Adsorption Of Human Albumin Research Articles

Impact of Shape and Pore Size of Mesoporous Silica Nanoparticles on Serum Protein Adsorption and RBCs Hemolysis

With the rapid development of nanotechnology, mesoporous silica nanoparticles (MSNs) with numerous forms and structures have been synthesized and extensively applied in biomedicine in the past decades. However, our knowledge about the biocompatibility of the developed MSNs has not matched their development. Therefore, in this work, we have synthesized sphere-shaped MSNs with different pore scales (s-SPs and l-SPs) and rod-shape (RPs-3) MSNs to evaluate the influence of the morphology and pore size on their interaction with serum proteins and red blood cells (RBCs). The adsorption of human albumin (HSA), globulin (HGG), and fibrinogen (HSF) onto different kinds of MSNs has been analyzed by pseudo second-order kinetic model, and the conformational changes of the adsorbed proteins have been studied by FTIR spectroscopy. We find that the conformation of absorbed HSA and HSF, while not HGG, will be affected by the pore size and morphology of the MSNs. The conformational changes of the adsorbed proteins will further affect their saturated adsorption capacity. However, the initial adsorption rate is only determined by the property of MSNs and proteins. Additional hemolysis assay shows that the pore size and morphology of the MSNs will also affect their hemolytic activity in RBCs which will be extremely depressed by the formation of protein corona. These systematic studies will provide an overall understanding in the blood compatibility of MSNs as well as useful guidelines for fabrication of blood-compatible nanomaterials.

Study of Protein Adsorption on Biomaterial Surfaces by SPR

The aim of this study was to set up a SPR sensor and to investigate protein adsorption onto biomaterial surface using it. Methods: The adsorption of human albumin (Alb), fibrinogen (Fib) and immunoglobulin G (IgG) onto polyurethane (PU) H50-50 and Au surface were measured using this SPR sensor. Results: The results of protein adsorption showed that the amount of Alb, Fib and IgG adsorbed on PU (H50-50) are smaller than Au, and on these two material surfaces, the amount sequence of adsorbed protein is: IgG> Fib > Alb. Both the Alb/Fib ratio and Alb/IgG ratio on PU (H50-50) surface are higher than Au. Conclusion: The antithrombogenicity of PU (H50-50) is better than Au.

Adsorption of human serum albumin on to synthesized dye-like polystyrene gel beads

In bioseparation, adsorption of proteins on to various polymer surfaces plays an important role in different fields, particularly in pseudo-affinity chromatography techniques. In this context, this study aims to synthesize cross-linking polystyrene gel beads as packing material in column chromatography for albumin purification. Suitable chemical groups, such as sulfonate and l-cysteine with high affinity towards human serum albumin were introduced on the aromatic ring of the hydrophobic adsorbing polystyrene support. These functional groups were chosen on the basis of the interactions of albumin with their exogenous and endogenous ligands in such manner to confer this material a highly binding ability and enhance its efficacy. Adsorption of human albumin on to these two synthesized adsorbents was performed at 37 °C in physiological pH 7.3 during 20 min of incubation. The adsorbed albumin content at interface allows to establish the adsorption isotherm curves. The adsorption rate on both resins was found to be significantly high and the affinity constants, evaluated by the Langmuir model, were: 7.5×10 5 and 1.45×10 6 M −1 for poly(styrene sodium sulfonate) and poly(styrene cysteine sulfamide), respectively. Thus, the obtained material gel beads could be used advantageously as a dye-like stationary phase in chromatographic separation of albumin instead of other conventional supports.

Adsorbed serum proteins responsible for surface dependent human macrophage behavior

Substrate specific cellular responses are the result of a complex biological system that includes protein adsorption, receptor–ligand binding, and signal transduction. This investigation attempted to identify specific proteins adsorbed from human serum that may be responsible for the previously reported in vitro surface dependent behavior of human macrophages and foreign body giant cells (FBGCs). The adsorption of human albumin, α2-macroglobulin, complement factor 3b, fibronectin, IgG, thrombospondin, vitronectin (VN), and von Willebrand factor (vWF) from a 25% serum solution was quantified with 125I-labeled protein. Adsorption substrates included clean glass, alkyl-silane modified glass, amino-silane modified glass, poly(ethylene oxide) (PEO)-coupled glass, and the reference biomaterials poly(etherurethane urea), Silastic®, and poly(tetrafluoroethylene) (PTFE). Following quantification of 2-h adsorption, surfaces were treated with sodium dodecyl sulfate (SDS) and the level of adsorbed proteins remaining was quantified. The pre- and post-SDS adsorption were both compared to previously reported surface dependent in vitro macrophage and FBGC behavior on the same surfaces; however, no correlations could be made. Adsorption strength, defined as the percentage of initially adsorbed protein that remained adsorbed after SDS treatment, correlated well with previously reported in vitro cellular behavior indicating that adsorbed vWF, IgG, and VN may be involved in the modulation of adherent macrophage and FBGC behavior. Those surfaces that strongly adsorbed vWF also inhibited long-term macrophage adhesion, while those surfaces that strongly adsorbed IgG promoted long-term macrophage adhesion. In addition, the highest levels of FBGC formation had been observed only on those surfaces that strongly adsorbed VN. Subsequent human monocyte cultures on protein preadsorbed substrates confirmed the inhibitory effect of adsorbed vWF and the promoting effect of IgG on longterm macrophage adhesion as predicted by adsorption strength correlations. However, preadsorbed VN was not observed to modulate FBGC formation, which is in contrast to the conclusions of the adsorption correlations. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 49, 435–447, 2000.

