Study on protein conformation and adsorption behaviors in nanodiamond particle-protein complexes

Energy Technology Data Exchange (ETDEWEB)

Wang Haidong [Department of Biomedical Engineering, University of Saskatchewan, Saskatoon, S7N 5A9 (Canada); Niu, Catherine Hui [Department of Chemical Engineering, University of Saskatchewan, Saskatoon, S7N 5A9 (Canada); Yang Qiaoqin [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, S7N 5A9 (Canada); Badea, Ildiko, E-mail: catherine.niu@usask.ca [Drug Design and Discovery Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, S7N 5C9 (Canada)

2011-04-08

In the present research, the conformation of bovine serum albumin (BSA) in the nanodiamond particle (ND)-BSA complex was studied by Fourier transform infrared spectroscopy, fluorescence spectroscopy, UV-vis spectroscopy, and circular dichroism spectroscopy. The spectroscopic study revealed that most BSA structural features could be preserved in the complex though the BSA underwent conformational changes in the complex due to ND-BSA interaction. In addition, BSA adsorption isotherms and zeta-potential measurements were employed to investigate the pH dependence of the ND-BSA interaction. The changes in surface charge of the ND-BSA complex with pH variations indicated that the binding of BSA to ND might lead to not only the adsorption of BSA onto the ND surface but also the partial breakup of ND aggregates into relatively small ND-BSA aggregates because of the strong binding force between ND and BSA. The results show that ND is an excellent platform for protein immobilization with high affinity and holds great potential to be used for biosensor applications.

Protein adsorption at nanopatterned surfaces studied by QCM-D and SPR

DEFF Research Database (Denmark)

Kristensen, Stine; Pedersen, Gitte Albinus; Nejsum, Lene Niemann

2013-01-01

This paper presents the use of the quartz microbalance with dissipation combined with surface plasmon resonance to probe protein adsorption at nanopatterned surfaces. Three different types of adsorbing materials, representing rigid discrete nanoparticles, dense protein films and soft low density ...

Sputter deposited bioceramic coatings: surface characterisation and initial protein adsorption studies using surface-MALDI-MS

DEFF Research Database (Denmark)

Boyd, A. R.; Burke, G. A.; Duffy, H.

2011-01-01

Protein adsorption onto calcium phosphate (Ca–P) bioceramics utilised in hard tissue implant applications has been highlighted as one of the key events that influences the subsequent biological response, in vivo. This work reports on the use of surface-matrix assisted laser desorption ionisation...... to a combination of growth factors and lipoproteins present in serum. From the data obtained here it is evident that surface-MALDI-MS has significant utility as a tool for studying the dynamic nature of protein adsorption onto the surfaces of bioceramic coatings, which most likely plays a significant role...

Adsorption behavior of protein onto siloxane microspheres

International Nuclear Information System (INIS)

Liu Bailing; Cao Shunsheng; Deng Xiaobo; Li Songjun; Luo Rong

2006-01-01

The siloxane microspheres with core-shell structure (PMMA/PMPS) (MMA, methyl methacrylate; MPS, 3-methacryloxypropyl-trimethoxysilane) have been prepared by dispersion polymerization as described in our previous work. In this paper, the developed poly(MMA-MPS) microspheres, as a carrier, are used to investigate the adsorption behavior of bovine serum albumin (BSA) on them. The Langmuir and Freundlich models have been applied to describe the adsorption behavior. The experimental results indicated that the presence of PMPS evidently increases the adsorption rate and the amount of protein, and it also influences the interaction of BSA molecules. The adsorption of BSA on the poly(MMA-MPS) microspheres seems to be sensitive to pH and ionic strength. The fittings curves from Langmuir and Freundlich models showed that the adsorption was actually more complicated than ideal situation because one or more interactions were involved in the process. For understanding the electronic contribution, the Zeta potential was used to measure the reactive system before and after protein adsorption

Adsorption behavior of protein onto siloxane microspheres

Energy Technology Data Exchange (ETDEWEB)

Liu Bailing [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China)]. E-mail: Blliuchem@hotmail.com; Cao Shunsheng [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Deng Xiaobo [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Li Songjun [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Luo Rong [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China)

2006-09-15

The siloxane microspheres with core-shell structure (PMMA/PMPS) (MMA, methyl methacrylate; MPS, 3-methacryloxypropyl-trimethoxysilane) have been prepared by dispersion polymerization as described in our previous work. In this paper, the developed poly(MMA-MPS) microspheres, as a carrier, are used to investigate the adsorption behavior of bovine serum albumin (BSA) on them. The Langmuir and Freundlich models have been applied to describe the adsorption behavior. The experimental results indicated that the presence of PMPS evidently increases the adsorption rate and the amount of protein, and it also influences the interaction of BSA molecules. The adsorption of BSA on the poly(MMA-MPS) microspheres seems to be sensitive to pH and ionic strength. The fittings curves from Langmuir and Freundlich models showed that the adsorption was actually more complicated than ideal situation because one or more interactions were involved in the process. For understanding the electronic contribution, the Zeta potential was used to measure the reactive system before and after protein adsorption.

Competitive Protein Adsorption on Polysaccharide and Hyaluronate Modified Surfaces

Science.gov (United States)

Ombelli, Michela; Costello, Lauren; Postle, Corinne; Anantharaman, Vinod; Meng, Qing Cheng; Composto, Russell J.; Eckmann, David M.

2011-01-01

We measured adsorption of bovine serum albumin (BSA) and fibrinogen (Fg) onto six distinct bare and dextran- and hyaluronate-modified silicon surfaces created using two dextran grafting densities and three hyaluronic acid (HA) sodium salts derived from human umbilical cord, rooster comb and streptococcus zooepidemicus. Film thickness and surface morphology depended on HA molecular weight and concentration. BSA coverage was enhanced on surfaces upon competitive adsorption of BSA:Fg mixtures. Dextranization differentially reduced protein adsorption onto surfaces based on oxidation state. Hyaluronization was demonstrated to provide the greatest resistance to protein coverage, equivalent to that of the most resistant dextranized surface. Resistance to protein adsorption was independent of the type of hyaluronic acid utilized. With changing bulk protein concentration from 20 to 40 µg ml−1 for each species, Fg coverage on silicon increased by 4×, whereas both BSA and Fg adsorption on dextran and HA were far less dependent of protein bulk concentration. PMID:21623481

Competitive protein adsorption to polymer surface from human serum

DEFF Research Database (Denmark)

Holmberg, Maria; Jensen, Karin Bagger Stibius; Larsen, Niels Bent

2008-01-01

Surface modification by "soft" plasma polymerisation to obtain a hydrophilic and non-fouling polymer surface has been validated using radioactive labelling. Adsorption to unmodified and modified polymer surfaces, from both single protein and human serum solutions, has been investigated. By using...... different radioisotopes, albumin and Immunoglobulin G (IgG) adsorption has been monitored simultaneously during competitive adsorption processes, which to our knowledge has not been reported in the literature before. Results show that albumin and IgG adsorption is dependent on adsorption time...... and on the presence and concentration of other proteins in bulk solutions during adsorption. Generally, lower albumin and IgG adsorption was observed on the modified and more hydrophilic polymer surfaces, but otherwise the modified and unmodified polymer surfaces showed the same adsorption characteristics....

Hydrophilic crosslinked-polymeric surface capable of effective suppression of protein adsorption

Energy Technology Data Exchange (ETDEWEB)

Kamon, Yuri; Inoue, Naoko; Mihara, Erika; Kitayama, Yukiya; Ooya, Tooru; Takeuchi, Toshifumi, E-mail: takeuchi@gold.kobe-u.ac.jp

2016-08-15

Highlights: • Three hydrophilic crosslinked polymers were examined for protein adsorption. • All polymers showed low nonspecific adsorption of negatively charged proteins. • Poly(MMPC) showed the lowest adsorption for positively charged proteins. • Poly(MMPC) is able to reduce nonspecific adsorption of a wide range of proteins. - Abstract: We investigated the nonspecific adsorption of proteins towards three hydrophilic crosslinked-polymeric thin layers prepared by surface-initiated atom transfer radical polymerization using N,N′-methylenebisacrylamide, 2-(methacryloyloxy)ethyl-[N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), or 6,6′-diacryloyl-trehalose crosslinkers. Protein binding experiments were performed by surface plasmon resonance with six proteins of different pI values including α-lactalbumin, bovine serum albumin (BSA), myoglobin, ribonuclease A, cytochrome C, and lysozyme in buffer solution at pH 7.4. All of the obtained crosslinked-polymeric thin layers showed low nonspecific adsorption of negatively charged proteins at pH 7.4 such as α-lactalbumin, BSA, and myoglobin. Nonspecific adsorption of positively charged proteins including ribonuclease A, cytochrome C, and lysozyme was the lowest for poly(MMPC). These results suggest poly(MMPC) can effectively reduce nonspecific adsorption of a wide range of proteins that are negatively or positively charged at pH 7.4. MMPC is a promising crosslinker for a wide range of polymeric materials requiring low nonspecific protein binding.

Protein Adsorption and Subsequent Fibroblasts Adhesion on Hydroxyapatite Nanocrystals

International Nuclear Information System (INIS)

Tagaya, Motohiro; Ikoma, Toshiyuki; Yoshioka, Tomohiko; Tanaka, Junzo; Takemura, Taro; Hanagata, Nobutaka

2011-01-01

Quartz crystal microbalance with dissipation (QCM-D) technique was employed for protein adsorption and subsequent fibroblast adhesion on hydroxyapatite (HAp) nanocrystals. The pre-adsorption of three proteins (albumin (BSA) or fibronectin (Fn) or collagen (Col)) and subsequent adsorption of fetal bovine serum (FBS), and the adhesion of fibroblasts on the surface were in situ monitored, and evaluated with the frequency shift (Δf) and dissipation energy shift (ΔD), and the viscoelastic change as ΔD-Δf plot. The Col adsorption showed larger Δf and ΔD values compared with BSA or Fn adsorption, and the subsequent FBS adsorption depended on the pre-adsorbed proteins. The ΔD-Δf plot of the cell adhesion also showed the different behaviour on the surfaces, indicating the process affected by cell-protein interactions. The confocal laser scanning microscope images of adherent cells showed the different morphology and pseudopod on the surfaces. The cells adhered on the surfaces modified with Fn and Col had the uniaxially expanded shape with fibrous pseudopods, while those modified with BSA had round shape. The different cell-protein interaction would cause the arrangement of extracellular matrix and cytoskeleton changes at the interfaces.

Protein Adsorption and Subsequent Fibroblasts Adhesion on Hydroxyapatite Nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Tagaya, Motohiro; Ikoma, Toshiyuki; Yoshioka, Tomohiko; Tanaka, Junzo [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, Tokyo, Tokyo 152-8550 (Japan); Takemura, Taro; Hanagata, Nobutaka, E-mail: tagaya.m.aa@m.titech.ac.jp [Biomaterials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan)

2011-10-29

Quartz crystal microbalance with dissipation (QCM-D) technique was employed for protein adsorption and subsequent fibroblast adhesion on hydroxyapatite (HAp) nanocrystals. The pre-adsorption of three proteins (albumin (BSA) or fibronectin (Fn) or collagen (Col)) and subsequent adsorption of fetal bovine serum (FBS), and the adhesion of fibroblasts on the surface were in situ monitored, and evaluated with the frequency shift ({Delta}f) and dissipation energy shift ({Delta}D), and the viscoelastic change as {Delta}D-{Delta}f plot. The Col adsorption showed larger {Delta}f and {Delta}D values compared with BSA or Fn adsorption, and the subsequent FBS adsorption depended on the pre-adsorbed proteins. The {Delta}D-{Delta}f plot of the cell adhesion also showed the different behaviour on the surfaces, indicating the process affected by cell-protein interactions. The confocal laser scanning microscope images of adherent cells showed the different morphology and pseudopod on the surfaces. The cells adhered on the surfaces modified with Fn and Col had the uniaxially expanded shape with fibrous pseudopods, while those modified with BSA had round shape. The different cell-protein interaction would cause the arrangement of extracellular matrix and cytoskeleton changes at the interfaces.

Adsorption of plasma proteins : adsorption behaviour on apolar surfaces and effect on colloid stability

NARCIS (Netherlands)

van der Scheer, Albert

1978-01-01

In this thesis the adsorption of some plasma proteins (human albumin (HSA) and fibrinogen (HFb)) on non polar surfaces is studied, together with the influence of these proteins on the stability of polystyrene latices. The aim of these investigations is a better understanding of the processes

Electrostatic interactions in protein adsorption probed by comparing lysozyme and succinylated lysozyme

NARCIS (Netherlands)

Veen, van der M.; Norde, W.; Cohen Stuart, M.A.

2004-01-01

The influence of electrostatic interactions on protein adsorption was studied by comparing the adsorption of lysozyme and succinylated lysozyme at silica surfaces. The succinylation affects the charge of the protein, but also the stability. Although changes in stability can have an influence on

Contributions of depth filter components to protein adsorption in bioprocessing.

Science.gov (United States)

Khanal, Ohnmar; Singh, Nripen; Traylor, Steven J; Xu, Xuankuo; Ghose, Sanchayita; Li, Zheng J; Lenhoff, Abraham M

2018-04-16

Depth filtration is widely used in downstream bioprocessing to remove particulate contaminants via depth straining and is therefore applied to harvest clarification and other processing steps. However, depth filtration also removes proteins via adsorption, which can contribute variously to impurity clearance and to reduction in product yield. The adsorption may occur on the different components of the depth filter, that is, filter aid, binder, and cellulose filter. We measured adsorption of several model proteins and therapeutic proteins onto filter aids, cellulose, and commercial depth filters at pH 5-8 and ionic strengths filter component in the adsorption of proteins with different net charges, using confocal microscopy. Our findings show that a complete depth filter's maximum adsorptive capacity for proteins can be estimated by its protein monolayer coverage values, which are of order mg/m 2 , depending on the protein size. Furthermore, the extent of adsorption of different proteins appears to depend on the nature of the resin binder and its extent of coating over the depth filter surface, particularly in masking the cation-exchanger-like capacity of the siliceous filter aids. In addition to guiding improved depth filter selection, the findings can be leveraged in inspiring a more intentional selection of components and design of depth filter construction for particular impurity removal targets. © 2018 Wiley Periodicals, Inc.

Incorporating water-release and lateral protein interactions in modeling equilibrium adsorption for ion-exchange chromatography.

Science.gov (United States)

Thrash, Marvin E; Pinto, Neville G

2006-09-08

The equilibrium adsorption of two albumin proteins on a commercial ion exchanger has been studied using a colloidal model. The model accounts for electrostatic and van der Waals forces between proteins and the ion exchanger surface, the energy of interaction between adsorbed proteins, and the contribution of entropy from water-release accompanying protein adsorption. Protein-surface interactions were calculated using methods previously reported in the literature. Lateral interactions between adsorbed proteins were experimentally measured with microcalorimetry. Water-release was estimated by applying the preferential interaction approach to chromatographic retention data. The adsorption of ovalbumin and bovine serum albumin on an anion exchanger at solution pH>pI of protein was measured. The experimental isotherms have been modeled from the linear region to saturation, and the influence of three modulating alkali chlorides on capacity has been evaluated. The heat of adsorption is endothermic for all cases studied, despite the fact that the net charge on the protein is opposite that of the adsorbing surface. Strong repulsive forces between adsorbed proteins underlie the endothermic heat of adsorption, and these forces intensify with protein loading. It was found that the driving force for adsorption is the entropy increase due to the release of water from the protein and adsorbent surfaces. It is shown that the colloidal model predicts protein adsorption capacity in both the linear and non-linear isotherm regions, and can account for the effects of modulating salt.

Correlation Study of PVDF Membrane Morphology with Protein Adsorption: Quantitative Analysis by FTIR/ATR Technique

Science.gov (United States)

Ideris, N.; Ahmad, A. L.; Ooi, B. S.; Low, S. C.

2018-05-01

Microporous PVDF membranes were used as protein capture matrices in immunoassays. Because the most common labels in immunoassays were detected based on the colour change, an understanding of how protein concentration varies on different PVDF surfaces was needed. Herein, the correlation between the membrane pore size and protein adsorption was systematically investigated. Five different PVDF membrane morphologies were prepared and FTIR/ATR was employed to accurately quantify the surface protein concentration on membranes with small pore sizes. SigmaPlot® was used to find a suitable curve fit for protein adsorption and membrane pore size, with a high correlation coefficient, R2, of 0.9971.

[Blood plasma protein adsorption capacity of perfluorocarbon emulsion stabilized by proxanol 268 (in vitro and in vivo studies)].

Science.gov (United States)

Sklifas, A N; Zhalimov, V K; Temnov, A A; Kukushkin, N I

2012-01-01

The adsorption abilities of the perfluorocarbon emulsion stabilized by Proxanol 268 were investigated in vitro and in vivo. In vitro, the saturation point for the blood plasma proteins was nearly reached after five minutes of incubation of the emulsion with human/rabbit blood plasma and was stable for all incubation periods studied. The decrease in volume ratio (emulsion/plasma) was accompanied by the increase in the adsorptive capacity of the emulsion with maximal values at 1/10 (3.2 and 1.5 mg of proteins per 1 ml of the emulsion, for human and rabbit blood plasma, respectively) that was unchanged at lower ratios. In vivo, in rabbits, intravenously injected with the emulsion, the proteins with molecular masses of 12, 25, 32, 44, 55, 70, and 200 kDa were adsorbed by the emulsion (as in vitro) if it was used 6 hours or less before testing. More delayed testing (6 h) revealed elimination of proteins with molecular masses of 25 and 44 kDa and an additional pool of adsorpted new ones of 27, 50, and 150 kDa. Specific adsorptive capacity of the emulsion enhanced gradually after emulsion injection and reached its maximum (3.5-5 mg of proteins per 1 ml of the emulsion) after 24 hours.

TIRF and its application to protein adsorption : electrostatics and orientation

NARCIS (Netherlands)

Bos, M.A.

1994-01-01

The aim of the study in this thesis was to develop a method for determining the orientation of adsorbed protein molecules and to study the influence of the electrical potential of the interface on the interfacial properties of proteins, including their orientation.

In the adsorption

Equilibrium of adsorption of mixed milk protein/surfactant solutions at the water/air interface.

Science.gov (United States)

Kotsmar, C; Grigoriev, D O; Xu, F; Aksenenko, E V; Fainerman, V B; Leser, M E; Miller, R

2008-12-16

Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

Protein aggregation and degradation during iodine labeling and its consequences for protein adsorption to biomaterials

DEFF Research Database (Denmark)

Holmberg, Maria; Jensen, Karin Bagger Stibius; Ndoni, Sokol

2007-01-01

Protein adsorption on modified and unmodified polymer surfaces investigated through radiolabeling experiments showed a tendency for higher than expected albumin and immunoglobulin G (IgG) adsorption. Possible enhanced protein aggregation and degradation caused by the iodine labeling method used w...

Effects of thermal treatments on protein adsorption of Co-Cr-Mo ASTM-F75 alloys.

Science.gov (United States)

Duncan, L A; Labeed, F H; Abel, M-L; Kamali, A; Watts, J F

2011-06-01

Post-manufacturing thermal treatments are commonly employed in the production of hip replacements to reduce shrinkage voids which can occur in cast components. Several studies have investigated the consequences of these treatments upon the alloy microstructure and tribological properties but none have determined if there are any biological ramifications. In this study the adsorption of proteins from foetal bovine serum (FBS) on three Co-Cr-Mo ASTM-F75 alloy samples with different metallurgical histories, has been studied as a function of protein concentration. Adsorption isotherms have been plotted using the surface concentration of nitrogen as a diagnostic of protein uptake as measured by X-ray photoelectron spectroscopy. The data was a good fit to the Langmuir adsorption isotherm up to the concentration at which critical protein saturation occurred. Differences in protein adsorption on each alloy have been observed. This suggests that development of the tissue/implant interface, although similar, may differ between as-cast (AC) and heat treated samples.

A review of the thermodynamics of protein association to ligands, protein adsorption, and adsorption isotherms

DEFF Research Database (Denmark)

Mollerup, Jørgen

2008-01-01

The application of thermodynamic models in the development of chromatographic separation processes is discussed. The paper analyses the thermodynamic principles of protein adsorption. It can be modeled either as a reversible association between the adsorbate and the ligands or as a steady...

Protein adsorption on tailored substrates: long-range forces and conformational changes

Energy Technology Data Exchange (ETDEWEB)

Bellion, M; Santen, L [Department of Theoretical Physics, Saarland University, 66041 Saarbruecken (Germany); Mantz, H; Haehl, H; Quinn, A; Nagel, A; Gilow, C; Weitenberg, C; Schmitt, Y; Jacobs, K [Department of Experimental Physics, Saarland University, 66041 Saarbruecken (Germany)], E-mail: k.jacobs@physik.uni-saarland.de

2008-10-08

Adsorption of proteins onto solid surfaces is an everyday phenomenon that is not yet fully understood. To further the current understanding, we have performed in situ ellipsometry studies to reveal the adsorption kinetics of three different proteins, lysozyme, {alpha}-amylase and bovine serum albumin. As substrates we offer Si wafers with a controlled Si oxide layer thickness and a hydrophilic or hydrophobic surface functionalization, allowing the tailoring of the influence of short- and long-range interactions. Our studies show that not only the surface chemistry determines the properties of an adsorbed protein layer but also the van der Waals contributions of a composite substrate. We compare the experimental findings to results of a colloidal Monte Carlo approach that includes conformational changes of the adsorbed proteins induced by density fluctuations.

A comparison of the adsorption of saliva proteins and some typical proteins onto the surface of hydroxyapatite

NARCIS (Netherlands)

Kawasaki, K; Kambara, M; Matsumura, H; Norde, W

2003-01-01

Adsorption of protein from saliva on hydroxyapatite was compared with adsorption of several typical proteins with different electric charges, i.e. lysozyme, human serum albumin, beta-lactoglobulin and ovalbumin. Adsorbed amounts of these proteins were determined and electrophoretic mobilities of

A comparison of the adsorption of saliva proteins and some typical proteins onto the surface of hydroxyapatite

NARCIS (Netherlands)

Kawasaki, K.; Kambara, M.; Matsumura, H.; Norde, W.

2003-01-01

Adsorption of protein from saliva on hydroxyapatite was compared with adsorption of several typical proteins with different electric charges, i.e. lysozyme, human serum albumin, @b-lactoglobulin and ovalbumin. Adsorbed amounts of these proteins were determined and electrophoretic mobilities of

Self-colored nanoparticles containing naphthalene-bisimide derivatives: Synthesis and protein adsorption study

Energy Technology Data Exchange (ETDEWEB)

Polpanich, Duangporn, E-mail: duangporn@nanotec.or.th [National Nanotechnology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120 (Thailand); Asawapirom, Udom; Thiramanas, Raweewan; Piyakulawat, Phimwipha [National Nanotechnology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120 (Thailand)

2011-09-15

Highlights: {yields} Novel polymerizable naphthalene-bisimide dyes were designed and synthesized. {yields} Highly monodispersed self-colored nanoparticles were successfully prepared. {yields} Good colloidal stability of the nanoparticles was achieved after protein adsorption. - Abstract: An approach to covalently bound the novel polymerizable dyes, 2,3,6,7-tetrathienyl-1,4,5,8-naphthalenetetracarboxylic-N,N' -di(2-methylallyl)-bisimide (ALN4T) and 2,3,6,7-tetra(2,2'-bithiophene)-1,4,5,8-naphthalenetetracarboxylic-N,N' -di(2-methylallyl)-bisimide (ALN8T), and vinyl monomers for tailoring the self-colored nanoparticles (NPs) was demonstrated. Using the miniemulsion polymerization technique, the NPs with high conversion were synthesized. Examining the particles by scanning electron micrograph (SEM) revealed a uniform size distribution. UV/vis spectroscopy results showed that the colored NPs comprising of ALN4T exhibited the same absorption maxima compared to that of the parent dye, while a hypsochromic shift was observed when using ALN8T. By using bovine serum albumin (BSA) as a model, the amount of protein adsorption ({Gamma}{sub ads}) onto the surface of the colored NPs was evaluated. The {Gamma}{sub ads} on the colored NPs was found to be dictated by synergistic effects of the conformation change of BSA at a given pH and the electrostatic interaction between the protein and the particle surface. The good colloidal stability of the NPs after BSA adsorption was observed by zeta potential measurement. Therefore, the prepared self-colored NPs have potential application in biomedical areas.

Protein Adsorption to Titanium and Zirconia Using a Quartz Crystal Microbalance Method

Directory of Open Access Journals (Sweden)

You Kusakawa

2017-01-01

Full Text Available Protein adsorption onto titanium (Ti or zirconia (ZrO2 was evaluated using a 27 MHz quartz crystal microbalance (QCM. As proteins, fibronectin (Fn, a cell adhesive protein, and albumin (Alb, a cell adhesion-inhibiting protein, were evaluated. The Ti and ZrO2 sensors for QCM were characterized by atomic force microscopy and electron probe microanalysis observation, measurement of contact angle against water, and surface roughness. The amounts of Fn and Alb adsorbed onto the Ti and ZrO2 sensors and apparent reaction rate were obtained using QCM measurements. Ti sensor showed greater adsorption of Fn and Alb than the ZrO2 sensor. In addition, amount of Fn adsorbed onto the Ti or ZrO2 sensors was higher than that of Alb. The surface roughness and hydrophilicity of Ti or ZrO2 may influence the adsorption of Fn or Alb. With regard to the adsorption rate, Alb adsorbed more rapidly than Fn onto Ti. Comparing Ti and ZrO2, Alb adsorption rate to Ti was faster than that to ZrO2. Fn adsorption will be effective for cell activities, but Alb adsorption will not. QCM method could simulate in vivo Fn and Alb adsorption to Ti or ZrO2.

Competitive Protein Adsorption of Albumin and Immunoglobulin G from Human Serum onto Polymer Surfaces

DEFF Research Database (Denmark)

Holmberg, Maria; Hou, Xiaolin

2010-01-01

protein adsorption from diluted human serum solutions with relatively low protein concentrations, but the nonfouling character was weakened when less diluted human serum solutions with higher protein concentrations were used. The observed adsorption trend is independent of adsorption time, indicating...

A KINETIC MODEL FOR MONO-LAYER GLOBULAR PROTEIN ADSORPTION ON SOLID/LIQUID INTERFACES

Directory of Open Access Journals (Sweden)

Kamal I. M. Al-Malah

2012-12-01

Full Text Available A kinetic model was derived for globular protein adsorption. The model takes into account the three possible scenarios of a protein molecule in solution, being exposed to an interface: adsorption step from the solution to the interface; the possible desorption back into the solution; and the surface-induced unfolding or spreading of the protein unto the substrate surface. A globular protein molecule is visualized as a sphere with radius D. In addition to the general case of protein adsorption, which portrays either the surface coverage (Theta or surface concentration (� as a function of the adsorption time, special cases, like equilibrium condition, lowsurface coverage, irreversible, and Langmuirian were also presented and treated in light of the derived model. The general model was simplified for each of the subset cases. The irreversibility versus reversibility of protein adsorption was discussed. The substrate surface energetics or effects are accounted for via the proposition of the percent relative change in D/V ratio for the adsorbing protein, called (D/VPRC parameter. (D/VPRC is calculated with respect to the monolayer surface concentration of protein, where the latter is given by D/Vratio. This can be used as a landmark to protein adsorption isotherms or even kinetics. This is visualized as an indicator for solid substrate effects on the adsorbing proteins. (D/VPRC can be zero (fresh monolayer, negative (aged monolayer, or positive (multi-layer. The reference surface concentration is reported for some selected proteins.

Adsorption of Hydrophobin-Protein Mixtures at the Air-Water Interface: The Impact of pH and Electrolyte.

Science.gov (United States)

Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Cox, Andrew R; Hedges, Nick

2015-09-15

The adsorption of the proteins β-casein, β-lactoglobulin, and hydrophobin, and the protein mixtures of β-casein/hydrophobin and β-lactoglobulin/hydrophobin have been studied at the air-water interface by neutron reflectivity, NR. Changing the solution pH from 7 to 2.6 has relatively little impact on the adsorption of hydrophobin or β-lactoglobulin, but results in a substantial change in the structure of the adsorbed layer of β-casein. In β-lactoglobulin/hydrophobin mixtures, the adsorption is dominated by the hydrophobin adsorption, and is independent of the hydrophobin or β-lactoglobulin concentration and solution pH. At pH 2.6, the adsorption of the β-casein/hydrophobin mixtures is dominated by the hydrophobin adsorption over the range of β-casein concentrations studied. At pH 4 and 7, the adsorption of β-casein/hydrophobin mixtures is dominated by the hydrophobin adsorption at low β-casein concentrations. At higher β-casein concentrations, β-casein is adsorbed onto the surface monolayer of hydrophobin, and some interpenetration between the two proteins occurs. These results illustrate the importance of pH on the intermolecular interactions between the two proteins at the interface. This is further confirmed by the impact of PBS, phosphate buffered saline, buffer and CaCl2 on the coadsorption and surface structure. The results provide an important insight into the adsorption properties of protein mixtures and their application in foam and emulsion stabilization.

Gold nanoparticles: role of size and surface chemistry on blood protein adsorption

Energy Technology Data Exchange (ETDEWEB)

Benetti, F., E-mail: filippo.benetti@unitn.it; Fedel, M. [BIOtech Research Centre (Italy); Minati, L.; Speranza, G. [Fondazione Bruno Kessler (Italy); Migliaresi, C. [BIOtech Research Centre (Italy)

2013-06-15

Material interaction with blood proteins is a critical issue, since it could influence the biological processes taking place in the body following implantation/injection. This is particularly important in the case of nanoparticles, where innovative properties, such as size and high surface to volume ratio can lead to a behavioral change with respect to bulk macroscopic materials and could be responsible for a potential risk for human health. The aim of this work was to compare gold nanoparticles (AuNP) and planar surfaces to study the role of surface curvature moving from the macro- to the nano-size in the process of blood protein adsorption. In the course of the study, different protocols were tested to optimize the analysis of protein adsorption on gold nanoparticles. AuNP with different size (10, 60 and 200 nm diameter) and surface coatings (citrate and polyethylene glycol) were carefully characterized. The stabilizing action of blood proteins adsorbed on AuNP was studied measuring the variation of size and solubility of the nanoparticles following incubation with single protein solutions (human serum albumin and fibrinogen) and whole blood plasma. In addition, we developed a method to elute proteins from AuNP to study the propensity of gold materials to adsorb plasma proteins in function of dimensional characteristics and surface chemistry. We showed a different efficacy of the various eluting media tested, proving that even the most aggressive agent cannot provide a complete detachment of the protein corona. Enhanced protein adsorption was evidenced on AuNP if compared to gold laminae (bare and PEGylated) used as macroscopic control, probably due to the superior AuNP surface reactivity.

A modified Poisson-Boltzmann equation applied to protein adsorption.

Science.gov (United States)

Gama, Marlon de Souza; Santos, Mirella Simões; Lima, Eduardo Rocha de Almeida; Tavares, Frederico Wanderley; Barreto, Amaro Gomes Barreto

2018-01-05

Ion-exchange chromatography has been widely used as a standard process in purification and analysis of protein, based on the electrostatic interaction between the protein and the stationary phase. Through the years, several approaches are used to improve the thermodynamic description of colloidal particle-surface interaction systems, however there are still a lot of gaps specifically when describing the behavior of protein adsorption. Here, we present an improved methodology for predicting the adsorption equilibrium constant by solving the modified Poisson-Boltzmann (PB) equation in bispherical coordinates. By including dispersion interactions between ions and protein, and between ions and surface, the modified PB equation used can describe the Hofmeister effects. We solve the modified Poisson-Boltzmann equation to calculate the protein-surface potential of mean force, treated as spherical colloid-plate system, as a function of process variables. From the potential of mean force, the Henry constants of adsorption, for different proteins and surfaces, are calculated as a function of pH, salt concentration, salt type, and temperature. The obtained Henry constants are compared with experimental data for several isotherms showing excellent agreement. We have also performed a sensitivity analysis to verify the behavior of different kind of salts and the Hofmeister effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of protein adsorption onto a polyurethane nanofiber surface having different segment distributions

Energy Technology Data Exchange (ETDEWEB)

Morita, Yuko; Koizumi, Gaku [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan); Sakamoto, Hiroaki, E-mail: hi-saka@u-fukui.ac.jp [Tenure-Track Program for Innovative Research, University of Fukui (Japan); Suye, Shin-ichiro [Frontier Fiber Technology and Science, Graduate School of Engineering, University of Fukui (Japan)

2017-02-01

Electrospinning is well known to be an effective method for fabricating polymeric nanofibers with a diameter of several hundred nanometers. Recently, the molecular-level orientation within nanofibers has attracted particular attention. Previously, we used atomic force microscopy to visualize the phase separation between soft and hard segments of a polyurethane (PU) nanofiber surface prepared by electrospinning. The unstretched PU nanofibers exhibited irregularly distributed hard segments, whereas hard segments of stretched nanofibers prepared with a high-speed collector exhibited periodic structures along the long-axis direction. PU was originally used to inhibit protein adsorption, but because the surface segment distribution was changed in the stretched nanofiber, here, we hypothesized that the protein adsorption property on the stretched nanofiber might be affected. We investigated protein adsorption onto PU nanofibers to elucidate the effects of segment distribution on the surface properties of PU nanofibers. The amount of adsorbed protein on stretched PU nanofibers was increased compared with that of unstretched nanofibers. These results indicate that the hard segment alignment on stretched PU nanofibers mediated protein adsorption. It is therefore expected that the amount of protein adsorption can be controlled by rotation of the collector. - Highlights: • The hard segments of stretched PU nanofibers exhibit periodic structures. • The adsorbed protein on stretched PU nanofibers was increased compared with PU film. • The hard segment alignment on stretched PU nanofibers mediated protein adsorption.

Protein Exposed Hydrophobicity Reduces the Kinetic Barrier for Adsorption of Ovalbumin to the Air-Water Interface

NARCIS (Netherlands)

Wierenga, P.A.; Meinders, M.B.J.; Egmond, M.R.; Voragen, F.A.G.J.; Jongh, H.H.J. de

2003-01-01

Using native and caprylated ovalbumin, the role of exposed hydrophobicity on the kinetics of protein adsorption to the air - water interface is studied. First, changes in the chemical properties of the protein upon caprylation were characterized followed by measurement of the changes in adsorption

Kinetics of protein adsorption/desorption mediated by pH-responsive polymer layer

International Nuclear Information System (INIS)

Su Xiao-Hang; Lei Qun-Li; Ren Chun-Lai

2015-01-01

We propose a new way of regulating protein adsorption by using a pH-responsive polymer. According to the theoretical results obtained from the molecular theory and kinetic approaches, both thermodynamics and kinetics of protein adsorption are verified to be well controlled by the solution pH. The kinetics and the amount of adsorbed proteins at equilibrium are greatly increased when the solution environment changes from acid to neutral. The reason is that the increased pH promotes the dissociation of the weak polyelectrolyte, resulting in more charged monomers and more stretched chains. Thus the steric repulsion within the polymer layer is weakened, which effectively lowers the barrier felt by the protein during the process of adsorption. Interestingly, we also find that the kinetics of protein desorption is almost unchanged with the variation of pH. It is because although the barrier formed by the polymer layer changes along with the change of pH, the potential at contact with the surface varies equally. Our results may provide useful insights into controllable protein adsorption/desorption in practical applications. (paper)

Protein adsorption on low temperature alpha alumina films for surgical instruments

Energy Technology Data Exchange (ETDEWEB)

Cloud, A.N., E-mail: acloud@uark.ed [University of Arkansas, Fayetteville, AR 72701 (United States); Kumar, S. [Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095 (Australia); Kavdia, M.; Abu-Safe, H.H.; Gordon, M.H. [University of Arkansas, Fayetteville, AR 72701 (United States)

2009-08-31

Bulk alumina has been shown to exhibit reduced protein adsorption, a property that can be exploited for developing alumina-coated surgical instruments and devices. Alpha alumina thin films were deposited on surgical stainless steel substrates to investigate the adsorption of a model protein (BSA, bovine serum albumin). The films were deposited at 480 {sup o}C by AC inverted cylindrical magnetron sputtering. Films were obtained at 6 kW and 50% oxygen partial pressure by volume. The presence of alpha-phase alumina has been shown by transmission electron microscopy. Results indicate that there was a 50% reduction in protein adsorption for samples with the alumina coating compared to those with no coating.

AFM-based force spectroscopy on polystyrene brushes: effect of brush thickness on protein adsorption.

Science.gov (United States)

Hentschel, Carsten; Wagner, Hendrik; Smiatek, Jens; Heuer, Andreas; Fuchs, Harald; Zhang, Xi; Studer, Armido; Chi, Lifeng

2013-02-12

Herein we present a study on nonspecific binding of proteins at highly dense packed hydrophobic polystyrene brushes. In this context, an atomic force microscopy tip was functionalized with concanavalin A to perform single-molecule force spectroscopy measurements on polystyrene brushes with thicknesses of 10 and 60 nm, respectively. Polystyrene brushes with thickness of 10 nm show an almost two times stronger protein adsorption than brushes with a thickness of 60 nm: 72 pN for the thinner and 38 pN for the thicker layer, which is in qualitative agreement with protein adsorption studies conducted macroscopically by fluorescence microscopy.

Mechanical properties of protein adsorption layers at the air/water and oil/water interface: a comparison in light of the thermodynamical stability of proteins.

Science.gov (United States)

Mitropoulos, Varvara; Mütze, Annekathrin; Fischer, Peter

2014-04-01

Over the last decades numerous studies on the interfacial rheological response of protein adsorption layers have been published. The comparison of these studies and the retrieval of a common parameter to compare protein interfacial activity are hampered by the fact that different boundary conditions (e.g. physico-chemical, instrumental, interfacial) were used. In the present work we review previous studies and attempt a unifying approach for the comparison between bulk protein properties and their adsorption films. Among many common food grade proteins we chose bovine serum albumin, β-lactoglobulin and lysozyme for their difference in thermodynamic stability and studied their adsorption at the air/water and limonene/water interface. In order to achieve this we have i) systematically analyzed protein adsorption kinetics in terms of surface pressure rise using a drop profile analysis tensiometer and ii) we addressed the interfacial layer properties under shear stress using an interfacial shear rheometer under the same experimental conditions. We could show that thermodynamically less stable proteins adsorb generally faster and yield films with higher shear rheological properties at air/water interface. The same proteins showed an analog behavior when adsorbing at the limonene/water interface but at slower rates. Copyright © 2013 Elsevier B.V. All rights reserved.

Preventing protein adsorption from a range of surfaces using an aqueous fish protein extract

DEFF Research Database (Denmark)

Pillai, Saju; Arpanaei, Ayyoob; Meyer, Rikke L.

2009-01-01

We utilize an aqueous extract of fish proteins (FPs) as a coating for minimizing the adsorption of fibrinogen (Fg) and human serum albumin (HSA). The surfaces include stainless steel (SS), gold (Au), silicon dioxide (SiO2), and poly(styrene) (PS). The adsorption processes (kinetics and adsorbed...

