HSA and selectivity. Four analogues, egg white albumin (EWA), bovine serum albumin (BSA), lysozyme (Lyz), and creatinine (Cre) were selected to study the binding efficiency of MIPs in single and binary protein solutions. We studied the influence on recognition ability for HSA and found that prepolymer mixture and matrix flexibility of the optimized thin polymer layer (35 ± 10 nm) on the submicrosilica particles. The high‐binding affinity (QMIP, 86.7 mg g−1) and fast kinetics (180 min) were observed for this synthesized HSA‐MIP when compared with other reported HSA‐MIPs in surface imprinting (5.9 and 11.3 mg g−1) and epitope surface imprinting (46.6 mg g−1) methods. We demonstrated the application in real and synthetic urine samples that the approach allowed the efficient adsorption of HSA in real urine (129.48 mg g−1) is almost double to the binding of HSA in synthetic urine (67.84 mg g−1). Apart from this, only minor interference of Cre (2.74 mg g−1) was observed, eventhough Cre is the final metabolite in urine. These adsorptive submicrosilica materials have potential in the pharmaceutical industry and clinical analysis applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46894.

Surface modification of polyurethane with a hydrophilic, antibacterial polymer for improved antifouling and antibacterial function.

Antimicrobial surface is important for the inhibition of bacteria or biofilm formation on biomaterials. The objective of this study was to immobilize a novel hydrophilic polymer containing the antibacterial moiety onto polyurethane surface via a simple surface coating technology to make the surface not only antibacterial but also antifouling. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized, characterized and incorporated onto polyvinylpyrrolidone containing succinimidyl functional groups, followed by coating onto the polyurethane surface. Contact angle, antibacterial function and protein adsorption of the modified surface were evaluated. The result shows that the modified surface exhibited significantly enhanced hydrophilicity with a 54-65% decrease in contact angle, increased antibacterial activity to Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa with a 24-57% decrease in viability, and reduced human serum albumin adsorption with a 64-70% decrease in adsorption, as compared to the original polyurethane.

Enhanced Luminescent Properties of Photo-Stable Copper Nanoclusters through Formation of "Protein-Corona"-Like Assemblies.

In this study, interactions of synthesized copper nanoclusters (CuNCs) with a model transport protein, human serum albumin (HSA), have been systematically investigated by using various spectroscopic approaches. The interactions give rise to the formation of "protein-corona" like assemblies and the luminescence properties (both steady-state and time-resolved) are enhanced due to gradual adsorption of the protein on the surface of the NCs. The associated thermodynamics and binding parameters have been estimated resorting to luminescent experimental techniques as well as isothermal titration calorimetry (ITC) studies, indicating that every NC is surrounded by (4±1) protein molecules. The adsorption of HSA on the surface of the NCs has been characterized by dynamic light scattering (DLS) and time-resolved anisotropy measurements. Finally, fluorescence correlation spectroscopy (FCS) data substantiate the emergence of new "protein-corona" like assemblies resulting in slower translational diffusion motions and concomitant rise of the hydrodynamic diameters.

Kinetics of human serum albumin adsorption at silica sensor: Unveiling dynamic hydration function.

Adsorption kinetics of human serum albumin (HSA) at a silica substrate was studied using the QCM-D and AFM methods. Measurements were performed at pH 3.5 for various bulk suspension concentrations and ionic strengths. The QCM experimental data were compared with the dry coverage of HSA derived from AFM and from the solution of the mass transfer equation. In this way, the dynamic hydration functions and water factors of HSA monolayers were quantitatively evaluated as a function of dry coverage for various ionic strengths. Using the hydration functions, the HSA adsorption runs derived from QCM-D measurements were converted to the dry coverage vs. the time relationships. In this way, the maximum coverage of irreversibly bound HSA molecules was determined. It was equal to 0.35 and 1.4 mg m-2 for NaCl concentration of 0.001 and 0.15 M, respectively. These results agree with previous experimental data derived by streaming potential measurements for mica and with theoretical modeling. Therefore, the side-on mechanism of HSA adsorption at silica sensor at pH 3.5 was confirmed. Also, a quantitative analysis of the desorption runs allowed one to calculate the binding energy of the reversibly bound HSA fraction. Beside significance to basic science, these results enable to develop a robust technique of preparing HSA monolayers at silica sensor of well-controlled coverage and molecule orientation.