Adsorbed serum proteins responsible for surface dependent human macrophage behavior.

Substrate specific cellular responses are the result of a complex biological system that includes protein adsorption, receptor-ligand binding, and signal transduction. This investigation attempted to identify specific proteins adsorbed from human serum that may be responsible for the previously reported in vitro surface dependent behavior of human macrophages and foreign body giant cells (FBGCs). The adsorption of human albumin, alpha(2)-macroglobulin, complement factor 3b, fibronectin, IgG, thrombospondin, vitronectin (VN), and von Willebrand factor (vWF) from a 25% serum solution was quantified with (125)I-labeled protein. Adsorption substrates included clean glass, alkyl-silane modified glass, amino-silane modified glass, poly(ethylene oxide) (PEO)-coupled glass, and the reference biomaterials poly(etherurethane urea), Silastic(R), and poly(tetrafluoroethylene) (PTFE). Following quantification of 2-h adsorption, surfaces were treated with sodium dodecyl sulfate (SDS) and the level of adsorbed proteins remaining was quantified. The pre- and post-SDS adsorption were both compared to previously reported surface dependent in vitro macrophage and FBGC behavior on the same surfaces; however, no correlations could be made. Adsorption strength, defined as the percentage of initially adsorbed protein that remained adsorbed after SDS treatment, correlated well with previously reported in vitro cellular behavior indicating that adsorbed vWF, IgG, and VN may be involved in the modulation of adherent macrophage and FBGC behavior. Those surfaces that strongly adsorbed vWF also inhibited long-term macrophage adhesion, while those surfaces that strongly adsorbed IgG promoted long-term macrophage adhesion. In addition, the highest levels of FBGC formation had been observed only on those surfaces that strongly adsorbed VN. Subsequent human monocyte cultures on protein preadsorbed substrates confirmed the inhibitory effect of adsorbed vWF and the promoting effect of IgG on longterm macrophage adhesion as predicted by adsorption strength correlations. However, preadsorbed VN was not observed to modulate FBGC formation, which is in contrast to the conclusions of the adsorption correlations.

Interaction of IgG and albumin with functionalized silicas

Studies of the adsorption of IgG and albumin to modified silica particles are reported. The silica particles were functionalized with so-called thiophilic and other groups designed to promote the specific adsorption of IgG according to Oscarrson and Porath, (in T.T. Ngo (Ed.), Molecular Interactions in Bioseparations, Plenum, New York, 1993, pp. 403–414). Porous silica beads were first coated with dextran which had been substituted with a calculated amount of positively charged diethylaminoethyl (DEAE) functions. This treatment was designed to “passivate” the silica, i.e. to minimize nonspecific protein adsorption via the silanol groups. The DEAE-dextran coated silica was functionalized with 2-mercaptoethanol via the coupling agent divinylsulfone. This treatment provides the thiophilic groups of Oscarrson and Porath. Ligands consisting of cysteine methyl ester and divinylsulfone residues were also coupled to the passivated silica to provide related chemical functions. The adsorption isotherms of human IgG to these materials from buffer were determined. All the functionalized materials showed an increase in adsorption of IgG in comparison with the passivated silica. The apparent affinities of the functionalized materials for IgG binding were all similar, thus demonstrating the importance of the sulfone group in the so-called thiophilic interaction. The adsorption of IgG from serum onto the functionalized materials showed the same specificity of IgG for these materials but the amounts of adsorbed IgG were lower than from buffer, indicating that other proteins in serum compete with IgG. IgG adsorption from serum also showed the Vroman effect, i.e. a maximum in adsorption as a function of serum dilution, indicating that initially adsorbed IgG is displaced by proteins of higher affinity. Human albumin adsorption from buffer showed an increase compared to the control surface on only one of the functionalized materials, i.e. the thiophilic material. Of the three derivatized materials, the cysteine methyl ester material shows the greatest binding capacity for IgG both from buffer and serum, and essentially no specificity for albumin binding. It would thus probably be the most effective of the materials studied for chromatography of IgG.

