Protein loaded mesoporous silica spheres as a controlled delivery platform

BACKGROUND: The adsorption of bovine serum albumin (BSA) onto mesoporous silica spheres (MPS) synthesized from silica colloids was studied employing real time in situ measurements. The stabilities of the BSA at different pH values, their isoelectric points and zeta potentials were determined in order to probe the interactions between the protein and the mesoporous silica. RESULTS: The pore size of MPS was designed for protein, and this, coupled with an in depth understanding of the physico‐chemical characteristics of the protein and MPS has yielded a better binding capacity and delivery profile. The adsorption isotherm at pH 4.2 fitted the Langmuir model and displayed the highest adsorption capacity (71.43 mg mL^?1 MPS). Furthermore, the delivery rates of BSA from the MPS under physiological conditions were shown to be dependent on the ionic strength of the buffer and protein loading concentration. CONCLUSION: Economics and scale‐up considerations of mesoporous material synthesized via destabilization of colloids by electrolyte indicate the scaleability and commercial viability of this technology as a delivery platform for biopharmaceutical applications. Copyright © 2007 Society of Chemical Industry     

Kinetic and Mass Transfer Model for Separation of Protein Using Ceramic Monoliths as a Stationary Phase

Rigid adsorbents used as matrix skeleton have advantages over soft gel media for downstream processing of proteins. The adsorption of bovine serum albumin (BSA) has been investigated on a rigid ceramic monolith coated with cross-linked microporous agarose (D5). The physical properties of the adsorbent and the adsorption equilibria, adsorption kinetics, and mass transfer behavior have been studied for five different flow rates, with a pH value ranging from pH 4.5 to 7.0. The optimal working flow rate was 14.0?cm³/min, and using this flow rate, increasing the pH does not generate a significant improvement in the adsorption capacity. The rates of BSA adsorption have been measured and it was possible to describe a theoretical model, in which the mass transfer involves a dispersion coefficient (k_disp), which describes the mass transfer in the adsorbent surface, from the volume of the protein solution to the agarose surface. This parameter presents an exponential tendency by increasing the flow rate from 2.37?×?10^?6 to 87.40?×?10^?6?cm/s for n?=?1. Values obtained for the adsorption kinetic constant (k_ads) followed the trend of the mass transfer parameter, increasing with the flow rate from 1.94?×?10⁴ to 117.39?×?10⁴?cm²/mol?s. The theoretical model predicts the protein concentration in equilibrium for successive column reuses and it can be readily used to determine the optimal reuse of column. Likewise, for a maximum flow rate of 14?cm³/min, pressure drop was 0.04?MPa, being an advantage in front of packed columns that have higher pressure drop.     

Biological evaluation of chitosan‐based in situ‐forming hydrogel with low phase transition temperature

The aims of current study were to choose a method for preparing sterile chitosan‐α,β‐glycerophosphate (CS‐α,β‐GP) in situ‐forming hydrogel which had potential applications in tissue engineering and evaluated its biocompatibility and degradation characteristics. The results of sterilization stability tests indicated that sterile formulations could be obtained by ultraviolet irradiation of CS powders, 0.22 µm filtration of α,β‐GP and lactic acid solutions, and sterile preparation of CS‐α,β‐GP formulations. The obtained sterile CS‐α,β‐GP formulations showed low hemolysis rates and low BSA adsorption at physiological conditions. When injected in vivo the CS‐α,β‐GP sol turned into gel implant in situ and could be degraded gradually. A minimal inflammatory reaction which could not be found by macroscopic evaluation was induced after injection and new capillary formation was found around the hydrogel humps, making the CS‐α,β‐GP hydrogel worthwhile to be considered for tissue engineering and biomedical applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41594.     