Reusable hydroxyapatite nanocrystal sensors for protein adsorption

International Nuclear Information System (INIS)

Tagaya, Motohiro; Ikoma, Toshiyuki; Hanagata, Nobutaka; Chakarov, Dinko; Kasemo, Bengt; Tanaka, Junzo

2010-01-01

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

Reusable hydroxyapatite nanocrystal sensors for protein adsorption

Directory of Open Access Journals (Sweden)

Motohiro Tagaya, Toshiyuki Ikoma, Nobutaka Hanagata, Dinko Chakarov, Bengt Kasemo and Junzo Tanaka

2010-01-01

Full Text Available The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp nanocrystal sensors was investigated by Fourier transform infrared (FTIR spectroscopy and quartz crystal microbalance with dissipation (QCM-D monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i ammonia/hydrogen peroxide mixture (APM, (ii ultraviolet light (UV, (iii UV/APM, (iv APM/UV and (v sodium dodecyl sulfate (SDS treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

Adsorption, desorption and biodegradation in soil of CrylAb toxin protein from Bt transgenic rice

International Nuclear Information System (INIS)

Wang Haiyan; Ye Qingfu

2004-01-01

The equilibrium adsorption and binding of CrylAb toxin from Bt transgenic rice, to 7 different soils and the biodegradation of the bound toxin were studied. The adsorption rate of Bt in soils improved with decreasing of the added Bt purified protein concentration. Adsorption rate (125 and 780 nm/ml) in powdery-muddy paddy soil, Fluvio-marine yellow loamy and Coastal saline soil were 24.85% and 40.81%, 9.1% and 31.67%, 12.47% and 30.75%, respectively. Desorption rate in the soils dropped with content of soil-absorbed protein decreased. Its adsorption ratio in powdery-muddy paddy soil was 12.95% and 5.88%, respectively. The relationship between adsorption amount and concentration of Bt purified protein in different soils was notably positive correlation (P 0 e -λt ); Half life of Bt protein in soils was among 15.2-97.6 d; Degradation of pruified Bt protein was rapid at the initial incubation time (30 d), but slow at 150d incubation; The degradation of purified Bt protein in Intertidal sandy soil was the slowest with half-life of 97.6d. The protein in the soil amended with 1.25 μg/g could be still detectable after incubation of 345d; the degradation of purified Bt protein in Coastal saline soil and Aquic light saline sandy soil were faster. Their half-lives were 19.6 d and 15.2 d, respecitvely. The residue time of Bt purified protein in the soils was all more than 150 d. (authors)

Kinetics of protein adsorption/desorption mediated by pH-responsive polymer layer

Science.gov (United States)

Su, Xiao-Hang; Lei, Qun-Li; Ren, Chun-Lai

2015-11-01

We propose a new way of regulating protein adsorption by using a pH-responsive polymer. According to the theoretical results obtained from the molecular theory and kinetic approaches, both thermodynamics and kinetics of protein adsorption are verified to be well controlled by the solution pH. The kinetics and the amount of adsorbed proteins at equilibrium are greatly increased when the solution environment changes from acid to neutral. The reason is that the increased pH promotes the dissociation of the weak polyelectrolyte, resulting in more charged monomers and more stretched chains. Thus the steric repulsion within the polymer layer is weakened, which effectively lowers the barrier felt by the protein during the process of adsorption. Interestingly, we also find that the kinetics of protein desorption is almost unchanged with the variation of pH. It is because although the barrier formed by the polymer layer changes along with the change of pH, the potential at contact with the surface varies equally. Our results may provide useful insights into controllable protein adsorption/desorption in practical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 21274062, 11474155, and 91027040).

Effect of DOPE and cholesterol on the protein adsorption onto lipid nanoparticles

International Nuclear Information System (INIS)

Caracciolo, Giulio; Pozzi, Daniela; Capriotti, Anna Laura; Cavaliere, Chiara; Laganà, Aldo

2013-01-01

Upon administration, nanoparticles (NPs) are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a “protein corona”. NP–protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here, we have investigated the effect of neutral dioleoylphosphatidylethanolamine (DOPE) and cholesterol on the adsorption of human plasma proteins onto the surface of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based cationic liposomes of 100 nm in diameter. Quantitative analysis of the protein corona revealed that replacing cationic DOTAP lipids with neutral lipids, being indifferently DOPE or cholesterol, reduces the affinity of fibrinogen, prothrombin, vitamin K, and vitronectin for the lipid surface. On the other side, DOPE specifically promotes the adsorption of apolipoproteins and serum albumin, while cholesterol induces the preferential binding of immunoglobulins and complement proteins. The results of this study will help to explain why NPs of different lipid compositions have a dramatic difference in their in vivo transfection efficiency and will be useful for design of lipid NPs with optimal circulation profiles.

Effect of DOPE and cholesterol on the protein adsorption onto lipid nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Caracciolo, Giulio, E-mail: giulio.caracciolo@uniroma1.it; Pozzi, Daniela [' Sapienza' University of Rome, Department of Molecular Medicine (Italy); Capriotti, Anna Laura; Cavaliere, Chiara; Lagana, Aldo [' Sapienza' University of Rome, Department of Chemistry (Italy)

2013-03-15

Upon administration, nanoparticles (NPs) are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a 'protein corona'. NP-protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here, we have investigated the effect of neutral dioleoylphosphatidylethanolamine (DOPE) and cholesterol on the adsorption of human plasma proteins onto the surface of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based cationic liposomes of 100 nm in diameter. Quantitative analysis of the protein corona revealed that replacing cationic DOTAP lipids with neutral lipids, being indifferently DOPE or cholesterol, reduces the affinity of fibrinogen, prothrombin, vitamin K, and vitronectin for the lipid surface. On the other side, DOPE specifically promotes the adsorption of apolipoproteins and serum albumin, while cholesterol induces the preferential binding of immunoglobulins and complement proteins. The results of this study will help to explain why NPs of different lipid compositions have a dramatic difference in their in vivo transfection efficiency and will be useful for design of lipid NPs with optimal circulation profiles.

Polysaccharide charge density regulating protein adsorption to air/water interfaces by protein/polysaccharide complex formation

NARCIS (Netherlands)

Ganzevles, R.A.; Kosters, H.; Vliet, T. van; Stuart, M.A.C.; Jongh, H.H.J. de

2007-01-01

Because the formation of protein/polysaccharide complexes is dominated by electrostatic interaction, polysaccharide charge density is expected to play a major role in the adsorption behavior of the complexes. In this study, pullulan (a non-charged polysaccharide) carboxylated to four different

Protein adsorption at air-water interfaces: A combination of details

NARCIS (Netherlands)

Jongh, de H.H.J.; Kosters, H.A.; Kudryashova, E.; Meinders, M.B.J.; Trofimova, D.; Wierenga, P.A.

2004-01-01

Using a variety of spectroscopic techniques, a number of molecular functionalities have been studied in relation to the adsorption process of proteins to air-water interfaces. While ellipsometry and drop tensiometry are used to derive information on adsorbed amount and exerted surface pressure,

Protein Adsorption at Air-Water Interfaces: A Combination of Details

NARCIS (Netherlands)

Jongh, H.H.J.de; Kosters, H.A.; Kudryashova, E.; Meinders, M.B.J.; Trofimova, D.; Wierenga, P.A.

2004-01-01

Using a variety of spectroscopic techniques, a number of molecular functionalities have been studied in relation to the adsorption process of proteins to air-water interfaces. While ellipsometry and drop tensiometry are used to derive information on adsorbed amount and exerted surface pressure,

Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Yuan, Huihui; Qian, Bin; Zhang, Wei; Lan, Minbo

2016-01-01

Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm"2, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Yuan, Huihui; Qian, Bin; Zhang, Wei [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Lan, Minbo, E-mail: minbolan@ecust.edu.cn [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2016-02-15

Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm{sup 2}, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

[Inclusion of proteins into polyelectrolyte microcapsules by coprecipitation and adsorption].

Science.gov (United States)

Kochetkova, O Iu; Kazakova, L I; Moshkov, D A; Vinokurov, M G; Shabarchina, L I

2013-01-01

In present study microcapsules composed of synthetic (PSS and PAA) and biodegradable (DS and PAr) polyelectrolytes on calcium carbonate microparticles were obtained. The ultrastructural organization of biodegradable microcapsules was studied using transmission electron microscopy. The envelope of such capsules consisting of six polyelectrolyte layers is already well-formed, having the average thickness of 44 ± 3.0 nm, and their internal polyelectrolyte matrix is sparser compared to the synthetic microcapsules. Spectroscopy was employed to evaluate the efficiency of incorporation of FITC-labeled BSA into synthetic microcapsules by adsorption, depending on the number of polyelectrolyte layers. It was shown that the maximal amount of protein incorporated into the capsules with 6 or 7 polyelectrolyte layers (4 and 2 pg/capsule, correspondingly). As a result we conclude that, in comparison with co-precipitation, the use of adsorption allows to completely avoid the loss of protein upon encapsulation.

Characteristics of selective fluoride adsorption by biocarbon-Mg/Al layered double hydroxides composites from protein solutions: kinetics and equilibrium isotherms study.

Science.gov (United States)

Ma, Wei; Lv, Tengfei; Song, Xiaoyan; Cheng, Zihong; Duan, Shibo; Xin, Gang; Liu, Fujun; Pan, Decong

2014-03-15

In the study, two novel applied biocarbon-Mg/Al layered double hydroxides composites (CPLDH and CPLDH-Ca) were successfully prepared and characterized by TEM, ICP-AES, XFS, EDS, FTIR, XRD, BET and pHpzc. The fluoride removal efficiency (RF) and protein recovery ratio (RP) of the adsorbents were studied in protein systems of lysozyme (LSZ) and bovine serum albumin (BSA). The results showed that the CPLDH-Ca presented remarkable performance for selective fluoride removal from protein solution. It reached the maximum RF of 92.1% and 94.8% at the CPLDH-Ca dose of 2.0g/L in LSZ and BSA system, respectively. The RP in both systems of LSZ and BSA were more than 90%. Additionally, the RP of CPLDH-Ca increased with the increase of ionic strengths, and it almost can be 100% with more than 93% RF. Fluoride adsorption by the CPLDH-Ca with different initial fluoride concentrations was found to obey the mixed surface reaction and diffusion controlled adsorption kinetic model, and the overall reaction rate is probably controlled by intra-particle diffusion, boundary layer diffusion and reaction process. The adsorption isotherms of fluoride in BSA system fit the Langmuir-Freundlich model well. The BSA has synergistic effect on fluoride adsorption and the degree increased with the increase of the initial BSA concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

Atomistic simulation of the coupled adsorption and unfolding of protein GB1 on the polystyrenes nanoparticle surface

Science.gov (United States)

Xiao, HuiFang; Huang, Bin; Yao, Ge; Kang, WenBin; Gong, Sheng; Pan, Hai; Cao, Yi; Wang, Jun; Zhang, Jian; Wang, Wei

2018-03-01

Understanding the processes of protein adsorption/desorption on nanoparticles' surfaces is important for the development of new nanotechnology involving biomaterials; however, an atomistic resolution picture for these processes and for the simultaneous protein conformational change is missing. Here, we report the adsorption of protein GB1 on a polystyrene nanoparticle surface using atomistic molecular dynamic simulations. Enabled by metadynamics, we explored the relevant phase space and identified three protein states, each involving both the adsorbed and desorbed modes. We also studied the change of the secondary and tertiary structures of GB1 during adsorption and the dominant interactions between the protein and surface in different adsorption stages. The results we obtained from simulation were found to be more adequate and complete than the previous one. We believe the model presented in this paper, in comparison with the previous ones, is a better theoretical model to understand and explain the experimental results.

Use of quasi-isoelectric buffers to limit protein adsorption in capillary zone electrophoresis.

Science.gov (United States)

Poitevin, Martine; Hammad, Karim; Ayed, Ichraf; Righetti, Pier Giorgio; Peltre, Gabriel; Descroix, Stephanie

2008-08-01

The use of quasi-isoelectric buffers consisting of narrow pH cuts of carrier ampholytes (NC) has been investigated to limit protein adsorption on capillary walls during capillary zone electrophoresis experiments. To quantify protein adsorption on the silica surface, a method derived from that of Towns and Regnier has been developed. alpha-Lactalbumin (14 kDa, pI 4.8) and alpha-chymotrypsinogen A (25 kDa, pI 9.2) have been used as model proteins. Acidic narrow pH cuts of carrier ampholytes (NC, pH 3.0) obtained from fractionation of Serva 4-9 carrier ampholytes were used as BGE in bare-silica capillaries, and allowed to decrease significantly protein adsorption, as compared to experiments performed with classical formate buffer. The use of NC as BGE appeared to be as efficient as the use of polydimethylacrylamide coating to prevent protein adsorption. This increase of protein recovery when using NC was attributed to the interaction of carrier ampholytes with the silica surface, leading to a shielding of the capillary wall.

Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry

Energy Technology Data Exchange (ETDEWEB)

Silva-Bermudez, P., E-mail: suriel21@yahoo.com [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico); Unidad de Posgrado, Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, CU, 04510, Mexico D.F. (Mexico); Rodil, S.E.; Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico)

2011-12-15

Thin films of tantalum, niobium, zirconium and titanium oxides were deposited by reactive magnetron sputtering and their wettability and surface energy, optical properties, roughness, chemical composition and microstructure were characterized using contact angle measurements, spectroscopic ellipsometry, profilometry, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The purpose of the work was to correlate the surface properties of the films to the Bovine Serum Albumin (BSA) adsorption, as a first step into the development of an initial in vitro test of the films biocompatibility, based on standardized protein adsorption essays. The films were immersed into BSA solutions with different protein concentrations and protein adsorption was monitored in situ by dynamic ellipsometry; the adsorption-rate was dependent on the solution concentration and the immersion time. The overall BSA adsorption was studied in situ using spectroscopic ellipsometry and it was found to be influenced by the wettability of the films; larger BSA adsorption occurred on the more hydrophobic surface, the ZrO{sub 2} film. On the Ta{sub 2}O{sub 5}, Nb{sub 2}O{sub 5} and TiO{sub 2} films, hydrophilic surfaces, the overall BSA adsorption increased with the surface roughness or the polar component of the surface energy.

Protein-adsorption and Ca-phosphate formation on chitosan-bioactive glass composite coatings

Science.gov (United States)

Wagener, V.; Boccaccini, A. R.; Virtanen, S.

2017-09-01

In the last years, chitosan-bioactive glass (BG) composites have been developed and investigated as bioactive coatings for orthopedic applications. The increase of bioactivity occurs due to the stimulation of calcium-phosphate/hydroxyapatite formation on the surface while the coating is degrading. In the present work, protein adsorption and its influence on calcium-phosphate precipitation was studied for the first time on such composite coatings. The experiments involved coating of 316L stainless steel substrates with chitosan (Ch) and chitosan-bioactive glass (Ch-BG) and immersion of the coated samples in two different bovine serum albumin (BSA) containing solutions, namely DI H2O (with pH adjusted to about 7.2 with diluted NaOH) and simulated body fluid (SBF). In order to investigate the influence of protein adsorption on calcium-phosphate precipitation, samples were also immersed in DI H2O and in SBF without BSA. Samples were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Surface analysis revealed that adsorption of BSA takes place on all studied samples and that protein adsorption is influenced by the presence of Ca2+ and PO43- ions. Bioactivity in the form of hydroxyapatite pre-stage formation is significantly increased on Ch-BG composite coating as compared with bare stainless steel surface. However, calcium-phosphate precipitation in SBF is reduced by the presence of BSA.

The interplay between nanostructured carbon-grafted chitosan scaffolds and protein adsorption on the cellular response of osteoblasts: structure-function property relationship.

Science.gov (United States)

Depan, D; Misra, R D K

2013-04-01

The rapid adsorption of proteins occurs during the early stages of biomedical device implantation into physiological systems. In this regard, the adsorption of proteins is a strong function of the nature of a biomedical device, which ultimately governs the biological functions. The objective of this study was to elucidate the interplay between nanostructured carbon-modified (graphene oxide and single-walled carbon nanohorn) chitosan scaffolds and consequent protein adsorption and biological function (osteoblast function). We compare and contrast the footprint of protein adsorption on unmodified chitosan and nanostructured carbon-modified chitosan. A comparative analysis of cell-substrate interactions using an osteoblast cell line (MC3T3-E1) implied that biological functions were significantly enhanced in the presence of nanostructured carbon, compared with unmodified chitosan. The difference in their respective behaviors is related to the degree and topography of protein adsorption on the scaffolds. Furthermore, there was a synergistic effect of nanostructured carbon and protein adsorption in terms of favorably modulating biological functions, including cell attachment, proliferation and viability, with the effect being greater on nanostructured carbon-modified scaffolds. The study also underscores that protein adsorption is favored in nanostructured carbon-modified scaffolds such that bioactivity and biological function are promoted. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis of magnetite/graphene oxide/chitosan composite and its application for protein adsorption

Energy Technology Data Exchange (ETDEWEB)

Ye, Nengsheng, E-mail: yensh@cnu.edu.cn; Xie, Yali; Shi, Pengzhi; Gao, Ting; Ma, Jichao

2014-12-01

In this study, a facile and novel strategy was developed to fabricate magnetite/graphene oxide/chitosan (Fe{sub 3}O{sub 4}/GO/CS) composite, and the composite was used as a magnetic adsorbent for the enrichment of protein, and followed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF MS) analysis. The phase composition, chemical structure and morphology of the composite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electronic microscope (SEM) and vibrating sample magnetometer (VSM). Protein cytochrome c was chosen as model target to evaluate the adsorptive property of Fe{sub 3}O{sub 4}/GO/CS. After enrichment procedure and magnetic separation, protein bounded with the material was analyzed by MALDI-TOF MS without desorption. The results indicated that Fe{sub 3}O{sub 4}/GO/CS composite exhibited a good adsorptive capacity for protein, and Fe{sub 3}O{sub 4}/GO/CS composite had a promising potential in magnetic separation research. - Highlights: • Magnetite/graphene oxide/chitosan composite was synthesized by novel route. • The composite was used as magnetic absorbent for protein enrichment. • The composite had excellent adsorption performance for protein enrichment.

Surface properties of nanocrystalline TiO2 coatings in relation to the in vitro plasma protein adsorption

International Nuclear Information System (INIS)

Lorenzetti, M; Kobe, S; Novak, S; Bernardini, G; Santucci, A; Luxbacher, T

2015-01-01

This study reports on the selective adsorption of whole plasma proteins on hydrothermally (HT) grown TiO 2 -anatase coatings and its dependence on the three main surface properties: surface charge, wettability and roughness. The influence of the photo-activation of TiO 2 by UV irradiation was also evaluated. Even though the protein adhesion onto Ti-based substrates was only moderate, better adsorption of any protein (at pH = 7.4) occurred for the most negatively charged and hydrophobic substrate (Ti non-treated) and for the most nanorough and hydrophilic surface (HT Ti3), indicating that the mutual action of the surface characteristics is responsible for the attraction and adhesion of the proteins. The HT coatings showed a higher adsorption of certain proteins (albumin ‘passivation’ layer, apolipoproteins, vitamin D-binding protein, ceruloplasmin, α-2-HS-glycoprotein) and higher ratios of albumin to fibrinogen and albumin to immunoglobulin γ-chains. The UV pre-irradiation affected the surface properties and strongly reduced the adsorption of the proteins. These results provide in-depth knowledge about the characterization of nanocrystalline TiO 2 coatings for body implants and provide a basis for future studies on the hemocompatibility and biocompatibility of such surfaces. (paper)

In vitro investigation of protein adsorption and platelet adhesion on inorganic biomaterial surfaces

Energy Technology Data Exchange (ETDEWEB)

Yan Huang [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China); Lue Xiaoying [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)], E-mail: luxy@seu.edu.cn; Ma Jingwu [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China); Nan Huang [Institute of Biomaterials and Surface Engineering, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: nhuang@263.com

2008-11-15

The aim of this paper was to study the surface properties, protein adsorption and platelet adhesion behaviors of diamond-like carbon (DLC) and titanium (Ti) films. The surface energy and microstructures of these films were characterized by contact angle measurement and atomic force microscopy (AFM). A modified Coomassie brilliant blue (CBB) protein assay was used to study the amount of adsorbed proteins. Platelet adhesion was assessed by scanning electron microscopy (SEM). The AFM results show that the DLC film is smoother than Ti. Protein adsorption results from CBB protein assay show that the ratio of adsorbed albumin (Alb) to IgG (R{sub A/I}) on DLC is larger than Ti, which coincide with the sequence of the ratio of interfacial tension between solid surface and Alb ({gamma}{sub S,Alb}) to interfacial tension between surface and IgG ({gamma}{sub S,IgG}) ({gamma}{sub S,Alb}/{gamma}{sub S,IgG}). The DLC film has a preferential adsorption for Alb. The results suggest that the ratio of {gamma}{sub S,Alb}/{gamma}{sub S,IgG} may indicate an Alb/IgG affinity ratio of materials. More platelets adhere on Ti film than on DLC, which may correspond to the surface roughness of materials. The conclusion is the blood compatibility of DLC seems to be better than Ti.

Regular Nanoscale Protein Patterns via Directed Adsorption through Self-Assembled DNA Origami Masks.

Science.gov (United States)

Ramakrishnan, Saminathan; Subramaniam, Sivaraman; Stewart, A Francis; Grundmeier, Guido; Keller, Adrian

2016-11-16

DNA origami has become a widely used method for synthesizing well-defined nanostructures with promising applications in various areas of nanotechnology, biophysics, and medicine. Recently, the possibility to transfer the shape of single DNA origami nanostructures into different materials via molecular lithography approaches has received growing interest due to the great structural control provided by the DNA origami technique. Here, we use ordered monolayers of DNA origami nanostructures with internal cavities on mica surfaces as molecular lithography masks for the fabrication of regular protein patterns over large surface areas. Exposure of the masked sample surface to negatively charged proteins results in the directed adsorption of the proteins onto the exposed surface areas in the holes of the mask. By controlling the buffer and adsorption conditions, the protein coverage of the exposed areas can be varied from single proteins to densely packed monolayers. To demonstrate the versatility of this approach, regular nanopatterns of four different proteins are fabricated: the single-strand annealing proteins Redβ and Sak, the iron-storage protein ferritin, and the blood protein bovine serum albumin (BSA). We furthermore demonstrate the desorption of the DNA origami mask after directed protein adsorption, which may enable the fabrication of hierarchical patterns composed of different protein species. Because selectivity in adsorption is achieved by electrostatic interactions between the proteins and the exposed surface areas, this approach may enable also the large-scale patterning of other charged molecular species or even nanoparticles.

Protein Adsorption and Antibacterial Behavior for Hydroxyapatite Nanocrystals Prepared by Hydrothermal Method

OpenAIRE

笠原, 英充; 小形, 信男; 荻原, 隆

2005-01-01

Homogeneous hydroxyapatite nanocrystals which have aspect ratio with more than four were synthesized by hydrothermal method. X-ray fluorescence analysis revealed that the Ca/P ratio of hydroxyapatite nanocrystals was maintaining start composition. The protein adsorption properties and bacteria-resistant of hydroxyapatite nanocrystals were investigated. The protein adsorption properties of hydroxyapatite nanocrystals were improvement after the hydrothermal treatment. Bacteria-resistant behavio...

Proteins at fluid interfaces: adsorption layers and thin liquid films.

Science.gov (United States)

Yampolskaya, Galina; Platikanov, Dimo

2006-12-21

A review in which many original published results of the authors as well as many other papers are discussed. The structure and some properties of the globular proteins are shortly presented, special accent being put on the alpha-chymotrypsin (alpha-ChT), lysozyme (LZ), human serum albumin (HSA), and bovine serum albumin (BSA) which have been used in the experiments with thin liquid films. The behaviour of protein adsorption layers (PAL) is extensively discussed. The dynamics of PAL formation, including the kinetics of adsorption as well as the time evolution of the surface tension of protein aqueous solutions, are considered. A considerable place is devoted to the surface tension and adsorption isotherms of the globular protein solutions, the simulation of PAL by interacting hard spheres, the experimental surface tension isotherms of the above mentioned proteins, and the interfacial tension isotherms for the protein aqueous solution/oil interface. The rheological properties of PAL at fluid interfaces are shortly reviewed. After a brief information about the experimental methods for investigation of protein thin liquid (foam or emulsion) films, the properties of the protein black foam films are extensively discussed: the conditions for their formation, the influence of the electrolytes and pH on the film type and stability, the thermodynamic properties of the black foam films, the contact angles film/bulk and their dynamic hysteresis. The next center of attention concerns some properties of the protein emulsion films: the conditions for formation of emulsion black films, the formation and development of a dimpling in microscopic, circular films. The protein-phospholipid mixed foam films are also briefly considered.

A study on poly (N-vinyl-2-pyrrolidone covalently bonded NiTi surface for inhibiting protein adsorption

Directory of Open Access Journals (Sweden)

Hongyan Yu

2016-12-01

Full Text Available Near equiatomic NiTi alloys have been extensively applied as biomaterials owing to its unique shape memory effect, superelasticity and biocompatibility. It has been demonstrated that surfaces capable of preventing plasma protein adsorption could reduce the reactivity of biomaterials with human blood. This motivated a lot of researches on the surface modification of NiTi alloy. In the present work, following heat and alkaline treatment and silanization by trichlorovinylsilane (TCVS, coating of poly (N-vinyl-2-pyrrolidone (PVP was produced on the NiTi alloy by gamma ray induced chemical bonding. The structures and properties of modified NiTi were characterized and in vitro biocompatibility of plasma protein adsorption was investigated. The results indicated that heat treatment at 823 K for 1 h could result in the formation of a protective TiO2 layer with “Ni-free” zone on NiTi surface. It was found that PVP was covalently bonded on NiTi surface to create a hydrophilic layer for inhibiting protein adsorption on the surface. The present work offers a green approach to introduce a bioorganic surface on metal and other polymeric or inorganic substrates by gamma irradiation.

Using mathematical models to understand the effect of nanoscale roughness on protein adsorption for improving medical devices

Directory of Open Access Journals (Sweden)

Ercan B

2013-09-01

Full Text Available Batur Ercan,1 Dongwoo Khang,2 Joseph Carpenter,3 Thomas J Webster1 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2School of Materials Science and Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South Korea; 3School of Medicine, Stanford University, Stanford, CA, USA Abstract: Surface roughness and energy significantly influence protein adsorption on to biomaterials, which, in turn, controls select cellular adhesion to determine the success and longevity of an implant. To understand these relationships at a fundamental level, a model was originally proposed by Khang et al to correlate nanoscale surface properties (specifically, nanoscale roughness and energy to protein adsorption, which explained the greater cellular responses on nanostructured surfaces commonly reported in the literature today. To test this model for different surfaces from what was previously used to develop that model, in this study we synthesized highly ordered poly(lactic-co-glycolic acid surfaces of identical chemistry but altered nanoscale surface roughness and energy using poly(dimethylsiloxane molds of polystyrene beads. Fibronectin and collagen type IV adsorption studies showed a linear adsorption behavior as the surface nanoroughness increased. This supported the general trends observed by Khang et al. However, when fitting such data to the mathematical model established by Khang et al, a strong correlation did not result. Thus, this study demonstrated that the equation proposed by Khang et al to predict protein adsorption should be modified to accommodate for additional nanoscale surface property contributions (ie, surface charge to make the model more accurate. In summary, results from this study provided an important step in developing future mathematical models that can correlate surface properties (such as nanoscale roughness and surface energy to initial protein adsorption events important to

Magnetic polymeric microspheres for protein adsorption

International Nuclear Information System (INIS)

Felinto, M.C.F.C.; Parra, D.F.; Lugao, A.B.; Batista, M.P.; Higa, O.Z.; Yamaura, M.; Camilo, R.L.; Ribela, M.T.C.P.; Sampaio, L.C.

2005-01-01

Magnetic beads consisting of polymer-coated manganese ferrite nanoparticles were prepared by the precipitation reaction of manganese ferrite into the channels of methyl methacrylate polymer beads by sodium hydroxide, resulting in MnMagBead. MnMagBead was characterized by infrared spectra (FTIR), thermogravimetric analysis of TGA/DTG and indicates the presence of -CO (carbonyl) groups and the MnFe 2 O 4 on the beads. Magnetization measurements were obtained at room temperature in magnetic fields up to 10 KOe using a vibrating sample magnetometer. Introductory Protein adsorption biological tests were processed using labeled I-125 albumin (BSA), and the activity was measured in a gamma counting spectrometer. These superparamagnetic beads exhibit the capacity to bind biological molecules such as proteins like albumin, with a good capability (5 x 10 -6 ) μg/100 mg of beads as compared with other magnetic resins studied in our group

Apatite nano-crystalline surface modification of poly(lactide-co-glycolide) sintered microsphere scaffolds for bone tissue engineering: implications for protein adsorption.

Science.gov (United States)

Jabbarzadeh, Ehsan; Nair, Lakshmi S; Khan, Yusuf M; Deng, Meng; Laurencin, Cato T

2007-01-01

A number of bone tissue engineering approaches are aimed at (i) increasing the osteconductivity and osteoinductivity of matrices, and (ii) incorporating bioactive molecules within the scaffolds. In this study we examined the growth of a nano-crystalline mineral layer on poly(lactide-co-glycolide) (PLAGA) sintered microsphere scaffolds for tissue engineering. In addition, the influence of the mineral precipitate layer on protein adsorption on the scaffolds was studied. Scaffolds were mineralized by incubation in simulated body fluid (SBF). Scanning electron microscopy (SEM) analysis revealed that mineralized scaffolds possess a rough surface with a plate-like nanostructure covering the surface of microspheres. The results of protein adsorption and release studies showed that while the protein release pattern was similar for PLAGA and mineralized PLAGA scaffolds, precipitation of the mineral layer on PLAGA led to enhanced protein adsorption and slower protein release. Mineralization of tissue-engineered surfaces provides a method for both imparting bioactivity and controlling levels of protein adsorption and release.

Adsorptive loss of secreted recombinant proteins in transgenic rice cell suspension cultures.

Science.gov (United States)

Kwon, Jun-Young; Lee, Kyoung-Hoon; Cheon, Su-Hwan; Ryu, Hyun-Nam; Kim, Sun Jin; Kim, Dong-Il

2012-03-01

Adsorptive loss of human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) in transgenic rice cell suspension cultures was investigated using glass flasks, plastic flasks, disposable vessels, and stainless steel vessels. When hCTLA4Ig was added to the glass flasks containing sterile AA medium, a rapid decrease in the concentration of hCTLA4Ig, independent on pH, was observed resulting in more than 90% of the protein loss within 1 h due to the surface adsorption. When the same experiments were performed on four different types of culture equipments mentioned above, the lowest adsorption level was observed in the plastic flasks and the highest level was observed in the glass flasks. The use of the plastic flasks retarded the adsorptive loss of hCTLA4Ig at the early stage of the protein production. There was a significant increase in the production of hCTLA4Ig when the flasks were coated with bovine serum albumin. However, the spike test of purified hCTLA4Ig at two different concentrations of 15 and 100 mg L(-1) in 500-mL spinner flasks confirmed that the amount of hCTLA4Ig adsorbed was dependent on the surface area of the flasks but not on the concentrations. In conclusion, although the protein adsorption affected the total amount of the protein yielded to some extent, it could be regarded as a minor factor in transgenic plant cell cultures with higher titer.

Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption.

Science.gov (United States)

Cai, Zhu-Yun; Peng, Fan; Zi, Yun-Peng; Chen, Feng; Qian, Qi-Rong

2015-07-31

Synthetic calcium phosphate (CaP)-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP) nanostructure was prepared under weak acidic conditions (pH 5), while the HAP nanorod was prepared under neutral (pH 7) and weak alkali (pH 9) condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb) as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption

Directory of Open Access Journals (Sweden)

Zhu-Yun Cai

2015-07-01

Full Text Available Synthetic calcium phosphate (CaP-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP nanostructure was prepared under weak acidic conditions (pH 5, while the HAP nanorod was prepared under neutral (pH 7 and weak alkali (pH 9 condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

Hydrogel covered bimetallic Co:Ni magnetic nano alloy for protein adsorption in biomedical application

Science.gov (United States)

Rajar, Kausar; Alveroglu, Esra

2017-10-01

In this study, polyacrylamide (PAAm) hydrogel covered CoNi magnetic nanoalloys with various Co/Ni molar ratio (from 1/4 to 4/1) were synthesized, characterized and used for adsorption of Bovine Serum Albumin (BSA). XRD, EDS, VSM, SEM, AFM, Automated Gas Sorption Analyzer and Fluorescence measurements were used for characterizations and adsorption studies. The results confirm that all the synthesized nanoalloys have soft ferromagnetic nature and particles size were determined to be in the range of 8.60-12.19 nm. Adsorption performances of magnetic nanoalloys were investigated on bovine serum albumin (BSA) as a model protein. The results showed that prepared CoNi:PAAm composites have multistage adsorption kinetics for BSA and increasing Ni content in the CoNi nanoalloys enhance the adsorption rate constant and the rate constant can be tuned between 0.003 s-1 and 0.009 s-1 and between 0.01 s-1 and 0.60 s-1 for the first order adsorption and the second order adsorption stages, respectively. These results show that CoNi:PAAm composites can open new pathways for preparing a special composite material which has specific adsorption kinetic for bio-separation technology.

Use of polysaccharides to control protein adsorption to the air-water interface

NARCIS (Netherlands)

Ganzevles, R.A.; Cohen Stuart, M.A.; Vliet, T.v.; Jongh, H.H.J.de

2006-01-01

In order to understand foaming behaviour of mixed protein/anionic polysaccharide solutions, we investigated the effect of β-lactoglobulin/pectin interaction in the bulk on β-lactoglobulin adsorption to the air-water interface. Adsorption kinetics were evaluated by following surface pressure

Protein adsorption at polymer-grafted surfaces: Comparison between a mixture of saliva proteins and some well-defined model proteins

NARCIS (Netherlands)

Kawasaki, K.; Kambara, M.; Matsumura, H.; Norde, W.

2003-01-01

Grafting a dense layer of soluble polymers onto a surface is a well-established method for controlling protein adsorption. In the present study, polyethylene oxide (PEO) layers of three different grafting densities were prepared, i.e. 10-15 nm2, 5.5 nm2 and 4 nm2 per polymer chain, respectively. The

Interplay between grain structure and protein adsorption on functional response of osteoblasts: ultrafine-grained versus coarse-grained substrates.

Science.gov (United States)

Misra, R D K; Nune, C; Pesacreta, T C; Somani, M C; Karjalainen, L P

2013-01-01

The rapid adsorption of proteins is the starting and primary biological response that occurs when a biomedical device is implanted in the physiological system. The biological response, however, depends on the surface characteristics of the device. Considering the significant interest in nano-/ultrafine surfaces and nanostructured coatings, we describe here, the interplay between grain structure and protein adsorption (bovine serum albumin: BSA) on osteoblasts functions by comparing nanograined/ultrafine-grained (NG/UFG) and coarse-grained (CG: grain size in the micrometer range) substrates by investigating cell-substrate interactions. The protein adsorption on NG/UFG surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability, whereas the effect was less pronounced on protein adsorbed CG surface. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein adsorbed NG/UFG surface. The functional response followed the sequence: NG/UFG(BSA) > NG/UFG > CG(BSA) > CG. The differences in the cellular response on bare and protein adsorbed NG/UFG and CG surfaces are attributed to cumulative contribution of grain structure and degree of hydrophilicity. The study underscores the potential advantages of protein adsorption on artificial biomedical devices to enhance the bioactivity and regulate biological functions. Copyright © 2012 Wiley Periodicals, Inc.

Comb-like temperature-responsive polyhydroxyalkanoate-graft-poly(2-dimethylamino-ethylmethacrylate) for controllable protein adsorption

DEFF Research Database (Denmark)

Yao, Hui; Wei, Daixu; Che, Xuemei

2016-01-01

%. Graft copolymer PHA-g-PDMAEMA showed enhanced thermal stability, biocompatibility and controllable hydrophilicity compared with non-grafted P(3HDD-co-3H9D). The grafted material presented an obvious tendency of increasing protein adsorptions over the lower critical solution temperature (LCST 47.5 °C...... controllable protein adsorption for biomedical usages....

Using X-PEEM to study biomaterials: Protein and peptide adsorption to a polystyrene-poly(methyl methacrylate)-b-polyacrylic acid blend

Energy Technology Data Exchange (ETDEWEB)

Leung, Bonnie O. [Chemistry and Chemical Biology, BIMR, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Hitchcock, Adam P., E-mail: aph@mcmaster.ca [Chemistry and Chemical Biology, BIMR, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Cornelius, Rena M.; Brash, John L. [School of Biomedical Engineering, McMaster University, Hamilton, ON, Canada L8S 4M1 (Canada); Scholl, Andreas; Doran, Andrew [Advanced Light Source, Berkeley Lab, Berkeley, CA 94720 (United States)

2012-10-15

Highlights: Black-Right-Pointing-Pointer We review applications of synchrotron X-PEEM to biomaterials. Black-Right-Pointing-Pointer We report characterization of a PS/PMMA-b-PAA blend surface by AFM and X-PEEM. Black-Right-Pointing-Pointer We report quantitative mapping of protein (HSA) and peptide adsorption on PS/PMMA-b-PAA. Black-Right-Pointing-Pointer We report how this adsorption changes with pH. -- Abstract: Recent synchrotron-based soft X-ray photoemission electron microscopy (X-PEEM) studies of protein and peptide interaction with phase segregated and patterned polymer surfaces in the context of optimization of candidate biomaterials are reviewed and a study of a new system is reported. X-PEEM and atomic force microscopy (AFM) were used to investigate the morphology of a phase-segregated thin film of a polystyrene/poly(methyl methacrylate)-b-polyacrylic acid (PS/PMMA-PAA) blend, and its interactions with negatively charged human serum albumin (HSA) and positively charged SUB-6 (a cationic antimicrobial peptide, RWWKIWVIRWWR-NH{sub 2}) at several pHs. At neutral pH, where the polymer surface is partially negatively charged, HSA and SUB-6 peptide showed contrasting adsorption behavior which is interpreted in terms of differences in their electrostatic interactions with the polymer surface.

Effect of thermal stability on protein adsorption to silica using homologous aldo-keto reductases.