Adsorption of human serum albumin on functionalized single-walled carbon nanotubes reduced cytotoxicity

With the potential uses of carbon nanotubes (CNTs) in biomedical and biotechnological applications, and the growing concerns about nanotoxicity of these engineered nanoparticles, the importance of protein–nanoparticle interaction has not been well stressed. In this study, we used both experimental and theoretical approaches to investigate the interactions of different functionalized single-walled CNTs (SWCNTs) with human serum albumin (HSA). It was found that the HSA adsorption capacities of CNTs followed the order carboxylated SWCNTs > hydroxylated SWCNTs > amined SWCNTs. The fluorescence intensity of HSA was quenched by all of the three SWCNTs in static mode, which was authenticated by Stern-Volmer calculations. Our molecular dynamics simulations revealed that both atom-atom contact numbers and binding energies between functionalized SWCNTs and HSA played critical roles in determining their adsorption capacity, in agreement with the experimental findings. Additional cytotoxicity assays revealed that coating of carboxylated CNTs with HSA more significantly reduced their cytotoxicity than the other two CNTs, in agreement with their protein adsorption capacities in vitro. These findings will be helpful to clarify the mechanism of interactions of functionalized SWCNTs with human serum proteins, and provide more insight into the understanding of how to design the safe nanoparticles by preconsideration of their interactions with proteins.

Expanded bed adsorption of albumin and immunoglobulin G from human serum onto a cation exchanger mixed mode adsorbent

Adsorption of human serum albumin (HSA) and immunoglobulin G (IgG), two most relevant proteins in blood serum were measured separately on a new mixed-mode adsorbent (MabDirect MM), especially designed for expanded bed adsorption process. Expanded bed behavior characterization by residence time distribution experiments for different columns (Streamline 50 for HSA study, Omnifit 66/20 and XK 16/20 for IgG study) are presented together with breakthrough adsorption of HSA and IgG for different conditions and compared with simulation results by a mathematical model. Regarding HSA adsorption, all four experiments were conducted at the same buffer solution (pH 5.0 without salt), and it was obtained a dynamic binding capacity of 8.9, 9.7, 7.5 and 7.0 mg·gdry−1 (24.8, 27.0, 21.0 and 19.5 mg·cm−3) at 10% of breakthrough, corresponding to a 41, 39, 38 and 30% of the saturation capacity for runs 1–4, respectively. The results from the simulation of the mathematical model fitted well with the breakthrough experiments. Elution stage was optimized by lowering flow rate and changing the buffer solution pH and NaCl concentration. Concerning IgG adsorption, for IgG feed concentration of 0.53 g·dm−3 in 20 mM citrate buffer, pH 5.0 with 0.4 M NaCl, at 2.2 cm3·min−1, it was obtained a DBC of 3.3 mg·gdry−1 (9.1 mg·cm−3) at 10% of breakthrough, representing 22% of the saturation capacity. While for a feed concentration of 0.11 g·dm−3 of IgG in the same buffer solution, at 6 cm3·min−1, it was obtained a DBC of 2.7 mg·gdry−1 (7.4 mg·cm−3) at 10% of breakthrough, representing 34% of the saturation capacity.

Albumin adsorption at solid substrates: A quest for a unified approach

Adsorption of human serum albumin (HSA), recombinant HSA (rHSA) and the albumin dimer (dHSA) at solid/electrolyte interfaces is reviewed with the emphasis put on quantitative analysis of this process. Initially, various physicochemical data characterizing bulk properties of albumin molecules are discussed such as electrophoretic mobility, electrokinetic charge, zeta potential and diffusion coefficient. Adsorption kinetics of HSA, rHSA and dHSA at mica derived from AFM, streaming potential and XPS measurements is analyzed. Maximum coverages of irreversibly adsorbed molecules under various ionic strengths and pHs are quantitatively interpreted in terms of the random sequential adsorption model. Thorough acid-basic characteristic of albumin monolayers of well-controlled coverage are also presented. The results derived from the colloid deposition method that unveil albumin molecule orientation and charge distribution are discussed and interpreted in terms of the random site theory. Subsequently, adsorption of albumins at negatively and positively charged polymeric microparticles studied by the electrokinetic and the AFM aided concentration depletion methods is analyzed. These results are theoretically interpreted by applying the bead model of HSA and dHSA molecules. Orientation of adsorbed molecules and the stability of albumin monolayers in respect to pH cyclic changes are discussed. A universal, electrostatic interaction driven, mechanism of albumin adsorption at macroscopic surfaces and polymer microparticles is confirmed.