Supramolecular Bioconjugates for Protein and Small Drug Delivery

Supramolecular conjugation techniques have been developed to produce novel nanosized systems by assembling materials with diverse physicochemical and biological features. These techniques have been adapted to obtain innovative bioconjugates to deliver drugs with poor biopharmaceutical properties and nano-devices with potential “theranostic” activity. Supramolecular drug delivery systems include polymer therapeutics such as drug–polymer bioconjugates, and colloidal carriers such as micelles, liposomes, polyplexes, and organic and inorganic nanoparticles. By virtue of their wide array of chemical composition and properties, polymers represent key elements for the construction of novel supramoelcular formulations. Polymer bioconjugation is a fledged technique for fabrication of protein–polymer conjugates. PEGylation, in particular, produces derivatives with enhanced pharmacokinetic, immunological, and stability properties as compared to the parent protein. Over the years, new methods have been set up to obtain site-directed polymer conjugation. In this review we report few grafting to and growing from PEGylation examples for the preparation of therapeutically effective protein bioconjugates. Supramolecular formulations with unique properties can be also obtained by assembling functional polymers, targeting agents, physicochemical modifiers, and biomodulators. These systems may be designed for disease tissue disposition and cell recognition/penetration. Cyclodextrins, for example, have been functionalized with polyethylene glycol and folic acid to produce tumor-targeted drug carriers. Interesting results have been obtained with this novel class of drug delivery systems. In addition, responsive polymers have been conjugated to gold nanoparticles to endow a new colloidal platform with triggerable cell disposition properties, which can be exploited either in biomedicine or diagnosis.     

Green Production of Anionic Surfactant Obtained from Pea Protein

A pea protein isolate was hydrolyzed by a double enzyme treatment method in order to obtain short peptide sequences used as raw materials to produce lipopeptides-based surfactants. Pea protein hydrolysates were prepared using the combination of Alcalase and Flavourzyme. The influence of the process variables was studied to optimize the proteolytic degradation to high degrees of hydrolysis. The average peptide chain lengths were obtained at 3–5 amino acid units after a hydrolysis of 30 min with the mixture of enzymes. Then, N-acylation in water, in presence of acid chloride (C12 and C16), carried out with a conversion rate of amine functions of 90%, allowed to obtain anionic surfactant mixtures (lipopeptides and sodium fatty acids). These two steps were performed in water, in continuous and did not generate any waste. This process was therefore in line with green chemistry principles. The surface activities (CMC, foaming and emulsifying properties) of these mixtures were also studied. These formulations obtained from natural renewable resources and the reactions done under environmental respect, could replace petrochemical based surfactants for some applications,.     

Water Sorption and Glass Transition Temperature of Spray-Dried Mussel Meat Protein Hydrolysate

The water sorption behavior at 25°C and glass transition temperature (T _g ) of mussel meat protein hydrolysate powder without and with maltodextrin 10 DE or gum arabic at 15 and 30% (w/w) were studied in this work. The sorption isotherms were determined by the gravimetric method, and the glass transition temperature was obtained by differential scanning calorimetry (DSC) after powder conditioning at various water activities. Sorption isotherms data were well fitted by a modified Brunauer-Emmett-Teller (BET) model. Powder without additives showed the highest water adsorption followed by those produced with 15 and 30% of carrier agent, respectively. The Gordon-Taylor model was able to predict the effect of water on the glass transition temperature. At 25°C, the critical water content that ensured the glassy state of the mussel hydrolysate powder during storage increased from 0.05 to 0.12 g water/g product and the critical water activity increased from 0.24 to 0.60 when the concentration of carrier agents was increased to 30%.     

Fractionation and Some Chemical Studies on Ailanthus excelsa Roxb. Seed Protein

The unavailability of protein foods, particularly in the context of population growth, has been an important factor in the protein malnutrition encountered in developing countries. The fractionation, gel filtration and polyacrylamide gel electrophoresis (PAGE) of Ailanthus excelsa seed (a nontraditional source containing 15.81% protein) proteins were carried out in the present study, and their solubility profiles, surface topographies and amino acid compositions were evaluated. The globulin fraction dominated the seed protein composition, accounting for 51.31% (w/w) of the total soluble proteins in the seeds. Protein isolate and protein fractions of A. excelsa seeds showed similar topographical structures to those of other plant seed proteins. Analysis of the isolated proteins identified 17 amino acids, of which nine were essential. Gel filtration on Sephadex G-200 revealed the presence of seven components. PAGE detected different polypeptide bands in the range of 28.8−154.9 kDa in the protein isolate as well as in protein fractions for A. excelsa. The amino acid compositions, the solubility patterns and the high abundances of low molecular weight proteins indicate that the isolated seed protein of A. excelsa may be a potential food protein.     