Science.gov (United States)

Felsovalyi, Flora; Patel, Tushar; Mangiagalli, Paolo; Kumar, Sanat K; Banta, Scott

2012-08-01

Gaining more insight into the mechanisms governing the behavior of proteins at solid/liquid interfaces is particularly relevant in the interaction of high-value biologics with storage and delivery device surfaces, where adsorption-induced conformational changes may dramatically affect biocompatibility. The impact of structural stability on interfacial behavior has been previously investigated by engineering nonwild-type stability mutants. Potential shortcomings of such approaches include only modest changes in thermostability, and the introduction of changes in the topology of the proteins when disulfide bonds are incorporated. Here we employ two members of the aldo-keto reductase superfamily (alcohol dehydrogenase, AdhD and human aldose reductase, hAR) to gain a new perspective on the role of naturally occurring thermostability on adsorbed protein arrangement and its subsequent impact on desorption. Unexpectedly, we find that during initial adsorption events, both proteins have similar affinity to the substrate and undergo nearly identical levels of structural perturbation. Interesting differences between AdhD and hAR occur during desorption and both proteins exhibit some level of activity loss and irreversible conformational change upon desorption. Although such surface-induced denaturation is expected for the less stable hAR, it is remarkable that the extremely thermostable AdhD is similarly affected by adsorption-induced events. These results question the role of thermal stability as a predictor of protein adsorption/desorption behavior. Copyright © 2012 The Protein Society.

Competitive Adsorption of Plasma Proteins on Polysaccharide-Modified Silicon Surfaces

National Research Council Canada - National Science Library

Ombelli, Michela; Costello, Lauren B; Meng, Qing C; Composto, Russell J; Eckmann, David M

2005-01-01

.... Competitive protein adsorption plays a key role in the hemocompatibility of the surface. The synthesis of nonfouling surfaces is therefore one of the major prerequisites for devices for biomedical applications...

Application of Kevin-Voigt Model in Quantifying Whey Protein Adsorption on Polyethersulfone Using QCM-D

Science.gov (United States)

The study of protein adsorption on the membrane surface is of great importance to cheese-making processors that use polymeric membrane-based processes to recover whey protein from the process waste streams. Quartz crystal microbalance with dissipation (QCM-D) is a lab-scale, fast analytical techniq...

Ice-surface adsorption enhanced colligative effect of antifreeze proteins in ice growth inhibition

Science.gov (United States)

Mao, Yougang; Ba, Yong

2006-09-01

This Communication describes a mechanism to explain antifreeze protein's function to inhibit the growth of ice crystals. We propose that the adsorption of antifreeze protein (AFP) molecules on an ice surface induces a dense AFP-water layer, which can significantly decrease the mole fraction of the interfacial water and, thus, lower the temperature for a seed ice crystal to grow in a super-cooled AFP solution. This mechanism can also explain the nearly unchanged melting point for the ice crystal due to the AFP's ice-surface adsorption. A mathematical model combining the Langmuir theory of adsorption and the colligative effect of thermodynamics has been proposed to find the equilibrium constants of the ice-surface adsorptions, and the interfacial concentrations of AFPs through fitting the theoretical curves to the experimental thermal hysteresis data. This model has been demonstrated by using the experimental data of serial size-mutated beetle Tenebrio molitor (Tm) AFPs. It was found that the AFP's ice-surface adsorptions could increase the interfacial AFP's concentrations by 3 to 4 orders compared with those in the bulk AFP solutions.

Controlling nonspecific protein adsorption in a plug-based microfluidic system by controlling interfacial chemistry using fluorous-phase surfactants.

Science.gov (United States)

Roach, L Spencer; Song, Helen; Ismagilov, Rustem F

2005-02-01

Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid-liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contact with the hydrophobic surface of the microchannel. Protein adsorption at the aqueous-fluorous interface was controlled by using surfactants that were soluble in fluorocarbon oil but insoluble in aqueous solutions. Three perfluorinated alkane surfactants capped with different functional groups were used: a carboxylic acid, an alcohol, and a triethylene glycol group that was synthesized from commercially available materials. Using complementary methods of analysis, adsorption was characterized for several proteins (bovine serum albumin (BSA) and fibrinogen), including enzymes (ribonuclease A (RNase A) and alkaline phosphatase). These complementary methods involved characterizing adsorption in microliter-sized droplets by drop tensiometry and in nanoliter plugs by fluorescence microscopy and kinetic measurements of enzyme catalysis. The oligoethylene glycol-capped surfactant prevented protein adsorption in all cases. Adsorption of proteins to the carboxylic acid-capped surfactant in nanoliter plugs could be described by using the Langmuir model and tensiometry results for microliter drops. The microfluidic system was fabricated using rapid prototyping in poly(dimethylsiloxane) (PDMS). Black PDMS microfluidic devices, fabricated by curing a suspension of charcoal in PDMS, were used to measure the changes in fluorescence intensity more sensitively. This system will be useful for microfluidic bioassays, enzymatic kinetics, and protein crystallization, because it does not require

Protein adsorption at the electrified air-water interface: implications on foam stability.

Science.gov (United States)

Engelhardt, Kathrin; Rumpel, Armin; Walter, Johannes; Dombrowski, Jannika; Kulozik, Ulrich; Braunschweig, Björn; Peukert, Wolfgang

2012-05-22

The surface chemistry of ions, water molecules, and proteins as well as their ability to form stable networks in foams can influence and control macroscopic properties such as taste and texture of dairy products considerably. Despite the significant relevance of protein adsorption at liquid interfaces, a molecular level understanding on the arrangement of proteins at interfaces and their interactions has been elusive. Therefore, we have addressed the adsorption of the model protein bovine serum albumin (BSA) at the air-water interface with vibrational sum-frequency generation (SFG) and ellipsometry. SFG provides specific information on the composition and average orientation of molecules at interfaces, while complementary information on the thickness of the adsorbed layer can be obtained with ellipsometry. Adsorption of charged BSA proteins at the water surface leads to an electrified interface, pH dependent charging, and electric field-induced polar ordering of interfacial H(2)O and BSA. Varying the bulk pH of protein solutions changes the intensities of the protein related vibrational bands substantially, while dramatic changes in vibrational bands of interfacial H(2)O are simultaneously observed. These observations have allowed us to determine the isoelectric point of BSA directly at the electrolyte-air interface for the first time. BSA covered air-water interfaces with a pH near the isoelectric point form an amorphous network of possibly agglomerated BSA proteins. Finally, we provide a direct correlation of the molecular structure of BSA interfaces with foam stability and new information on the link between microscopic properties of BSA at water surfaces and macroscopic properties such as the stability of protein foams.

Tailored Poly(2-oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

KAUST Repository

Zhang, Ning

2012-05-18

POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tailored Poly(2-oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

KAUST Repository

Zhang, Ning; Pompe, Tilo; Amin, Ihsan; Luxenhofer, Robert; Werner, Carsten; Jordan, Rainer

2012-01-01

POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Driving force behind adsorption-induced protein unfolding: a time-resolved X-ray reflectivity study on lysozyme adsorbed at an air/water interface.

Science.gov (United States)

Yano, Yohko F; Uruga, Tomoya; Tanida, Hajime; Toyokawa, Hidenori; Terada, Yasuko; Takagaki, Masafumi; Yamada, Hironari

2009-01-06

Time-resolved X-ray reflectivity measurements for lysozyme (LSZ) adsorbed at an air/water interface were performed to study the mechanism of adsorption-induced protein unfolding. The time dependence of the density profile at the air/water interface revealed that the molecular conformation changed significantly during adsorption. Taking into account previous work using Fourier transform infrared (FTIR) spectroscopy, we propose that the LSZ molecules initially adsorbed on the air/water interface have a flat unfolded structure, forming antiparallel beta-sheets as a result of hydrophobic interactions with the gas phase. In contrast, as adsorption continues, a second layer forms in which the molecules have a very loose structure having random coils as a result of hydrophilic interactions with the hydrophilic groups that protrude from the first layer.

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

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Qing Chen

2017-01-01

Full Text Available Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.

Dissociation coefficients of protein adsorption to nanoparticles as quantitative metrics for description of the protein corona: A comparison of experimental techniques and methodological relevance

KAUST Repository

Hü hn, Jonas; Fedeli, Chiara; Zhang, Qian; Masood, Atif; del Pino, Pablo; Khashab, Niveen M.; Papini, Emanuele; Parak, Wolfgang J.

2015-01-01

Protein adsorption to nanoparticles is described as a chemical reaction in which proteins attach to binding sites on the nanoparticle surface. This process can be described with a dissociation coefficient, which tells how many proteins are adsorbed per nanoparticle in dependence of the protein concentration. Different techniques to experimentally determine dissociation coefficients of protein adsorption to nanoparticles are reviewed. Results of more than 130 experiments in which dissociation coefficients have been determined are compared. Data show that different methods, nanoparticle systems, and proteins can lead to significantly different dissociation coefficients. However, we observed a clear tendency of smaller dissociation coefficients upon less negative towards more positive zeta potentials of the nanoparticles. The zeta potential thus is a key parameter influencing protein adsorption to the surface of nanoparticles. Our analysis highlights the importance of the characterization of the parameters governing protein-nanoparticle interaction for quantitative evaluation and objective literature comparison.

Dissociation coefficients of protein adsorption to nanoparticles as quantitative metrics for description of the protein corona: A comparison of experimental techniques and methodological relevance

KAUST Repository

Hühn, Jonas

2015-12-31

Protein adsorption to nanoparticles is described as a chemical reaction in which proteins attach to binding sites on the nanoparticle surface. This process can be described with a dissociation coefficient, which tells how many proteins are adsorbed per nanoparticle in dependence of the protein concentration. Different techniques to experimentally determine dissociation coefficients of protein adsorption to nanoparticles are reviewed. Results of more than 130 experiments in which dissociation coefficients have been determined are compared. Data show that different methods, nanoparticle systems, and proteins can lead to significantly different dissociation coefficients. However, we observed a clear tendency of smaller dissociation coefficients upon less negative towards more positive zeta potentials of the nanoparticles. The zeta potential thus is a key parameter influencing protein adsorption to the surface of nanoparticles. Our analysis highlights the importance of the characterization of the parameters governing protein-nanoparticle interaction for quantitative evaluation and objective literature comparison.

Synthesis and characterization of hydroxyapatite nanoparticles and their application in protein adsorption

Energy Technology Data Exchange (ETDEWEB)

Vazquez-Hernandez, F., E-mail: fvazquez@cinvestav.mx [Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Departamento de Ingenieria Electrica, Distrito Federal 07360 (Mexico); Mendoza-Barrera, C.; Altuzar, V. [Universidad Veracruzana, MICRONA, Laboratorio de Bionanotecnologia, Boca del Rio, Veracruz 94294 (Mexico); Melendez-Lira, M. [Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Departamento de Fisica, Distrito Federal 07360 (Mexico); Santana-Aranda, M.A. [Universidad de Guadalajara, CUCEI, Departamento de Fisica, Guadalajara, Jalisco 44430 (Mexico); Olvera, M. de la L [Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Departamento de Ingenieria Electrica, Distrito Federal 07360 (Mexico)

2010-10-25

Hydroxyapatite (HAp) is a bioceramic material used to decrease the operatory time for bone trauma fixing, protein purification, prosthetic covering, and complementing the consolidation and substitution in bone solutions since this material works in favor of the bone neoformation when it is in touch with the physiological tissue. In this work the hydrothermal method, by using a starting solution containing hydrate dipotassium hydrogen phosphate, K{sub 2}HPO{sub 4}.3H{sub 2}O, and cetyltrimethylammonium bromide, CTAB, dissolved in deionized water was employed to synthesize HAp nanoparticles with sizes between 15 and 60 nm, high policrystallinity and Ca/P and Ca/O ratios close to the theoretical. The synthesized HAp particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Pellets with a diameter of 5 mm and weight of 150 mg were used to support the fibrinogen (FGN) and bovine serum albumin (BSA) adsorption (0.15, 0.7, and 1.5 mg/ml) studies. The protein adsorption studies were carried out via atomic force microscopy (AFM).

Evaluations of cellulose accessibilities of lignocelluloses by solute exclusion and protein adsorption techniques

Science.gov (United States)

Q.Q. Wang; Z. He; Z. Zhu; Y.-H.P. Zhang; Y. Ni; X.L. Luo; J.Y. Zhu

2012-01-01

Cellulose accessibilities of a set of hornified lignocellulosic substrates derived by drying the never dried pretreated sample and a set of differently pretreated lodgepople pine substrates, were evaluated using solute exclusion and protein adsorption methods. Direct measurements of cellulase adsorption onto cellulose surface of the set of pretreated substrates were...

Enhanced protein adsorption and patterning on nanostructured latex-coated paper.

Science.gov (United States)

Juvonen, Helka; Määttänen, Anni; Ihalainen, Petri; Viitala, Tapani; Sarfraz, Jawad; Peltonen, Jouko

2014-06-01

Specific interactions of extracellular matrix proteins with cells and their adhesion to the substrate are important for cell growth. A nanopatterned latex-coated paper substrate previously shown to be an excellent substrate for cell adhesion and 2D growth was studied for directed immobilization of proteins. The nanostructured latex surface was formed by short-wavelength IR irradiation of a two-component latex coating consisting of a hydrophilic film-forming styrene butadiene acrylonitrile copolymer and hydrophobic polystyrene particles. The hydrophobic regions of the IR-treated latex coating showed strong adhesion of bovine serum albumin (cell repelling protein), fibronectin (cell adhesive protein) and streptavidin. Opposite to the IR-treated surface, fibronectin and streptavidin had a poor affinity toward the untreated pristine latex coating. Detailed characterization of the physicochemical surface properties of the latex-coated substrates revealed that the observed differences in protein affinity were mainly due to the presence or absence of the protein repelling polar and charged surface groups. The protein adsorption was assisted by hydrophobic (dehydration) interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of polymethacrylic acid-grafted HEMA/PVP microspheres and preliminary study on basic protein adsorption.

Science.gov (United States)

Gao, Baojiao; Hu, Hongyan; Guo, Jianfeng; Li, Yanbin

2010-06-01

The crosslinked copolymeric microspheres (HEMA/NVP) of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) were prepared using inverse suspension polymerization method. Subsequently, the reaction of methacryloyl chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, leading to the introduction of polymerisable double bonds onto the surfaces of microspheres HEMA/NVP. Afterward, methacrylic acid was allowed to be graft-polymerized on microspheres HEMA/NVP in the manner of "grafting from", resulting in the grafted microspheres PMAA-HEMA/NVP. The grafted microspheres PMAA-HEMA/NVP were fully characterized with several means. The graft-polymerization of MAA on microspheres HEMA/NVP was studied in detail, and the optimal reaction conditions were determined. Thereafter, the adsorption property of the grafted microspheres PMAA-HEMA/NVP for lysozyme as a basic protein model was preliminarily examined to explore the feasibility of removing deleterious basic protein such as density lipoprotein from blood. The experimental results indicate that the PMAA grafting degree on microspheres HEMA/NVP is limited because an enwinding polymer layer as a kinetic barrier on the surfaces of HEMA/NVP microspheres will be formed during the graft-polymerization, and block the graft-polymerization. In order to enhance PMAA grafting degree, reaction temperature, monomer concentration and the used amount of initiator should be effectively controlled. The experimental results also reveal that the grafted microspheres PMAA-HEMA/NVP possess very strong adsorption ability for lysozyme by right of strong electrostatic interaction. Copyright 2010 Elsevier B.V. All rights reserved.

Temperature and pH influence adsorption of cellobiohydrolase onto lignin by changing the protein properties.

Science.gov (United States)

Lu, Xianqin; Wang, Can; Li, Xuezhi; Zhao, Jian

2017-12-01

Non-productive adsorption of cellulase onto lignin restricted the movement of cellulase and also hindered the cellulase recycling in bioconversion of lignocellulose. In this study, effect of temperature and pH on adsorption and desorption of cellobiohydrolase (CBH) on lignin and its possible mechanism were discussed. It found that pH value and temperature influenced the adsorption and desorption behaviors of CBH on lignin. Different thermodynamic models suggested that the action between lignin and CBH was physical action. More CBH was adsorbed onto lignin, but lower initial adsorption velocity was detected at 50°C comparing with 4°C. Elevating pH value could improve desorption of cellulase from lignin. The changes of hydrophobicity and electric potential on protein surface may partially explain the impact of environmental conditions on the adsorption and desorption behaviors of CBH on lignin, and comparing to electrical interaction, the hydrophobicity may be the dominating factor influencing the behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced Hydrophilicity and Protein Adsorption of Titanium Surface by Sodium Bicarbonate Solution

Directory of Open Access Journals (Sweden)

Shengnan Jia

2015-01-01

Full Text Available The aim of this study was to investigate a novel and convenient method of chemical treatment to modify the hydrophilicity of titanium surfaces. Sand-blasted and acid-etched (SLA titanium surfaces and machined titanium surfaces were treated with sodium bicarbonate (NaHCO3 solution. The wetting behavior of both kinds of surfaces was measured by water contact angle (WCA test. The surface microstructure was assessed with scanning electron microscopy (SEM and three-dimensional (3D optical microscopy. The elemental compositions of the surfaces were analyzed by X-ray photoelectron spectroscopy (XPS. The protein adsorption analysis was performed with fibronectin. Results showed that, after 1 M NaHCO3 treatment, the hydrophilicity of both SLA and machined surfaces was enhanced. No significant microstructural change presented on titanium surfaces after NaHCO3 treatment. The deprotonation and ion exchange activities might cause the enhanced hydrophilicity of titanium surfaces. The increased protein adsorption of NaHCO3-treated SLA surfaces might indicate their improved tissue-integration in clinical use.

Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features

Energy Technology Data Exchange (ETDEWEB)

Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu [College of Science, Sichuan Agricultural University, Ya' an 625014 (China); He, Hua [Institute of Animal Genetics and Breeding, Sichuan Agricultural University, Wenjiang, Sichuan 611130 (China); Rao, Hanbing, E-mail: rhbscu@gmail.com [College of Science, Sichuan Agricultural University, Ya' an 625014 (China)

2015-07-01

The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g{sup −1}, respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. - Highlights: • A novel protein adsorption studies based on sheet, rod and whisker of HA were designed. • Kinetic and thermodynamics parameters of BMP-2 and HA bonded materials were evaluated. • Surface topographies of the HA effect BMP-2 adsorption • The HA-whisker material had excellent adsorption performance for protein enrichment. • The electrostatic interaction is responsible for the

Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features

International Nuclear Information System (INIS)

Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu; He, Hua; Rao, Hanbing

2015-01-01

The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g −1 , respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. - Highlights: • A novel protein adsorption studies based on sheet, rod and whisker of HA were designed. • Kinetic and thermodynamics parameters of BMP-2 and HA bonded materials were evaluated. • Surface topographies of the HA effect BMP-2 adsorption • The HA-whisker material had excellent adsorption performance for protein enrichment. • The electrostatic interaction is responsible for the BMP-2

Unified superresolution experiments and stochastic theory provide mechanistic insight into protein ion-exchange adsorptive separations.

Science.gov (United States)

Kisley, Lydia; Chen, Jixin; Mansur, Andrea P; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Chen, Wen-Hsiang; Dhamane, Sagar; Willson, Richard C; Landes, Christy F

2014-02-11

Chromatographic protein separations, immunoassays, and biosensing all typically involve the adsorption of proteins to surfaces decorated with charged, hydrophobic, or affinity ligands. Despite increasingly widespread use throughout the pharmaceutical industry, mechanistic detail about the interactions of proteins with individual chromatographic adsorbent sites is available only via inference from ensemble measurements such as binding isotherms, calorimetry, and chromatography. In this work, we present the direct superresolution mapping and kinetic characterization of functional sites on ion-exchange ligands based on agarose, a support matrix routinely used in protein chromatography. By quantifying the interactions of single proteins with individual charged ligands, we demonstrate that clusters of charges are necessary to create detectable adsorption sites and that even chemically identical ligands create adsorption sites of varying kinetic properties that depend on steric availability at the interface. Additionally, we relate experimental results to the stochastic theory of chromatography. Simulated elution profiles calculated from the molecular-scale data suggest that, if it were possible to engineer uniform optimal interactions into ion-exchange systems, separation efficiencies could be improved by as much as a factor of five by deliberately exploiting clustered interactions that currently dominate the ion-exchange process only accidentally.

Influence of surface features of hydroxyapatite on the adsorption of proteins relevant to bone regeneration.

Science.gov (United States)

Fernández-Montes Moraleda, Belén; San Román, Julio; Rodríguez-Lorenzo, Luís M

2013-08-01

Protein-surface interaction may determine the success or failure of an implanted device. Not much attention have been paid to the specific surface parametes of hydroxyapatite (OHAp) that modulates and determines the formation and potential activity of the layer of proteins that is first formed when the material get in contact with the host tissue. the influence of specific surface area (SSA), crystallite size (CS) and particle size (PS) of OHAp on the adsorption of proteins relevant for bone regeneration is evaluated in this article. OHAp have been prepared by a wet chemical reaction of Ca(OH)2 with H3PO4. One set of reactions included poly acrylic acid in the reactant solution to modify the properties of the powder. Fibrinogen (Fg) Fraction I, type I: from Human plasma, (67% Protein), and Fibronectin (Fn) from Human plasma were selected to perform the adsorption experiments. The analysis of protein adsorption was carried out by UV/Vis spectrometry. A lower SSA and a different aspect ratio are obtained when the acrylic acid is included in the reaction badge. The deconvolution of the amide I band on the Raman spectra of free and adsorbed proteins reveals that the interaction apatite-protein happens through the carboxylate groups of the proteins. The combined analysis of CS, SSA and PS should be considered on the design of OHAp materials intended to interact with proteins. Copyright © 2013 Wiley Periodicals, Inc.

Load-dependent surface diffusion model for analyzing the kinetics of protein adsorption onto mesoporous materials.

Science.gov (United States)

Marbán, Gregorio; Ramírez-Montoya, Luis A; García, Héctor; Menéndez, J Ángel; Arenillas, Ana; Montes-Morán, Miguel A

2018-02-01

The adsorption of cytochrome c in water onto organic and carbon xerogels with narrow pore size distributions has been studied by carrying out transient and equilibrium batch adsorption experiments. It was found that equilibrium adsorption exhibits a quasi-Langmuirian behavior (a g coefficient in the Redlich-Peterson isotherms of over 0.95) involving the formation of a monolayer of cyt c with a depth of ∼4nm on the surface of all xerogels for a packing density of the protein inside the pores of 0.29gcm -3 . A load-dependent surface diffusion model (LDSDM) has been developed and numerically solved to fit the experimental kinetic adsorption curves. The results of the LDSDM show better fittings than the standard homogeneous surface diffusion model. The value of the external mass transfer coefficient obtained by numerical optimization confirms that the process is controlled by the intraparticle surface diffusion of cyt c. The surface diffusion coefficients decrease with increasing protein load down to zero for the maximum possible load. The decrease is steeper in the case of the xerogels with the smallest average pore diameter (∼15nm), the limit at which the zero-load diffusion coefficient of cyt c also begins to be negatively affected by interactions with the opposite wall of the pore. Copyright © 2017 Elsevier Inc. All rights reserved.

Fibrinogen adsorption on blocked surface of albumin.

Science.gov (United States)

Holmberg, Maria; Hou, Xiaolin

2011-05-01

We have investigated the adsorption of albumin and fibrinogen onto PET (polyethylene terephthalate) and glass surfaces and how pre-adsorption of albumin onto these surfaces can affect the adsorption of later added fibrinogen. For materials and devices being exposed to blood, adsorption of fibrinogen is often a non-wanted event, since fibrinogen is part of the clotting cascade and unspecific adsorption of fibrinogen can have an influence on the activation of platelets. Albumin is often used as blocking agent for avoiding unspecific protein adsorption onto surfaces in devices designed to handle biological samples, including protein solutions. It is based on the assumption that proteins adsorbs as a monolayer on surfaces and that proteins do not adsorb on top of each other. By labelling albumin and fibrinogen with two different radioactive iodine isotopes that emit gamma radiation with different energies, the adsorption of both albumin and fibrinogen has been monitored simultaneously on the same sample. Information about topography and coverage of adsorbed protein layers has been obtained using AFM (Atomic Force Microscopy) analysis in liquid. Our studies show that albumin adsorbs in a multilayer fashion on PET and that fibrinogen adsorbs on top of albumin when albumin is pre-adsorbed on the surfaces. Copyright © 2010 Elsevier B.V. All rights reserved.

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications

Energy Technology Data Exchange (ETDEWEB)

Sheikh, Zeeshan [Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, 150 College Street, Toronto, ON M5S 3E2 (Canada); School of Engineering and Materials Science, Queen Mary, University of London, Mile End Rd, London, E1 4NS (United Kingdom); Khan, Abdul Samad, E-mail: draskhan@ciitlahore.edu.pk [Interdisciplinary Research Centre in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Roohpour, Nima [Oral Care R& D, GSK St., Georges Ave., Weybridge KT13 8PA (United Kingdom); Glogauer, Michael [Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, 150 College Street, Toronto, ON M5S 3E2 (Canada); Rehman, Ihtesham u [Department of Materials Science and Engineering, The Kroto Research Institute, North Campus, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom)

2016-11-01

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4′-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37 °C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86 ± 1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87 ± 3.16°). The ultimate tensile strength and elastic modulus of PEU (27 ± 1 MPa and 14 ± 2 MPa) and PEU-PDMS (8 ± 1 MPa and 26 ± 1 MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications

International Nuclear Information System (INIS)

Sheikh, Zeeshan; Khan, Abdul Samad; Roohpour, Nima; Glogauer, Michael; Rehman, Ihtesham u

2016-01-01

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4′-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37 °C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86 ± 1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87 ± 3.16°). The ultimate tensile strength and elastic modulus of PEU (27 ± 1 MPa and 14 ± 2 MPa) and PEU-PDMS (8 ± 1 MPa and 26 ± 1 MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial

Tissue-engineered matrices as functional delivery systems: adsorption and release of bioactive proteins from degradable composite scaffolds.

Science.gov (United States)

Cushnie, Emily K; Khan, Yusuf M; Laurencin, Cato T

2010-08-01

A tissue-engineered bone graft should imitate the ideal autograft in both form and function. However, biomaterials that have appropriate chemical and mechanical properties for grafting applications often lack biological components that may enhance regeneration. The concept of adding proteins such as growth factors to scaffolds has therefore emerged as a possible solution to improve overall graft design. In this study, we investigated this concept by loading porous hydroxyapatite-poly(lactide-co-glycolide) (HA-PLAGA) scaffolds with a model protein, cytochrome c, and then studying its release in a phosphate-buffered saline solution. The HA-PLAGA scaffold has previously been shown to be bioactive, osteoconductive, and to have appropriate physical properties for tissue engineering applications. The loading experiments demonstrated that the HA-PLAGA scaffold could also function effectively as a substrate for protein adsorption and release. Scaffold protein adsorptive loading (as opposed to physical entrapment within the matrix) was directly related to levels of scaffold HA-content. The HA phase of the scaffold facilitated protein retention in the matrix following incubation in aqueous buffer for periods up to 8 weeks. Greater levels of protein retention time may improve the protein's effective activity by increasing the probability for protein-cell interactions. The ability to control protein loading and delivery simply via composition of the HA-PLAGA scaffold offers the potential of forming robust functionalized bone grafts. (c) 2010 Wiley Periodicals, Inc.

Characterization of dextran-grafted hydrophobic charge-induction resins: Structural properties, protein adsorption and transport.

Science.gov (United States)

Liu, Tao; Angelo, James M; Lin, Dong-Qiang; Lenhoff, Abraham M; Yao, Shan-Jing

2017-09-29

The structural and functional properties of a series of dextran-grafted and non-grafted hydrophobic charge-induction chromatographic (HCIC) agarose resins were characterized by macroscopic and microscopic techniques. The effects of dextran grafting and mobile phase conditions on the pore dimensions of the resins were investigated with inverse size exclusion chromatography (ISEC). A significantly lower pore radius (17.6nm) was found for dextran-grafted than non-grafted resins (29.5nm), but increased salt concentration would narrow the gap between the respective pore radii. Two proteins, human immunoglobulin G (hIgG) and bovine serum albumin (BSA), were used to examine the effect of protein characteristics. The results of adsorption isotherms showed that the dextran-grafted resin with high ligand density had substantially higher adsorption capacity and enhanced the salt-tolerance property for hIgG, but displayed a significantly smaller benefit for BSA adsorption. Confocal laser scanning microscopy (CLSM) showed that hIgG presented more diffuse and slower moving adsorption front compared to BSA during uptake into the resins because of the selective binding of multiple species from polyclonal IgG; polymer-grafting with high ligand density could enhance the rate of hIgG transport in the dextran-grafted resins without salt addition, but not for the case with high salt and BSA. The results indicate that microscopic analysis using ISEC and CLSM is useful to improve the mechanistic understanding of resin structure and of critical functional parameters involving protein adsorption and transport, which would guide the rational design of new resins and processes. Copyright © 2017. Published by Elsevier B.V.

Effects of solution chemistry and aging time on prion protein adsorption and replication of soil-bound prions.

Directory of Open Access Journals (Sweden)

Samuel E Saunders

2011-04-01

Full Text Available Prion interactions with soil may play an important role in the transmission of chronic wasting disease (CWD and scrapie. Prions are known to bind to a wide range of soil surfaces, but the effects of adsorption solution chemistry and long-term soil binding on prion fate and transmission risk are unknown. We investigated HY TME prion protein (PrP(Sc adsorption to soil minerals in aqueous solutions of phosphate buffered saline (PBS, sodium chloride, calcium chloride, and deionized water using western blotting. The replication efficiency of bound prions following adsorption in these solutions was also evaluated by protein misfolding cyclic amplification (PMCA. Aging studies investigated PrP(Sc desorption and replication efficiency up to one year following adsorption in PBS or DI water. Results indicate that adsorption solution chemistry can affect subsequent prion replication or desorption ability, especially after incubation periods of 30 d or longer. Observed effects were minor over the short-term (7 d or less. Results of long-term aging experiments demonstrate that unbound prions or prions bound to a diverse range of soil surfaces can readily replicate after one year. Our results suggest that while prion-soil interactions can vary with solution chemistry, prions bound to soil could remain a risk for transmitting prion diseases after months in the environment.

Selective adsorption of bovine hemoglobin on functional TiO2 nano-adsorbents: surface physic-chemical properties determined adsorption activity

Science.gov (United States)

Guo, Shiguang; Zhang, Jianghua; Shao, Mingxue; Zhang, Xia; Liu, Yufeng; Xu, Junli; Meng, Hao; Han, Yide

2015-04-01

Surface functionalized nanoparticles are efficient adsorbents which have shown good potential for protein separation. In this work, we chose two different types of organic molecules, oleic acid (OA) and 3-glycidoxypropyltrimethoxy silane (GPTMS), to functionalize the surface of TiO2 nanoparticles, and we studied the effects of this modification on their surface physicochemical properties in correlation with their selective adsorption of proteins. The results showed that the surface zeta potential and the surface water wettability of the modified TiO2 were significantly changed in comparison with the original TiO2 nanoparticles. The adsorption activities of bovine hemoglobin (BHb) and bovine serum albumin (BSA) on these functionalized TiO2 samples were investigated under different conditions, including pH values, contact time, ion strength, and initial protein concentration. In comparison with the non-specific adsorption of original TiO2, however, both the OA-TiO2 and GPTMS-TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at the same time. Using a binary protein mixture as the adsorption object, a higher separation factor (SF) was obtained for OA-TiO2 under optimum conditions. The different adsorption activities of BHb and BSA on the modified TiO2 were correlated with different interactions at the protein/solid interface, and the chemical force as well as the electrostatic force played an important role in the selective adsorption process.

Adsorption, aggregation, and desorption of proteins on smectite particles.

Science.gov (United States)

Kolman, Krzysztof; Makowski, Marcin M; Golriz, Ali A; Kappl, Michael; Pigłowski, Jacek; Butt, Hans-Jürgen; Kiersnowski, Adam

2014-10-07

We report on adsorption of lysozyme (LYS), ovalbumin (OVA), or ovotransferrin (OVT) on particles of a synthetic smectite (synthetic layered aluminosilicate). In our approach we used atomic force microscopy (AFM) and quartz crystal microbalance (QCM) to study the protein-smectite systems in water solutions at pH ranging from 4 to 9. The AFM provided insights into the adhesion forces of protein molecules to the smectite particles, while the QCM measurements yielded information about the amounts of the adsorbed proteins, changes in their structure, and conditions of desorption. The binding of the proteins to the smectite surface was driven mainly by electrostatic interactions, and hence properties of the adsorbed layers were controlled by pH. At high pH values a change in orientation of the adsorbed LYS molecules and a collapse or desorption of OVA layer were observed. Lowering pH to the value ≤ 4 caused LYS to desorb and swelling the adsorbed OVA. The stability of OVT-smectite complexes was found the lowest. OVT revealed a tendency to desorb from the smectite surface at all investigated pH. The minimum desorption rate was observed at pH close to the isoelectric point of the protein, which suggests that nonspecific interactions between OVT and smectite particles significantly contribute to the stability of these complexes.

Quantification of protein based on single-molecule counting by total internal reflection fluorescence microscopy with adsorption equilibrium

International Nuclear Information System (INIS)

Wang Lei; Xu Guang; Shi Zhikun; Jiang Wei; Jin Wenrui

2007-01-01

We developed a sensitive single-molecule imaging method for quantification of protein by total internal reflection fluorescence microscopy with adsorption equilibrium. In this method, the adsorption equilibrium of protein was achieved between solution and glass substrate. Then, fluorescence images of protein molecules in a evanescent wave field were taken by a highly sensitive electron multiplying charge coupled device. Finally, the number of fluorescent spots corresponding to the protein molecules in the images was counted. Alexa Fluor 488-labeled goat anti-rat IgG(H + L) was chosen as the model protein. The spot number showed an excellent linear relationship with protein concentration. The concentration linear range was 5.4 x 10 -11 to 8.1 x 10 -10 mol L -1

Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

Science.gov (United States)

Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

2017-08-22

Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

NMR Studies of Protein Hydration and Protein-Ligand Interactions

Science.gov (United States)

Chong, Yuan

Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

Periodic protein adsorption at the gold/biotin aqueous solution interface: evidence of kinetics with time delay

Science.gov (United States)

Neff, H.; Laborde, H. M.; Lima, A. M. N.

2016-11-01

An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization.

Applications of functional polymer brushes for nanoparticle uptake and prevention of protein adsorption

Science.gov (United States)

Arifuzzaman, Shafi M.

The central theme of this Ph.D. dissertation is to develop novel multifunctional polymer coatings for understanding partition of proteins and nanoparticles on polymers grafted to flat surfaces (so-called brushes). Systematic investigation of the adsorption phenomena is accomplished by utilizing surface-anchored assemblies comprising grafted polymers with variation in physical properties (i.e., length or/and grafting density) and chemical functionality. The chemical composition of the brush is tailored by either "chemical coloring" of a parent homopolymer brush with selective chemical moieties or by sequential growth of two chemically dissimilar polymer blocks. We present preparation of two types of tailor-made, surface-grafted copolymers: (1) those composed of hydrophilic and hydrophobic blocks (so-called amphiphilic polymer brushes), and (2) those comprising of anionic and cationic polymer segments (so-called polyampholyte brushes). We describe the organization of functionality in the grafted polymer brushes and the partitioning of proteins and nanoparticles using a battery of complementary analytical probes. Specifically, we address how varying the molecular weight, grafting density, and chemical composition of the brush affects adsorbtion and desorbtion of model proteins and gold nanoparticles. Our observations indicate densely-populated responsive amphiphilic polymers are very efficient in suppressing protein adsorption. In addition, we have established that the length of poly(ethylene glycol) spacers attached to a parent homopolymer brush is a key factor governing uptake of gold nanoparticles. Both grafting density and molecular weight of the coating are important in controlling the kinetics and thermodynamics of protein adsorption on surfaces. Our findings and methodologies can lead to the development of next generation environmentally friendly antifouling surfaces and will find application in medical devices, antifouling coatings and anti reflection finishes.

Fibrinogen adsorption on blocked surface of albumin

DEFF Research Database (Denmark)

Holmberg, Maria; Hou, Xiaolin

2011-01-01

We have investigated the adsorption of albumin and fibrinogen onto PET (polyethylene terephthalate) and glass surfaces and how pre-adsorption of albumin onto these surfaces can affect the adsorption of later added fibrinogen. For materials and devices being exposed to blood, adsorption...... of fibrinogen is often a non-wanted event, since fibrinogen is part of the clotting cascade and unspecific adsorption of fibrinogen can have an influence on the activation of platelets. Albumin is often used as blocking agent for avoiding unspecific protein adsorption onto surfaces in devices designed to handle...... energies, the adsorption of both albumin and fibrinogen has been monitored simultaneously on the same sample. Information about topography and coverage of adsorbed protein layers has been obtained using AFM (Atomic Force Microscopy) analysis in liquid. Our studies show that albumin adsorbs in a multilayer...

Modification of polyetherurethane for biomedical application by radiation induced grafting. II. Water sorption, surface properties, and protein adsorption of grafted films

International Nuclear Information System (INIS)

Jansen, B.; Ellinghorst, G.

1984-01-01

A series of polyetherurethane films grafted by means of gamma radiation with hydrophilic or reactive monomers (2-hydroxyethyl methacrylate, 2,3-epoxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, and acrylamide) and partially chemically modified were subjected to various physico-chemical investigation methods involving water sorption, contact angle, and protein adsorption measurements. From contact angle data the interfacial free energy gamma sw between grafted films and water was calculated. It was found that the water uptake of grafted films increases with grafting yield or, in the case of grafted and afterwards chemically modified films, with reaction yield; the diffusion coefficient of water in the modified films also increases with grafting yield. Contact angle studies revealed all grafted films to have surfaces more hydrophilic than the ungrafted trunk polymer. The degree of hydrophilicity--especially of HEMA-grafted films--strongly depends on grafting conditions. For some grafted samples with high surface hydrophilicity very low interfacial free energies approaching zero were measured. The study of the competitive adsorption of bovine serum albumin, gamma-globulin, and fibrinogen from a synthetic protein solution onto modified films showed that the adsorption of albumin increases markedly with increasing grafting yields, whereas the fibrinogen and gamma-globulin adsorption only slightly increases. A correlation between interfacial free energy and protein adsorption in the sense of the minimum interfacial free energy hypothesis was found only for samples with grafting yields below 5%. At higher grafting yields the increased surface area complicates the analysis

The effect of amorphous silicon surface hydrogenation on morphology, wettability and its implication on the adsorption of proteins

Energy Technology Data Exchange (ETDEWEB)

Filali, Larbi, E-mail: larbifilali5@gmail.com [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique, Université d' Oran 1, Ahmed Ben Bella, BP 1524, El M' naouar 31100 Oran (Algeria); Brahmi, Yamina; Sib, Jamal Dine [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique, Université d' Oran 1, Ahmed Ben Bella, BP 1524, El M' naouar 31100 Oran (Algeria); Bouhekka, Ahmed [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique, Université d' Oran 1, Ahmed Ben Bella, BP 1524, El M' naouar 31100 Oran (Algeria); Département de Physique, Université Hassiba Ben Bouali, 02000 Chlef (Algeria); Benlakehal, Djamel; Bouizem, Yahya; Kebab, Aissa; Chahed, Larbi [Laboratoire de Physique des Couches Minces et Matériaux pour l' Electronique, Université d' Oran 1, Ahmed Ben Bella, BP 1524, El M' naouar 31100 Oran (Algeria)

2016-10-30

Highlights: • Hydrogenation of the surfaces had the effect of reducing the roughness by way of shadow etching. • Roughness was the driving factor affecting the wettability of the hydrogenated surfaces. • Bovine Serum Albumin proteins favored the surfaces with highest hydrogen content. • Surface modification induced secondary structure change of adsorbed proteins. - Abstract: We study the effect of amorphous silicon (a-Si) surface hydrogenation on Bovine Serum Albumin (BSA) adsorption. A set of (a-Si) films was prepared by radio frequency magnetron sputtering (RFMS) and after deposition; they were treated in molecular hydrogen ambient at different pressures (1–3 Pa). Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy and spectroscopic ellipsometry (SE) were used to study the hydrogenation effect and BSA adsorption. Atomic force microscopy (AFM) was used to evaluate morphological changes caused by hydrogenation. The wettability of the films was measured using contact angle measurement, and in the case of the hydrogenated surfaces, it was found to be driven by surface roughness. FTIR-ATR spectroscopy and SE measurements show that proteins had the strongest affinity toward the surfaces with the highest hydrogen content and their secondary structure was affected by a significant decrease of the α-helix component (-27%) compared with the proteins adsorbed on the un-treated surface, which had a predominantly α-helix (45%) structure. The adsorbed protein layer was found to be densely packed with a large thickness (30.9 nm) on the hydrogen-rich surfaces. The most important result is that the surface hydrogen content was the dominant factor, compared to wettability and morphology, for protein adsorption.