Protein adsorption of poly(ether methane) surfaces modified by amphiphilic and hydrophilic polymers

A commercial biomedical poly(ether urethane), Pellethane 2363-80AE, was surface modified through the use of amphiphilic polymeric additives, and through surface grafting with poly(ethylene glycol), PEG. Two different amphiphilic polymers, Polymer C and Pluronic PE9400, were used as additives. Polymer C, a segmented polyurethane, was prepared from PEG1500, 4,4′-diphenylmethane diisocyanate and a C 16–C 18 monoglyceride chain extender. Pluronic PE9400 is a propylene oxide-ethylene oxide tri-block co-polymer obtained from BASF. Adsorption of human albumin and fibrinogen to the modified surfaces was studied by means of radiolabelled proteins. By contact angle measurements and X-ray photoelectron spectra the amphiphilic polymers were shown to accumulate at the poly-rethane surfaces. Adsorption of fibrinogen, in particular, was significantly reduced by the amphiphilic additives to levels similar to those obtained for Pellethane surfaces grafted with PEG 20000. In vitro clotting times for citrate-buffered blood in contact with the amphiphilic surfaces increased as compared with the unmodified ones.

Relaxation behaviour of human albumin adsorbed at the solution/air interface

The adsorption kinetics of human albumin (HA) at the aqueous solution/air interface and the surface relaxation behaviour of HA adsorption layers after transient area disturbances are studied using an axisymmetric drop shape technique (ADSA). Transient relaxation measurements were performed with the ADSA technique by changing the volume of the pendent drop by definite increments. In the concentration interval studied, the relaxation behaviour of HA is not diffusion controlled. Relaxation phenomena observed during the induction time show the presence of structured adsorption layers. The relaxation behaviour of a quasi-equilibrium HA adsorption layer is independent of the HA concentration. The calculated apparent diffusion coefficients represent the order of magnitude of the rate constant of the real mechanism. A comparison of results calculated from adsorption kinetics and relaxation data shows good agreement with an apparent diffusion coefficient in the order of 0.001 cm 2s −1.

Protein-resistant surfaces prepared by PEO-containing block copolymer surfactants.

Polyethylene oxide(PEO)-containing nonionic polymeric surfactants were studied as a possible means to produce PEO-rich surfaces by a simple coating treatment of a common hydrophobic medical material--polyethylene. Surface tension and adsorption properties of PEO/polypropylene oxide(PPO) and PEO/polybutylene oxide(PBO) block copolymer surfactants on a hydrophobic surface (low density polyethylene, LDPE) were investigated, using the Wilhelmy plate surface tension technique and x-ray photoelectron spectroscopy(XPS). The protein resistance of the surfactant-treated surfaces was evaluated by XPS and 125I-labeled proteins. The data presented indicate that adsorption of the surfactants on LDPE is dependent on the molecular geometry of the surfactants. Adsorption of human albumin was significantly decreased on the surfactant-treated LDPE surfaces, as compared with the untreated surface. Surfactants suitable for the preparation of PEO-rich surfaces and possible mechanisms for their protein resistance are discussed.

Adsorption of human albumin onto hdroxyapatite. Static and dynamic studies

The adsorption of albumin onto hydroxyapatite powder (HA) was studied at equilibrium and kinetically with an experimental system allowing continuous monitoring of the excess interfacial protein concentration with time. By assuming a Langmuir model and by applying a mass conservation law, it was possible to calculate the adsorption and desorption rate constants K a and k d and the affinity constant K, and to compare them with the value of 2.5 × 10 9 cm 3 mol −1 deduced from equilibrium studies. In dynamic studies, significant decreases in the adsorption rate and affinity constants were observed when protein injection rates were increased. To explain this unexpected result, we propose the occurrence of a cooperative effect by the molecules already adsorbed — and perhaps partly denatured — which might promote further adsorption of dissolved molecules.

Adsorption of human albumin and fibrinogen onto heparin-like materials II. Desorption and exchange processes

The dynamic properties characterizing the interactions of adsorbed fibrinogen and albumin layers with three adsorbent surfaces have been examined using a method previously described (J.C. Voegel et al., Colloids and Surfaces, 10 (1984) 9–19). Solid surfaces were those of bare glass beads, glass beads covered with a strongly adsorbed polystyrene-sulfonate/poly(2-vinylpyridine) block copolymer and chemically modified polystyrene beads; the beads were packed into a minicolumn. As a general rule, the observed desorption or exchange processes are slow (relaxation times of the order of hours) and the extent of protein removal from the surface is higher in exchange experiments. On the time scale of our observations, two populations were identified in the adsorbed protein layer: exchangeable (or desorbable) and non-exchangeable adsorbed molecules. The extent of desorption or exchange is less important for fibrinogen than for albumin, which correlates well with the equilibrium studies of Part I (pp. 271–288). However, albumin desorption is very low on the surfaces containing sulfamide—glutamic acid groups. Finally, it is shown by radioactive labeling that the exchange process corresponds to a turnover between surface and solution molecules.