Photo-chemical Surface Modification for the Control of Protein Adsorption on Textile Substrates

Cell growth on fiber surfaces is an important aspect of many applications of technical textiles. The need to prevent clogging in artificial blood vessels or in textiles used for blood or water filtration as well as the anti-fouling properties of outdoor technical textiles are examples in this context. Since the adsorption of proteins forms the initial step of cell growth, a promising way to avoid biofouling is to prohibit protein adsorption by means of a suitable, permanent and non-toxic surface functionalization. Today, the deposition of poly(ethylene glycol)s (PEGs) is a well-known approach to decrease non-specific protein adsorption. In this work, a photo-chemical method to graft or cross-link PEGs on fiber surfaces was studied. Monomethacrylated PEG300MA and PEG2080MA as well as dimethacrylated PEG400DMA and PEG600DMA were considered, the numbers indicate average molar mass in g/mol. Textile fabrics made of poly(ethylene terephthalate) (PET) were impregnated with solutions of the PEGs and irradiated using either a KrCl* or a XeCl* excimer lamp (emission wavelengths 222 or 308 nm, respectively). Surface properties of the treated textiles were characterized as a function of process conditions using various surface sensitive analyses. UV cross-linking of PEG400DMA resulted in the deposition of a thick layer which effectively masked the texture of the fabric and its pore system. Much less coverage was observed in case of monomethacrylated PEGMAs, with a significant reduction in drop penetration time already after deposition of a marginal layer (less than 0.01 mg/mg). Highest reductions in adsorption of bovine serum albumin (BSA) were observed for samples prepared using PEG300MA or PEG400DMA under conditions where also the drop penetration time was at its minimum. The longer chain PEG2080MA was less effective. All results show clearly that the protein adsorption tendency can be significantly reduced by choice of suitable combinations of PEGylated monomer and UV irradiation conditions.     

Influence of Solvent–Evaporation Effect on the Structure and Properties of PVDF-g-PNIPAAm Membranes

Temperature-sensitive poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide)(PVDF-g-PNIPAAm) copolymer was synthesized and its flat membranes were prepared through phase inversion method with mixture of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) as solvent in water coagulation bath. The effects of “open time” (solvent–evaporation time) on the structure and performance of membranes were investigated by X-ray photoelectron spectroscopy, field-emission scanning electronic microscopy, contact angle, filtration experiments and static protein adsorption. It was found that the increasing “open time” endowed the membrane with more pores on the surface, higher flux and better hydrophilicity, provided the membrane with lower protein adsorption. Thus, the copolymer membranes showed a good antiprotein fouling.     

Visualization and Modeling of Protein Adsorption and Transport in DEAE- and DEAE-Dextran-Modified Bare Capillaries

This article reports a microscopic method to directly visualize protein adsorption and transport in bare capillaries modified with ion exchange groups. Silica capillaries were coated with poly(vinyl alcohol) to eliminate nonspecific protein absorption and then functionalized with diethylaminoethyl (DEAE) and DEAE-dextran to prepare anion-exchange capillaries denoted as D-C and D-dex-C, respectively. Protein concentration profiles acquired from microscopic images were analyzed with a one-dimensional diffusion-adsorption model to determine adsorption capacities and effective diffusivities. It revealed that surface diffusion of bound protein on the capillary surface in D-Cs was negligible, but that of bound proteins markedly contributed to protein transfer in D-dex-Cs because of the chain delivery effect of charged dextran chains. The chain delivery was little affected by protein concentration, but significantly increased with ionic capacity. The research thus provided new insight into protein adsorption and transport behaviors on the surfaces modified with ion exchange groups of different structures. © 2018 American Institute of Chemical Engineers AIChE J, 65: 305–316, 2019     

Fusion behavior of plastisols of PVC studied by ATR-FTIR

The behavior of PVC plastisols during gelation and fusion was studied by the ATR-FTIR technique (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy). DBP, DOP, and DIDP, three common phthalate plasticizers for PVC, were used in plastisols formulations. Three heating rates—5, 10 and 15°C/min—and formulations with different plasticizer concentrations were studied. The IR spectra of a plastisol coincides with the IR spectra of the plasticizer except for the bands at 1435 and 613 cm^?1 from the PVC (CH₂ wagging and C—Cl stretching, respectively). When the plastisol is heated, a progressive decrease of the plasticizer bands areas can be observed, while bands from PVC increase their intensity, probably because of the adsorption of the plasticizer by the resin. On cooling, the area of all bands follows the same path as when heating, but the paths separate at a certain temperature, showing the irreversible nature of this process. The analysis of the band at 1280 cm^?1 (C(O)—O from plasticizer) during heating and cooling, shows that the temperature of separation areas (T_s) takes place at temperatures coherent with plasticizer compatibility. Studies at different heating rates and different plasticizer content are in good agreement with results using other techniques, available in the literature.     