Proteins at interfaces : the adsorption of human plasma albumin and bovine pancreas ribonuclease on polystyrene latices

NARCIS (Netherlands)

Norde, W.

1976-01-01

The adsorption from (aqueous) solution of proteins is very complex. The interfacial behaviour of proteins is determined by the properties of, and the mutual interactions between, the adsorbing interface, the protein molecules, the solvent (water) molecules and other solutes (e.g. ions).

Poly(l-glutamic acid)-g-poly(ethylene glycol) external layer in polyelectrolyte multilayer films: Characterization and resistance to serum protein adsorption.

Science.gov (United States)

Szczepanowicz, Krzysztof; Kruk, Tomasz; Świątek, Wiktoria; Bouzga, Aud M; Simon, Christian R; Warszyński, Piotr

2018-06-01

Formation of protein-resistant surfaces is a major challenge in the design of novel biomaterials and an important strategy to prevent protein adsorption is the formation of protein-resistant coatings. It can be achieved by proper modification of surfaces, e.g., by immobilization of hydrophilic polymers such as poly(ethylene glycol) (PEG). An appropriate method to immobilize PEG at charged surfaces is the adsorption of copolymers with PEG chains grafted onto polyelectrolyte backbone. The growing interest in the use of polyelectrolyte multilayer coatings in biomedical applications to improve biocompatibility and/or to prepare coating with antiadhesive properties has been the main reason for these studies. Therefore the aim was to produce protein resistant polyelectrolyte multilayer films. They were formed via the layer-by-layer approach, while their pegylation by the deposition of pegylated polyanion, PGA-g-PEG, as an external layer. The influence of PEG chain length and grafting density of PGA-g-PEG copolymers on the protein antiadhesive properties of pegylated polyelectrolyte multilayer films was investigated. To monitor the formation of pegylated and non-pegylated multilayer films, adsorption of the following proteins: HSA, Fibrinogen, and FBS were measured by quartz crystal microbalance (QCM - D). We found that protein adsorption onto all pegylated polyelectrolyte multilayers was significantly reduced in comparison to non-pegylated ones. Long-term performance tests confirmed the stability and the durability of the protein resistant properties of the pegylated multilayers. Antiadhesive properties of tested surfaces pegylated by PGA-g-PEG were compared to the available data for pegylated polycation PLL-g-PEG. Copyright © 2018 Elsevier B.V. All rights reserved.

Surface-water interface induces conformational changes critical for protein adsorption: Implications for monolayer formation of EAS hydrophobin

Directory of Open Access Journals (Sweden)

Kamron eLey

2015-11-01

Full Text Available The class I hydrophobin EAS is part of a family of small, amphiphilic fungal proteins best known for their ability to self-assemble into stable monolayers that modify the hydrophobicity of a surface to facilitate further microbial growth. These proteins have attracted increasing attention for industrial and biomedical applications, with the aim of designing surfaces that have the potential to maintain their clean state by resisting non-specific protein binding. To gain a better understanding of this process, we have employed all-atom molecular dynamics to study initial stages of the spontaneous adsorption of monomeric EAS hydrophobin on fully hydroxylated silica, a commonly used industrial and biomedical substrate. Particular interest has been paid to the Cys3-Cys4 loop, which has been shown to exhibit disruptive behavior in solution, and the Cys7-Cys8 loop, which is believed to be involved in the aggregation of EAS hydrophobin at interfaces. Specific and water mediated interactions with the surface were also analyzed. We have identified two possible binding motifs, one which allows unfolding of the Cys7-Cys8 loop due to the surfactant-like behavior of the Cys3-Cys4 loop, and another which has limited unfolding due to the Cys3-Cys4 loop remaining disordered in solution. We have also identified intermittent interactions with water which mediate the protein adsorption to the surface, as well as longer lasting interactions which control the diffusion of water around the adsorption site. These results have shown that EAS behaves in a similar way at the air-water and surface-water interfaces, and have also highlighted the need for hydrophilic ligand functionalization of the silica surface in order to prevent the adsorption of EAS hydrophobin.

Investigation of protein adsorption performance of Ni2+-attached diatomite particles embedded in composite monolithic cryogels.

Science.gov (United States)

Ünlü, Nuri; Ceylan, Şeyda; Erzengin, Mahmut; Odabaşı, Mehmet

2011-08-01

As a low-cost natural adsorbent, diatomite (DA) (2 μm) has several advantages including high surface area, chemical reactivity, hydrophilicity and lack of toxicity. In this study, the protein adsorption performance of supermacroporous composite cryogels embedded with Ni(2+)-attached DA particles (Ni(2+)-ADAPs) was investigated. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic composite cryogel column embedded with Ni(2+)-ADAPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA) both from aqueous solutions and human serum. The chemical composition and surface area of DA was determined by XRF and BET method, respectively. The characterization of composite cryogel was investigated by SEM. The effect of pH, and embedded Ni(2+)-ADAPs amount, initial HSA concentration, temperature and flow rate on adsorption were studied. The maximum amount of HSA adsorption from aqueous solution at pH 8.0 phosphate buffer was very high (485.15 mg/g DA). It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Ni(2+)-ADAPs in poly(2-hydroxyethyl methacrylate) composite cryogel without significant loss of adsorption capacity. The efficiency of albumin adsorption from human serum before and after albumin adsorption was also investigated with SDS-PAGE analyses. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of protein solution components in the adsorption of Herbaspirillum seropedicae GlnB protein on mica.

Science.gov (United States)

Ferreira, Cecília F G; Benelli, Elaine M; Klein, Jorge J; Schreiner, Wido; Camargo, Paulo C

2009-10-15

The adsorption of proteins and its buffer solution on mica surfaces was investigated by atomic force microscopy (AFM). Different salt concentration of the Herbaspirillum seropedicae GlnB protein (GlnB-Hs) solution deposited on mica was investigated. This protein is a globular, soluble homotrimer (36kDa), member of PII-like proteins family involved in signal transducing in prokaryote. Supramolecular structures were formed when this protein was deposited onto bare mica surface. The topographic AFM images of the GlnB-Hs films showed that at high salt concentration the supramolecular structures are spherical-like, instead of the typical doughnut-like shape for low salt concentration. AFM images of NaCl and Tris from the buffer solution showed structures with the same pattern as those observed for high salt protein solution, misleading the image interpretation. XPS experiments showed that GlnB protein film covers the mica surface without chemical reaction.

Surface modification of poly (styrene-b-(ethylene-co-butylene)-b-styrene) elastomer and its plasma protein adsorption by QCM-D

Energy Technology Data Exchange (ETDEWEB)

Li, Rui [Northeast Normal University, School of Physics, Changchun 130022 (China); Jin, Jing, E-mail: jjin@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Sun, Yingchun, E-mail: sunyc149@nenu.edu.cn [Northeast Normal University, School of Physics, Changchun 130022 (China)

2014-05-01

Graphical abstract: - Highlights: • Grafting concentration of PEG was defined by the peak-area ratio of [C–O]/[C]. • Quantitatively investigated the adsorption processes of BSA and fibrinogen using QCM-D. • The inactivated BSA on SEBS surface could induce the subsequent fibrinogen adsorption. • SEBS-g-PEG with graft concentration of 0.207 has excellent protein resistance. - Abstract: Protein adsorption is a dynamic process and plays a major role in determining the hemocompatibility of biomaterials. We have obtained different poly (ethylene glycol) (PEG) graft concentrations of SEBS-g-PEG and the surface chemical compositions are confirmed by X-ray photoelectron spectroscopy (XPS). Graft concentration is defined by peak-area ratio of [C-O]/[C] on modified SEBS surface. With increasing graft concentration, water contact angles of the modified SEBS have significantly decreased. The platelet adhesion and static protein adsorption demonstrate that the hemocompatibility of copolymers films are improved effectively and SEBS-g-PEG-2 with larger graft concentration has more superior anticoagulation than that of SEBS-g-PEG-1. Moreover, we have quantitatively investigated the adsorption process of bovine serum albumin (BSA) and fibrinogen (Fib) on the surfaces of pristine SEBS and modified SEBS using quartz crystal microbalance with dissipation (QCM-D) in real time. The results indicate that the inactivated BSA on the pristine SEBS can continuously induce the subsequent Fib adsorption. The hemocompatibility of SEBS-g-PEG-2 with the graft concentration of 0.207 has excellent anti-protein property and the bio-inert BSA layer on the film can resist the subsequent Fib adsorption.

A colloidal assembly approach to synthesize magnetic porous composite nanoclusters for efficient protein adsorption

Science.gov (United States)

Yang, Qi; Lan, Fang; Yi, Qiangying; Wu, Yao; Gu, Zhongwei

2015-10-01

A combination strategy of the inverse emulsion crosslinking approach and the colloidal assembly technique is first proposed to synthesize Fe3O4/histidine composite nanoclusters as new-type magnetic porous nanomaterials. The nanoclusters possess uniform morphology, high magnetic content and excellent protein adsorption capacity, exhibiting their great potential for bio-separation.A combination strategy of the inverse emulsion crosslinking approach and the colloidal assembly technique is first proposed to synthesize Fe3O4/histidine composite nanoclusters as new-type magnetic porous nanomaterials. The nanoclusters possess uniform morphology, high magnetic content and excellent protein adsorption capacity, exhibiting their great potential for bio-separation. Electronic supplementary information (ESI) available: Experimental details. See DOI: 10.1039/c5nr05800g

Protein Adsorption Patterns and Analysis on IV Nanoemulsions-The Key Factor Determining the Organ Distribution.

Science.gov (United States)

Keck, Cornelia M; Jansch, Mirko; Müller, Rainer H

2012-12-21

Intravenous nanoemulsions have been on the market for parenteral nutrition since the 1950s; meanwhile, they have also been used successfully for IV drug delivery. To be well tolerable, the emulsions should avoid uptake by the MPS cells of the body; for drug delivery, they should be target-specific. The organ distribution is determined by the proteins adsorbing them after injection from the blood (protein adsorption pattern), typically analyzed by two-dimensional polyacrylamide gel electrophoresis, 2-D PAGE. The article reviews the 2-D PAGE method, the analytical problems to be faced and the knowledge available on how the composition of emulsions affects the protein adsorption patterns, e.g., the composition of the oil phase, stabilizer layer and drug incorporation into the interface or oil core. Data were re-evaluated and compared, and the implications for the in vivo distribution are discussed. Major results are that the interfacial composition of the stabilizer layer is the main determining factor and that this composition can be modulated by simple processes. Drug incorporation affects the pattern depending on the localization of the drug (oil core versus interface). The data situation regarding in vivo effects is very limited; mainly, it has to be referred to in the in vivo data of polymeric nanoparticles. As a conclusion, determination of the protein adsorption patterns can accelerate IV nanoemulsion formulation development regarding optimized organ distribution and related pharmacokinetics.

Routine detection of calcium-binding proteins following their adsorption to nitrocellulose membrane filters

International Nuclear Information System (INIS)

Hincke, M.T.

1988-01-01

A routine semiquantitative procedure which permits soluble calcium-binding proteins to be detected following their adsorption to nitrocellulose membrane filters by liquid scintillation counting of specifically bound 45 Ca is described. Proteins with high affinity for calcium such as calmodulin and troponin can be detected with a detection threshold of about 2 μg per 400 μl. Modifications to decrease this limit are feasible and are discussed. This technique should allow calcium-binding proteins of unknown function to be assayed during their purification. It was necessary to treat solutions containing 45 Ca with chelex-100 in order to prevent loss of calcium binding which occurred as the decay product (SC 3+ ) accumulated, suggesting that all studies utilizing 45 Ca as a tracer should evaluate possible interference by this ion

The Accelerated Late Adsorption of Pulmonary Surfactant

Science.gov (United States)

2011-01-01

Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster adsorption rather than any feature of the equation of state that relates γ to surface concentration (Γ). Adsorption accelerates when γ reaches a critical value rather than after an interval required to reach that γ. The hydrophobic surfactant proteins (SPs) represent key constituents, both for reaching the γ at which the acceleration occurs and for producing the acceleration itself. The γ at which rates of adsorption increase, however, is unaffected by the Γ of protein in the films. In the absence of the proteins, a phosphatidylethanolamine, which, like the SPs, induces fusion of the vesicles with the interfacial film, also causes adsorption to accelerate. Our results suggest that the late acceleration is characteristic of adsorption by fusion of vesicles with the nascent film, which proceeds more favorably when the Γ of the lipids exceeds a critical value. PMID:21417351

Self-consistent field theory of protein adsorption in a non-Gaussian polyelectrolyte brush

NARCIS (Netherlands)

Biesheuvel, P.M.; Leermakers, F.A.M.; Stuart, M.A.C.

2006-01-01

To describe adsorption of globular protein molecules in a polyelectrolyte brush we use the strong-stretching approximation of the Edwards self-consistent field equation, combined with corrections for a non-Gaussian brush. To describe chemical potentials in this mixture of (globular) species of

Experimental approach to controllably vary protein oxidation while minimizing electrode adsorption for boron-doped diamond electrochemical surface mapping applications.

Science.gov (United States)

McClintock, Carlee S; Hettich, Robert L

2013-01-02

Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent (i.e., hydroxyl radicals) for these measurements; however, these approaches range significantly in their complexity and expense of operation. This research expands upon earlier work to enhance the controllability of boron-doped diamond (BDD) electrochemistry as an easily accessible tool for producing hydroxyl radicals in order to oxidize a range of intact proteins. Efforts to modulate the oxidation level while minimizing the adsorption of protein to the electrode involved the use of relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber. Additionally, a different cell activation approach using variable voltage to supply a controlled current allowed us to precisely tune the extent of oxidation in a protein-dependent manner. In order to gain perspective on the level of protein adsorption onto the electrode surface, studies were conducted to monitor protein concentration during electrolysis and gauge changes in the electrode surface between cell activation events. This report demonstrates the successful use of BDD electrochemistry for greater precision in generating a target number of oxidation events upon intact proteins.

Protein Adsorption Patterns and Analysis on IV Nanoemulsions—The Key Factor Determining the Organ Distribution

Directory of Open Access Journals (Sweden)

Mirko Jansch

2012-12-01

Full Text Available Intravenous nanoemulsions have been on the market for parenteral nutrition since the 1950s; meanwhile, they have also been used successfully for IV drug delivery. To be well tolerable, the emulsions should avoid uptake by the MPS cells of the body; for drug delivery, they should be target-specific. The organ distribution is determined by the proteins adsorbing them after injection from the blood (protein adsorption pattern, typically analyzed by two-dimensional polyacrylamide gel electrophoresis, 2-D PAGE. The article reviews the 2-D PAGE method, the analytical problems to be faced and the knowledge available on how the composition of emulsions affects the protein adsorption patterns, e.g., the composition of the oil phase, stabilizer layer and drug incorporation into the interface or oil core. Data were re-evaluated and compared, and the implications for the in vivo distribution are discussed. Major results are that the interfacial composition of the stabilizer layer is the main determining factor and that this composition can be modulated by simple processes. Drug incorporation affects the pattern depending on the localization of the drug (oil core versus interface. The data situation regarding in vivo effects is very limited; mainly, it has to be referred to in the in vivo data of polymeric nanoparticles. As a conclusion, determination of the protein adsorption patterns can accelerate IV nanoemulsion formulation development regarding optimized organ distribution and related pharmacokinetics.

Adsorption properties of BSA and DsRed proteins deposited on thin SiO2 layers: optically non-absorbing versus absorbing proteins

Science.gov (United States)

Scarangella, A.; Soumbo, M.; Villeneuve-Faure, C.; Mlayah, A.; Bonafos, C.; Monje, M.-C.; Roques, C.; Makasheva, K.

2018-03-01

Protein adsorption on solid surfaces is of interest for many industrial and biomedical applications, where it represents the conditioning step for micro-organism adhesion and biofilm formation. To understand the driving forces of such an interaction we focus in this paper on the investigation of the adsorption of bovine serum albumin (BSA) (optically non-absorbing, model protein) and DsRed (optically absorbing, naturally fluorescent protein) on silica surfaces. Specifically, we propose synthesis of thin protein layers by means of dip coating of the dielectric surface in protein solutions with different concentrations (0.01-5.0 g l-1). We employed spectroscopic ellipsometry as the most suitable and non-destructive technique for evaluation of the protein layers’ thickness and optical properties (refractive index and extinction coefficient) after dehydration, using two different optical models, Cauchy for BSA and Lorentz for DsRed. We demonstrate that the thickness, the optical properties and the wettability of the thin protein layers can be finely controlled by proper tuning of the protein concentration in the solution. These results are correlated with the thin layer morphology, investigated by AFM, FTIR and PL analyses. It is shown that the proteins do not undergo denaturation after dehydration on the silica surface. The proteins arrange themselves in a lace-like network for BSA and in a rod-like structure for DsRed to form mono- and multi-layers, due to different mechanisms driving the organization stage.

Dynamic Contact Angle Analysis of Protein Adsorption on Polysaccharide Multilayer’s Films for Biomaterial Reendothelialization

Directory of Open Access Journals (Sweden)

Safiya Benni

2014-01-01

Full Text Available Atherosclerosis is a major cardiovascular disease. One of the side effects is restenosis. The aim of this work was to study the coating of stents by dextran derivates based polyelectrolyte’s multilayer (PEM films in order to increase endothelialization of injured arterial wall after stent implantation. Films were composed with diethylaminoethyl dextran (DEAE as polycation and dextran sulphate (DS as polyanion. One film was composed with 4 bilayers of (DEAE-DS4 and was labeled D−. The other film was the same as D− but with an added terminal layer of DEAE polycation: (DEAE-DS4-DEAE (labeled D+. The dynamic adsorption/desorption of proteins on the films were characterized by dynamic contact angle (DCA and atomic force microscopy (AFM. Human endothelial cell (HUVEC adhesion and proliferation were quantified and correlated to protein adsorption analyzed by DCA for fibronectin, vitronectin, and bovine serum albumin (BSA. Our results showed that the endothelial cell response was optimal for films composed of DS as external layer. Fibronectin was found to be the only protein to exhibit a reversible change in conformation after desorption test. This behavior was only observed for (DEAE-DS4 films. (DEAE-DS4 films could enhance HUVEC proliferation in agreement with fibronectin ability to easily change from conformation.

The adsorption and unfolding kinetics determines the folding state of proteins at the air-water interface and thereby the equation of state

NARCIS (Netherlands)

Wierenga, P.A.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J.de

2006-01-01

Unfolding of proteins has often been mentioned as an important factor during the adsorption process at air-water interfaces and in the increase of surface pressure at later stages of the adsorption process. This work focuses on the question whether the folding state of the adsorbed protein depends

Adsorption studies on Pt(111)

International Nuclear Information System (INIS)

Hopster, H.

1977-06-01

The adsorption of O 2 , CO, and C 2 H 2 as well as the CO oxidation on Pt(111) were studied by high-resolution electron spectroscopy. Using a platinum monocrystal sample with a contonuous stage density, the adhesion coefficient for O 2 and the reaction probability for CO were determined as a function of stage density and oxygen cover by measuring the oxygen cover and its time behaviour. The study of vibrations of adsorbed CO showed that CO is bound in linear form on two different adsorption sites. The adsorption of acetylene was studied at 140 K and 300 K. The frequencies of the C-H stretching and flexural vibrations as well as the C-C-H bonding angle were determined. (orig./GSC) [de

Controlled surface chemistry of diamond/β-SiC composite films for preferential protein adsorption.

Science.gov (United States)

Wang, Tao; Handschuh-Wang, Stephan; Yang, Yang; Zhuang, Hao; Schlemper, Christoph; Wesner, Daniel; Schönherr, Holger; Zhang, Wenjun; Jiang, Xin

2014-02-04

Diamond and SiC both process extraordinary biocompatible, electronic, and chemical properties. A combination of diamond and SiC may lead to highly stable materials, e.g., for implants or biosensors with excellent sensing properties. Here we report on the controllable surface chemistry of diamond/β-SiC composite films and its effect on protein adsorption. For systematic and high-throughput investigations, novel diamond/β-SiC composite films with gradient composition have been synthesized using the hot filament chemical vapor deposition (HFCVD) technique. As revealed by scanning electron microscopy (SEM), the diamond/β-SiC ratio of the composite films shows a continuous change from pure diamond to β-SiC over a length of ∼ 10 mm on the surface. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to unveil the surface termination of chemically oxidized and hydrogen treated surfaces. The surface chemistry of the composite films was found to depend on diamond/β-SiC ratio and the surface treatment. As observed by confocal fluorescence microscopy, albumin and fibrinogen were preferentially adsorbed from buffer: after surface oxidation, the proteins preferred to adsorb on diamond rather than on β-SiC, resulting in an increasing amount of proteins adsorbed to the gradient surfaces with increasing diamond/β-SiC ratio. By contrast, for hydrogen-treated surfaces, the proteins preferentially adsorbed on β-SiC, leading to a decreasing amount of albumin adsorbed on the gradient surfaces with increasing diamond/β-SiC ratio. The mechanism of preferential protein adsorption is discussed by considering the hydrogen bonding of the water self-association network to OH-terminated surfaces and the change of the polar surface energy component, which was determined according to the van Oss method. These results suggest that the diamond/β-SiC gradient film can be a promising material for biomedical applications which

ADSORPTION AND RELEASING PROPERTIES OF BEAD CELLULOSE

Institute of Scientific and Technical Information of China (English)

A. Morales; E. Bordallo; V. Leon; J. Rieumont

2004-01-01

The adsorption of some dyes on samples of bead cellulose obtained in the Unit of Research-Production "Cuba 9"was studied. Methylene blue, alizarin red and congo red fitted the adsorption isotherm of Langmuir. Adsorption kinetics at pH = 6 was linear with the square root of time indicating the diffusion is the controlling step. At pH = 12 a non-Fickian trend was observed and adsorption was higher for the first two dyes. Experiments carried out to release the methylene blue occluded in the cellulose beads gave a kinetic behavior of zero order. The study of cytochrome C adsorption was included to test a proteinic material. Crosslinking of bead cellulose was performed with epichlorohydrin decreasing its adsorption capacity in acidic or alkaline solution.

Effects of cloud-point grafting, chain length, and density of PEG layers on competitive adsorption of ocular proteins

DEFF Research Database (Denmark)

Kingshott, P.; Thissen, H.; Griesser, H.J.

2002-01-01

The effects of pinning density, chain length, and 'cloud point' (CP) versus non-CP grafting conditions have been studied on the ability of polyethylene glycol (PEG) layers to minimize adsorption from a multicomponent (lysozyme, human serum albumin (HSA), IgG and lactoferrin) protein solution...... density) r.f.g.d. polymer layers. The PEG graft density was varied also by increasing the temperature and salt (K2SO4) content of the grafting solution; it reached a maximum at the CP of the PEGs. The CP reaction conditions were critical for producing PEG layers capable of minimizing protein adsorption. X...... density and chain length are interrelated, but the key factor is optimization of PEG chain density by use of the CP conditions, provided that a sufficient density of pinning sites exists. (C) 2002 Elsevier Science Ltd. Al l rights reserved....

Protein Adsorption onto Nanomaterials for the Development of Biosensors and Analytical Devices: A Review

Science.gov (United States)

Bhakta, Samir A.; Evans, Elizabeth; Benavidez, Tomás E.; Garcia, Carlos D.

2014-01-01

An important consideration for the development of biosensors is the adsorption of the bio recognition element to the surface of a substrate. As the first step in the immobilization process, adsorption affects most immobilization routes and much attention is given into the research of this process to maximize the overall activity of the bio sensor. The use of nanomaterials, specifically nanoparticles and nanostructured films, offers advantageous properties that can be fine-tuned for interaction with specific proteins to maximize activity, minimize structural changes, and enhance the catalytic step. In the biosensor field, protein-nanomaterial interactions are an emerging trend that span across many disciplines. This review addresses recent publications about the proteins most frequently used, their most relevant characteristics, and the conditions required to adsorb them to nanomaterials. When relevant and available, subsequent analytical figures of merits are discussed for selected biosensors. The general trend amongst the research papers allows concluding that the use of nanomaterials has already provided significant improvements in the analytical performance of many biosensors and that this research field will continue to grow. PMID:25892065

The Effect of Simulated Microgravity Environment of RWV Bioreactors on Surface Reactions and Adsorption of Serum Proteins on Bone-bioactive Microcarriers

Science.gov (United States)

Radin, Shula; Ducheyne, P.; Ayyaswamy, P. S.

2003-01-01

Biomimetically modified bioactive materials with bone-like surface properties are attractive candidates for use as microcarriers for 3-D bone-like tissue engineering under simulated microgravity conditions of NASA designed rotating wall vessel (RWV) bioreactors. The simulated microgravity environment is attainable under suitable parametric conditions of the RWV bioreactors. Ca-P containing bioactive glass (BG), whose stimulatory effect on bone cell function had been previously demonstrated, was used in the present study. BG surface modification via reactions in solution, resulting formation of bone-like minerals at the surface and adsorption of serum proteins is critical for obtaining the stimulatory effect. In this paper, we report on the major effects of simulated microgravity conditions of the RWV on the BG reactions surface reactions and protein adsorption in physiological solutions. Control tests at normal gravity were conducted at static and dynamic conditions. The study revealed that simulated microgravity remarkably enhanced reactions involved in the BG surface modification, including BG dissolution, formation of bone-like minerals at the surface and adsorption of serum proteins. Simultaneously, numerical models were developed to simulate the mass transport of chemical species to and from the BG surface under normal gravity and simulated microgravity conditions. The numerical results showed an excellent agreement with the experimental data at both testing conditions.

Multi-component adsorption model for pellicle formation: the influence of salivary proteins and non-salivary phospho proteins on the binding of histatin 5 onto hydroxyapatite.

Science.gov (United States)

Yin, A; Margolis, H C; Yao, Y; Grogan, J; Oppenheim, F G

2006-02-01

The acquired enamel pellicle formed by selective adsorption of proteins in whole saliva is a protective integument on the tooth surface. The purpose of the present study was to investigate the formation of human acquired enamel pellicle using an in vitro hydroxyapatite (HA) model and 3H-histatin 5 to allow accurate measurement of histatin 5 binding in a multi-component experimental system. A binary system was employed by mixing 3H-histatin 5 with one unlabeled protein prior to incubation with HA or by first incubating 3H-histatin 5 with the HA which had been pre-coated with one of a panel of unlabeled proteins (human albumin, salivary amylase, lysozyme, acidic PIFs, statherin, the N-terminal fragment of statherin, and egg yolk phosvitin). A ternary system was employed by mixing 3H-histatin 5 with HA sequentially pre-coated with two different unlabeled proteins, including recombinant histatin 1. The results showed that only salivary statherin and egg yolk phosvitin promote histatin 5 adsorption significantly. The amount of histatin 5 adsorbed was also found to increase as a function of the amount of phosvitin and statherin used to pre-coat HA up to a maximum level that was two- to four-fold greater than that observed on untreated HA. These data suggest that specific protein-protein interactions may play important roles in pellicle formation in vivo.

An Experimental Approach to Controllably Vary Protein Oxidation While Minimizing Electrode Adsorption for Boron-Doped Diamond Electrochemical Surface Mapping Applications

Science.gov (United States)

McClintock, Carlee S; Hettich, Robert L.

2012-01-01

Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent – hydroxyl radicals – for these measurements; however, these approaches range significantly in their complexity and expense of operation. This research expands upon earlier work to enhance the controllability of boron-doped diamond (BDD) electrochemistry as an easily accessible tool for producing hydroxyl radicals in order to oxidize a range of intact proteins. Efforts to modulate oxidation level while minimizing the adsorption of protein to the electrode involved the use of relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber. Additionally, a different cell activation approach using variable voltage to supply a controlled current allowed us to precisely tune the extent of oxidation in a protein-dependent manner. In order to gain perspective on the level of protein adsorption onto the electrode surface, studies were conducted to monitor protein concentration during electrolysis and gauge changes in the electrode surface between cell activation events. This report demonstrates the successful use of BDD electrochemistry for greater precision in generating a target number of oxidation events upon intact proteins. PMID:23210708

Formation of protein/surfactant adsorption layer at the air/water interface as studied by dilational surface rheology.

Science.gov (United States)

Mikhailovskaya, A A; Noskov, B A; Lin, S-Y; Loglio, G; Miller, R

2011-08-25

The dynamic dilatational surface elasticity of mixed solutions of globular proteins (β-lactoglobulin (BLG) and bovine serum albumin (BSA)) with cationic (dodecyltrimethylammonium bromide (DTAB)) and anionic (sodium dodecyl sulfate (SDS)) surfactants was measured as a function of the surfactant concentration and surface age. If the cationic surfactant concentration exceeds a certain critical value, the kinetic dependencies of the dynamic surface elasticity of BLG/DTAB and BSA/DTAB solutions become nonmonotonous and resemble those of mixed solutions of proteins with guanidine hydrochloride. This result indicates not only the destruction of the protein tertiary structure in the surface layer of mixed solution but also a strong perturbation of the secondary structure. The corresponding kinetic dependencies for protein solutions with added anionic surfactants are always monotonous, thereby revealing a different mechanism of the adsorption layer formation. One can assume that the secondary structure is destroyed to a lesser extent in the latter case and hinders the formation of loops and tails at the interface. The increase of the solution's ionic strength by the addition of sodium chloride results in stronger changes of the protein conformations in the surface layer and the appearance of a local maximum in the kinetic dependencies of the dynamic surface elasticity in a relatively narrow range of SDS concentration. © 2011 American Chemical Society

pH dependence of the kinetics of interfacial tension changes during protein adsorption from sessile droplets on FEP-Teflon

NARCIS (Netherlands)

VanderVegt, W; Norde, W; VanderMei, HC; Busscher, HJ

Interfacial tension changes during protein adsorption at both the solid-liquid and the liquid-vapor interface were measured simultaneously by ADSA-P from sessile droplets of protein solutions on fluoroethylenepropylene-Teflon. Four globular proteins of similar size, viz. lysozyme, ribonuclease,

Kinetics of adsorption of whey proteins and hydroxypropyl-methyl-cellulose mixtures at the air-water interface.

Science.gov (United States)

Pérez, Oscar E; Carrera Sánchez, Cecilio; Pilosof, Ana M R; Rodríguez Patino, Juan M

2009-08-15

The aim of this research is to quantify the competitive adsorption of a whey protein concentrate (WPC) and hydroxypropyl-methyl-cellulose (HPMC so called E4M, E50LV and F4M) at the air-water interface by means of dynamic surface tensiometry and Brewster angle microscopy (BAM). These biopolymers are often used together in many food applications. The concentration of both protein and HPMC, and the WPC/HPMC ratio in the aqueous bulk phase were variables, while pH (7), the ionic strength (0.05 M) and temperature (20 degrees C) were kept constant. The differences observed between mixed systems were in accordance with the relative bulk concentration of these biopolymers (C(HPMC) and C(WPC)) and the molecular structure of HPMC. At short adsorption times, the results show that under conditions where both WPC and HPMC could saturate the air-water interface on their own or when C(HPMC) > or = C(WPC), the polysaccharide dominates the surface. At concentrations where none of the biopolymers was able to saturate the interface, a synergistic behavior was observed for HPMC with lower surface activity (E50LV and F4M), while a competitive adsorption was observed for E4M (the HPMC with the highest surface activity). At long-term adsorption the rate of penetration controls the adsorption of mixed components. The results reflect complex competitive/synergistic phenomena under conditions of thermodynamic compatibility or in the presence of a "depletion mechanism". Finally, the order in which the different components reach the interface will influence the surface composition and the film properties.

Persistence of detectable insecticidal proteins from Bacillus thuringiensis (Cry) and toxicity after adsorption on contrasting soils

International Nuclear Information System (INIS)

Hung, T.P.; Truong, L.V.; Binh, N.D.; Frutos, R.; Quiquampoix, H.; Staunton, S.

2016-01-01

Insecticidal Cry, or Bt, proteins are produced by the soil-endemic bacterium, Bacillus thuringiensis and some genetically modified crops. Their environmental fate depends on interactions with soil. Little is known about the toxicity of adsorbed proteins and the change in toxicity over time. We incubated Cry1Ac and Cry2A in contrasting soils subjected to different treatments to inhibit microbial activity. The toxin was chemically extracted and immunoassayed. Manduca sexta was the target insect for biotests. Extractable toxin decreased during incubation for up to four weeks. Toxicity of Cry1Ac was maintained in the adsorbed state, but lost after 2 weeks incubation at 25 °C. The decline in extractable protein and toxicity were much slower at 4 °C with no significant effect of soil sterilization. The major driving force for decline may be time-dependent fixation of adsorbed protein, leading to a decrease in the extraction yield in vitro, paralleled by decreasing solubilisation in the larval gut. - Graphical abstract: Biotest, presenting Cry-contaminated feed to Manduca sexta larvae in individual Perspex boxes. Display Omitted - Highlights: • Toxicity of Cry protein is initially conserved after adsorption on soil. • Toxicity and extractability decline with time, more rapidly at 25 °C than 4 °C. • Similar dynamics of Cry1AC and Cry2A on soil with varying texture and organic C. • Sterilization of soil does not change Cry dynamics or temperature effect in soil. • Cry decline is determined by progressive fixation on soil not microbial breakdown. - Toxicity was initially maintained after adsorption on soil and both extractable Cry and toxicity declined rapidly, more slowly at low temperature, due to different fixation dynamics. Toxicity of Cry protein is initially conserved after adsorption on soil.

Molecular printboards as a general platform for protein immobilization: A supramolecular solution to nonspecific adsorption

NARCIS (Netherlands)

Ludden, M.J.W.; Mulder, A.; Tampe, Robert; Reinhoudt, David; Huskens, Jurriaan

2007-01-01

Be specific: A supramolecular adsorbate consisting of an adamantyl group (red) and an oligo(ethylene glycol) chain has been designed to prevent nonspecific protein adsorption at cyclodextrin molecular printboards. The adamantyl group allows specific and reversible interactions. Specific

Elucidating the mechanisms of protein antigen adsorption to the CAF/NAF liposomal vaccine adjuvant systems

DEFF Research Database (Denmark)

Hamborg, Mette; Rose, Fabrice; Jorgensen, Lene

2014-01-01

is generally known about how antigens and adjuvants interact at the molecular level. The aim of this study was to elucidate the mechanisms of interactions between the equally sized, but oppositely charged model protein antigens α-lactalbumin and lysozyme, and i) the clinically tested cationic liposomal...... antigens are presented to antigen-presenting cells, and may play an important role for the efficacy of the vaccine-induced immune response. These studies thus exemplify the importance of characterizing the molecular interactions between the vaccine antigen and adjuvant along with immunogenicity......The reverse vaccinology approach has recently resulted in the identification of promising protein antigens, which in combination with appropriate adjuvants can stimulate customized, protective immune responses. Although antigen adsorption to adjuvants influences vaccine efficacy and safety, little...

Adsorption of acidic, basic, and neutral proteins from aqueous samples using Fe3O4 magnetic nanoparticles modified with an ionic liquid

International Nuclear Information System (INIS)

Kamran, S.; Asadi, M.; Absalan, G.

2013-01-01

We have prepared and characterized Fe 3 O 4 nanoparticles and their binary mixtures (IL-Fe 3 O 4 ) with 1-hexyl-3-methylimidazolium bromide as ionic liquid for use in the adsorption of lysozyme (LYS), bovine serum albumin (BSA), and myoglobin (MYO). The optimum operational conditions for the adsorption of proteins (at 0.05-2.0 mg mL -1 ) were 4.0 mg mL -1 of nanoparticles and a contact time of 10 min. The maximum adsorption capacities are 455, 182 and 143 mg for LYS, BSA, and MYO per gram of adsorbent, respectively. The Langmuir model better fits the adsorption isotherms, with adsorption constants of 0.003, 0.015 and 0.008 L mg -1 , in order, for LYS, BSA, MYO. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. The adsorption processes are endothermic. The proteins can be desorbed from the nanoparticles by using NaCl solution at pH 9.5, and the nanoparticles thus can be recycled. (author)

Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features.

Science.gov (United States)

Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu; He, Hua; Rao, Hanbing

2015-01-01

The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g(-1), respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. Copyright © 2015 Elsevier B.V. All rights reserved.

Is there an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors? Part II

Energy Technology Data Exchange (ETDEWEB)

Wang Huajie, E-mail: wanghuajie972001@163.com; Sun Yuanyuan; Cao Ying, E-mail: caoying1130@sina.com; Wang Kui; Yang Lin [Henan Normal University, College of Chemistry and Environmental Science (China); Zhang Yidong; Zheng Zhi [Xuchang University, Institute of Surface Micro and Nano Materials (China)

2012-05-15

Although nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured surfaces, whether there is an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors is still controversial. In this study, porous aluminum oxide membranes with different pore sizes ranging from 25 to 120 nm were prepared by the anodic oxidation technique. The surface morphology, topography and wettability were analyzed by scanning electron microscope, atomic force microscope and water contact angle measurement, respectively. The results indicated that the synergistic action of the nano-topography structure and hydrophilic/hydrophobic properties resulted in a highest protein adsorption on the aluminum oxide membrane with 80 nm pore size. Additionally, the morphological, metabolic and cell counting methods showed that cells had different sensitivity to porous aluminum oxide membranes with different surface features. Furthermore, this sensitivity was cell type dependent. The optimal pore size of aluminum oxide membranes for cell growth was 80 nm for PC12 cells and 50 nm for NIH 3T3 cells.

Modeling chromatographic columns. Non-equilibrium packed-bed adsorption with non-linear adsorption isotherms

NARCIS (Netherlands)

Özdural, A.R.; Alkan, A.; Kerkhof, P.J.A.M.