High-throughput screening and optimization of mixed-mode resins for human serum albumin separation with microtiter filter plate

High-throughput approaches become increasingly important on process development for protein separation. In this work, four mixed-mode resins (Capto adhere, Capto MMC, MX-Trp–650 M and Nuvia cPrime) were investigated for human serum albumin (HSA) separation and compared with two ion-exchangers (Q Sepharose FF and SP Sepharose FF). High-throughput method based on microtiter filter plate was used to determine adsorption properties and optimize separation conditions. For resins with anion-exchange groups alkaline condition would be favorable for HSA adsorption, while acidic condition for resins with cation-exchange groups. Mixed-mode resins showed obviously salt-tolerant properties. Salt addition had little effect on Nuvia cPrime, and could promote HSA adsorption for Capto MMC and MX-Trp–650 M. The elution conditions were also optimized and high recovery could be obtained. In addition, the optimized conditions obtained by high-throughput approaches were verified by lab-scale column chromatography. It was found that Capto MMC and MX-Trp–650 M would be more suitable for HSA separation and DBC10% could reach more than 40 mg/ml under 200 mM NaCl addition. Finally, rHSA separation from P. pastoris culture broth was tested with MX-Trp–650 M, and high purity and recovery could be obtained. This study demonstrated that high-throughput screening method is a powerful tool to optimize the chromatographic separation. Mixed-mode cation-exchange resins showed an efficient practicability for HSA separation with high capacity, suitable salt-tolerance and high elution recovery.

Effect of protein adsorption layers and solution treatments on hydroxyapatite deposition on polystyrene plate surfaces in simulated body fluids.

We have developed a method to functionalize polystyrene (PS) cell culture plates with hydroxyapatite (HAp) via protein adsorption layers such as human serum albumin (HSA) in simulated body fluids (SBFs). In order to investigate the versatility the method, in this study the effect of protein adsorption layers on HAp deposition on PS plate surfaces in SBF was evaluated. Pretreatments with alternate soaking process (ASP) using solutions containing calcium ions and phosphate ions followed by incubation with SBF for 24 h resulted in HAp deposition on PS plates with adsorption layers of HSA, type I collagen, hen egg white lysozyme, and poly L-glutamic acid, an acidic protein analogue: the deposition behaviors were correlated with adsorption ability and charge state of proteins. We also demonstrated that commercially available tissue culture-treated PS (TCPS) were directly coated with bone-like HAp using the same ASP and SBF processes. Human mesenchymal stem cells adhered and stretched on the HAp-coated TCPS plates in a similar manner to the case of the HAp-coated PS plates prepared via HSA adsorption layers. The results indicate that the present methods are useful for preparing bone-like HAp-coated cell culture plates that can be utilized function of adsorbed proteins and that are obtainable conveniently and at low-cost.

Surface reactivity of octacalcium phosphate-derived fluoride-containing apatite in the presence of polyols and fluoride.

The present study was designed to characterize co-precipitated fluoridated apatitic materials from octacalcium phosphate (OCP) precursor and to investigate their surface reactions with polyols including glycerol in the presence of fluoride ions. Laboratory-synthesized fluoridated apatite crystals (LS-FA) were obtained in a solution containing fluoride (F) from 25 to 500 ppm. LS-FAs and commercially available fluoroapatite (FA) and hydroxyapatite (HA) were characterized by physical techniques, such as X-ray diffraction. LS-FA obtained in the presence of 100 ppmF (100 ppm-LS-FA) had an apatitic structure, but its solubility was close to HA in a culture medium (α-MEM) despite the fact it contains over 3 wt % of F. 100 ppm-LS-FA, FA, and HA were then subjected to the human serum albumin (HSA) adsorption test at pH 7.4 (in a 150 mM Tris-HCl buffer) and the dissolution and re-mineralization experiments in the presence of xylitol, D-sorbitol, or glycerol, and F under acidic and neutral conditions. Adsorption affinity of HSA was estimated as highest for FA and lowest for LS-FA. LS-FA, FA, and HA were immersed in a lactic acid solution with the polyols and/or F ion-containing solution up to 200 ppm to analyze the dissolution behavior. LS-FA had the highest dissolution tendency in the conditions examined. Glycerol enhanced the dissolution of phosphate from apatite crystals in particular from LS-FA. The results suggest that the apatite crystals, obtained through the hydrolysis of OCP in the presence of F, provide a more reactive surface than FA or HA under physiological environments. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2235-2244, 2018.