Binary Adsorption of n‐Butane or Toluene and Water Vapor

To clean the air in cars of noxious gases by adsorption, predominantly activated carbon is used. The height of the activated carbon layer is especially small in cabin air filtration. As test substances for adsorptive filters in cabin air filtration, toluene and n‐butane are prescribed in several engineering standards, e.g., ISO TS 11155‐2. In the study presented, the differences in binary adsorption between toluene or n‐butane and water vapor are investigated with emphasis on adsorption equilibrium and kinetics at temperatures between 15 °C and 33 °C, and relative humidity varying between 0 % and 90 %. The range of input concentrations is from 2 ppm_V up to 80 ppm_V.     

Preparation and characterization of a macroporous agarose monolith as a stationary phase in IMAC chromatography

A macroporous monolith used as stationary phase for the separation of biomolecules by immobilized metal ion affinity chromatography (IMAC), based on D5 agarose (D5) chemically modified was proposed. The characterization of physical properties was studied. Pressure drop was <0.4?MPa, being a very low value compared to other similar chromatographic supports. The adsorption/desorption process was carried out using bovine serum albumin (BSA) at pH 7.4 as a target protein. The monolith was re-used for 20 adsorption/desorption cycles and it was possible to verify that the average percentage of adsorption in all cycles was 89.65%. It was also possible to apply a model in order to obtain the kinetic adsorption constant (k_a), desorption constant (k_d) and equilibrium constant (K_e) by the proposed system. These results indicate that this system is governed by the adsorption process.     

Recovery of proteins and other biological compounds using fibrous materials: I. Adsorption by salt addition

An adsorption and filtration process for the recovery of proteins and other biological compounds from aqueous streams has been developed, using cellulose‐based fibrous materials. Of the many cellulose derivatives studied, cellulose acetate fibrets (CAF) and cellulose triacetate fibrets (CTF) have been shown to be the most effective. In the presence of salts, they lead to protein adsorption by hydrophobic interactions. Model proteins, such as bovine serum albumin (BSA), have been recovered by incubating these solutions with CTF in the presence of ammonium sulfate, followed by filtration through a 20 µm pore size filter. The amount of salt necessary varies with the protein type, but decreases with increasing temperature and protein concentration. High protein recovery has been obtained from an actual wastewater system at low salt dosages. © 1999 Society of Chemical Industry     

Effect of different anchor groups on adsorption behavior and effectiveness of poly(N,N‐dimethylacrylamide‐co‐Ca 2‐acrylamido‐2‐methylpropanesulfonate) as cement fluid loss additive in presence of acetone–formaldehyde–sulfite dispersant

The impact of various anchor groups on adsorption behavior of AMPS® copolymers was studied. The anchor groups differ in anionic charge density. Copolymer adsorption and water retention of oil well cement slurries achieved from CaAMPS®‐co‐NNDMA in the presence of an acetone–formaldehyde–sulfite (AFS) dispersant were improved by incorporation of minor amounts (～ 1% by weight of polymer) of acrylic acid (CaAMPS®‐co‐NNDMA‐co‐AA), maleic acid anhydride (CaAMPS®‐co‐NNDMA‐co‐MAA), or vinyl phosphonic acid (CaAMPS®‐co‐NNDMA‐co‐VPA), respectively. Performance of these terpolymers was studied by measuring static filtration properties of oil well cement slurries at 27°C and 70 bar pressure. All fluid loss additives possess comparable molar masses and show the same adsorption behavior and effectiveness when no other admixture is present. In the presence of AFS dispersant, however, adsorption of CaAMPS®‐co‐NNDMA and hence fluid loss control is dramatically reduced, whereas effectiveness of CaAMPS®‐co‐NNDMA‐co‐AA is less influenced because of acrylic acid incorporated as additional anchor group. Even more, CaAMPS®‐co‐NNDMA‐co‐MAA combined with AFS allows simultaneous adsorption of both polymers and thus produces good fluid loss control. CaAMPS®‐co‐NNDMA‐co‐VPA no longer allows adsorption of AFS dispersant. This was also confirmed by rheological measurements. The results show that, in a binary admixture system, adsorption of the anionic polymer with anchor groups possessing higher charge density is preferred. Surface affinity of the anchor groups studied increase in the order ? SO → ? COO^? → vic‐(? COO^?)₂→ ? PO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