2004-01-01

In this work a new mathematical model, based on non-equilibrium conditions, describing the dynamic adsorption of proteins in columns packed with spherical adsorbent particles is used to study the performance of chromatographic systems. Simulations of frontal chromatography, including axial

Adsorption of ammonium and phosphate by feather protein based semi-interpenetrating polymer networks hydrogel as a controlled-release fertilizer.

Science.gov (United States)

Su, Yuan; Liu, Jia; Yue, Qinyan; Li, Qian; Gao, Baoyu

2014-01-01

A new feather protein-grafted poly(potassium acrylate)/polyvinyl alcohol (FP-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was produced through graft copolymerization with FP as a basic macromolecular skeletal material, acrylic acid as a monomer and PVA as a semi-IPNs polymer. The adsorption of ammonium and phosphate ions from aqueous solution using the new hydrogel as N and P controlled-release fertilizer with water-retention capacity was studied. The effects of pH value, concentration, contact time and ion strength on NH4+ and PO3-4 removal by FP-g-PKA/PVA semi-IPNs hydrogel were investigated using batch adsorption experiments. The results indicated that the hydrogel had high adsorption capacities and fast adsorption rates for NH4+ and PO3-4 in wide pH levels ranging from 4.0 to 9.0. Kinetic analysis presented that both NH4+ and PO3-4 removal were closely fitted with the pseudo-second-order model. Furthermore, the adsorption isotherms of hydrogel were best represented by the Freundlich model. The adsorption-desorption experimental results showed the sustainable stability of FP-g-PKA/PVA semi-IPNs hydrogel for NH4+ and PO3-4 removal. Overall, FP-g-PKA/PVA could be considered as an efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer.

Particle size effects on protein and virus-like particle adsorption on perfusion chromatography media.

Science.gov (United States)

Wu, Yige; Abraham, Dicky; Carta, Giorgio

2015-01-02

The resin structure, chromatographic behavior, and adsorption kinetics of proteins and virus-like-particles (VLPs) are studied for POROS HS 20 and POROS HS 50 (23 and 52 μm mean diameter, respectively) to determine the effects of particle size on perfusion chromatography and to determine the predictive ability of available models. Transmission electron microscopy (TEM) and inverse size-exclusion chromatography (iSEC) show similar structures for the two resins, both containing 200-1000 nm pores that transect a network of much smaller pores. For non-binding conditions, trends of the height equivalent to a theoretical plate (HETP) as a function of reduced velocity are consistent with perfusion. The estimated intraparticle flow fractions for these conditions are 0.0018 and 0.00063 for POROS HS 20 and HS 50, respectively. For strong binding conditions, confocal laser scanning microscopy (CLSM) shows asymmetrical intraparticle concentrations profiles and enhanced rates of IgG adsorption on POROS HS 20 at 1000 cm/h. The corresponding effective diffusivity under flow is 2-3 times larger than for non-flow conditions and much larger than observed for POROS HS 50, consistent with available models. For VLPs, however, adsorption is confined to a thin layer near the particle surface for both resins, suggesting that the bound VLPs block the pores. Copyright © 2014 Elsevier B.V. All rights reserved.

Platelet adhesion and plasma protein adsorption control of collagen surfaces by He+ ion implantation

International Nuclear Information System (INIS)

Kurotobi, K.; Suzuki, Y.; Nakajima, H.; Suzuki, H.; Iwaki, M.

2003-01-01

He + ion implanted collagen-coated tubes with a fluence of 1 x 10 14 ions/cm 2 were exhibited antithrombogenicity. To investigate the mechanisms of antithrombogenicity of these samples, plasma protein adsorption assay and platelet adhesion experiments were performed. The adsorption of fibrinogen (Fg) and von Willebrand factor (vWf) was minimum on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 . Platelet adhesion (using platelet rich plasma) was inhibited on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was accelerated on the untreated collagen and ion implanted collagen with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Platelet activation with washed platelets was observed on untreated collagen and He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was inhibited with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Generally, platelets can react with a specific ligand inside the collagen (GFOGER sequence). The results of platelets adhesion experiments using washed platelets indicated that there were no ligands such as GFOGER on the He + ion implanted collagen over a fluence of 1 x 10 13 ions/cm 2 . On the 1 x 10 14 ions/cm 2 implanted collagen, no platelet activation was observed due to the influence of plasma proteins. >From the above, it is concluded that the decrease of adsorbed Fg and vWf caused the antithrombogenicity of He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and that plasma protein adsorption took an important role repairing the graft surface

Evaluation of a combined drug-delivery system for proteins assembled with polymeric nanoparticles and porous microspheres; characterization and protein integrity studies.

Science.gov (United States)

Alcalá-Alcalá, Sergio; Benítez-Cardoza, Claudia G; Lima-Muñoz, Enrique J; Piñón-Segundo, Elizabeth; Quintanar-Guerrero, David

2015-07-15

This work presents an evaluation of the adsorption/infiltration process in relation to the loading of a model protein, α-amylase, into an assembled biodegradable polymeric system, free of organic solvents and made up of poly(D,L-lactide-co-glycolide) acid (PLGA). Systems were assembled in a friendly aqueous medium by adsorbing and infiltrating polymeric nanoparticles into porous microspheres. These assembled systems are able to load therapeutic amounts of the drug through adsorption of the protein onto the large surface area characteristic of polymeric nanoparticles. The subsequent infiltration of nanoparticles adsorbed with the protein into porous microspheres enabled the controlled release of the protein as a function of the amount of infiltrated nanoparticles, since the surface area available on the porous structure is saturated at different levels, thus modifying the protein release rate. Findings were confirmed by both the BET technique (N2 isotherms) and in vitro release studies. During the adsorption process, the pH of the medium plays an important role by creating an environment that favors adsorption between the surfaces of the micro- and nano-structures and the protein. Finally, assays of α-amylase activity using 2-chloro-4-nitrophenyl-α-D-maltotrioside (CNP-G3) as the substrate and the circular dichroism technique confirmed that when this new approach was used no conformational changes were observed in the protein after release. Copyright © 2015 Elsevier B.V. All rights reserved.

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

OpenAIRE

Chen, Qing; Tian, Yuanyuan; Li, Peng; Yan, Changhui; Pang, Yu; Zheng, Li; Deng, Hucheng; Zhou, Wen; Meng, Xianghao

2017-01-01

Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indi...

Adsorption dynamics and equilibrium studies of Zn (II)

Indian Academy of Sciences (India)

Batch equilibration studies are conducted to determine the nature of adsorption of zinc (II) over chitosan. The factors affecting the adsorption process like particle size, contact time, dosage, pH, effects of chloride and nitrate are identified. The influence of temperature and co-ions on the adsorption process is verified.

Effects of atomic-level nano-structured hydroxyapatite on adsorption of bone morphogenetic protein-7 and its derived peptide by computer simulation.

Science.gov (United States)

Wang, Qun; Wang, Menghao; Lu, Xiong; Wang, Kefeng; Fang, Liming; Ren, Fuzeng; Lu, Guoming

2017-11-09

Hydroxyapatite (HA) is the principal inorganic component of bones and teeth and has been widely used as a bone repair material because of its good biocompatibility and bioactivity. Understanding the interactions between proteins and HA is crucial for designing biomaterials for bone regeneration. In this study, we evaluated the effects of atomic-level nano-structured HA (110) surfaces on the adsorption of bone morphogenetic protein-7 (BMP-7) and its derived peptide (KQLNALSVLYFDD) using molecular dynamics and density functional theory methods. The results indicated that the atomic-level morphology of HA significantly affected the interaction strength between proteins and HA substrates. The interactions of BMP-7 and its derived peptide with nano-concave and nano-pillar HA surfaces were stronger than those with flat or nano-groove HA surfaces. The results also revealed that if the groove size of nano-structured HA surfaces matched that of residues in the protein or peptide, these residues were likely to spread into the grooves of the nano-groove, nano-concave, and nano-pillar HA, further strengthening the interactions. These results are helpful in better understanding the adsorption behaviors of proteins onto nano-structured HA surfaces, and provide theoretical guidance for designing novel bioceramic materials for bone regeneration and tissue engineering.

Certain patterns of IgG adsorption by polystyrene bead surfaces

Energy Technology Data Exchange (ETDEWEB)

Mamedov, M K

1985-01-01

The article reports on tests of domestic Soviet polystyrene beads that permit a simplified modification of the enzyme-adsorption method to identify the alpha hepatitis virus and its antibody in nonspecialized, general laboratories. Only patterns of Ig immunoglobulin adsorption were studied. Human IgG was conjugated with the radioactive isotope /sup 125/I by a chloramine method, with mean radioactivity and protein concentration measured frequently. Bovine serum albumin (BSA) and an anionic detergent Tween-20, and a phosphate-salt buffer with pH 5.8-8.2, were used to produce m-Ig and Ig. Adsorption involved incubation of the beads in various solutions, followed by measurement of their radioactivity. Results of several series of tests were subjected to Student-Fisher evaluation. This suggested that the presence of albumin in physiological concentrations in the solution had no important impact on m-Ig adsorption on the bead surface, which effectively adsorbed Ig from solutions without additional proteins, but also from Ig solutions containing serum albumin in physiological concentrations. Thus, it was possible to coat the beads with alpha Ig hepatitis virus. The Tween-20 weak detergent was effective for eliminating unwanted protein adsorption. 9 references, 3 figures.

Characterization of protein adsorption onto FePt nanoparticles using dual-focus fluorescence correlation spectroscopy

Directory of Open Access Journals (Sweden)

Pauline Maffre

2011-07-01

Full Text Available Using dual-focus fluorescence correlation spectroscopy, we have analyzed the adsorption of three human blood serum proteins, namely serum albumin, apolipoprotein A-I and apolipoprotein E4, onto polymer-coated, fluorescently labeled FePt nanoparticles (~12 nm diameter carrying negatively charged carboxyl groups on their surface. For all three proteins, a step-wise increase in hydrodynamic radius with protein concentration was observed, strongly suggesting the formation of protein monolayers that enclose the nanoparticles. Consistent with this interpretation, the absolute increase in hydrodynamic radius can be correlated with the molecular shapes of the proteins known from X-ray crystallography and solution experiments, indicating that the proteins bind on the nanoparticles in specific orientations. The equilibrium dissociation coefficients, measuring the affinity of the proteins to the nanoparticles, were observed to differ by almost four orders of magnitude. These variations can be understood in terms of the electrostatic properties of the proteins. From structure-based calculations of the surface potentials, positively charged patches of different extents can be revealed, through which the proteins interact electrostatically with the negatively charged nanoparticle surfaces.

Study of 63Ni adsorption on NKF-6 zeolite

International Nuclear Information System (INIS)

Zhang Hui; Yu Xianjin; Chen Lei; Jing Yongjie; Ge Zhiwei

2010-01-01

The adsorption of 63 Ni from aqueous solutions using NKF-6 zeolite was investigated by a batch technique under ambient conditions. The adsorption was investigated as a function of contact time, pH, ionic strength, foreign ions, humic substances (FA/HA) and temperature. The kinetic adsorption was well described by the pseudo-second-order rate equation. The adsorption of 63 Ni on NKF-6 zeolite was strongly dependent on pH and ionic strength, and the adsorption of 63 Ni increased with increasing NKF-6 zeolite content. At low pH values, the presence of FA enhanced the adsorption of 63 Ni on NKF-6 zeolite, but the presence of HA had no drastic effect. At high pH values, the presence of FA or HA decreased the adsorption of 63 Ni on NKF-6 zeolite. The adsorption isotherms were well represented by the Langmuir model. The thermodynamic parameters (i.e., ΔH 0 , ΔS 0 and ΔG 0 ) for the adsorption of 63 Ni were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15 o K, respectively, and the results indicate that the adsorption reaction was favored at high temperature. The results suggest that the adsorption process of 63 Ni on NKF-6 zeolite is spontaneous and endothermic. - Research highlights: → As an economical and efficient method, adsorption technique has been widely applied in the disposal of wastewaters. The study of 63 Ni on NKF-6 zeolite, especially the thermodynamic data of 63 Ni adsorption on NKF-6 zeolite and the effect of humic substances on 63 Ni uptake to humic-zeolite hybrids, is still scarce. In this paper, the sorption of 63 Ni on NKF-6 zeolite is studied as a function of various environmental conditions such as contact time, pH, ionic strength, foreign ions, humic substances and temperature. Based on the obtained experimental results, the adsorption mechanism of 63 Ni on NKF-6 zeolite is stated in detail. This study will have an important reference value in evaluating the physiochemical behavior of radionuclide 63 Ni.

Effects of gramicidin-A on the adsorption of phospholipids to the air–water interface

Science.gov (United States)

Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

2012-01-01

Prior studies suggest that the hydrophobic surfactant proteins, SP-B and SP-C, promote adsorption of the lipids in pulmonary surfactant to an air–water interface by stabilizing a negatively curved rate-limiting structure that is intermediate between bilayer vesicles and the surface film. This model predicts that other peptides capable of stabilizing negative curvature should also promote lipid adsorption. Previous reports have shown that under appropriate conditions, gramicidin-A (GrA) induces dioleoyl phosphatidylcholine (DOPC), but not dimyristoyl phosphatidylcholine (DMPC), to form the negatively curved hexagonal-II (HII) phase. The studies reported here determined if GrA would produce the same effects on adsorption of DMPC and DOPC that the hydrophobic surfactant proteins have on the surfactant lipids. Small angle X-ray scattering and 31P-nuclear magnetic resonance confirmed that at the particular conditions used to study adsorption, GrA induced DOPC to form the HII phase, but DMPC remained lamellar. Measurements of surface tension showed that GrA in vesicles produced a general increase in the rate of adsorption for both phospholipids. When restricted to the interface, however, in preexisting films, GrA with DOPC, but not with DMPC, replicated the ability of the surfactant proteins to promote adsorption of vesicles containing only the lipids. The correlation between the structural and functional effects of GrA with the two phospholipids, and the similar effects on adsorption of GrA with DOPC and the hydrophobic surfactant proteins with the surfactant lipids fit with the model in which SP-B and SP-C facilitate adsorption by stabilizing a rate-limiting intermediate with negative curvature. PMID:16242116

Effect of thermal stability on protein adsorption to silica using homologous aldo-keto reductases

OpenAIRE

Felsovalyi, Flora; Patel, Tushar; Mangiagalli, Paolo; Kumar, Sanat K; Banta, Scott

2012-01-01

Gaining more insight into the mechanisms governing the behavior of proteins at solid/liquid interfaces is particularly relevant in the interaction of high-value biologics with storage and delivery device surfaces, where adsorption-induced conformational changes may dramatically affect biocompatibility. The impact of structural stability on interfacial behavior has been previously investigated by engineering nonwild-type stability mutants. Potential shortcomings of such approaches include only...

In vitro haematic proteins adsorption and cytocompatibility study on acrylic copolymer to realise coatings for drug-eluting stents

International Nuclear Information System (INIS)

Gagliardi, Mariacristina

2012-01-01

In the present paper, a preliminary in vitro analysis of biocompatibility of newly-synthesised acrylic copolymers is reported. In particular, with the aim to obtain coatings for drug-eluting stents, blood protein absorption and cytocompatibility were studied. For protein absorption tests, bovine serum albumin and bovine plasma fibrinogen were considered. Cytocompatibility was tested using C2C12 cell line as model, analysing the behaviour of polymeric matrices and of drug-eluting systems, obtained loading polymeric matrices with paclitaxel, an anti-mitotic drug, in order to evaluate the efficacy of a pharmacological treatment locally administered from these materials. Results showed that the amount of albumin absorbed was greater than the amount of fibrinogen (comprised in the range of 70%–85% and 10%–22% respectively) and it is a good behaviour in terms of haemocompatibility. Cell culture tests showed good adhesion properties and a relative poor proliferation. In addition, a strong effect related to drug elution and a correlation with the macromolecular composition were detected. In this preliminary analysis, tested materials showed good characteristics and can be considered possible candidates to obtain coatings for drug-eluting stents. Highlights: ► Preliminary evaluation of haemo- and cytocompatibility of newly-synthesised acrylic copolymers ► Materials adsorb higher amounts of albumin and with a faster rate than fibrinogen. ► Protein adsorption depended on the macromolecular composition and surface properties. ► Cell viability on pure samples and efficacy of paclitaxel release were verified in C2C12 cultures.

In vitro haematic proteins adsorption and cytocompatibility study on acrylic copolymer to realise coatings for drug-eluting stents

Energy Technology Data Exchange (ETDEWEB)

Gagliardi, Mariacristina, E-mail: mariacristina.gagliardi@iit.it

2012-12-01

In the present paper, a preliminary in vitro analysis of biocompatibility of newly-synthesised acrylic copolymers is reported. In particular, with the aim to obtain coatings for drug-eluting stents, blood protein absorption and cytocompatibility were studied. For protein absorption tests, bovine serum albumin and bovine plasma fibrinogen were considered. Cytocompatibility was tested using C2C12 cell line as model, analysing the behaviour of polymeric matrices and of drug-eluting systems, obtained loading polymeric matrices with paclitaxel, an anti-mitotic drug, in order to evaluate the efficacy of a pharmacological treatment locally administered from these materials. Results showed that the amount of albumin absorbed was greater than the amount of fibrinogen (comprised in the range of 70%-85% and 10%-22% respectively) and it is a good behaviour in terms of haemocompatibility. Cell culture tests showed good adhesion properties and a relative poor proliferation. In addition, a strong effect related to drug elution and a correlation with the macromolecular composition were detected. In this preliminary analysis, tested materials showed good characteristics and can be considered possible candidates to obtain coatings for drug-eluting stents. Highlights: Black-Right-Pointing-Pointer Preliminary evaluation of haemo- and cytocompatibility of newly-synthesised acrylic copolymers Black-Right-Pointing-Pointer Materials adsorb higher amounts of albumin and with a faster rate than fibrinogen. Black-Right-Pointing-Pointer Protein adsorption depended on the macromolecular composition and surface properties. Black-Right-Pointing-Pointer Cell viability on pure samples and efficacy of paclitaxel release were verified in C2C12 cultures.

A DFT study on benzene adsorption over tungsten sulfides: surface model and adsorption geometries

NARCIS (Netherlands)

Koide, R.; Hensen, E.J.M.; Paul, J.F.; Cristol, S.; Payen, E.; Nakamura, H.; Santen, van R.A.

2007-01-01

Benzene adsorption on a WS2(100) surface was studied by ab initio periodic DFT computations. Benzene adsorption is facile on the bridge site of the bare W edge via ¿2 or ¿3 coordination. Taking into account the stable configuration at the W edge under typical hydrotreating reaction conditions (623

Glucose Oxidase Adsorption on Sequential Adsorbed Polyelectrolyte Films Studied by Spectroscopic Techniques

Science.gov (United States)

Tristán, Ferdinando; Solís, Araceli; Palestino, Gabriela; Gergely, Csilla; Cuisinier, Frédéric; Pérez, Elías

2005-04-01

The adsorption of Glucose Oxidase (GOX) on layers of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) deposited on Sequentially Adsorbed Polyelectrolyte Films (SAPFs) were studied by three different spectroscopic techniques. These techniques are: Optical Wave Light Spectroscopy (OWLS) to measure surface density; Fluorescence Resonance Energy Transfer (FRET) to verify the adsorption of GOX on the surface; and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection mode (FTIR-HATR) to inspect local structure of polyelectrolytes and GOX. Two positive and two negative polyelectrolytes are used: Cationic poly(ethyleneimine) (PEI) and poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrene sulfonate) (PSS) and poly(acrylic acid) (PAA). These spectroscopic techniques do not require any labeling for GOX or SAPFs, specifically GOX and PSS are naturally fluorescent and are used as a couple donor-acceptor for the FRET technique. The SAPFs are formed by a (PEI)-(PSS/PAH)2 film followed by (PAA/PAH)n bilayers. GOX is finally deposited on top of SAPFs at different values of n (n=1..5). Our results show that GOX is adsorbed on positive ended SAPFs forming a monolayer. Contrary, GOX adsorption is not observed on negative ended film polyelectrolyte. GOX stability was tested adding a positive and a negative polyelectrolyte after GOX adsorption. Protein is partially removed by PAH and PAA, with lesser force by PAA.

Simple approach to study biomolecule adsorption in polymeric microfluidic channels

Energy Technology Data Exchange (ETDEWEB)

Gubala, Vladimir, E-mail: V.Gubala@kent.ac.uk [Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9 (Ireland); Medway School of Pharmacy, University of Kent, Central Avenue, Anson 120, Chatham Maritime, Kent ME4 4TB (United Kingdom); Siegrist, Jonathan; Monaghan, Ruairi; O' Reilly, Brian; Gandhiraman, Ram Prasad [Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9 (Ireland); Daniels, Stephen [Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9 (Ireland); National Centre for Plasma Science and Technology (NCPST), Dublin City University, Dublin 9 (Ireland); Williams, David E. [Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9 (Ireland); MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical Sciences, University of Auckland, Auckland 1142 (New Zealand); Ducree, Jens [Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9 (Ireland)

2013-01-14

Highlights: Black-Right-Pointing-Pointer A simple tool to assess biomolecule adsorption onto the surfaces of microchannels. Black-Right-Pointing-Pointer Development for dilution by surface-adsorption based depletion of protein samples. Black-Right-Pointing-Pointer It can easily be done using a readily available apparatus like a spin-coater. Black-Right-Pointing-Pointer The assessment tool is facile and quantitative. Black-Right-Pointing-Pointer Straightforward comparison of different surface chemistries. - Abstract: Herein a simple analytical method is presented for the characterization of biomolecule adsorption on cyclo olefin polymer (COP, trade name: Zeonor{sup Registered-Sign }) substrates which are widely used in microfluidic lab-on-a-chip devices. These Zeonor{sup Registered-Sign} substrates do not possess native functional groups for specific reactions with biomolecules. Therefore, depending on the application, such substrates must be functionalized by surface chemistry methods to either enhance or suppress biomolecular adsorption. This work demonstrates a microfluidic method for evaluating the adsorption of antibodies and oligonucleotides surfaces. The method uses centrifugal microfluidic flow-through chips and can easily be implemented using common equipment such as a spin coater. The working principle is very simple. The user adds 40 L of the solution containing the sample to the starting side of a microfluidic channel, where it is moved through by centrifugal force. Some molecules are adsorbed in the channel. The sample is then collected at the other end in a small reservoir and the biomolecule concentration is measured. As a pilot application, we characterized the adsorption of goat anti-human IgG and a 20-mer DNA on Zeonor{sup Registered-Sign }, and on three types of functionalized Zeonor: 3-aminopropyltriethoxysilane (APTES) modified surface with mainly positive charge, negatively charged surface with immobilized bovine serum albumin (BSA), and

Simple approach to study biomolecule adsorption in polymeric microfluidic channels

International Nuclear Information System (INIS)

Gubala, Vladimir; Siegrist, Jonathan; Monaghan, Ruairi; O’Reilly, Brian; Gandhiraman, Ram Prasad; Daniels, Stephen; Williams, David E.; Ducrée, Jens

2013-01-01

Highlights: ► A simple tool to assess biomolecule adsorption onto the surfaces of microchannels. ► Development for dilution by surface-adsorption based depletion of protein samples. ► It can easily be done using a readily available apparatus like a spin-coater. ► The assessment tool is facile and quantitative. ► Straightforward comparison of different surface chemistries. - Abstract: Herein a simple analytical method is presented for the characterization of biomolecule adsorption on cyclo olefin polymer (COP, trade name: Zeonor ® ) substrates which are widely used in microfluidic lab-on-a-chip devices. These Zeonor ® substrates do not possess native functional groups for specific reactions with biomolecules. Therefore, depending on the application, such substrates must be functionalized by surface chemistry methods to either enhance or suppress biomolecular adsorption. This work demonstrates a microfluidic method for evaluating the adsorption of antibodies and oligonucleotides surfaces. The method uses centrifugal microfluidic flow-through chips and can easily be implemented using common equipment such as a spin coater. The working principle is very simple. The user adds 40 L of the solution containing the sample to the starting side of a microfluidic channel, where it is moved through by centrifugal force. Some molecules are adsorbed in the channel. The sample is then collected at the other end in a small reservoir and the biomolecule concentration is measured. As a pilot application, we characterized the adsorption of goat anti-human IgG and a 20-mer DNA on Zeonor ® , and on three types of functionalized Zeonor: 3-aminopropyltriethoxysilane (APTES) modified surface with mainly positive charge, negatively charged surface with immobilized bovine serum albumin (BSA), and neutral, hydrogel-like film with polyethylene glycol (PEG) characteristics. This simple analytical approach adds to the fundamental understanding of the interaction forces in real

Adsorption/Desorption Transition of Recombinant Human Neurotrophin 4: Physicochemical Characterization.

Science.gov (United States)

Dąbkowska, Maria; Adamczak, Małgorzata; Barbasz, Jakub; Cieśla, Michał; Machaliński, Bogusław

2017-09-26

Bulk physicochemical properties of neurotrophin 4 (NT-4) in electrolyte solutions and its adsorption/desorption on/from mica surfaces have been studied using dynamic light scattering (DLS), microelectrophoresis, a solution depletion technique (enzyme-linked immunosorbent assay, ELISA), and AFM imaging. Our study presents a determination of the diffusion coefficient, hydrodynamic diameters, electrophoretic mobility, and isoelectric point of the NT-4 under various ionic strength and pH conditions. The size of the NT-4 homodimer for an ionic strength of 0.015 M was substantially independent of pH and equal to 5.1 nm. It has been found that the number of electrokinetic charges per NT-4 molecule was equal to zero for all studied ionic strengths at pH 8.1, which was identified as the isoelectric point (iep). The protein adsorption/desorption on/from mica surfaces was examined as a function of ionic strength and pH. The kinetics of neurotrophin adsorption/desorption were evaluated at pH 3.5, 7.4, and 11 by direct AFM imaging and the ELISA technique. A monotonic increase in the maximum coverage of adsorbed NT-4 molecules with ionic strength (up to 5.5 mg/m 2 ) was observed at pH 3.5. These results were interpreted in terms of the theoretical model postulating an irreversible adsorption of the protein governed by the random sequential adsorption (RSA). Our measurements revealed a significant role of ionic strength, pH, and electrolyte composition in the lateral electrostatic interactions among differently charged NT-4 molecules. The transition between adsorption/desorption processes is found for the region of high pH and low surface concentration of adsorbed neurotrophin molecules at constant ionic strength. Additionally, results presented in this work show that the adsorption behavior of neurotrophin molecules may be governed by intrasolvent electrostatic interactions yielding an aggregation process. Understanding polyvalent neurotrophin interactions may have an impact on

In vitro study of proteins surface activity by tritium probe

International Nuclear Information System (INIS)

Chernysheva, M.G.; Badun, G.A.

2010-01-01

A new technique for in vitro studies of biomacromolecules interactions, their adsorption at aqueous/organic liquid interfaces and distribution in the bulk of liquid/liquid systems was developed. The method includes (1) tritium labeling of biomolecules by tritium thermal activation method and (2) scintillation phase step with organic phase, which can be concerned as a model of cellular membrane. Two globular proteins lysozyme and human serum albumin tested. We have determined the conditions of tritium labeling when labeled by-products can be easy separated by means of dialysis and size-exclusion chromatography. Scintillation phase experiments were conducted for three types of organic liquids. Thus, the influences of the nature of organic phase on proteins adsorption and its distribution in the bulk of aqueous/organic liquid system were determined. It was found that proteins possess high surface activity at aqueous/organic liquid interface. Furthermore, values of hydrophobicity of globular proteins were found by the experiment. (author)

Adsorption and Interfacial Electron Transfer of Saccharomyces Cerevisiae

DEFF Research Database (Denmark)

Hansen, Allan Glargaard; Boisen, Anja; Nielsen, Jens Ulrik

2003-01-01

We have studied the adsorption and electron-transfer dynamics of Saccharomyces cerevisiae (yeast) iso-l-cytochrome c adsorbed on Au(lll) electrodes in aqueous phosphate buffer media. This cytochrome possesses a thiol group dos e to the protein surface (Cysl02) suitable for linking the protein...

Adsorption of lysozyme unto silica and polystyrene surfaces in ...

African Journals Online (AJOL)

user

2011-04-11

Apr 11, 2011 ... surfaces were well fitted by the Langmuir adsorption isotherm model with maximum adsorption .... following reasons: (1) Lysozyme is a globular protein with ... vigorously for 1 h to attain equilibrium adsorption and allowed to.

Foaming and adsorption behavior of bovine and camel proteins mixed layers at the air/water interface.

Science.gov (United States)

Lajnaf, Roua; Picart-Palmade, Laetitia; Attia, Hamadi; Marchesseau, Sylvie; Ayadi, M A

2017-03-01

The aim of this work was to examine foaming and interfacial behavior of three milk protein mixtures, bovine α-lactalbumin-β-casein (M1), camel α-lactalbumin-β-casein (M2) and β-lactoglobulin-β-casein (M3), alone and in binary mixtures, at the air/water interface in order to better understand the foaming properties of bovine and camel milks. Different mixture ratios (100:0; 75:25; 50:50; 25:75; 0:100) were used during foaming tests and interfacial protein interactions were studied with a pendant drop tensiometer. Experimental results evidenced that the greatest foam was obtained with a higher β-casein amount in all camel and bovine mixtures. Good correlation was observed with the adsorption and the interfacial rheological properties of camel and bovine protein mixtures. The proteins adsorbed layers are mainly affected by the presence of β-casein molecules, which are probably the most abundant protein at interface and the most efficient in reducing the interfacial properties. In contrast of, the globular proteins, α-lactalbumin and β-lactoglobulin that are involved in the protein layer composition, but could not compact well at the interface to ensure foams creation and stabilization because of their rigid molecular structure. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of human fibrinogen and albumin onto hydrophobic and hydrophilic Ti6Al4V powder

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Sánchez, Jesús; Gallardo-Moreno, Amparo M.; Bruque, José M.; González-Martín, M. Luisa, E-mail: mlglez@unex.es

2016-07-15

Adsorption of proteins on solid surfaces has been widely studied because of its importance in various biotechnological, medical and technical applications, such as medical implants or biosensors. One of the main problems is the adsorption-induced conformational changes because they often modify the biological activity of the proteins, which is believed to be a key factor on the subsequent cellular adhesion. The aim of this work is the study of the adsorption of human fibrinogen (Fg) and human serum albumin (HSA) onto Ti6Al4V particles, commercially available on different size, that are used to elaborate scaffolds to provide structural support to cell proliferation, promoting tissue development and bone regeneration among others. The study was done through the analysis of the adsorption isotherms and the electrical characterization of surfaces after adsorption in terms of the zeta potential (ζ). From this analysis it seems that Fg adsorbs preferentially vertically oriented (end-on) and HSA moves sequentially over the surface of the Ti6Al4V particles through dimmer formation, allowing adsorption progress over this initial bilayer. The zeta potential values of both proteins remain constant when the monolayer is formed. The study also extends the analysis of both adsorption behaviour and ζ potential characterization factors to the influence of the substrate hydrophobicity as this property can be modified for the Ti6Al4V by irradiating it with ultraviolet light (UV-C) without changes on its chemical composition [1,2]. Differences at low protein concentrations were found for both isotherms and zeta-potential values.

Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

Science.gov (United States)

Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

2011-08-01

Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

Study on the adsorption of 233Pa in glass

International Nuclear Information System (INIS)

Natsumi, R.R.; Saiki, M.; Lima, F.W. de.

1982-08-01

It is intended to examine the adsorption of protactinium on glass in relation to pH, presence of complexing agents concentration and type of electrolytes. The study was made by using carrier-free 233 Pa solution and Pyrex glass tube was selected as adsorbent glass material surface. The adsorption curve of protactinium on glass surface as a function of the pH of the tracer solution showed the existence of two pronounced adsorption regions. It was found that this adsorption can be reduced by using electrolytes or complexing agents. Desorption of protactinium previously adsorbed on the Pyrex glass tube was also studied. Hidrochloric, oxalic and hydrofluoric acid solutions were used for the desorption experiments. (Author) [pt

Shotgun proteomic analytical approach for studying proteins adsorbed onto liposome surface

KAUST Repository

Capriotti, Anna Laura

2011-07-02

The knowledge about the interaction between plasma proteins and nanocarriers employed for in vivo delivery is fundamental to understand their biodistribution. Protein adsorption onto nanoparticle surface (protein corona) is strongly affected by vector surface characteristics. In general, the primary interaction is thought to be electrostatic, thus surface charge of carrier is supposed to play a central role in protein adsorption. Because protein corona composition can be critical in modifying the interactive surface that is recognized by cells, characterizing its formation onto lipid particles may serve as a fundamental predictive model for the in vivo efficiency of a lipidic vector. In the present work, protein coronas adsorbed onto three differently charged cationic liposome formulations were compared by a shotgun proteomic approach based on nano-liquid chromatography-high-resolution mass spectrometry. About 130 proteins were identified in each corona, with only small differences between the different cationic liposome formulations. However, this study could be useful for the future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins into body fluids. © 2011 Springer-Verlag.

Decreased Bacterial Attachment and Protein Adsorption to Coatings Produced by Low Enegy Plasma Polymerization

DEFF Research Database (Denmark)

Andersen, T.E.; Kingshott, Peter; Benter, M.

.figure) .and E. coli grown on uncoated silicone compared to PP-PVP coated silicone (right figure). Results from the flow chamber analysis shows PP-PVP to be very good at preventing E. coli colonization during prolonged growth in flow chamber. At this point other surfaces and bacteria remains to be tested...... adsorption and bacteria attachment/colonization. This is emphasized by the fact that long dwelling urinary catheters, which is a typical silicone medical device, causes 5% per day incidence of urinary tract infection [1,2]. A demand therefore exists for surface modifications providing the silicone material......-coated crystals were then treated with one of the plasma polymerized coatings. Adsorption of fibrinogen, human serum albumin or immunoglobulin G was measured using a QCM-D instrument [5] (model E4, Q-Sense AB, Vastra Frolunda, Sweden) using a solution of 50llg/1 protein in PBS buffer. Results and Discussion: Our...

A first-principles study of oxygen adsorption on Ir(111) surface

Energy Technology Data Exchange (ETDEWEB)

Gao, Hengjiao, E-mail: gaohengjiao@163.com; Xiong, Yuqing, E-mail: xiongyq@hotmail.com; Liu, Xiaoli, E-mail: shantianzi@126.com; Zhao, Dongcai, E-mail: zhaodongc@163.com; Feng, Yudong, E-mail: yudong_feng@sina.com; Wang, Lanxi, E-mail: wanglanxi@live.com; Wang, Jinxiao, E-mail: coldwind716@gmail.com

2016-12-15

Highlights: • Adsorption of oxygen on Ir(111) surface was studied by density functional theory. • The most stable adsorption site was determined by adsorption energy calculation. • Adsorption of oxygen at bridge and top site on Ir surface was the most stable ones. • Interaction of O 2p and Ir 5d orbits is relatively strong and formed hybridization. - Abstract: In order to understand deposition mechanism of iridium thin film by atomic layer deposition, the adsorption of oxygen on Ir(111) surface was studied by use of density functional theory and a periodical slab model. By calculating the adsorption energy and structure of oxygen at four adsorption sites (top, bridge, fcc-hollow and hcp-hollow) on Ir(111) surface, the most stable adsorption site was determined. On this basis, the banding mechanism of O and Ir atoms was studied by density of states of oxygen and iridium atoms. Oxygen adsorbed at hcp(parallel) site on Ir(111) surface was the most stable one according to the adsorption energy calculation results. Orbital charge analysis indicate that charge transferred from 5p and 5d orbit to 2p orbit of adsorbed O atoms, and 6s orbit of iridium atoms. Meanwhile, density of state study indicated that adsorption of oxygen on Ir(111) surface is mainly due to the interaction between 2p orbit of O atoms and 5d orbit of iridium atoms.

Adsorption of oxazole and isoxazole on BNNT surface: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Kaur, Jasleen, E-mail: jasleen.chem@gmail.com; Singla, Preeti, E-mail: preetisingla21@gmail.com; Goel, Neetu, E-mail: neetugoel@pu.ac.in

2015-02-15

Highlights: • The adsorption of oxazole and isoxazole over (6,0) and (5,5) BNNTs is studied. • The adsorption energies and structural changes are inductive of covalent adsorption. • The solvent plays an important role in improving the adsorption properties. • The adsorption witnesses substantial changes in electronic properties of the BNNT. • The functionalization of the BNNTs open up their applicability as drug carrier. - Abstract: The adsorption behavior of oxazole and isoxazole heterocycles over the (6,0) zigzag and (5,5) armchair boron nitride nanotube (BNNT) has been studied within the formalism of density functional theory (DFT). The adsorption energies, the frontier molecular orbital (FMO) analysis and the structural changes at the adsorption site are indicative of covalent adsorption on the zigzag BNNT surface, while the adsorption is physical in nature on the armchair BNNT surface. The role of solvent in improving the adsorption properties over the BNNT surface is elucidated by reoptimizing the structures in aqueous phase. The solvation energy is indicative of remarkable increase in the solubility of BNNTs after adsorption of heterocyclic rings. The Density of states (DOS) Plots, natural bond orbital (NBO) analysis and the quantum molecular descriptors (QMD) are witness to the substantial changes in the electronic properties of the BNNT systems following the attachment of these heterocycles with the tube surface. The study envisages the functionalization of the BNNT as well as its applicability as carrier of the drugs containing heterocyclic rings oxazole and isoxazole with marked sensitivity to the type of adsorbate and the adsorbent.

Protein Attachment on Nanodiamonds.

Science.gov (United States)

Lin, Chung-Lun; Lin, Cheng-Huang; Chang, Huan-Cheng; Su, Meng-Chih

2015-07-16

A recent advance in nanotechnology is the scale-up production of small and nonaggregated diamond nanoparticles suitable for biological applications. Using detonation nanodiamonds (NDs) with an average diameter of ∼4 nm as the adsorbents, we have studied the static attachment of three proteins (myoglobin, bovine serum albumin, and insulin) onto the nanoparticles by optical spectroscopy, mass spectrometry, and dynamic light scattering, and electrophoretic zeta potential measurements. Results show that the protein surface coverage is predominantly determined by the competition between protein-protein and protein-ND interactions, giving each protein a unique and characteristic structural configuration in its own complex. Specifically, both myoglobin and bovine serum albumin show a Langmuir-type adsorption behavior, forming 1:1 complexes at saturation, whereas insulin folds into a tightly bound multimer before adsorption. The markedly different adsorption patterns appear to be independent of the protein concentration and are closely related to the affinity of the individual proteins for the NDs. The present study provides a fundamental understanding for the use of NDs as a platform for nanomedical drug delivery.

Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

International Nuclear Information System (INIS)

Alyoshina, Nonna A.; Parfenyuk, Elena V.

2013-01-01

A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N 2 adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica

Adsorption on smooth electrodes: A radiotracer study

International Nuclear Information System (INIS)

Rice-Jackson, L.M.