Formation mechanism of human serum albumin monolayers on positively charged polymer microparticles

Human serum albumin (HSA) adsorption on positively and negatively charged polystyrene microparticles was studied at various pHs and NaCl concentrations. Thorough electrophoretic mobility measurements were carried out that enabled to monitor in situ the progress of protein adsorption. The maximum coverage of irreversibly adsorbed HSA on microparticles was determined by different concentration depletion methods, one of them involving AFM imaging of residual molecules. An anomalous adsorption of HSA on the positive microparticles was observed at pH 3.5 where the maximum coverage attained 1.0mgm−2 for NaCl concentrations of 0.05M despite that the molecules were on average positively charged. For comparison, the maximum coverage of HSA on negatively charged microparticles was equal to 1.3mgm−2 at this pH and NaCl concentration. At pH 7.4 the maximum coverage on positive microparticles was equal to 2.1mgm−2 for 0.05M NaCl concentration. On the other hand, for negative microparticles, negligible adsorption of HSA was observed at pH 7.4 and 9.7. These experimental data were adequately interpreted in terms of the random sequential adsorption approach exploiting the bead model of the HSA molecule. Different orientations of adsorbed molecules, inert alia, the edge-on orientation prevailing for positively charged microparticles at pH 7.4, were confirmed. This was explained in terms of a heterogeneous charge distribution over the HSA molecule prevailing for a wide range of pHs.

Titanium dioxide nanoparticles preferentially bind in subdomains IB, IIA of HSA and minor groove of DNA

Titanium dioxide nanoparticles (TiO2-NPs) interaction with human serum albumin (HSA) and DNA was studied by UV–visible spectroscopy, spectrofluorescence, circular dichroism (CD), and transmission electron microscopy (TEM) to analyze the binding parameters and protein corona formation. TEM revealed protein corona formation on TiO2-NPs surface due to adsorption of HSA. Intrinsic fluorescence quenching data suggested significant binding of TiO2-NPs (avg. size 14.0 nm) with HSA. The Stern–Volmer constant (Ksv) was determined to be 7.6 × 102 M−1 (r2 = 0.98), whereas the binding constant (Ka) and number of binding sites (n) were assessed to be 5.82 × 102 M−1 and 0.97, respectively. Synchronous fluorescence revealed an apparent decrease in fluorescence intensity with a red shift of 2 nm at Δλ = 15 nm and Δλ = 60 nm. UV–visible analysis also provided the binding constant values for TiO2-NPs–HSA and TiO2-NPs-DNA complexes as 2.8 × 102 M−1 and 5.4 × 103 M−1. The CD data demonstrated loss in α-helicity of HSA and transformation into β-sheet, suggesting structural alterations by TiO2-NPs. The docking analysis of TiO2-NPs with HSA revealed its preferential binding with aromatic and non-aromatic amino acids in subdomain IIA and IB hydrophobic cavity of HSA. Also, the TiO2-NPs docking revealed the selective binding with A-T bases in minor groove of DNA.

Influence of buffer solutions in the adsorption of human serum proteins onto layered double hydroxide

The adsorption of human immunoglobulin G (IgG) and human serum albumin (HSA) on a non-calcined Mg-Al layered double hydroxide (3:1 Mg-Al LDH) was studied in batch and fixed bed experiments, focusing on the effect of buffer solution and pH over sorbent uptake. Mg-Al LDH was synthesized and characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms at −196°C, X-ray photoelectron spectroscopy (XPS), Zero point charge (pHzpc), particle size distribution and Fourier transform infra-red (FTIR). Batch adsorption experiments were performed in order to investigate the effects of pH on IgG and HSA adsorption with different buffers: sodium acetate (ACETATE), sodium phosphate (PHOSPHATE), 3-(N-morpholino) propanesulfonic acid (MOPS), 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES) and trizma-hydrochloric acid (TRIS-HCl). Maximum adsorption capacities estimated by the Langmuir model were 239mgg−1 for IgG and 105mgg−1 for HSA in TRIS-HCl buffer. On the other hand, the highest selectivity for IgG adsorption over HSA was obtained with buffer PHOSPHATE (pH 6.5). The maximum IgG and HSA adsorption uptake in this case were 165 and 36mgg−1, respectively. Fixed bed experiments were carried out with both proteins using PHOSPHATE buffer (pH 6.5), which confirmed that IgG was more selectively adsorbed than HSA on Mg-Al LDH and both could be fully recovered by elution with sodium chloride (NaCl).