An integrated downstream processing strategy for the recovery and partial purification of penicillin acylase from crude media

An integrated process strategy for the recovery of penicillin acylase was developed, based on precipitation of non‐enzymatic proteins directly from Escherichia coli homogenates or crude extracts using Rolquat (quaternary ammonium salt) and adsorption of the enzyme on Amp‐Seph (3.8 µmole ampicillin cm^?3) under pseudo‐affinity conditions. The effect of pH, concentrations of ammonium sulfate and Rolquat, and also concentrations of protein and cell debris on the precipitation of non‐enzymatic proteins from homogenates and crude extracts of penicillin acylase were analysed. The method of addition of Rolquat to homogenates and crude extracts significantly influenced the size of the precipitated particles. Improved results on the specific activity of penicillin acylase were obtained for 22% and 1% (w/v) of ammonium sulfate and Rolquat, respectively, added sequentially to enzyme solutions and at room temperature. Under these experimental conditions, the specific activity of penicillin acylase in homogenates and crude extracts was enhanced 2.5–3.0‐fold. Finally, the integrated process strategy was implemented first by precipitation of non‐enzymatic proteins and recovery of penicillin acylase directly from the enzyme solution treated with Rolquat using an adsorption/filtration system with an overall yield of 86%. This system allows simultaneously the filtration of cell debris and fine precipitated particles, in situ recovery of penicillin acylase by its adsorption on Amp‐Seph, and selective desorption of the enzyme with a specific activity of 11 IU (mg prot)^?1 and a desorption yield of 95%. © 2002 Society of Chemical Industry     

PMMA‐multigraft copolymers derived from linseed oil,soybean oil,and linoleic acid: Protein adsorption and bacterial adherence

Synthesis of Poly(methyl methacrylate), PMMA‐multigraft copolymers derived from linseed oil, soybean oil, and linoleic acid PMMA‐g‐polymeric oil/oily acid‐g‐poly(3‐hydroxy alkanoate) (PHA), and their protein adsorption and bacterial adherence have been described. Polymeric oil/oily acid peroxides [polymeric soybean oil peroxide (PSB), polymeric linseed oil peroxide (PLO), and polymeric linoleic acid peroxide (PLina)] initiated the copolymerization of MMA and unsaturated PHA‐soya to yield PMMA–PLO–PHA, PMMA–PSB–PHA, and PMMA–PLina–PHA multigraft copolymers. PMMA–PLina–PHA multigraft copolymers were completely soluble while PMMA–PSB–PHA and PMMA–PLO–PHA multigraft copolymers were partially crosslinked. Crosslinked parts of the PLO‐ and PSB‐multigraft copolymers were isolated by the sol gel analysis and characterized by swelling measurements in CHCl₃. Soluble part of the PLO‐ and PSB‐multigraft copolymers and completely soluble PLina‐multigraft copolymers were obtained and characterized by spectroscopic, thermal, gel permeation chromatography (GPC), and scanning electron microscopy (SEM) techniques. In the mechanical properties of the PHA–PLina–PMMA, the elongation at break is reduced up to ～ 9%, more or less preserving the high stress values at its break point (48%) when compared to PLina‐g‐PMMA. The solvent casting film surfaces were studied by means of adsorption of blood proteins and bacterial adhesion. Insertion of the PHA into the multigraft copolymers caused the dramatic increase in bacterial adhesion on the polymer surfaces. PHA insertion into the graft copolymers also increased the protein adsorption. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Chemical Protein Analysis: A Comparison of Kjeldahl Crude Protein and Total Ninhydrin Protein from Wild, Tropical Vegetation