1990-01-01

Adsorption on solids is a complicated process and in most cases, occurs as the early stage of other more complicated processes, i.e. chemical reactions, electrooxidation, electroreduction. The research reported here combines the electroanalytical method, cyclic voltammetry, and the use of radio-labeled isotopes, soft beta emitters, to study adsorption processes at smooth electrodes. The in-situ radiotracer method is highly anion (molecule) specific and provides information on the structure and composition of the electric double layer. The emphasis of this research was on studying adsorption processes at smooth electrodes of copper, gold, and platinum. The application of the radiotracer method to these smooth surfaces have led to direct in-situ measurements from which surface coverage was determined; anions and molecules were identified; and weak interactions of adsorbates with the surface of the electrodes were readily monitored. 179 refs

Surface adsorption of lattice HP proteins: Thermodynamics and structural transitions using Wang-Landau sampling

International Nuclear Information System (INIS)

Li Yingwai; Landau, David P; Wüst, Thomas

2012-01-01

Wang-Landau sampling has been applied to investigate the thermodynamics and structural properties of a lattice hydrophobic-polar heteropolymer (the HP protein model) interacting with an attractive substrate. For simplicity, we consider a short HP sequence consisting of only 36 monomers interacting with a substrate which attracts all monomers in the sequence. The conformational “phase transitions” have been identified by a canonical analysis of the specific heat and suitable structural observables. Three major “transitions”, namely, adsorption, hydrophobic core formation and “flattening” of adsorbed structures, are observed. Depending on the surface attractive strength relative to the intra-protein attraction among the H monomers, these processes take place in different sequences upon cooling.

Development of a tuned interfacial force field parameter set for the simulation of protein adsorption to silica glass.

Science.gov (United States)

Snyder, James A; Abramyan, Tigran; Yancey, Jeremy A; Thyparambil, Aby A; Wei, Yang; Stuart, Steven J; Latour, Robert A

2012-12-01

Adsorption free energies for eight host-guest peptides (TGTG-X-GTGT, with X = N, D, G, K, F, T, W, and V) on two different silica surfaces [quartz (100) and silica glass] were calculated using umbrella sampling and replica exchange molecular dynamics and compared with experimental values determined by atomic force microscopy. Using the CHARMM force field, adsorption free energies were found to be overestimated (i.e., too strongly adsorbing) by about 5-9 kcal/mol compared to the experimental data for both types of silica surfaces. Peptide adsorption behavior for the silica glass surface was then adjusted using a modified version of the CHARMM program, which we call dual force-field CHARMM, which allows separate sets of nonbonded parameters (i.e., partial charge and Lennard-Jones parameters) to be used to represent intra-phase and inter-phase interactions within a given molecular system. Using this program, interfacial force field (IFF) parameters for the peptide-silica glass systems were corrected to obtain adsorption free energies within about 0.5 kcal/mol of their respective experimental values, while IFF tuning for the quartz (100) surface remains for future work. The tuned IFF parameter set for silica glass will subsequently be used for simulations of protein adsorption behavior on silica glass with greater confidence in the balance between relative adsorption affinities of amino acid residues and the aqueous solution for the silica glass surface.

Kinetics of the Adsorption of Bovine Serum Albumin of White Wine ...

African Journals Online (AJOL)

This study investigates the kinetics of adsorption of bovine serum albumin, BSA, in white wine model solutions onto activated carbon, AC, and alumina, AL. Pseudo-first order and pseudo-second order models were applied to determine the rate and mechanism of adsorption of the white wine protein during the haze removal ...

Study of cesium and strontium adsorption on slovak bentonite

International Nuclear Information System (INIS)

Galambos, M.

2010-01-01

Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal systems for high-level radioactive waste and spent nuclear fuel. It is intended to isolate metal canisters with highly radioactive waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by adsorption. Slovak Republic avails of many significant deposits of bentonite. Adsorption of Cs and Sr on five Slovak bentonite of deposits (Jelsovy potok, Kopernica, Lieskovec, Lastovce and Dolna Ves) and montmorillonite K10 (Sigma-Aldrich) has been studied with the using batch of radiometric techniques. Natural, irradiated and natrified samples, in three different kinds of grain size: 15, 45 and 250 μm have been used in the experiments. The adsorptions of Cs and Sr on bentonite under various experimental conditions, such as contact time, adsorbent and adsorbate concentrations, pH after adsorption and effect of pH change, chemical modification, competitive ions and organic agents on the adsorption have been studied. The K d have been determined for adsorbent-Cs/Sr solution system as a function of contact time and adsorbate and adsorbent concentration. The data have been interpreted in terms of Langmuir isotherm. The adsorption of Cs and Sr has increased with increasing metal concentrations. Adsorption of Cs and Sr has been suppressed by presence of organic agents; and of bivalent cations more than univalent cations. By adsorption on natrified samples colloidal particles and pH value increase have been formed. Adsorption experiments carried out show that the most suitable materials intended for use as barriers surrounding a canister of spent nuclear fuel are bentonite of the Jelsovy potok and Kopernica deposits. (author)

Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

Energy Technology Data Exchange (ETDEWEB)

Alyoshina, Nonna A.; Parfenyuk, Elena V., E-mail: evp@iscras.ru

2013-09-15

A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N{sub 2} adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica.

Modification of nanoelectrode ensembles by thiols and disulfides to prevent non specific adsorption of proteins

Energy Technology Data Exchange (ETDEWEB)

Silvestrini, M. [Department of Molecular Sciences and Nanosystems, University Ca' Foscari of Venice, Santa Marta 2137, 30123 Venice (Italy); Schiavuta, P.; Scopece, P. [Associazione CIVEN, via delle Industrie 5, 30175 Marghera - Venice (Italy); Pecchielan, G.; Moretto, L.M. [Department of Molecular Sciences and Nanosystems, University Ca' Foscari of Venice, Santa Marta 2137, 30123 Venice (Italy); Ugo, P., E-mail: ugo@unive.it [Department of Molecular Sciences and Nanosystems, University Ca' Foscari of Venice, Santa Marta 2137, 30123 Venice (Italy)

2011-09-01

Highlights: > Complex nanostructures are built on the gold surface of ensembles of nanoelectrodes. > Gold surface of nanoelectrodes was functionalized with SAM of organic sulphurs. > The polycarbonate surrounding nanoelectrodes was functionalized with proteins. > SAMs protect the nanoelectrodes from undesired proteins adsorption. - Abstract: The possibility to functionalize selectively with thiols or disulfides the surface of the gold nanoelectrodes of polycarbonate templated nanoelectrode ensembles (NEEs) is studied. It is shown that the Au nanoelectrodes can be coated by a self assembled monolayer (SAM) of thioctic acid (TA) or 2-mercaptoethanesulfonic (MES) acid. The study of the electrochemical behavior of SAM-modified NEEs by cyclic voltammetry (CV) at different solution pH, using ferrocenecarboxylate as an anionic redox probe (FcCOO{sup -}) and (ferrocenylmethyl)trimethylammonium (FA{sup +}) as a cationic redox probe, demonstrate that the SAM-modified nanoelectrodes are permselective, in that only cationic or neutral probes can access the SAM-coated nanoelectrode surface. CV, AFM and FTIR-ATR data indicate that proteins such as casein or bovine serum albumin, which are polyanionic at pH 7, adsorb on the surface of NEEs untreated with thiols, tending to block the electron transfer of the ferrocenyl redox probes. On the contrary, the pre-treatment of the NEE with an anionic SAM protects the nanoelectrodes from protein fouling, allowing the detection of well shaped voltammetric patterns for the redox probe. Experimental results indicate that, in the case of MES treated NEEs, the protein is bound only onto the polycarbonate surface which surrounds the nanoelectrodes, while the tips of the gold nanoelectrodes remain protein free.

Modification of nanoelectrode ensembles by thiols and disulfides to prevent non specific adsorption of proteins

International Nuclear Information System (INIS)

Silvestrini, M.; Schiavuta, P.; Scopece, P.; Pecchielan, G.; Moretto, L.M.; Ugo, P.

2011-01-01

Highlights: → Complex nanostructures are built on the gold surface of ensembles of nanoelectrodes. → Gold surface of nanoelectrodes was functionalized with SAM of organic sulphurs. → The polycarbonate surrounding nanoelectrodes was functionalized with proteins. → SAMs protect the nanoelectrodes from undesired proteins adsorption. - Abstract: The possibility to functionalize selectively with thiols or disulfides the surface of the gold nanoelectrodes of polycarbonate templated nanoelectrode ensembles (NEEs) is studied. It is shown that the Au nanoelectrodes can be coated by a self assembled monolayer (SAM) of thioctic acid (TA) or 2-mercaptoethanesulfonic (MES) acid. The study of the electrochemical behavior of SAM-modified NEEs by cyclic voltammetry (CV) at different solution pH, using ferrocenecarboxylate as an anionic redox probe (FcCOO - ) and (ferrocenylmethyl)trimethylammonium (FA + ) as a cationic redox probe, demonstrate that the SAM-modified nanoelectrodes are permselective, in that only cationic or neutral probes can access the SAM-coated nanoelectrode surface. CV, AFM and FTIR-ATR data indicate that proteins such as casein or bovine serum albumin, which are polyanionic at pH 7, adsorb on the surface of NEEs untreated with thiols, tending to block the electron transfer of the ferrocenyl redox probes. On the contrary, the pre-treatment of the NEE with an anionic SAM protects the nanoelectrodes from protein fouling, allowing the detection of well shaped voltammetric patterns for the redox probe. Experimental results indicate that, in the case of MES treated NEEs, the protein is bound only onto the polycarbonate surface which surrounds the nanoelectrodes, while the tips of the gold nanoelectrodes remain protein free.

Surface adsorption behaviour of milk whey protein and pectin mixtures under conditions of air-water interface saturation.

Science.gov (United States)

Perez, Adrián A; Sánchez, Cecilio Carrera; Patino, Juan M Rodríguez; Rubiolo, Amelia C; Santiago, Liliana G

2011-07-01

Milk whey proteins (MWP) and pectins (Ps) are biopolymer ingredients commonly used in the manufacture of colloidal food products. Therefore, knowledge of the interfacial characteristics of these biopolymers and their mixtures is very important for the design of food dispersion formulations (foams and/or emulsions). In this paper, we examine the adsorption and surface dilatational behaviour of MWP/Ps systems under conditions in which biopolymers can saturate the air-water interface on their own. Experiments were performed at constant temperature (20 °C), pH 7 and ionic strength 0.05 M. Two MWP samples, β-lactoglobulin (β-LG) and whey protein concentrate (WPC), and two Ps samples, low-methoxyl pectin (LMP) and high-methoxyl pectin (HMP) were evaluated. The contribution of biopolymers (MWP and Ps) to the interfacial properties of mixed systems was evaluated on the basis of their individual surface molecular characteristics. Biopolymer bulk concentration capable of saturating the air-water interface was estimated from surface pressure isotherms. Under conditions of interfacial saturation, dynamic adsorption behaviour (surface pressure and dilatational rheological characteristics) of MWP/Ps systems was discussed from a kinetic point of view, in terms of molecular diffusion, penetration and configurational rearrangement at the air-water interface. The main adsorption mechanism in MWP/LMP mixtures might be the MWP interfacial segregation due to the thermodynamic incompatibility between MWP and LMP (synergistic mechanism); while the interfacial adsorption in MWP/HMP mixtures could be characterized by a competitive mechanism between MWP and HMP at the air-water interface (antagonistic mechanism). The magnitude of these phenomena could be closely related to differences in molecular composition and/or aggregation state of MWP (β-LG and WPC). Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of boron addition to Ti–13Zr–13Nb alloy on MG63 osteoblast cell viability and protein adsorption

Energy Technology Data Exchange (ETDEWEB)

Majumdar, P., E-mail: m.pallab@gmail.com [School of Mechanical Science, Indian Institute of Technology, Bhubaneswar (India); Singh, S.B. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Dhara, S. [School Medical Science and Technology, Indian Institute of Technology, Kharagpur (India); Chakraborty, M. [School of Mechanical Science, Indian Institute of Technology, Bhubaneswar (India)

2015-01-01

Cell proliferation, cell morphology and protein adsorption on near β-type Ti–13Zr–13Nb (TZN) alloy and Ti–13Zr–13Nb–0.5B (TZNB) composite have been investigated and compared to evaluate the effect of boron addition which has been added to the Ti alloy to improve their poor tribological properties by forming in situ TiB precipitates. MG63 cell proliferation on substrates with different chemistry but the same topography was compared. The MTT assay test showed that the cell viability on the TZN alloy was higher than the boron containing TZNB composite after 36 h of incubation and the difference was pronounced after 7 days. However, both the materials showed substantially higher cell attachment than the control (polystyrene). For the same period of incubation in fetal bovine serum (FBS), the amount of protein adsorbed on the surface of boron free TZN samples was higher than that in the case of boron containing TZNB composite. The presence of boron in the TZN alloy influenced protein adsorption and cell response and they are lower in TZNB than in TZN as a result of the associated difference in chemical characteristics. - Highlights: • The influence of boron addition on biocompatibility of Ti–13Zr–13Nb • Boron forms in situ TiB in TZN matrix and decreases cell proliferation on TZN surfaces. • Protein adsorption is lower in TZNB than in TZN. • Compared to TZNB composite, TZN alloy is more suitable for bone grafting applications.

Adsorption kinetics of c-Fos and c-Jun to air-water interfaces.

Science.gov (United States)

Del Boca, Maximiliano; Nobre, Thatyane Morimoto; Zaniquelli, Maria Elisabete Darbello; Maggio, Bruno; Borioli, Graciela A

2007-11-01

The kinetics of adsorption to air-water interfaces of the biomembrane active transcription factors c-Fos, c-Jun and their mixtures is investigated. The adsorption process shows three distinct stages: a lag time, a fast pseudo zero-order stage, and a halting stage. The initial stage determines the course of the process, which is concentration dependent until the end of the fast stage. We show that c-Fos has faster adsorption kinetics than c-Jun over all three stages and that the interaction between both proteins is apparent in the adsorption profiles of the mixtures. Protein molecular reorganization at the interface determines the transition to the final adsorption stage of the pure proteins as well as that of the mixtures.

Adsorption of U(VI) onto kaolin studied by batch method

International Nuclear Information System (INIS)

Hongxia Zhang; Zhi Liu; Peizhuo Hu; Tonghuan Liu; Wangsuo Wu

2013-01-01

Adsorption of U(VI) on purified kaolin was studied by batch methods under ambient conditions, including contact time, pH, fulvic acid, etc. Three kinetic models were used to model the kinetic adsorption which was very well described by the pseudo-second-order rate equation, and the activation energy of adsorption was 52.20 kJ/mol. The Freundlich and Dubinin-Radushkevich models fitted the experimental data better than the Langmuir model for the adsorption and desorption isotherms. The thermodynamic parameters indicated that the adsorption of U(VI) on kaolin was an endothermic and spontaneous process. (author)

Equilibrium and kinetics studies of metal ion adsorption on dyed ...

African Journals Online (AJOL)

Batch equilibration studies were conducted to determine the nature of adsorption of Zn (II) and Cu (II) onto dyed coconut pollens. The nature of adsorption of metal ions was explained using the Langmuir equation. The calculated values of equilibrium parameter indicated favourable adsorption by the adsorbents. Also the ...

Adsorption of Candida rugosa lipase at water-polymer interface: The case of poly( DL)lactide

Science.gov (United States)

Kamel, Gihan; Bordi, Federico; Chronopoulou, Laura; Lupi, Stefano; Palocci, Cleofe; Sennato, Simona; Verdes, Pedro V.

2011-12-01

Insights into the interactions between biological macromolecules and polymeric surfaces are of great interest because of potential uses in developing biotechnologies. In this study we focused on the adsorption of a model lipolytic enzyme, Candida rugosa lipase (CRL), on poly-(D,L)-lactic acid (PDLLA) polymer with the aim to gain deeper insights into the interactions between the enzyme and the carrier. Such studies are of particular relevance in order to establish the optimal conditions for enzyme immobilization and its applications. We employed two different approaches; by analyzing the influence of adsorbed CRL molecules on the thermodynamic behavior of Langmuir films of PDLLA deposited at air-water interface, we gained interesting information on the molecular interactions between the protein and the polymer. Successively, by a systematic analysis of the adsorption of CRL on PDLLA nanoparticles, we showed that the adsorption of a model lipase, CRL, on PDLLA is described in terms of a Langmuir-type adsorption behavior. In this model, only monomolecular adsorption takes place (i.e. only a single layer of the protein adsorbs on the support) and the interactions between adsorbed molecules and surface are short ranged. Moreover, both the adsorption and desorption are activated processes, and the heat of adsorption (the difference between the activation energy for adsorption and desorption) is independent from the surface coverage of the adsorbing species. Finally, we obtained an estimate of the number of molecules of the protein adsorbed per surface unit on the particles, a parameter of a practical relevance for applications in biocatalysis, and a semi-quantitative estimate of the energies (heat of adsorption) involved in the adsorption process.

Thermodynamic study on the adsorption of strontium on polyantimonic acid exchanger

International Nuclear Information System (INIS)

Li Mingyu; Chen Jing; Wang Jianchen; Zhao Jing

2007-01-01

The adsorption of strontium on the polyantimonic acid adsorbent was studied. The equilibrium data for the adsorption of strontium on polyantimonic acid exchanger from aqueous solutions were obtained and correlated with Langmuir-type and Freundlich-type isotherm equation within the temperature range of 293-323 K and the experimental concentration range. Freundlich adsorption isotherms and the isosteric enthalpy indicate that the adsorption of strontium on polyantimonic acid is an endothermic process from aqueous solutions. The enthalpy, free energy, and entropy of adsorption were calculated. The results indicate that the adsorption process is a complex interaction of physical and chemical processes. The adsorption behaviors were reasonably explained. (authors)

Shotgun proteomic analytical approach for studying proteins adsorbed onto liposome surface

KAUST Repository

Capriotti, Anna Laura; Caracciolo, Giulio; Cavaliere, Chiara; Crescenzi, Carlo; Pozzi, Daniela; Laganà , Aldo

2011-01-01

The knowledge about the interaction between plasma proteins and nanocarriers employed for in vivo delivery is fundamental to understand their biodistribution. Protein adsorption onto nanoparticle surface (protein corona) is strongly affected

Prevention of adsorption losses during radioimmunoassay of polypeptide hormones: effectiveness of albumins, gelatin, caseins, Tween 20 and plasma

International Nuclear Information System (INIS)

Livesey, J.H.; Donald, R.A.

1982-01-01

It is well known that polypeptide hormones adsorb to glass and plastic surfaces and that this adsorption may be reduced by adding a relatively large quantity of another protein. Consequently proteins (or sometimes detergents) are added almost universally to peptide hormone radioimmunassays to minimise loss of analyte by adsorption. This study was undertaken because there are few reports of the relative effectiveness of the proteins so used. The results suggest that moderate concentrations of the widely used albumins of Tween 20 do not always adequately prevent the adsorption of hormonal polypeptides to surfaces. Casein and alkali-treated casein appear to be more effective than the adsorption inhibitors in general use in radioimmunoassay for the range of hormones and adsorptive surfaces tested. They were also found to be very effective for preventing the adsorption of radio-labelled human luteinizing hormone, human growth hormone and Tyr-somatostatin. (Auth.)

Theoretical study of cisplatin adsorption on silica

Energy Technology Data Exchange (ETDEWEB)

Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Company, A. Diaz; Brizuela, G.; Juan, A. [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

2011-11-15

The adsorption of cisplatin and its complexes, cis-[PtCl(NH{sub 3}){sub 2}]{sup +} and cis-[Pt(NH{sub 3}){sub 2}]{sup 2+}, on a SiO{sub 2}(1 1 1) hydrated surface has been studied by the Atom Superposition and Electron Delocalization method. The adiabatic energy curves for the adsorption of the drug and its products on the delivery system were considered. The electronic structure and bonding analysis were also performed. The molecule-surface interactions are formed at expenses of the OH surface bonds. The more important interactions are the Cl-H bond for cis-[PtCl{sub 2}(NH{sub 3}){sub 2}] and cis-[PtCl(NH{sub 3}){sub 2}]{sup +} adsorptions, and the Pt-O interaction for cis-[Pt(NH{sub 3}){sub 2}]{sup 2+} adsorption. The Cl p orbitals and Pt s, p y d orbitals of the molecule and its complexes, and the s H orbital and, the s and p orbitals of the O atoms of the hydrated surface are the main contribution to the surface bonds.

Mechanism underlying bioinertness of self-assembled monolayers of oligo(ethyleneglycol)-terminated alkanethiols on gold: protein adsorption, platelet adhesion, and surface forces.

Science.gov (United States)

Hayashi, Tomohiro; Tanaka, Yusaku; Koide, Yuki; Tanaka, Masaru; Hara, Masahiko

2012-08-07

The mechanism underlying the bioinertness of the self-assembled monolayers of oligo(ethylene glycol)-terminated alkanethiol (OEG-SAM) was investigated with protein adsorption experiments, platelet adhesion tests, and surface force measurements with an atomic force microscope (AFM). In this work, we performed systematic analysis with SAMs having various terminal groups (-OEG, -OH, -COOH, -NH(2), and -CH(3)). The results of the protein adsorption experiment by the quartz crystal microbalance (QCM) method suggested that having one EG unit and the neutrality of total charges of the terminal groups are essential for protein-resistance. In particular, QCM with energy dissipation analyses indicated that proteins absorb onto the OEG-SAM via a very weak interaction compared with other SAMs. Contrary to the protein resistance, at least three EG units as well as the charge neutrality of the SAM are found to be required for anti-platelet adhesion. When the identical SAMs were formed on both AFM probe and substrate, our force measurements revealed that only the OEG-SAMs possessing more than two EG units showed strong repulsion in the range of 4 to 6 nm. In addition, we found that the SAMs with other terminal groups did not exhibit such repulsion. The repulsion between OEG-SAMs was always observed independent of solution conditions [NaCl concentration (between 0 and 1 M) and pH (between 3 and 11)] and was not observed in solution mixed with ethanol, which disrupts the three-dimensional network of the water molecules. We therefore concluded that the repulsion originated from structured interfacial water molecules. Considering the correlation between the above results, we propose that the layer of the structured interfacial water with a thickness of 2 to 3 nm (half of the range of the repulsion observed in the surface force measurements) plays an important role in deterring proteins and platelets from adsorption or adhesion.

Interfacial dilational properties of tea polyphenols and milk proteins with gut epithelia and the role of mucus in nutrient adsorption.

Science.gov (United States)

Guri, Anilda; Li, Yang; Corredig, Milena

2015-12-01

By interacting with nutrients, the mucus layer covering the intestinal epithelium may mediate absorption. This study aimed to determine possible interactions between epigallocatechin-3-gallate (EGCG), skim milk proteins or their complexes with human intestinal mucin films. The films were extracted from postconfluent monolayers of HT29-MTX, a human intestinal cell line, and a model system was created using drop shape tensiometry. The EGCG uptake tested in vitro on postconfluent Caco-2 cells or co-cultures of Caco-2/HT29-MTX (mucus producing) showed recovery of bioavailable EGCG only for Caco-2 cell monolayers, suggesting an effect of mucus on absorption. Interfacial dilational rheology was employed to characterize the properties of the interface mixed with mucus dispersion. Adsorption of polyphenols greatly enhanced the viscoelastic modulus of the mucus film, showing the presence of interactions between the nutrient molecules and mucus films. On the other hand, in situ digestion of milk proteins using trypsin showed higher surface activities as a result of protein unfolding and competitive adsorption of the hydrolyzed products. There was an increase of viscoelastic modulus over the drop ageing time for the mixed interfaces, indicating the formation of a stiffer interfacial network. These results bring new insights into the role of the mucus layer in nutrient absorption and the interactions of mucus and dairy products.

Nitrotyrosine adsorption on carbon nanotube: a density functional theory study

Science.gov (United States)

Majidi, R.; Karami, A. R.

2014-05-01

We have studied the effect of nitrotyrosine on electronic properties of different single-wall carbon nanotubes by density functional theory. Optimal adsorption configurations of nitrotyrosine adsorbed on carbon nanotube have been determined by calculation of adsorption energy. Adsorption energies indicate that nitrotyrosine is chemisorbed on carbon nanotubes. It is found that the nitrotyrosine adsorption modifies the electronic properties of the semiconducting carbon nanotubes significantly and these nanotubes become n-type semiconductors, while the effect of nitrotyrosine on metallic carbon nanotubes is not considerable and these nanotubes remain metallic. Results clarify sensitivity of carbon nanotubes to nitrotyrosine adsorption and suggest the possibility of using carbon nanotubes as biosensor for nitrotyrosine detection.

Theoretical study of adsorption of lithium atom on carbon nanotube

OpenAIRE

Senami, Masato; Ikeda, Yuji; Fukushima, Akinori; Tachibana, Akitomo

2011-01-01

We investigate the adsorption of lithium atoms on the surface of the (12, 0) single wall carbon nanotube (SWCNT) by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsiv...

Interfacial adsorption of insulin - Conformational changes and reversibility of adsorption

NARCIS (Netherlands)

Mollmann, SH; Jorgensen, L; Bukrinsky, JT; Elofsson, U; Norde, W; Frokjaer, S

The adsorption of human insulin to Teflon particles was studied with respect to conformational changes and the reversibility of adsorption was examined by total internal reflection fluorescence (TIRF). Adsorption isotherms for the adsorption of human insulin indicated high affinity adsorption, even

The role of PEG conformation in mixed layers: from protein corona substrate to steric stabilization avoiding protein adsorption

Directory of Open Access Journals (Sweden)

Joan Comenge

2015-03-01

Full Text Available Although nanoparticles (NPs have been traditionally modified with a single ligand layer, mixture of ligands might help to combine different functionalities and to further engineer the NP surface. A detailed study of the competition between an alkanethiol (11-mercaptoundecanoic acid and SH-PEG for the surface of AuNPs and the resultant behaviors of this model nanoconjugate is presented here. As a result, the physicochemical properties of these conjugates can be progressively tuned by controlling the composition and especially the conformation of the mixed monolayer. This has implications in the physiological stability. The controlled changes on the SH-PEG conformation rather than its concentration induce a change in the stabilization mechanism from electrostatic repulsion to steric hindrance, which changes the biological fate of NPs. Importantly, the adsorption of proteins on the conjugates can be tailored by tuning the composition and conformation of the mixed layer.

The Adsorption of Dextranase onto Mg/Fe-Layered Double Hydroxide: Insight into the Immobilization

Directory of Open Access Journals (Sweden)

Yi Ding

2018-03-01

Full Text Available We report the adsorption of dextranase on a Mg/Fe-layered double hydroxide (Mg/Fe-LDH. We focused the effects of different buffers, pH, and amino acids. The Mg/Fe-LDH was synthesized, and adsorption experiments were performed to investigate the effects. The maximum adsorption occurred in pH 7.0 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES buffer, and the maximum dextranase adsorption uptake was 1.38 mg/g (416.67 U/mg; histidine and phenylalanine could affect the adsorption. A histidine tag could be added to the protein to increase the adsorption significantly. The performance features and mechanism were investigated with X-ray diffraction patterns (XRD and Fourier transform infrared spectra (FTIR. The protein could affect the crystal structure of LDH, and the enzyme was adsorbed on the LDH surface. The main interactions between the protein and LDH were electrostatic and hydrophobic. Histidine and phenylalanine could significantly affect the adsorption. The hexagonal morphology of LDH was not affected after adsorption.

Adsorption study of Ammonia Nitrogen by watermelon rind

Science.gov (United States)

Ibrahim, A.; Yusof, L.; Beddu, N. S.; Galasin, N.; Lee, P. Y.; Lee, R. N. S.; Zahrim, A. Y.

2016-06-01

The utilization of fruit waste for low-cost adsorbents as a replacement for costly conventional methods of removing ammonia nitrogen from wastewater has been reviewed. The adsorption studies were conducted as a function of contact time and adsorbent dosage and it were carried out on four different adsorbents; fresh watermelon rind and modified watermelon rind with sodium hydroxide (NaOH), potassium hydroxide (KOH) and sulphuric acid (H2SO4). Adsorbents were tested for characterization by using zeta potential test and all samples shows negative values thus makes it favourable for the adsorption process. The batch experimental result showed that adsorption process is rapid and equilibrium was established within 40 minutes of contact time. The ammonia nitrogen removal rate amounted in range of 96% to 99%, and the adsorption capacities were in range of 1.21 to 1.24 mg/g for all four different types of adsorbents used.

Adsorptive removal of Auramine-O: Kinetic and equilibrium study

International Nuclear Information System (INIS)

Mall, Indra Deo; Srivastava, Vimal Chandra; Agarwal, Nitin Kumar

2007-01-01

Present study deals with the adsorption of Auramine-O (AO) dye by bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH 0 ), contact time, adsorbent dose and initial concentration (C 0 ) for the removal of AO. Optimum conditions for AO removal were found to be pH 0 ∼ 7.0 and equilibrium time ∼30 min for BFA and ∼120 min for activated carbons. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2 g/l, respectively. Adsorption of AO followed pseudo-second order kinetics with the initial sorption rate for adsorption on BFA being the highest followed by those on ACL and ACC. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Equilibrium isotherms for the adsorption of AO on BFA, ACC and ACL were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin isotherm equations using linear correlation coefficient. Langmuir isotherm gave the best correlation of adsorption for all the adsorbents studied. Thermodynamic study showed that adsorption of AO on ACC (with a more negative Gibbs free energy value) is more favoured. BFA which was used without any pretreatment showed high surface area, pore volume and pore size exhibiting its potential to be used as an adsorbent for the removal of AO

Molecular structure-adsorption study on current textile dyes.

Science.gov (United States)

Örücü, E; Tugcu, G; Saçan, M T

2014-01-01

This study was performed to investigate the adsorption of a diverse set of textile dyes onto granulated activated carbon (GAC). The adsorption experiments were carried out in a batch system. The Langmuir and Freundlich isotherm models were applied to experimental data and the isotherm constants were calculated for 33 anthraquinone and azo dyes. The adsorption equilibrium data fitted more adequately to the Langmuir isotherm model than the Freundlich isotherm model. Added to a qualitative analysis of experimental results, multiple linear regression (MLR), support vector regression (SVR) and back propagation neural network (BPNN) methods were used to develop quantitative structure-property relationship (QSPR) models with the novel adsorption data. The data were divided randomly into training and test sets. The predictive ability of all models was evaluated using the test set. Descriptors were selected with a genetic algorithm (GA) using QSARINS software. Results related to QSPR models on the adsorption capacity of GAC showed that molecular structure of dyes was represented by ionization potential based on two-dimensional topological distances, chromophoric features and a property filter index. Comparison of the performance of the models demonstrated the superiority of the BPNN over GA-MLR and SVR models.

Study of neon adsorption on carbon nanocones using molecular dynamics simulation

International Nuclear Information System (INIS)

Majidi, R.; Ghafoori Tabrizi, K.

2010-01-01

We have used molecular dynamics simulation to study Ne adsorption on carbon nanocones. Adsorption isotherms were obtained at several temperatures between 22.67 and 49.82 K. Adsorption coverage, isosteric heat, and binding energy were calculated. Adsorption was observed both inside and outside of an individual carbon nanocone. The results indicate that the saturation coverage and saturation pressure depend on temperature. At saturation conditions, the maximum values of interior and exterior coverages are 0.17 and 0.39 neon per carbon, respectively. The results are compared to Ne adsorption on open-ended single-walled carbon nanotubes. It is found that adsorption coverages on carbon nanocones are greater than those on carbon nanotubes. The isosteric heat and binding energy of neon adsorption on nanocones indicate that nanocones and nanotubes have highly desirable characteristics as an adsorbent.

Study of neon adsorption on carbon nanocones using molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Majidi, R. [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839-63113 (Iran, Islamic Republic of); Ghafoori Tabrizi, K., E-mail: k-tabrizi@sbu.ac.i [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839-63113 (Iran, Islamic Republic of)

2010-04-15

We have used molecular dynamics simulation to study Ne adsorption on carbon nanocones. Adsorption isotherms were obtained at several temperatures between 22.67 and 49.82 K. Adsorption coverage, isosteric heat, and binding energy were calculated. Adsorption was observed both inside and outside of an individual carbon nanocone. The results indicate that the saturation coverage and saturation pressure depend on temperature. At saturation conditions, the maximum values of interior and exterior coverages are 0.17 and 0.39 neon per carbon, respectively. The results are compared to Ne adsorption on open-ended single-walled carbon nanotubes. It is found that adsorption coverages on carbon nanocones are greater than those on carbon nanotubes. The isosteric heat and binding energy of neon adsorption on nanocones indicate that nanocones and nanotubes have highly desirable characteristics as an adsorbent.

Adsorption studies of iron(III)

Indian Academy of Sciences (India)

Adsorption of ferric ions by chitin was studied by the batch equilibration method. The influence of particle size and dosage of the adsorbant, contact time, initial concentration of the adsorbate and temperature were experimentally verified. The effect of anions like chloride, nitrate and sulphate and also of cations like zinc, ...

Experimental study of adsorption chiller driven by variable heat source

Energy Technology Data Exchange (ETDEWEB)

Wang, D.C.; Wang, Y.J.; Zhang, J.P.; Tian, X.L. [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China); Wu, J.Y. [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China)

2008-05-15

A silica gel-water adsorption chiller has been developed in recent years and has been applied in an air conditioning system driven by solar energy. The heat source used to drive the adsorption chiller is variable at any moment because the solar radiation intensity or the waste heat from engines varies frequently. An adsorption cooling system may be badly impacted by a variable heat source with temperature variations in a large range. In this work, a silica gel-water adsorption chiller driven by a variable heat source is experimentally studied. The influences of the variable heat source on the performance of the chiller are analyzed, especially for a continuous temperature increase process and a continuous temperature decrease process of the heat source. As an example, the dynamic characteristics of the heat source are also analyzed when solar energy is taken as the heat source of the adsorption chiller. According to the experimental results for the adsorption chiller and the characteristics of the heat source from solar energy, control strategies of the adsorption chiller driven by solar energy are proposed. (author)

Experimental study of adsorption chiller driven by variable heat source

International Nuclear Information System (INIS)

Wang, D.C.; Wang, Y.J.; Zhang, J.P.; Tian, X.L.; Wu, J.Y.

2008-01-01

A silica gel-water adsorption chiller has been developed in recent years and has been applied in an air conditioning system driven by solar energy. The heat source used to drive the adsorption chiller is variable at any moment because the solar radiation intensity or the waste heat from engines varies frequently. An adsorption cooling system may be badly impacted by a variable heat source with temperature variations in a large range. In this work, a silica gel-water adsorption chiller driven by a variable heat source is experimentally studied. The influences of the variable heat source on the performance of the chiller are analyzed, especially for a continuous temperature increase process and a continuous temperature decrease process of the heat source. As an example, the dynamic characteristics of the heat source are also analyzed when solar energy is taken as the heat source of the adsorption chiller. According to the experimental results for the adsorption chiller and the characteristics of the heat source from solar energy, control strategies of the adsorption chiller driven by solar energy are proposed

Preparation of Cu{sup 2+}/NTA-derivatized branch polyglycerol magnetic nanoparticles for protein adsorption

Energy Technology Data Exchange (ETDEWEB)

ShiXing Wang, E-mail: wsxkm@sina.com; Sun Wentong [Yunnan Institute of Product Quality Supervision and Inspection (China); Zhou Yang, E-mail: zhouyang8250@sohu.co [Kunming University of Science and Technology, Faculty of Metallurgical and Energy Engineering (China)

2010-09-15

In this report, we described the preparation of Cu{sup 2+}/nitrilotriacetic acids (NTA)-derivatized branch polyglycerol magnetic nanoparticles for protein adsorption with avoidance of nonspecific interactions at the same time. Magnetic nanoparticles (MNPs) were synthesized by the coprecipitation method. The transmission electron microscopy results showed that the average diameter of MNPs was 15.8 {+-} 4.6 nm. X-ray photoelectron spectroscopy and Fourier Transform infrared measurements indicated that branch polyglycerols were grafted on MNPs via the ring-opening polymerization of glycidol and that Cu{sup 2+} ions had been successfully immobilized on the surface of MNPs. The protein immobilization effect was characterized by UV-Vis spectrum. The results proved that Cu{sup 2+}/NTA-derivatized branch polyglycerol magnetic nanoparticles effectively adsorbed bovine haemoglobin and rarely adsorbed lysozyme and {gamma}-globin.

Theoretical study of adsorption of lithium atom on carbon nanotube

Directory of Open Access Journals (Sweden)

Masato Senami

2011-12-01

Full Text Available We investigate the adsorption of lithium atoms on the surface of the (12,0 single wall carbon nanotube (SWCNT by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsive force between lithium atoms destabilizes a system for the large number of lithium atoms.

Feasibility study on the application of a heat-pipe type adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sang Hyeok; Chung, Jae Dong [Dept. of Mechanical Engineering, Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Energy System R and D Group, Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)

2017-01-15

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl{sub 2}) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature.

Feasibility study on the application of a heat-pipe type adsorption chiller

International Nuclear Information System (INIS)

Ahn, Sang Hyeok; Chung, Jae Dong; Kwon, Oh Kyung

2017-01-01

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl_2) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature

Effect of Oil Hydrophobicity on the Adsorption and Rheology of β-Lactoglobulin at Oil-Water Interfaces.

Science.gov (United States)

Bergfreund, Jotam; Bertsch, Pascal; Kuster, Simon; Fischer, Peter

2018-04-24

The adsorption of protein layers at oil-water interfaces is critical to the formation and stability of various emulsions in, for example, technical applications as well as in biological lipid storage. Effects of ionic strength, pH, temperature, and pretreatments of the proteins are well-known. However, the oil phase has been regarded as exchangeable and its role in protein adsorption has been widely ignored. Herein, the influence of systematically selected oil interfaces of high purity on the formation and properties of β-lactoglobulin (β-lg) adsorption layers was evaluated. Droplet profile tensiometry and interfacial rheometry were employed to determine the adsorption kinetics and dilatational and interfacial shear moduli. We show that depending on the molecular size, flexibility, hydrophobicity, polarity, and polarizability of the oils, globular proteins adsorb distinctively. Stronger interactions of polar oils with the hydrophilic exterior of the native β-lg lead to decelerated protein unfolding. This results in lower surface pressures and slower formation of viscoelastic networks. In addition, polar oils interact stronger with the protein network by hydrophilic bonding and thereby act as softening agents. The observed effects of hydrophobic subphases on the adsorbed protein layers provide knowledge, which promotes higher reproducibility in rheological studies and precise tailoring of interfacial films for enhanced formation and stability of emulsions.