Modified Random Sequential Adsorption Model for Understanding Kinetics of Proteins Adsorption at a Liquid-Solid Interface.

In this Article, we experimentally measure the adsorption kinetics of human serum albumin (HSA) on a hydrophobic hexadecanethiolated gold surface. We use micromachined quartz crystal resonators with fundamental frequency of 83 MHz to accomplish these measurements in real time. In this work, we focus on two key results: (i) asymptotic behavior of the sensor responses upon HSA adsorption and (ii) the jamming limit of adsorbed layer formed by both single-injection and multi-injection experiments with the same value of final concentration. We develop a new interface-depletion modified random sequential adsorption (RSA) model to elucidate the adsorption kinetics and the transport properties of the protein molecules. Analysis of the experimentally measured data shows that the results can be explained on the basis of the exponentially depleting interfacial layer RSA model. To better understand the origin of the formation of the interfacial depletion region where the supply of protein molecules is dramatically reduced, we performed a series of molecular dynamics (MD) simulations using the ReaxFF method. These simulations predict that the resulting adsorption of the protein molecules on the thiolated surface results in a specific orientation at the interface and the diffusion constant of the protein molecules in this layer is significantly reduced. This interplay between the surface adsorption rate and the reduced diffusion coefficient leads to the depletion of the protein molecules in the interfacial layer where the concentration of the protein molecules is much less than the bulk concentration and explains the observed slowdown of the HSA adsorption characteristics on a hydrophobic surface.

Controlling adsorption of albumin with hyaluronan on silica surfaces and sulfonated latex particles

Polysaccharides are known to modify binding of proteins at interfaces and this paper describes studies of these interactions and how they are modified by pH. Specifically, the adsorption of human serum albumin on to polystyrene latex and to silica is described, focusing on how this is affected by hyaluronan. Experiments were designed to test how such binding might be modified under relevant physiological conditions. Changes in adsorption of albumin alone and the co-adsorption of albumin and hyaluronan are driven by electrostatic interactions. Multilayer binding is found to be regulated by the pH of the solution and the molecular mass and concentration of hyaluronan. Highest adsorption was observed at pH below 4.8 and for low molecular mass hyaluronan (≤150kDa) at concentrations above 2mgml−1. On silica with grafted hyaluronan, albumin absorption is reversed by changes in solvent pH due to their strong electrostatic attraction. Albumin physisorbed on silica surfaces is also rinsed away with dilute hyaluronan solution at pH 4.8. The results demonstrate that the protein adsorption can be controlled both by changes of pH and by interaction with other biological macromolecules.

Direct quantification of dual protein adsorption dynamics in three dimensional systems in presence of cells

The biomaterial surface upon exposure to biological fluids is covered by a layer of proteins, which is modified over a period of time and dictates the fate of the biomaterial. In this study, we present and validate a new methodology for quantification of protein adsorption on to a three-dimensional polymer scaffold from unitary and binary systems, using fluorescence molecular tomography, an optical trans-illumination technique with picomolar sensitivity. In additional to being able to follow behavior of two proteins simultaneously, this methodology is also suitable for studying protein uptake in cells situated in a polymer environment. The ability to follow protein adsorption/uptake in a continuous manner opens up new possibilities to study the role of serum proteins in biomaterial compatibility.

A Segregation and Deprotection Approach for Hydrophilic Surfaces Using Amphiphilic Block Copolymers Possessing Polystyrene and Poly[(tri(ethylene glycol) methacrylate)] Segments

This paper fabricates spontaneously formed hydrophilic polymer brushes composed of poly[(tri(ethylene glycol) methacrylate)] (POH3MA) through spontaneous surface segregation of polystyrene‐block‐poly[(tri(ethylene glycol) tert‐butyldimethylsilyl ether methacrylate)] (PS‐b‐PSi3MA) in a polystyrene (PS) matrix followed by deprotection of PSi3MA to POH3MA at the PS/water interface. When protected, the tert‐butyl‐terminated hydrophilic PSi3MA blocks segregate at the air or vacuum surface at elevated temperatures. The surface‐segregated structures can be fixed by cooling to room temperature followed by deprotection of the PSi3MA groups to provide surfaces fully covered by unprotected POH3MA, with OH groups on glassy robust PS. Such hydrophilic POH3MA brushes prevent the adsorption of human serum albumin and are expected to be useful in antifouling surfaces. image