Various methods are available for measuring the protein content of vegetation. This paper reviews and tests some common methods in order to provide recommendations to wildlife ecologists and primatologists. The traditional Kjeldahl crude protein method, which requires the conversion factor of 6.25 (CP6.25), was compared to values obtained through total ninhydrin protein (NP) analysis and by calculating crude protein from a newly developed conversion factor of 4.3 (CP4.3). The NP analysis gave values that were not significantly different from the CP4.3 values, and both were significantly lower than the CP6.25 values. An additional method was compared (available CP), which is CP6.25 values corrected by subtracting the acid-detergent lignin-bound crude protein. Comparisons were also made between CP4.3 and the available CP. These two methods correct the protein values differently, and theoretically CP4.3 corrects more severely, as explained in the text, but in some situations they may be correcting for the same chemical category of unavailable nitrogen. For fruits and flowers these values were not significantly different. For leaves the results were not so clear-cut. The Ugandan leaves (N = 42), Indonesian mature leaves (N = 40), Zimbabwe leaves (N = 24), and northern USA leaves (N = 11) were significantly different, and the CP4.3 always corrected more severely. The rest of the leaf sets (Belize, N = 68; Zaire, N = 36; Sumatra, N = 10; St. Catherine's Island, Georgia, USA, N = 37; and southern USA, N = 18) did not give a significant difference between CP4.3 and available CP. The choice of which analysis method to use (NP or CP4.3 versus available CP) depends on whether it seems reasonable to severely penalize all nonprotein nitrogen, considering the animal species being studied, or whether removing only the lignin-bound nitrogenous compounds is sufficient. Overall, the traditional 6.25 conversion factor is too large a conversion value for most wild vegetation; crude protein corrected only for lignin-bound protein is probably more accurate.     

Adsorption behavior and effectiveness of poly(N,N‐dimethylacrylamide‐co‐Ca 2‐acrylamido‐2‐methylpropanesulfonate) as cement fluid loss additive in the presence of acetone‐formaldehyde‐sulfite dispersant

A copolymer of N,N‐dimethylacrylamide and Calcium 2‐acrylamido‐2‐methylpropanesulfonate was synthesized by free‐radical copolymerization. Its performance as anionic fluid loss additive (FLA) was studied by measuring static filtration properties of oil well cement slurries at 27°C and 70 bar pressure, respectively. It was found that cement filter cake permeability and API fluid loss decrease with increasing FLA dosage. Filtrate analysis revealed a linear correlation between fluid loss and the amount of FLA adsorbed on the cement surface. FLA adsorption on cement was determined by total organic carbon (TOC) analysis in cement filtrate and confirmed by ζ‐potential measurement. According to environmental scanning electron microscopy (ESEM) investigations, FLA does not alter the filter cake structure. In the presence of an anionic acetone–formaldehyde–sulfite (AFS) polycondensate dispersant, fluid loss control from FLA decreased and cement filter cake permeability increased because AFS reduces the amount of FLA adsorbed. In comparison to FLA, AFS shows stronger adsorption on the cement surface and succeeds in the competition with FLA. The different adsorption behavior of the two polymers is the reason for limited compatibility of this admixture com bination. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4341–4347, 2006     

Protein adsorption kinetics of mixed-mode adsorbent with benzylamine as functional ligand

Adsorption kinetics of bovine serum albumin (BSA) to mixed-mode adsorbent with benzylamine ligand was studied via stirred-batch uptake experiments. The effects of liquid-phase conditions, such as salt concentration and pH, on the uptake rates of BSA were evaluated by effective pore diffusivity (D_e) derived from the pore diffusion model (PDM). The results indicated that when electrostatic attractive interactions exist between protein and ligand, D_e increases firstly with increasing salt concentration and then turns to decreasing after reaching the maximum. When there are electrostatic repulsion protein/ligand interactions, it seems that the adsorption process is patch controlled, and the specific salt concentration to result in a minimum adsorption capacity could be found. The value of D_e showed a similar tendency to the change of adsorption capacities. With the increase of salt concentration, the increase in D_e value was considered due to the decrease of electrostatic repulsion interactions and increase of hydrophobic interactions between BSA and ligand. Since BSA has the most compact structure at the isoelectric point, which leads to lower hydrodynamic forces, it is reasonable that the maximum of effective diffusion coefficient could be found around the isoelectric point.