Quantitative description of the relation between protein net charge and protein adsorption to air-water interfaces

NARCIS (Netherlands)

Wierenga, P.A.; Meinders, M.B.J.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J.de

2005-01-01

In this study a set of chemically engineered variants of ovalbumin was produced to study the effects of electrostatic charge on the adsorption kinetics and resulting surface pressure at the air-water interface. The modification itself was based on the coupling of succinic anhydride to lysine

Adsorption mechanism of BMP-7 on hydroxyapatite (001) surfaces

International Nuclear Information System (INIS)

Zhou, Hailong; Wu, Tao; Dong, Xiuli; Wang, Qi; Shen, Jiawei

2007-01-01

Many properties and functions of bone-related proteins perform through the interface with the hydroxyapatite. However, the mechanism of difference of proteins adsorbing behaviors caused by the variation of calcium and phosphate ions on hydroxyapatite is still unclear at atomic level. In this work, we investigated the site-selective adhesion and the adsorption mechanism of protein BMP-7 to the hydroxyapatite surfaces in aqueous media during adsorption and desorption processes. Molecular dynamics (MD) and steered molecular dynamics (SMD) simulations combined with trajectory analysis were employed to give insight into the underlying behaviors of BMP-7 binding. The results suggest that the adsorption sites could be divided into two categories: COO - and NH 2 /NH3+. For COO - , the adsorption phenomenon is driven by the electrostatic interaction formed between the negative charged carboxylate groups and the Ca1 cations on the hydroxyapatite surface. While for NH 2 /NH3+, the interaction is through the intermolecular H-bonds between the N-containing groups and the phosphate on the hydroxyapatite surface

Phosphate adsorption from wastewater using zirconium (IV) hydroxide: Kinetics, thermodynamics and membrane filtration adsorption hybrid system studies.

Science.gov (United States)

Johir, M A H; Pradhan, M; Loganathan, P; Kandasamy, J; Vigneswaran, S

2016-02-01

Excessive phosphate in wastewater should be removed to control eutrophication of water bodies. The potential of employing amorphous zirconium (Zr) hydroxide to remove phosphate from synthetic wastewater was studied in batch adsorption experiments and in a submerged membrane filtration adsorption hybrid (MFAH) reactor. The adsorption data satisfactorily fitted to Langmuir, pseudo-first order and pseudo-second order models. Langmuir adsorption maxima at 22 °C and pHs of 4.0, 7.1, and 10.0 were 30.40, 18.50, and 19.60 mg P/g, respectively. At pH 7.1 and temperatures of 40 °C and 60 °C, they were 43.80 and 54.60 mg P/g, respectively. The thermodynamic parameters, ΔG° and ΔS° were negative and ΔH° was positive. FTIR, zeta potential and competitive phosphate, sulphate and nitrate adsorption data showed that the mechanism of phosphate adsorption was inner-sphere complexation. In the submerged MFAH reactor experiment, when Zr hydroxide was added at doses of 1-5 g/L once only at the start of the experiment, the removal of phosphate from 3 L of wastewater containing 10 mg P/L declined after 5 h of operation. However, when Zr hydroxide was repeatedly added at 5 g/L dose every 24 h, satisfactory removal of phosphate was maintained for 3 days. Copyright © 2015 Elsevier Ltd. All rights reserved.

In situ adsorption of bovine submaxillary mucin at the mica/aqueous solution interface

International Nuclear Information System (INIS)

Perez, E.; Proust, J.E.; Baszkin, A.; Boissonnade, M.M.

1984-01-01

An in situ adsorption measurement method at the mica/protein solution interface is described. An apparatus especially constructed for this purpose permits direct and continuous measurement of total adsorption (reversible and irreversible) of 14 C-labelled proteins. Bovine submaxillary mucin (BSM), extracted from salivary glands, was acetylated with (CH 3 14 CO) 2 O. The results show the increase of BSM adsorbed on mica surfaces with its concentration in solution and adsorption time. Pseudo plateaux are obtained for all concentrations studied, indicating the formation of thick layers. The loosely bound fraction of adsorbed mucin is proportional to the bulk concentration in solution. The amount of BSM adsorbed increases in the neighbourhood of the isoelectric point of BSM (pH 3). (Auth.)

A density functional study on the adsorption of hydrogen molecule ...

Indian Academy of Sciences (India)

tive adsorption of H2 onto the minimum energy copper clusters by using the density ... theoretical study of molecular oxygen and atomic oxy- gen adsorption onto small ...... the values for all singlet spin states are zero, indicating that no ...

Kinetic and Thermodynamic Studies on Adsorption of Sulphate from ...

African Journals Online (AJOL)

DELL USER

22, No. 1, 2017. 39. Kinetic and Thermodynamic Studies on Adsorption of Sulphate from Aqueous Solution by. Magnetite ... poison catalysts, and affect the .... C for 1 h in a stainless steel reactor placed in a furnace ... N2 gas for 30 min. 50 ml of ...... adsorption for designing and evaluating the ... is the equilibrium liquid-phase.

Study on adsorption mechanism of ammonia nitrogen in wastewater by natural heulandite

Directory of Open Access Journals (Sweden)

Xuekai JIN

2018-02-01

Full Text Available In order to explore the adsorption mechanism and optimal regeneration method of natural heulandite to high ammonia nitrogen wastewater, the natural heulandite from Hebei Province is selected as the research object. The adsorption kinetics, adsorption isotherms and adsorption thermodynamics are studied by single factor test. The results show that the adsorption process of ammonia nitrogen on heulandite with particle size range of 50~600 μm complies with the quasi-second order kinetic equation with ammonia nitrogen concentration of 500 mg/L at temperature of 25 ℃. Particle diffusion and liquid film diffusion are the dominated process of the adsorption. The adsorption capacity of heulandite is 7.81 mg/g at temperature of 45 ℃. The adsorption isotherm of ammonia nitrogen on the experimental heulandite is fitted well with Freundlich model. Gibbs free energy ΔG is calculated to be less than zero, indicating that the adsorption of ammonia nitrogen on the experimental heulandite is a spontaneous endothermic reaction. Additionally, the adsorption capacity of heulandite increases with appropriate increaseing in temperature. The optimal regeneration solvent of the saturated heulandite is 0.1 mol/L of NaCl, with which the desorption rate increases to 79%, and the times of elution and regeneration are more than 5. The results of this study can improve the economic benefits and environmental value of heulandite in the treatment of ammonia nitrogen wastewater. It can be seen that heulandite in the industrial wastewater treatment has broad prospects for application.

Study of adsorption properties on lithium doped activated carbon materials

International Nuclear Information System (INIS)

Los, S.; Daclaux, L.; Letellier, M.; Azais, P.

2005-01-01

A volumetric method was applied to study an adsorption coefficient of hydrogen molecules in a gas phase on super activated carbon surface. The investigations were focused on getting the best possible materials for the energy storage. Several treatments on raw samples were used to improve adsorption properties. The biggest capacities were obtain after high temperature treatment at reduced atmosphere. The adsorption coefficient at 77 K and 2 MPa amounts to 3.158 wt.%. The charge transfer between lithium and carbon surface groups via the doping reaction enhanced the energy of adsorption. It was also found that is a gradual decrease in the adsorbed amount of H 2 molecules due to occupation active sites by lithium ions. (author)

Bovine serum albumin adsorption onto functionalized polystyrene lattices: A theoretical modeling approach and error analysis

Science.gov (United States)

Beragoui, Manel; Aguir, Chadlia; Khalfaoui, Mohamed; Enciso, Eduardo; Torralvo, Maria José; Duclaux, Laurent; Reinert, Laurence; Vayer, Marylène; Ben Lamine, Abdelmottaleb

2015-03-01

The present work involves the study of bovine serum albumin adsorption onto five functionalized polystyrene lattices. The adsorption measurements have been carried out using a quartz crystal microbalance. Poly(styrene-co-itaconic acid) was found to be an effective adsorbent for bovine serum albumin molecule adsorption. The experimental isotherm data were analyzed using theoretical models based on a statistical physics approach, namely monolayer, double layer with two successive energy levels, finite multilayer, and modified Brunauer-Emmet-Teller. The equilibrium data were then analyzed using five different non-linear error analysis methods and it was found that the finite multilayer model best describes the protein adsorption data. Surface characteristics, i.e., surface charge density and number density of surface carboxyl groups, were used to investigate their effect on the adsorption capacity. The combination of the results obtained from the number of adsorbed layers, the number of adsorbed molecules per site, and the thickness of the adsorbed bovine serum albumin layer allows us to predict that the adsorption of this protein molecule can also be distinguished by monolayer or multilayer adsorption with end-on, side-on, and overlap conformations. The magnitudes of the calculated adsorption energy indicate that bovine serum albumin molecules are physisorbed onto the adsorbent lattices.

Kinetic and equilibrium study of adsorption of di-azo dyes on commercial activated carbon

International Nuclear Information System (INIS)

Hyali, E.A.S.A.; Abady, T.G.A.

2013-01-01

This research work is concerned with studying the adsorption of a number of di-azo dyes on commercial activated carbon (CAC). The synthesized dyes vary in their structures by the central parts. which are either ortho, meta or para phenvlene diamine. This variation affects the linearity of molecules, their spatial arrangement and electron movement throughout the molecule by resonance. Factors a fleeting adsorption process, such as the efiect of contact time, initial concentration, p1-I of the adsorption medium, adsorbent dose, effect of solvent and temperature were studied. The results indicated that, the adsorption process is fast in the first 10 mm, then gradually decreased with time and approaches maximum within 70-80 min for all the studied dyes. The increase of initial concentration and temperature decreased the adsorption efficiency. The results also shows that, the adsorption is found to be more efficient at low Ph value. The increase of the adsorbent dose increases the adsorption efficiency and decreases its capacity. The variation of solvent (ethanol-water ratio) indicates that the decrease of dielectric constant lowers the adsorption efficiency. The study included application of three adsorption isotherms, Freundlich, Langmuir and Tempkin on the experimental data of the studied systems. The results indicated that, Freundlich isotherm fits better the adsorption data. Kinetic analysis of the adsorption data was also conducted by employing 4 kinetic models; pseudo first order and pseudo second order, Elovich and intra particle diffusion equations. The results obtained conclude that, the studied systems follow the Pseudo second order model. (author)

BSA Nanoparticles for siRNA Delivery: Coating Effects on Nanoparticle Properties, Plasma Protein Adsorption, and In Vitro siRNA Delivery

Directory of Open Access Journals (Sweden)

Haran Yogasundaram

2012-01-01

Full Text Available Developing vehicles for the delivery of therapeutic molecules, like siRNA, is an area of active research. Nanoparticles composed of bovine serum albumin, stabilized via the adsorption of poly-L-lysine (PLL, have been shown to be potentially inert drug-delivery vehicles. With the primary goal of reducing nonspecific protein adsorption, the effect of using comb-type structures of poly(ethylene glycol (1 kDa, PEG units conjugated to PLL (4.2 and 24 kDa on BSA-NP properties, apparent siRNA release rate, cell viability, and cell uptake were evaluated. PEGylated PLL coatings resulted in NPs with ζ-potentials close to neutral. Incubation with platelet-poor plasma showed the composition of the adsorbed proteome was similar for all systems. siRNA was effectively encapsulated and released in a sustained manner from all NPs. With 4.2 kDa PLL, cellular uptake was not affected by the presence of PEG, but PEG coating inhibited uptake with 24 kDa PLL NPs. Moreover, 24 kDa PLL systems were cytotoxic and this cytotoxicity was diminished upon PEG incorporation. The overall results identified a BSA-NP coating structure that provided effective siRNA encapsulation while reducing ζ-potential, protein adsorption, and cytotoxicity, necessary attributes for in vivo application of drug-delivery vehicles.

Adsorption and desorption study of 14C-Chloropyrifos in two Malaysian agricultural soils

International Nuclear Information System (INIS)

Halimah Muhammad; Nashriyah Mat; Tan Yew Ai; Ismail, B.S.

2004-01-01

The adsorption equilibrium time and effects of pH and concentration of 14 C-labeled chloropyrifos 0,0-diethyl 0-(3, 5, 6 tricloro-2-pyridyl)-phosphorothiote in soil were investigated. Two types of Malaysian soil under oil palm were used in this study; namely clay loam and clay soil obtained from the Sungai Sedu and Kuala Lumpur International Airport (KLIA) Estates, respectively. Equilibrium studies of chloropyrifos between the agricultural soil and the pesticide solution were conducted. Adsorption equilibrium time was achieved within 6 and 24 hours for clay loam and clay soil, respectively. It was found that chloropyrifos adsorbed by the soil samples was characterized by an initial rapid adsorption after which adsorption remained approximately constant. The percentage of 14 C-labeled chloropyrifos adsorption on soil was found to be higher in clay loam than in clay soils. Results of the study demonstrated that pH affected the adsorption of chloropyrifos on both clay loam and clay soils. The adsorption of chloropyrifos on both types of soil was higher at low pH with the adsorption reduced as the pH increased. Results also suggest that chloropyrifos sorption by soil is concentration dependent. (Author)

Equilibrium, kinetic and thermodynamic studies on the adsorption of phenol onto graphene

Energy Technology Data Exchange (ETDEWEB)

Li, Yanhui, E-mail: liyanhui@tsinghua.org.cn [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Jiao, Yuqin [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Yanzhi, E-mail: xiayzh@qdu.edu.cn [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Linhua; Wang, Zonghua [Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Zhang, Wei; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai [Key Laboratory for Advanced Manufacturing by Material Processing Technology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

2012-08-15

Graphical abstract: The effect of temperature on phenol adsorbed by graphene shows that the equilibrium adsorption capacity of phenol increases with the increase in temperature from 285 to 333 K. Increasing adsorption capacities with temperature indicates that the adsorption of phenol is controlled by an endothermic reaction. Highlights: ► The graphene has high phenol adsorption capacity. ► The graphene has a high specific surface area of 305 m{sup 2}/g. ► The adsorption capacity is high at acidic pH range. ► The graphene has rapid phenol adsorption rate. ► Phenol adsorption is a spontaneous and endothermic process. -- Abstract: Graphene, a new member of carbon family, has been prepared, characterized and used as adsorbent to remove phenol from aqueous solution. The effect parameters including pH, dosage, contact time, and temperature on the adsorption properties of phenol onto graphene were investigated. The results showed that the maximum adsorption capacity can reach 28.26 mg/g at the conditions of initial phenol concentration of 50 mg/L, pH 6.3 and 285 K. Adsorption data were well described by both Freundlich and Langmuir models. The kinetic study illustrated that the adsorption of phenol onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of phenol onto graphene was endothermic and spontaneous.

Equilibrium, kinetic and thermodynamic studies on the adsorption of phenol onto graphene

International Nuclear Information System (INIS)

Li, Yanhui; Du, Qiuju; Liu, Tonghao; Sun, Jiankun; Jiao, Yuqin; Xia, Yanzhi; Xia, Linhua; Wang, Zonghua; Zhang, Wei; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai

2012-01-01

Graphical abstract: The effect of temperature on phenol adsorbed by graphene shows that the equilibrium adsorption capacity of phenol increases with the increase in temperature from 285 to 333 K. Increasing adsorption capacities with temperature indicates that the adsorption of phenol is controlled by an endothermic reaction. Highlights: ► The graphene has high phenol adsorption capacity. ► The graphene has a high specific surface area of 305 m 2 /g. ► The adsorption capacity is high at acidic pH range. ► The graphene has rapid phenol adsorption rate. ► Phenol adsorption is a spontaneous and endothermic process. -- Abstract: Graphene, a new member of carbon family, has been prepared, characterized and used as adsorbent to remove phenol from aqueous solution. The effect parameters including pH, dosage, contact time, and temperature on the adsorption properties of phenol onto graphene were investigated. The results showed that the maximum adsorption capacity can reach 28.26 mg/g at the conditions of initial phenol concentration of 50 mg/L, pH 6.3 and 285 K. Adsorption data were well described by both Freundlich and Langmuir models. The kinetic study illustrated that the adsorption of phenol onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of phenol onto graphene was endothermic and spontaneous.

Adsorption isotherm special study. Final report

International Nuclear Information System (INIS)

1993-05-01

The study was designed to identify methods to determine adsorption applicable to Uranium Mill Tailings Remedial Action (UMTRA) Project sites, and to determine how changes in aquifer conditions affect metal adsorption, resulting retardation factors, and estimated contaminant migration rates. EPA and ASTM procedures were used to estimate sediment sorption of U, As, and Mo under varying groundwater geochemical conditions. Aquifer matrix materials from three distinct locations at the DOE UMTRA Project site in Rifle, CO, were used as the adsorbents under different pH conditions; these conditions stimulated geochemical environments under the tailings, near the tailings, and downgradient from the tailings. Grain size, total surface area, bulk and clay mineralogy, and petrography of the sediments were characterized. U and Mo yielded linear isotherms, while As had nonlinear ones. U and Mo were adsorbed strongly on sediments acidified to levels similar to tailings leachate. Changes in pH had much less effect on As adsorption. Mo was adsorbed very little at pH 7-7.3, U was weakly sorbed, and As was moderately sorbed. Velocities were estimated for metal transport at different pHs. Results show that the aquifer materials must be characterized to estimate metal transport velocities in aquifers and to develop groundwater restoration strategies for the UMTRA project

Study on the adsorption-desorption characteristics of 14C-pirimicarb in soils

International Nuclear Information System (INIS)

Guo Jiangfeng; Sun Jinhe; Li Xingming

1995-01-01

14 C-pirimicarb was used to study its adsorption-desorption behavior in 8 kinds of soils. The results indicated that there were significant differences in its adsorption with different kinds of soil. The lowest adsorption percentage was only 13.16% and the highest one was 87.75%. The amount of adsorption in the same kind of soil increased with the concentration of pesticide, but concentration had little influence on the adsorption within the certain range of concentrations. Multiple linear regression equation was developed for prediction of adsorption and determination of the relative importance of the soil parameters. It was significant that the key factors, soil pH and clay content were negatively and positively correlated with the adsorption respectively. The adsorption equilibrium of pirimicarb in soils could be well described by both the Freundlich isotherm and the Langmuir isotherm. The adsorbed 14 C-pirimicarb could disrobe from soil and its desorption was also influenced by soil properties described by multiple linear regression equation

SeO{sub 2} adsorption on CaO surface: DFT study on the adsorption of a single SeO{sub 2} molecule

Energy Technology Data Exchange (ETDEWEB)

Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Li, Liangliang [Key Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)

2017-08-15

Highlights: • Adsorption mechanisms of SeO{sub 2} on CaO surface under O{sub 2} were firstly studied by DFT. • The adsorption energies, bond length and electron density maps were calculated. • The electronic structure changes upon adsorption were studied. - Abstract: Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO{sub 2} in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO{sub 2} due to its low cost. In this paper, the adsorption mechanisms of single SeO{sub 2} on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO{sub 2} on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O{sub 2} atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO{sub 2} and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

Analysis of plasma protein adsorption onto DC-Chol-DOPE cationic liposomes by HPLC-CHIP coupled to a Q-TOF mass spectrometer

KAUST Repository

Capriotti, Anna Laura; Caracciolo, Giulio; Caruso, Giuseppe; Cavaliere, Chiara; Pozzi, Daniela; Samperi, Roberto; Laganà , Aldo

2010-01-01

Plasma protein adsorption is regarded as a key factor in the in vivo organ distribution of intravenously administered drug carriers, and strongly depends on vector surface characteristics. The present study aimed to characterize the "protein corona" absorbed onto DC-Chol-DOPE cationic liposomes. This system was chosen because it is one of the most efficient and widely used non-viral formulations in vitro and a potential candidate for in vivo transfection of genetic material. After incubation of human plasma with cationic liposomes, nanoparticle-protein complex was separated from plasma by centrifugation. An integrated approach based on protein separation by one-dimensional 12% polyacrylamide gel electrophoresis followed by the automated HPLC-Chip technology coupled to a high-resolution mass spectrometer was employed for protein corona characterization. Thirty gel lanes, approximately 2 mm, were cut, digested and analyzed by HPLC-MS/MS. Fifty-eight human plasma proteins adsorbed onto DC-Chol-DOPE cationic liposomes were identified. The knowledge of the interactions of proteins with liposomes can be exploited for future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins in body fluids. © 2010 Springer-Verlag.

Analysis of plasma protein adsorption onto DC-Chol-DOPE cationic liposomes by HPLC-CHIP coupled to a Q-TOF mass spectrometer

KAUST Repository

Capriotti, Anna Laura

2010-09-22

Plasma protein adsorption is regarded as a key factor in the in vivo organ distribution of intravenously administered drug carriers, and strongly depends on vector surface characteristics. The present study aimed to characterize the "protein corona" absorbed onto DC-Chol-DOPE cationic liposomes. This system was chosen because it is one of the most efficient and widely used non-viral formulations in vitro and a potential candidate for in vivo transfection of genetic material. After incubation of human plasma with cationic liposomes, nanoparticle-protein complex was separated from plasma by centrifugation. An integrated approach based on protein separation by one-dimensional 12% polyacrylamide gel electrophoresis followed by the automated HPLC-Chip technology coupled to a high-resolution mass spectrometer was employed for protein corona characterization. Thirty gel lanes, approximately 2 mm, were cut, digested and analyzed by HPLC-MS/MS. Fifty-eight human plasma proteins adsorbed onto DC-Chol-DOPE cationic liposomes were identified. The knowledge of the interactions of proteins with liposomes can be exploited for future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins in body fluids. © 2010 Springer-Verlag.

The Study of Cr3+ Adsorption Wukirsari Pumice

International Nuclear Information System (INIS)

Samin; Susanna TS

2002-01-01

As an alternative to solve an environmental problem of Cr 3+ , the use of Wukirsari pumice has been studied. Before used as an adsorbent. 100-200 mesh of Wukirsari pumice was washed and calcinate. The elements composition of adsorbent was analyzed using Atomic Adsorption Spectrophotometer (AAS) method and presented as their oxides. After calcination, the pumice was saturated by NaCI and then converted to its ceramic. The mineral composition of pumice and its ceramic was determined using XRD method. Experimental results show optimum temperature for calcination was 500 o C and 5 hours duration of contact time was found from adsorption of Na + , with the value of 505 mg/g pumice. The other results show that pH of the solution influence the adsorption. The ion exchange between Na + and Cr 3+ did not follow ideal solution, and one ion Cr 3+ could replace only one ion Na + hence optimum adsorption of Cr 3+ was 1141.47 mg/g pumice. The data XRD shows that mineral composition of the pumice was magnetite, anorthite, and montmorilonite, while composition of its ceramic was feldspar and cristobalite. (author)

Resistance to protein adsorption and adhesion of fibroblasts on nanocrystalline diamond films: the role of topography and boron doping

Czech Academy of Sciences Publication Activity Database

Alcaide, M.; Papaioannou, S.; Taylor, Andrew; Fekete, Ladislav; Gurevich, L.; Zachar, V.; Pennisi, C.P.

2016-01-01

Roč. 27, č. 5 (2016), s. 90-1-12 ISSN 0957-4530 R&D Projects: GA MŠk LO1409 Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568 Institutional support: RVO:68378271 Keywords : protein adsorption * fibroblasts adhesion * nanocrystalline diamond * boron doping * topography Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.325, year: 2016

Patterns of the adsorption of bovine serum albumin on carboxymethyl dextran and carboxymethyl cellulose films

Science.gov (United States)

Paribok, I. V.; Solomyanskii, A. E.; Zhavnerko, G. K.

2016-02-01

Patterns of the adsorption of bovine serum albumin on carboxymethyl dextran and carboxymethyl cellulose films are studied by means of microcontact printing, atomic force microscopy, and quartz crystal microbalance. It is shown that both the charge of polysaccharide macromolecules and the technique for deposition of their films onto the surface (via adsorption from a solution or covalent cross-linking) are factors that determine the degree of nonspecific adsorption of the protein on such films.

Adsorption of saturated fatty acid in urea complexation: Kinetics and equilibrium studies

Science.gov (United States)

Setyawardhani, Dwi Ardiana; Sulistyo, Hary; Sediawan, Wahyudi Budi; Fahrurrozi, Mohammad

2018-02-01

Urea complexation is fractionation process for concentrating poly-unsaturated fatty acids (PUFAs) from vegetable oil or animal fats. For process design and optimization in commercial industries, it is necessary to provide kinetics and equilibrium data. Urea inclusion compounds (UICs) as the product is a unique complex form which one molecule (guest) is enclosed within another molecule (host). In urea complexation, the guest-host bonding exists between saturated fatty acids (SFAs) and crystalline urea. This research studied the complexation is analogous to an adsorption process. The Batch adsorption process was developed to obtain the experimental data. The ethanolic urea solution was mixed with SFA in certain compositions and adsorption times. The mixture was heated until it formed homogenous and clear solution, then it cooled very slowly until the first numerous crystal appeared. Adsorption times for the kinetic data were determined since the crystal formed. The temperature was maintained constant at room temperature. Experimental sets of data were observed with adsorption kinetics and equilibrium models. High concentration of saturated fatty acid (SFA) was used to represent adsorption kinetics and equilibrium parameters. Kinetic data were examined with pseudo first-order, pseudo second-order and intra particle diffusion models. Linier, Freundlich and Langmuir isotherm were used to study the equilibrium model of this adsorption. The experimental data showed that SFA adsorption in urea crystal followed pseudo second-order model. The compatibility of the data with Langmuir isotherm showed that urea complexation was a monolayer adsorption.

Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

Energy Technology Data Exchange (ETDEWEB)

Kato, Katsuya, E-mail: katsuya-kato@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Nakamura, Hitomi [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8570 (Japan)

2014-07-01

Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO){sub 20}(PO){sub 70}(EO){sub 20}) or F127 ((EO){sub 106}(PO){sub 70}(EO){sub 106}), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films.

Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

International Nuclear Information System (INIS)

Kato, Katsuya; Nakamura, Hitomi; Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro

2014-01-01

Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO) 20 (PO) 70 (EO) 20 ) or F127 ((EO) 106 (PO) 70 (EO) 106 ), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films

Effect of fibronectin adsorption on osteoblastic cellular responses to hydroxyapatite and alumina

International Nuclear Information System (INIS)

Kawashita, Masakazu; Hasegawa, Maki; Kudo, Tada-aki; Kanetaka, Hiroyasu; Miyazaki, Toshiki; Hashimoto, Masami

2016-01-01

Initial cellular responses following implantation are important for inducing osteoconduction. We investigated cell adhesion, spreading, proliferation and differentiation of mouse MC3T3-E1 osteoblastic cells on untreated or fibronectin (Fn)-coated discs of hydroxyapatite (HAp) or alpha-type alumina (α-Al 2 O 3 ). Fn coating significantly enhanced adhesion and spreading of MC3T3-E1 cells on HAp, but did not affect MC3T3-E1 cell proliferation and differentiation on HAp or α-Al 2 O 3 . Fn-coated HAp likely does not stimulate pre-osteoblast cells to initiate the process of osteoconduction; however, Fn adsorption might affect the response of inflammatory cells to the implanted material or, in conjunction with other serum proteins, stimulate pre-osteoblast cell proliferation and differentiation. Further studies on the effect of serum proteins in cell culture and the efficacy of Fn-coated HAp and α-Al 2 O 3 in vivo are warranted. - Highlights: • We studied osteoblast-like MC3T3-E1 cell responses on fibronectin (Fn)-coated discs (HAp/α-Al 2 O 3 ). • Fn adsorption enhanced adhesion and spreading of MC3T3-E1 cells on HAp but not on α-Al 2 O 3 . • Fn adsorption hardly affected proliferation and differentiation of MC3T3-E1 cells on HAp and α-Al 2 O 3 . • Fn adsorption might stimulate osteoconduction on HAp along with other serum proteins.

Study of carbon dioxide adsorption on a Cu-nitroprusside polymorph

International Nuclear Information System (INIS)

Roque-Malherbe, R.; Lozano, C.; Polanco, R.; Marquez, F.; Lugo, F.; Hernandez-Maldonado, A.; Primera-Pedrozo, J.N.

2011-01-01

A careful structural characterization was carried out to unequivocally determine the structure of the synthesized material. The TGA, DRIFTS and a Pawley fitting of the XRD powder profiles indicate that the hydrated and in situ dehydrated polymorph crystallizes in the orthorhombic space group Pnma. Meanwhile, the CO 2 isosteric heat of adsorption appears to be independent of loading with an average value of 30 kJ/mol. This translates to a physisorption type interaction, where the adsorption energy corresponding to wall and lateral interactions are mutually compensated to produce, an apparently, homogeneous adsorption energy. The somewhat high adsorption energy is probably due to the confinement of the CO 2 molecules in the nitroprusside pores. Statistical Physics and the Dubinin theory for pore volume filling allowed model the CO 2 equilibrium adsorption process in Cu-nitroprusside. A DRIFTS test for the adsorbed CO 2 displayed a peak at about 2338 cm -1 that was assigned to a contribution due to physical adsorption of the molecule. Another peak found at 2362 cm -1 evidenced that this molecule interacts with the Cu 2+ , which appears to act as an electron accepting Lewis acid site. The aim of the present paper is to report a Pnma stable Cu-nitroprusside polymorph obtained by the precipitation method that can adsorb carbon dioxide. -- Graphical abstract: The adsorption space of a very well characterized Cu-nitroprusside polymorph, applying carbon dioxide as probe molecule, was studied. Display Omitted Highlights: → Accurate information about the geometry of the adsorption space was provided. → Truthful data about the interactions within the adsorption space was presented. → The structure of the tested Cu-NP polymorph was established. → Was evidenced adsorbed CO 2 molecules in the form of weakly bonded adducts. → Is proposed that adsorbed molecules could change the Cu-NP magnetic properties.

A comparative study for adsorption of lysozyme from aqueous samples onto Fe3O4 magnetic nanoparticles using different ionic liquids as modifier.

Science.gov (United States)

Kamran, Sedigheh; Absalan, Ghodratollah; Asadi, Mozaffar

2015-12-01

In this paper, nanoparticles of Fe3O4 as well as their modified forms with different ionic liquids (IL-Fe3O4) were prepared and used for adsorption of lysozyme. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption studies of lysozyme were performed under different experimental conditions in batch system on different modified magnetic nanoparticles such as, lysozyme concentration, pH of the solution, and contact time. Experimental results were obtained under the optimum operational conditions of pH 9.0 and a contact time of 10 min when initial protein concentrations of 0.05-2.0 mg mL(-1) were used. The isotherm evaluations revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The maximum obtained adsorption capacities were 370.4, 400.0 500.0 and 526.3 mg of lysozyme for adsorption onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br] per gram of adsorbent, respectively. The Langmuir adsorption constants were 0.004, 0.019, 0.024 and 0.012 L mg(-1) for adsorptions of lysozyme onto Fe3O4 and modified magnetic nanoparticles by [C4MIM][Br], [C6MIM][Br] and [C8MIM][Br], respectively. The adsorption capacity of lysozyme was found to be dependent on its chemical structure, pH of the solution, temperature and type of ionic liquid as modifier. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated. Furthermore, the thermodynamic parameters were calculated. Protein could desorb from IL-Fe3O4 nanoparticles by using NaCl solution at pH 9.5 and was reused.

A Study on adsorption of Li from aqueous solution using various adsorbents

Energy Technology Data Exchange (ETDEWEB)

Ryoo, Keon Sang [Dept. of Applied Chemistry, Andong National University, Andon (Korea, Republic of); Kim, Dae Ik [School of Electrical, Electronic Communication, and Computer Engineering, Chonnam National University, Yeosu (Korea, Republic of)

2015-04-15

The aim of the present study is to explore the possibility of utilizing fly ash, loess and activated charcoal for the adsorption of Li in aqueous solution. Batch adsorption experiments were performed to evaluate the influences of various factors like initial concentration, contact time, and temperature. The adsorption data showed that fly ash and activated charcoal are not effective for the adsorption of Li. On the contrary, loess showed much higher adsorption capacity for Li. The adsorption of Li on loess was highly concentration dependent. It was found that the adsorption capacity of loess is favored at a lower Li concentration. At equilibrium, approximately 95% of adsorption was achieved by loess. The equilibrium data were fitted well to the Freundlich isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher R 2 compared to the pseudo-first-order kinetic models. The thermodynamic parameters such as free energy ΔG, the enthalpy ΔH, and the entropy ΔS were calculated.

Polyether sulfone/hydroxyapatite mixed matrix membranes for protein purification

Energy Technology Data Exchange (ETDEWEB)

Sun, Junfen, E-mail: junfensun@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, North People Road 2999, Shanghai 201620 (China); Wu, Lishun [Department of Chemistry and Chemical Engineering, Heze University, Daxue Road 2269, Heze, Shandong Province 274015 (China)

2014-07-01

This work proposes a novel approach for protein purification from solution using mixed matrix membranes (MMMs) comprising of hydroxyapatite (HAP) inside polyether sulfone (PES) matrix. The influence of HAP particle loading on membrane morphology is studied. The MMMs are further characterized concerning permeability and adsorption capacity. The MMMs show purification of protein via both diffusion as well as adsorption, and show the potential of using MMMs for improvements in protein purification techniques. The bovine serum albumin (BSA) was used as a model protein. The properties and structures of MMMs prepared by immersion phase separation process were characterized by pure water flux, BSA adsorption and scanning electron microscopy (SEM).

Equilibrium, kinetic and thermodynamic studies of adsorption of Th(IV) from aqueous solution onto kaolin

International Nuclear Information System (INIS)

Hongxia Zhang; Zhiwei Niu; Zhi Liu; Zhaodong Wen; Weiping Li; Xiaoyun Wang; Wangsuo Wu

2015-01-01

The kinetics and thermodynamics of the adsorption of Th(IV) on the kaolin were studied by using batch method. In addition, the experimental data were studied by dynamic and thermodynamic models. The results showed that the adsorption capacity of the adsorbent increased with increasing temperature and solid liquid ratio, but decreased with increasing initial Th(IV) ion concentration, and the best fit was obtained for the pseudo-second-order kinetics model. The calculated activation energy for adsorption was about 45 kJ/mol, which indicated the adsorption process to be chemisorption. The adsorption isotherm data could be well described by the Langmuir as well as Dubinin-Radushkevich model. The mean free energy (E) of adsorption was calculated to be about 15 kJ/mol. The thermodynamic data calculated showed that the adsorption was spontaneous and enhanced at higher temperature. Considering kinetics and equilibrium studies, the adsorption on the sites was the rate-limiting step and that adsorption was mainly a chemisorption process through cation exchange. (author)

A novel system for continuous protein refolding and on-line capture by expanded bed adsorption

DEFF Research Database (Denmark)

Ferré, Henrik; Ruffet, E; Nielsen, L.L.B

2005-01-01

A novel two-step protein refolding strategy has been developed, where continuous renaturation-by-dilution is followed by direct capture on an expanded bed adsorption (EBA) column. The performance of the overall process was tested on a N-terminally tagged version of human beta(2)-microglobulin (HAT......-h beta(2)m) both at analytical, small, and preparative scale. In a single scalable operation, extracted and denatured inclusion body proteins from Escherichia coli were continuously diluted into refolding buffer, using a short pipe reactor, allowing for a defined retention and refolding time...... of the overall process was 45%, and the product loss was primarily a consequence of the refolding reaction rather than the EBA step. Full biological activity of HAT-h beta(2)m was demonstrated after removal of the HAT-tag. In contrast to batch refolding, a continuous refolding strategy allows the conditions...

Immunoglobulin adsorption on modified surfaces

NARCIS (Netherlands)

Bremer, M.G.E.G.

2001-01-01

Preservation of biological functioning of proteins during immobilisation is of special interest in various biomedical and biotechnical applications. In industry physical adsorption of immunoglobulins (IgGs) onto solid surfaces is still the predominant immobilisation procedure because it is

A study of uranium adsorption to single-crystal tungsten

Energy Technology Data Exchange (ETDEWEB)

Samin, Adib; Hastings, Aaron; Zhang, Jinsuo, E-mail: jzhang@osu.edu

2015-12-15

In this study we explore the adsorption of uranium to the (110) plane of tungsten. Potential functions were constructed to describe the interaction of adsorbed uranium atoms with the tungsten surface and the lateral interaction between adsorbed uranium atoms. Next, the behavior of the uranium adlayer under different conditions was studied through a Monte Carlo simulation of the grand canonical Hamiltonian in an off-lattice model. Our results are consistent with available studies in the literature. The simulation results indicate that the temperature and dipole–dipole interactions play an important role in governing the adsorption process.

A study of uranium adsorption to single-crystal tungsten

International Nuclear Information System (INIS)

Samin, Adib; Hastings, Aaron; Zhang, Jinsuo

2015-01-01

In this study we explore the adsorption of uranium to the (110) plane of tungsten. Potential functions were constructed to describe the interaction of adsorbed uranium atoms with the tungsten surface and the lateral interaction between adsorbed uranium atoms. Next, the behavior of the uranium adlayer under different conditions was studied through a Monte Carlo simulation of the grand canonical Hamiltonian in an off-lattice model. Our results are consistent with available studies in the literature. The simulation results indicate that the temperature and dipole–dipole interactions play an important role in governing the adsorption process.

Dyeing and Adsorption Studies of Madder (Rubia tinctorum on Wool Fibers

Directory of Open Access Journals (Sweden)

Mahmoud FEIZ

2015-03-01

Full Text Available In this study, the dyeing behavior of wool fabrics with madder has been studied. Three well-known types of adsorption isotherms i.e. the Nernst, Freundlich and Langmuir isotherms were used to fit the data. It was found that the adsorption isotherm of madder on wool fibers follows Freundlich type of adsorption. The exponent α in Freundlich isotherm equation (Cf = k.Csα was obtained 0.61 corresponding to 0.5 for the direct dyes on cellulosic fibers. The effect of salt and pH on dyeing of wool samples was investigated by the use of color characteristics measurements. The results showed that addition of salt and acid (pH 4.5 to the dyebath resulted in an increase of adsorption. DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5150

Adsorption study of cadmium (II) and lead (II) on radish peels

International Nuclear Information System (INIS)

Anwar, J.; Shafique, U.; Salman, M.; Zaman, W.; Memoona, M.

2009-01-01

The removal efficiency of heavy metals like Cd(II) and Pb(II) from aqueous solutions by adsorption on Raphanus sativus (Radish peels) has been studied. The effects of time, pH, concentration of adsorbent and agitation speed on adsorption have been evaluated. It is found that radish peels powder has high removal efficiency for both the metals. Batch adsorption study has shown that Cd(II) and Pb(II) has been removed up to 88% and 86% respectively. Adsorption equilibriums for both metals have been described by the Langmuir isotherm. The maximum amount of heavy metals (Q ) adsorbed at max equilibrium were 7.5 and 1.23 mg/g for Cd(II) and Pb(II) respectively as evaluated by Langmuir isotherm. It is concluded that waste materials like radish peels can be used for removal of heavy metals from aqueous streams. (author)

Adsorption effectiveness of β-lactoglobulin onto gold surface determined by quartz crystal microbalance.

Science.gov (United States)

Jachimska, B; Świątek, S; Loch, J I; Lewiński, K; Luxbacher, T

2018-06-01

Bovine β-lactoglobulin (LGB) is a transport protein that can bind to its structure hydrophobic bioactive molecules. Due to the lack of toxicity, high stability and pH-dependent molecular binding mechanism, lactoglobulin can be used as a carrier of sparingly soluble drugs. Dynamic light scattering has confirmed LGB's tendency to create oligomeric forms. The hydrodynamic diameter of LGB molecules varies from 4 nm to 6 nm in the pH range of 2-10 and ionic strength I = 0.001-0.15 M, which corresponds to the presence of mono or dimeric LGB forms. The LGB zeta potential varies from 26.5 mV to -33.3 mV for I = 0.01 M and from 13.3 mV to -16 mV for I = 0.15 M in the pH range of 2-10. The isoelectric point is at pH 4.8. As a result of strong surface charge compensation, the maximum effective ionization degree of the LGB molecule is 35% for ionic strength I = 0.01 M and 22% for I = 0.15 M. The effectiveness of adsorption is linked with the properties of the protein, as well as those of the adsorption surface. The functionalization of gold surfaces with β-lactoglobulin (LGB) was studied using a quartz crystal microbalance with energy dissipation monitoring (QCM-D). The effectiveness of LGB adsorption correlates strongly with a charge of gold surface and the zeta potential of the molecule. The greatest value of the adsorbed mass was observed in the pH range in which LGB has a positive zeta potential values, below pH 4.8. This observation shows that electrostatic interactions play a dominant role in LGB adsorption on gold surfaces. Based on the adsorbed mass, protein orientation on gold surfaces was determined. The preferential side-on orientation of LGB molecules observed in the adsorption layer is consistent with the direction of the molecule dipole momentum determined by molecular dynamics simulations of the protein (MD). The use of the QCM-D method also allowed us to determine the effectiveness of adsorption of LGB on gold

Interactions between protein molecules and the virus removal membrane surface: Effects of immunoglobulin G adsorption and conformational changes on filter performance.

Science.gov (United States)

Hamamoto, Ryo; Ito, Hidemi; Hirohara, Makoto; Chang, Ryongsok; Hongo-Hirasaki, Tomoko; Hayashi, Tomohiro

2018-03-01

Membrane fouling commonly occurs in all filter types during virus filtration in protein-based biopharmaceutical manufacturing. Mechanisms of decline in virus filter performance due to membrane fouling were investigated using a cellulose-based virus filter as a model membrane. Filter performance was critically dependent on solution conditions; specifically, ionic strength. To understand the interaction between immunoglobulin G (IgG) and cellulose, sensors coated with cellulose were fabricated for surface plasmon resonance and quartz crystal microbalance with energy dissipation measurements. The primary cause of flux decline appeared to be irreversible IgG adsorption on the surface of the virus filter membrane. In particular, post-adsorption conformational changes in the IgG molecules promoted further irreversible IgG adsorption, a finding that could not be adequately explained by DLVO theory. Analyses of adsorption and desorption and conformational changes in IgG molecules on cellulose surfaces mimicking cellulose-based virus removal membranes provide an effective approach for identifying ways of optimizing solution conditions to maximize virus filter performance. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:379-386, 2018. © 2017 American Institute of Chemical Engineers.

Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications

Directory of Open Access Journals (Sweden)

Zhao Wang

2018-02-01

Full Text Available In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose-b-poly(6-cholesteryloxyhexyl methacrylate (PMAgala-b-PMAChols, with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM and dynamic laser light scattering (DLS. In addition, the lectin (Ricinus communis agglutinin II, RCA120 recognition and bovine serum albumin (BSA adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

Study on the adsorption isosteres of the composite adsorbent CaCl2 and expanded graphite

International Nuclear Information System (INIS)

Li, S.L.; Wu, J.Y.; Xia, Z.Z.; Wang, R.Z.

2011-01-01

A test setup was built to study the adsorption performance of the composite adsorbent used in the adsorption system. The isovolume measurement method is adopted in the test setup to measure the adsorption isosteres of the composite adsorbent and ammonia working pair. The adsorption isosteres are the curves of the adsorption pressures variation with adsorption temperatures at constant adsorption quantity, which are convenient for the calculation of the adsorption heat and selection of the adsorption working pairs. The adsorption heats were calculated according to the adsorption isosteres, three clear crest values indicate that there were three types of reaction during the reaction processes of ammoniate calcium chloride and ammonia. The kinetic model of adsorption isosteres is obtained by the Temkin model, it is useful to estimate the adsorption performance of the working pairs and useful to guide the design of adsorption system.

Adsorption Properties of Doxorubicin Hydrochloride onto Graphene Oxide: Equilibrium, Kinetic and Thermodynamic Studies

Directory of Open Access Journals (Sweden)

Zonghua Wang

2013-05-01

Full Text Available Doxorubicin hydrochloride (DOX is an effective anticancer agent for leukemia chemotherapy, although its clinical use has been limited because of its side effects such as cardiotoxicity, alopecia, vomiting, and leucopenia. Attention has been focussed on developing new drug carriers with high adsorption capacity and rapid adsorption rate in order to minimize the side effects of DOX. Graphene oxide (GO, a new type of nanomaterial in the carbon family, was prepared by Hummers method and used as adsorbent for DOX from aqueous solution. The physico-chemical properties of GO were characterized by transmission electron microscope (TEM, Fourier transform infrared spectroscopy (FTIR, zeta potential, and element analysis. The adsorption properties of DOX on GO were studied as a function of contact time, adsorbent dosage, temperature and pH value. The results showed that GO had a maximum adsorption capacity of 1428.57 mg/g and the adsorption isotherm data fitted the Langmuir model. The kinetics of adsorption fits a pseudo-second-order model. The thermodynamic studies indicate that the adsorption of DOX on GO is spontaneous and endothermic in nature.

The Adsorption of Calmoduline via Nicotinamide Immobilized Poly(HEMA-GMA Cryogels

Directory of Open Access Journals (Sweden)

Kadir Erol

2016-12-01

Full Text Available The separation and purification methods for the isolation of an important biomolecule calmoduline protein is extremely important. Among these methods, the adsorption technique is extremely popular, and the cryogels as adsorbents with the macro porous structure and interconnected flow channels cryogel they have are preferred in this field. In this study, the adsorption of calmoduline via Ca(II immobilized poly (2-hydroxyethyl methacrylate-glycidyl methacrylate, poly (HEMA-GMA, cryogels through changing interaction time, calmoduline initial concentration and temperature conditions. For the characterization of cryogels, the swelling test, Fourier Transform Infrared (FT-IR Spectroscopy, Scanning Electron Microscopy (SEM, surface area (BET, elemental analysis and ICP-OES methods were performed. Nicotinamide molecule was used as Ca (II chelating agent and the adsorption capacity of the cryogels was estimated as 1.812 mg calmoduline / g cryogel. The adsorption models of the adsorption reaction were examined by the Langmuir and Freundlich isotherm models and was determined to be more appropriate for Langmuir isotherm model.

Studies on the adsorption characteristics of some heavy elements using Vermiculite

International Nuclear Information System (INIS)

Ezz El Deen, A.A.; Waly, S.A.; EL Adham, K.A.; Dakroury, A.M.; Shoukry, M.M

2012-01-01

The uncontrolled release of liquid wastes into the environment may lead to hazard to the human and the environment. There have been extensive studies for development of various technologies for removal of Cd 2+ and Co 2+ from wastes The removal of Cd 2+ and Co 2+ ions from aqueous solution by Vermiculite has been investigated. The Vermiculite was characterized by Particle size, Surface area, and chemical analysis. The adsorption behavior of Vermiculite has been studied as a function of the solution agitation time, ph, initial metal concentration in solution, particle size, and temperature. Kinetic studies were undertaken to show the mechanistic aspects of the process. It was showed that the process was first order reaction for the two metal ions. Sorption data have been correlated with both, Langmuir and Freundlich adsorption models. Thermodynamic parameters such as ΔH degree, ΔS degree, and ΔG degree were calculated from the slope and intercept of linear plot of lnK D against 1/T. The ΔH degree and ΔG degree values of metal ions adsorption on the two adsorbents show endothermic heat of adsorption. But there is a negative free energy value, indicating that the process of ions adsorption is favored at high temperatures.

Nanoparticle Surface Specific Adsorption of Zein and Its Self-assembled Behavior of Nanocubes Formation in Relation to On-Off SERS: Understanding Morphology Control of Protein Aggregates.

Science.gov (United States)

Navdeep; Banipal, Tarlok Singh; Kaur, Gurinder; Bakshi, Mandeep Singh

2016-01-27

Zein, an industrially important protein, is characterized in terms of its food and pharmaceutical coating applications by using surface enhanced Raman spectroscopy (SERS) on Au, Ag, and PbS nanoparticles (NPs). Its specific surface adsorption behavior on Ag NPs produced self-assembled zein nanocubes which demonstrated on and off SERS activity. Both SERS characterization as well as nanocube formation of zein helped us to understand the complex protein aggregation behavior in shape controlled morphologies, a process with significant ramifications in protein crystallization to achieve ordered morphologies. Interestingly, nanocube formation was promoted in the presence of Ag rather than Au or PbS NPs under in situ synthesis and discussed in terms of specific adsorption. Zein fingerprinting was much more clear and enhanced on Au surface in comparison to Ag while PbS did not demonstrate SERS due to its semiconducting nature.

Adsorption studies on bleaching of palm-kernel oil with activated ...

African Journals Online (AJOL)

Adsorption studies were performed on bleaching of palm-kernel oil (PKO) with different weight ratios of activated bentonite clay/PKO, ranging from 0.25% to 3% and at different temperatures of 70ºC, 80ºC, 90ºC and 100ºC. The equilibrium data generated were subsequently fitted with Langmuir and Freundlich adsorption ...

Study of algae's adsorption to uranium ion in water solution

International Nuclear Information System (INIS)

Du Yang; Qiu Yongmei; Dan Guiping; Zhang Dong; Lei Jiarong

2007-01-01

The adsorption efficiencies of the algae to uranium ion were determined at various pH, uranium ion concentrations, adsorption temperatures and the species of coexisted metal ions, and the effect of coexisted metal ion on the adsorption efficiency was researched. The experimental results at pH= 5-8 are as follows. 1) the adsorption capacity is a constant to be about 1.40 μg/g for the Yantai red alga and the sea spinach, and is changeable in the range of 1.03-2.23 μg/g with pH for the sea edible fungus; 2) for the algae the adsorption efficiency and adsorption capacity are related to uranium ion concentration, and the maximum adsorption efficiency and capacity is 95.8% and 65.4 μg/g, respectively; 3) the adsorption process for 24 h is not dependent on the temperature; 4) the effect of the species of coexisted metal ions on the adsorption capacity of uranium ion is various with the time during adsorption process. (authors)

Study on adsorption refrigeration performance of MIL-101-isobutane working pair

International Nuclear Information System (INIS)

Ma, Liejun; Yang, Huan; Wu, Qi; Yin, Yu; Liu, Zongjian; Cui, Qun; Wang, Haiyan

2015-01-01

Rising concerns about pro-environment and energy conservation bring about the escalating interests in adsorption cooling systems using renewable energy. Adsorption chillers with common refrigerants (water, ethanol, methanol, etc.) face the problem that advanced technologies and intricate design considerations are required to maintain high vacuum. This paper aims at the parameters optimization of adsorption system being operated with the novel working pair, MIL-101-isobutane, under typical conditions of ice making and air-condition. Adsorption isotherms and dynamic of isobutane on MIL-101 are discussed simultaneously. When the hot water inlet temperature, cooling water temperature and desorption time are 95 °C, 30 °C and 30 min, respectively, the cooling capacity is 45.7 kJ/kg, which is 1.7 times as much as that of activated carbon–isobutane pair. Structural stability of MIL-101 subjected to 500 times adsorption/desorption cycles has been successfully verified by XRD (X-ray diffraction). - Highlights: • Adsorption isotherms and kinetic of isobutane on MIL-101 were studied. • A single bed adsorption chiller with MIL-101-isobutane pair was built. • System performed better than that using activated carbon–isobutane pair. • Stability of MIL-101 subjected to 500 ad/desorption cycles has been verified.

Study on adsorption behavior of radioiodine gas using incense stick aerosol

International Nuclear Information System (INIS)

Murata, Mikio; Noguchi, Hiroshi; Kato, Shohei; Kokubu, Morinobu

1987-01-01

Adsorption of radioactive elemental iodine gas ( 131 I 2 ) on incense stick aerosol particles has been studied to provide basic data for a realistic and precise assessment of dose to the public due to radioiodine released from nuclear facilities. A mixture of iodine gas and aerosol was passed once through a glass vessel to cause the adsorption reaction. The adsorption was studied at different reaction times, initial I 2 gas concentrations and particle number concentrations. The results showed that the adsorption reached an equilibrium in about 2 min at the initial I 2 gas concentration of 10 -10 g/cm 3 . The proportion of iodine adsorbed by the aerosol particles was almost constant, about 25 % at the initial I 2 gas concentrations below 10 -11 g/cm 3 and at the reaction time of 1 min, and decreased with increase of the initial concentration over 10 -11 g/cm 3 . The adsorption isotherm of the aerosol for the gas was obtained from the experimental data. The semi-empirical equations to explain the adsorption reaction were also obtained based on the experimental data and the FUCHS's equation relating to vaporization of a droplet. The sticking probability in the equations was estimated to be 7.6 x 10 -3 . The calculated results using the equations were in good agreement with the experimental ones. (author)

Adsorption of guanidinium collectors on aluminosilicate minerals - a density functional study.

Science.gov (United States)

Nulakani, Naga Venkateswara Rao; Baskar, Prathab; Patra, Abhay Shankar; Subramanian, Venkatesan

2015-10-07

In this density functional theory based investigation, we have modelled and studied the adsorption behaviour of guanidinium cations and substituted (phenyl, methoxy phenyl, nitro phenyl and di-nitro phenyl) guanidinium cationic collectors on the basal surfaces of kaolinite and goethite. The adsorption behaviour is assessed in three different media, such as gas, explicit water and pH medium, to understand the affinity of GC collectors to the SiO4 tetrahedral and AlO6 octahedral surfaces of kaolinite. The tetrahedral siloxane surface possesses a larger binding affinity to GC collectors than the octahedral sites due to the presence of surface exposed oxygen atoms that are active in the intermolecular interactions. Furthermore, the inductive electronic effects of substituted guanidinium cations also play a key role in the adsorption mechanism. Highly positive cations result in a stronger electrostatic interaction and preferential adsorption with the kaolinite surfaces than low positive cations. Computed interaction energies and electron densities at the bond critical points suggest that the adsorption of guanidinium cations on the surfaces of kaolinite and goethite is due to the formation of intra/inter hydrogen bonding networks. Also, the electrostatic interaction favours the high adsorption ability of GC collectors in the pH medium than gas phase and water medium. The structures and energies of GC collectors pave an intuitive view for future experimental studies on mineral flotation.

Adsorption of proteins from plasma to a series of hydrophilic-hydrophobic copolymers. I. Analysis with the in situ radioiodination technique

International Nuclear Information System (INIS)

Horbett, T.A.; Weathersby, P.K.

1981-01-01

The adsorption of proteins affects cellular interactions with foreign surfaces and thus plays an important role in determining the biocompatibility of implants. Previous studies have indicated differences in the affinity of various proteins for a given polymer, and differences in the affinity of fibrinogen for a series of polymers varying in hydrophilicity. These studies suggest that differences in the composition of the protein layer adsorbed to polymers from plasma might exist. To examine this hypothesis, the proteins adsorbed from plasma to a series of polymers varying in hydrophilicity were analyzed with the iodogram technique. Copolymers of hydroxyethyl methacrylate and ethyl methacrylate made by the radiation grafting technique were exposed to plasma for 0.5 or 150 min. The adsorbed proteins were iodinated, eluted with SDS, and separated with polyacrylamide gel electrophoresis. Fibrinogen, immunoglobulin G, hemoglobin, and a peak tentatively ascribed to prothrombin were the major proteins detected. Very little iodine was incorporated into adsorbed albumin, even though it was shown to be present by a separate experiment using dye binding. The fraction of total radioactivity associated with each of nine proteins was found to vary markedly and systematically among the surfaces. The distribution of radioactivity into the proteins was very different on 0.5 and 150-min plasma exposed polymers. The results reflect both compositional differences in the adsorbed protein layer on the polymers and differences in the accessibility of proteins to the labeling reagent in the adsorbed state. Differences in the organization of the adsorbed protein layer may play a key role in determining whether cell surface receptors can come in contact with the specific plasma protein able to further stimulate the cell

Copper adsorption on magnetite-loaded chitosan microspheres: A kinetic and equilibrium study

Energy Technology Data Exchange (ETDEWEB)

Podzus, P.E., E-mail: ppodzus@gmail.com [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Debandi, M.V. [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Daraio, M.E., E-mail: medit@fi.uba.ar [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina)

2012-08-15

A composite of Fe{sub 3}O{sub 4} nanoparticles and the biopolymer chitosan, chemically crosslinked, was prepared as microspheres and used to adsorb copper ions, which were chosen as a model of contaminant metal in water. The adsorption of copper on the magnetic microspheres was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 40 to 1100 ppm. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were well described by a pseudo-second-order kinetic model. It was found that the equilibrium data follow the Langmuir isotherm, with a maximum adsorption capacity of around 500 mg Cu/g chitosan. The used microspheres were removed and after desorption the material was able to be reused as an adsorbent. The prepared microspheres proved efficient in the removal of copper ions through an adsorption process whose kinetic and equilibrium characteristics were analyzed.

Copper adsorption on magnetite-loaded chitosan microspheres: A kinetic and equilibrium study

International Nuclear Information System (INIS)

Podzus, P.E.; Debandi, M.V.; Daraio, M.E.

2012-01-01

A composite of Fe 3 O 4 nanoparticles and the biopolymer chitosan, chemically crosslinked, was prepared as microspheres and used to adsorb copper ions, which were chosen as a model of contaminant metal in water. The adsorption of copper on the magnetic microspheres was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 40 to 1100 ppm. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were well described by a pseudo-second-order kinetic model. It was found that the equilibrium data follow the Langmuir isotherm, with a maximum adsorption capacity of around 500 mg Cu/g chitosan. The used microspheres were removed and after desorption the material was able to be reused as an adsorbent. The prepared microspheres proved efficient in the removal of copper ions through an adsorption process whose kinetic and equilibrium characteristics were analyzed.

Effect of fibronectin adsorption on osteoblastic cellular responses to hydroxyapatite and alumina

Energy Technology Data Exchange (ETDEWEB)

Kawashita, Masakazu, E-mail: m-kawa@ecei.tohoku.ac.jp [Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579 (Japan); Hasegawa, Maki [Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579 (Japan); Kudo, Tada-aki; Kanetaka, Hiroyasu [Graduate School of Dentistry, Tohoku University, Sendai 980-8575 (Japan); Miyazaki, Toshiki [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu 808-0196 (Japan); Hashimoto, Masami [Japan Fine Ceramics Center, Nagoya 456-8587 (Japan)

2016-12-01

Initial cellular responses following implantation are important for inducing osteoconduction. We investigated cell adhesion, spreading, proliferation and differentiation of mouse MC3T3-E1 osteoblastic cells on untreated or fibronectin (Fn)-coated discs of hydroxyapatite (HAp) or alpha-type alumina (α-Al{sub 2}O{sub 3}). Fn coating significantly enhanced adhesion and spreading of MC3T3-E1 cells on HAp, but did not affect MC3T3-E1 cell proliferation and differentiation on HAp or α-Al{sub 2}O{sub 3}. Fn-coated HAp likely does not stimulate pre-osteoblast cells to initiate the process of osteoconduction; however, Fn adsorption might affect the response of inflammatory cells to the implanted material or, in conjunction with other serum proteins, stimulate pre-osteoblast cell proliferation and differentiation. Further studies on the effect of serum proteins in cell culture and the efficacy of Fn-coated HAp and α-Al{sub 2}O{sub 3}in vivo are warranted. - Highlights: • We studied osteoblast-like MC3T3-E1 cell responses on fibronectin (Fn)-coated discs (HAp/α-Al{sub 2}O{sub 3}). • Fn adsorption enhanced adhesion and spreading of MC3T3-E1 cells on HAp but not on α-Al{sub 2}O{sub 3}. • Fn adsorption hardly affected proliferation and differentiation of MC3T3-E1 cells on HAp and α-Al{sub 2}O{sub 3}. • Fn adsorption might stimulate osteoconduction on HAp along with other serum proteins.

Study on the adsorption of bacteria in ceramsite and their synergetic effect on adsorption of heavy metals.

Science.gov (United States)

Qiu, Shan; Ma, Fang; Huang, Xu; Xu, Shanwen

2014-01-01

In this paper, heavy metal adsorption by ceramsite with or without Bacillus subtilis (B. subtilis) immobilization was studied, and the synergetic effect of ceramsite and bacteria was discussed in detail. To investigate the roles of the micro-pore structure of ceramsite and bacteria in removing heavy metals, the amount of bacteria immobilized on the ceramsite was determined and the effect of pH was evaluated. It was found that the immobilization of B. subtilis on the ceramsite was attributed to the electrostatic attraction and covalent bond. The scanning electron microscopy results revealed that, with the presence of ceramsite, there was the conglutination of B. subtilis cells due to the cell outer membrane dissolving. In addition, the B. subtilis immobilized ceramsite showed a different adsorption capacity for different heavy metals, with the adsorption capacity ranking of La(3+) > Cu(2+) > Mg(2+) > Na(+).

Studies on the mobility and adsorption of metalaxyl in soils

International Nuclear Information System (INIS)

Peng Genyuan; Qi Mengwen; Wang Huaguo

1995-01-01

Distribution of 14 C-metalaxyl alcohol in water and n-octyl and its mobility and adsorption in soils were studied. The results showed that distribution coefficient of metalaxyl between n-octyl alcohol and water was 12.01, and it was easy for metalaxyl to accumulate in biobody. The TLC of soil showed that metalaxyl was hardly mobile in black soil, but the mobilities in sandy soil and brown soil were at middle level. The results of adsorption showed that the adsorbed amount in soil proportionally increased with the concentration of metalaxyl and adsorption percentages were similar for the same soil and different for different soils

Study of adsorption properties of impregnated charcoal for airborne iodine and methyl iodide

International Nuclear Information System (INIS)

Qi-dong, L.; Sui-yuang, H.

1985-01-01

The adsorption characteristics of airborne radioiodine and methyl iodide on impregnated charcoal were investigated. The activated charcoal tested was made from home-made oil-palm shells, and KI and TEDA were used as impregnants. A new technique was used to plot the dynamic partial adsorption isotherm at challenge concentrations (concentration range of iodine: 1-20 ppm v/v). Some adsorption properties of the impregnated charcoal were estimated with the dynamic partial adsorption isotherm. The dependences of the adsorption capacity and penetration behavior for airborne iodine and methyl iodide on the ambient conditions (temperature, relative humidity, and superficial velocity) were studied

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

Science.gov (United States)

Berts, Ida; Fragneto, Giovanna; Porcar, Lionel; Hellsing, Maja S; Rennie, Adrian R

2017-10-15

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. Copyright © 2017 Elsevier Inc. All rights reserved.

Protein adsorption and cell adhesion on nanoscale bioactive coatings formed from poly(ethylene glycol) and albumin microgels

Science.gov (United States)

Scott, Evan A.; Nichols, Michael D.; Cordova, Lee H.; George, Brandon J.; Jun, Young-Shin; Elbert, Donald L.

2008-01-01

Late-term thrombosis on drug-eluting stents is an emerging problem that might be addressed using extremely thin, biologically-active hydrogel coatings. We report a dip-coating strategy to covalently link poly(ethylene glycol) (PEG) to substrates, producing coatings with crosslinked microgels and deviation from Flory-Stockmayer theory. Before macrogelation, the reacting solutions were diluted and incubated with nucleophile-functionalized surfaces. Using optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microbalance with dissipation (QCM-D), we identified a highly hydrated, protein-resistant layer with a thickness of approximately 75 nm. Atomic force microscopy in buffered water revealed the presence of coalesced spheres of various sizes but with diameters less than about 100 nm. Microgel-coated glass or poly(ethylene terephthalate) exhibited reduced protein adsorption and cell adhesion. Cellular interactions with the surface could be controlled by using different proteins to cap unreacted vinylsulfone groups within the coating. PMID:18771802

Adsorption studies of iron(III) on chitin

Indian Academy of Sciences (India)

Unknown

of particle size and dosage of the adsorbant, contact time, initial concentration of the adsorbate and tem- perature were experimentally ... Adsorption; chitin; variable parameters; fraction of adsorption; temperature effect. 1. Introduction. Iron is one of the ... about the presence of iron in drinking water is its ob- jectionable taste.

Adsorption of CO molecules on doped graphene: A first-principles study

Directory of Open Access Journals (Sweden)

Weidong Wang

2016-02-01

Full Text Available As a typical kinds of toxic gases, CO plays an important role in environmental monitoring, control of chemical processes, space missions, agricultural and medical applications. Graphene is considered a potential candidate of gases sensor, so the adsorption of CO molecules on various graphene, including pristine graphene, Nitrogen-doped graphene (N-doped graphene and Aluminum-doped graphene (Al-doped graphene, are studied by using first-principles calculations. The optimal configurations, adsorption energies, charge transfer, and electronic properties including band structures, density of states and differential charge density are obtained. The adsorption energies of CO molecules on pristine graphene and N-doped graphene are −0.01 eV, and −0.03 eV, respectively. In comparison, the adsorption energy of CO on Al-doped graphene is much larger, −2.69 eV. Our results also show that there occurs a large amount of charge transfer between CO molecules and graphene sheet after the adsorption, which suggests Al-doped graphene is more sensitive to the adsorption of CO than pristine graphene and N-doped graphene. Therefore, the sensitivity of gases on graphene can be drastically improved by introducing the suitable dopants.

Protein-surface interactions on stimuli-responsive polymeric biomaterials.

Science.gov (United States)

Cross, Michael C; Toomey, Ryan G; Gallant, Nathan D

2016-03-04

Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications.

The adsorption of amino acids and cations onto goethite: a prebiotic chemistry experiment.

Science.gov (United States)

Farias, Ana Paula S F; Carneiro, Cristine E A; de Batista Fonseca, Inês C; Zaia, Cássia T B V; Zaia, Dimas A M

2016-06-01

Few prebiotic chemistry experiments have assessed the adsorption of biomolecules by iron oxide-hydroxides. The present work investigated the effects of cations in artificial seawaters on the adsorption of Gly, α-Ala and β-Ala onto goethite, and vice versa. Goethite served to concentrate K and Mg cations from solution; these effects could have played important roles in peptide nucleoside formation. Goethite showed low adsorption of Gly and α-Ala. On the other hand, β-Ala (a non-protein amino acid) was highly adsorbed by goethite. Because Gly and α-Ala are the most common amino acids in living beings, and iron oxide-hydroxides are widespread on Earth, additional iron oxides should be studied. Increased ionic strength in artificial seawaters decreased the adsorption of amino acids by goethite. Because Na was highly abundant in the artificial seawater, it showed the highest effect on amino acid adsorption. β-Ala increased the adsorption of K and Ca by goethite, this effect could have been important for peptide synthesis.

Spontaneous adsorption of coiled-coil model peptides K and E to a mixed lipid bilayer.

Science.gov (United States)

Pluhackova, Kristyna; Wassenaar, Tsjerk A; Kirsch, Sonja; Böckmann, Rainer A

2015-03-26

A molecular description of the lipid-protein interactions underlying the adsorption of proteins to membranes is crucial for understanding, for example, the specificity of adsorption or the binding strength of a protein to a bilayer, or for characterizing protein-induced changes of membrane properties. In this paper, we extend an automated in silico assay (DAFT) for binding studies and apply it to characterize the adsorption of the model fusion peptides E and K to a mixed phospholipid/cholesterol membrane using coarse-grained molecular dynamics simulations. In addition, we couple the coarse-grained protocol to reverse transformation to atomistic resolution, thereby allowing to study molecular interactions with high detail. The experimentally observed differential binding of the peptides E and K to membranes, as well as the increased binding affinity of helical over unstructered peptides, could be well reproduced using the polarizable Martini coarse-grained (CG) force field. Binding to neutral membranes is shown to be dominated by initial binding of the positively charged N-terminus to the phospholipid headgroup region, followed by membrane surface-aligned insertion of the peptide at the interface between the hydrophobic core of the membrane and its polar headgroup region. Both coarse-grained and atomistic simulations confirm a before hypothesized snorkeling of lysine side chains for the membrane-bound state of the peptide K. Cholesterol was found to be enriched in peptide vicinity, which is probably of importance for the mechanism of membrane fusion. The applied sequential multiscale method, using coarse-grained simulations for the slow adsorption process of peptides to membranes followed by backward transformation to atomistic detail and subsequent atomistic simulations of the preformed peptide-lipid complexes, is shown to be a versatile approach to study the interactions of peptides or proteins with biomembranes.

Equilibrium and Thermodynamic Studies of Methane Adsorption on Multi-Walled Carbon Nanotube

OpenAIRE

Sanaz. Monemtabary; Mojtaba Shariati Niasar; Mohsen Jahanshahi; Ali Asghar Ghoreyshi

2013-01-01

In this work, The adsorption of methane onto multi-walled carbon nanotubes (MWCNTs) was studied, in which the influences of temperatureand pressure were investigated. The physical properties of the MWCNT were systematically characterised by Scanning Electron Microscopy (SEM) and Brunauere-Emmette-Teller (BET) surface area measurements. The equilibrium adsorption data were analyzed using threecommon adsorption models: Langmuir, Freundlich and Sips. All of the models fit the experimental result...

Effect of protein adsorption on the corrosion behavior of 70Cu-30Ni alloy in artificial seawater.

Science.gov (United States)

Torres Bautista, Blanca E; Carvalho, Maria L; Seyeux, Antoine; Zanna, Sandrine; Cristiani, Pierangela; Tribollet, Bernard; Marcus, Philippe; Frateur, Isabelle

2014-06-01

Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The objective of this work was to study the influence of protein adsorption, which is the first step in biofilm formation, on the electrochemical behavior of 70Cu-30Ni (wt.%) alloy in static artificial seawater and on the chemical composition of oxide layers. For that purpose, electrochemical measurements performed after 1h of immersion were combined to surface analyses. A model is proposed to analyze impedance data. In the presence of bovine serum albumin (BSA, model protein), the anodic charge transfer resistance deduced from EIS data at Ecorr is slightly higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of ~30nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)2) with a lower thickness (~10nm). Thus, the protein induces a decrease of the dissolution rate at Ecorr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness. © 2013.

Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

International Nuclear Information System (INIS)

Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

2009-01-01

An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained

[Studies on the process of Herba Clinopodii saponins purified with macroporous adsorption resin].

Science.gov (United States)

Zhang, Yi; Yan, Dan; Han, Yumei

2005-10-01

To study the technological parameters of the purification process of saponins with macroporous adsorption resin. The adsorptive characteristics and elutive parameters of the process were studied by taking the elutive and purified ratio of saponins as markers. 11.4 ml of the extraction of Herba Clinopodii (crude drugs 0.2 g/ml) was purified with a column of macroporous adsorption resin (phi15 mm x H90 mm, dry weight 2.5 g) and washed with 3BV of distilled water, then eluted with 3BV of 30% ethanol and 3BV of 70% ethanol. Most of saponins were collected in the 70% ethanol. With macroporous adsorption resin adsorbing and purifying,the elutive ratio of saponins is 86.8% and the purity reaches 153.2%. So this process of applying macroporous adsorption resin to adsorb and purify Saponins is feasible.

Equilibrium Kinetics and Thermodynamic Studies of the Adsorption of Tartrazine and Sunset Yellow

Directory of Open Access Journals (Sweden)

F. O. Okeola

2017-04-01

Full Text Available Batch adsorption experiment was carried out on freema (combination of Tartrazine and Sunset Yellow an adsorbent prepared from moringa pod. The adsorption capacity of the adsorbent was determined. Effect of such factors as initial concentration of the adsorbate solution, contact time with the adsorbent, pH of the dye solution, and temperature of the dye solution on the adsorption capacity of the absorbent was determined. The result showed that the optimum adsorption was attained at pH of 3, adsorption equilibrium was attained within 60 min. The adsorption capacity increases with increase in initial concentration of the dye solution. The result of the kinetics study showed that the adsorption process was better described by the pseudo-second order rate equation. The adsorption process fitted well with both Freundlich (R2 = 0.983 and Langmuir (R2 = 0.933 models. Thermodynamic result showed ΔH and ΔS were all negative. Gibbs free energy change (ΔG increases with increase in temperature of the dye solution.

Influence of mixed electrolytes and pH on adsorption of bovine serum albumin in hydrophobic interaction chromatography.

Science.gov (United States)

Hackemann, Eva; Hasse, Hans

2017-10-27

Using salt mixtures instead of single salts can be beneficial for hydrophobic interaction chromatography (HIC). The effect of electrolytes on the adsorption of proteins, however, depends on the pH. Little is known on that dependence for mixed electrolytes. Therefore, the effect of the pH on protein adsorption from aqueous solutions containing mixed salts is systematically studied in the present work for a model system: the adsorption of bovine serum albumin (BSA) on the mildly hydrophobic resin Toyopearl PPG-600M. The pH is adjusted to 4.0, 4.7 or 7.0 using 25mM sodium phosphate or sodium citrate buffer. Binary and ternary salt mixtures of sodium chloride, ammonium chloride, sodium sulfate and ammonium sulfate as well as the pure salts are used at overall ionic strengths between 1500 and 4200mM. The temperature is always 25°C. The influence of the mixed electrolytes on the adsorption behavior of BSA changes completely with varying pH. Positive as well as negative cooperative effects of the mixed electrolytes are observed. The results are analyzed using a mathematical model which was recently introduced by our group. In that model the influence of the electrolytes is described by a Taylor series expansion in the individual ion molarities. After suitable parametrization using a subset of the data determined in the present work, the model successfully predicts the influence of mixed electrolytes on the protein adsorption. Furthermore, results for BSA from the present study are compared to literature data for lysozyme, which are available for the same adsorbent, temperature and salts. By calculating the ratio of the loading of the adsorbent for both proteins particularly favorable separation conditions can be selected. Hence, a model-based optimization of solvents for protein separation is possible. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and characterization of antifouling poly(N-acryloylaminoethoxyethanol) with ultralow protein adsorption and cell attachment.

Science.gov (United States)

Chen, Hong; Zhang, Mingzhen; Yang, Jintao; Zhao, Chao; Hu, Rundong; Chen, Qiang; Chang, Yung; Zheng, Jie

2014-09-02

Rational design of effective antifouling polymers is challenging but important for many fundamental and applied applications. Herein we synthesize and characterize an N-acryloylaminoethoxyethanol (AAEE) monomer, which integrates three hydrophilic groups of hydroxyl, amide, and ethylene glycol in the same material. AAEE monomers were further grafted and polymerized on gold substrates to form polyAAEE brushes with well-controlled thickness via surface-initiated atomic transfer radical polymerization (SI-ATRP), with particular attention to a better understanding of the molecular structure-antifouling property relationship of hydroxyl-acrylic-based polymers. The surface hydrophilicity and antifouling properties of polyAAEE brushes as a function of film thickness are studied by combined experimental and computational methods including surface plasmon resonance (SPR) sensors, atomic force microscopy (AFM), cell adhesion assay, and molecular dynamics (MD) simulations. With the optimal polymer film thicknesses (∼10-40 nm), polyAAEE-grafted surfaces can effectively resist protein adsorption from single-protein solutions and undiluted human blood plasma and serum to a nonfouling level (i.e., antifouling properties. The molecular structure-antifouling properties relationship of a series of hydroxyl-acrylic-based polymers is also discussed. This work hopefully provides a promising structural motif for the design of new effective antifouling materials beyond traditional ethylene glycol-based antifouling materials.

Conformational changes of plasma fibronectin detected upon adsorption to solid substrates: A spin-label study

International Nuclear Information System (INIS)

Narasimhan, C.; Lai, Chingsan

1989-01-01

Changes in local environment of the free sulfhydryl groups in plasma fibronectin upon adsorption of the protein to polystyrene beads have been examined by electron spin resonance (ESR) spin-label spectroscopy. The two free sulfhydryl groups per subunit of plasma fibronectin were modified chemically with an [ 15 N, 2 H]maleimide spin-label. For soluble fibronectin, both free sulfhydryl groups shown to be in confined environments as evidenced from the labeled protein exhibiting a strongly immobilized ESR spectrum as described previously using [ 14 N, 1 H]maleimide spin-labels. When the labeled protein was adsorbed to the beads, half of the strongly immobilized component was found to convert into a weakly immobilized component, a result indicating that one of the two labeled sites becomes exposed and exhibits a fast tumbling motion. Experiments conducted using various spin-labeled fibronectin fragments suggest that the newly exposed labeled site is located between the DNA-binding and the cell-binding regions of the molecule. The data obtained indicate that, upon adsorption to polystyrene beads, plasma fibronectin undergoes a conformational change through which the buried free sulfhydryl group near the cell-binding region of the molecule is exposed. This observation may have important implications regarding the expression of cell adhesive properties of the fibronectin molecule

The adsorption of mercury on tungsten (100) studied by ultra-violet photoelectron spectroscopy

International Nuclear Information System (INIS)

Egelhoff, W.F. Jr.; Perry, D.L.; Linnett, J.W.

1976-01-01

In recent years, photoelectron spectroscopy has been applied to the study of adsorption on several metal surfaces. A popular choice of substrate has been the 100 face of single crystal tungsten, since adsorption on this surface has been well-characterised by a wide variety of experimental techniques. In this letter a study of the adsorption of mercury on W(100) by ultra-violet photoelectron spectroscopy (UPS) is reported. These results, seen in the context of previous UPS studies of chemisorption, show a number of interesting features. (Auth.)

Thermally responsive silicon nanowire arrays for native/denatured-protein separation

International Nuclear Information System (INIS)

Wang Hongwei; Wang Yanwei; Yuan Lin; Wang Lei; Yang Weikang; Wu Zhaoqiang; Li Dan; Chen Hong

2013-01-01

We present our findings of the selective adsorption of native and denatured proteins onto thermally responsive, native-protein resistant poly(N-isopropylacrylamide) (PNIPAAm) decorated silicon nanowire arrays (SiNWAs). The PNIPAAm–SiNWAs surface, which shows very low levels of native-protein adsorption, favors the adsorption of denatured proteins. The amount of denatured-protein adsorption is higher at temperatures above the lower critical solution temperature (LCST) of PNIPAAm. Temperature cycling surrounding the LCST, which ensures against thermal denaturation of native proteins, further increases the amount of denatured-protein adsorption. Moreover, the PNIPAAm–SiNWAs surface is able to selectively adsorb denatured protein even from mixtures of different protein species; meanwhile, the amount of native proteins in solution is kept nearly at its original level. It is believed that these results will not only enrich current understanding of protein interactions with PNIPAAm-modified SiNWAs surfaces, but may also stimulate applications of PNIPAAm–SiNWAs surfaces for native/denatured protein separation. (paper)

Chemistry and stability of thiol based polyethylene glycol surface coatings on colloidal gold and their relationship to protein adsorption and clearance in vivo

Science.gov (United States)

Carpinone, Paul

Nanomaterials have presented a wide range of novel biomedical applications, with particular emphasis placed on advances in imaging and treatment delivery. Of the many particulate nanomaterials researched for biomedical applications, gold is one of the most widely used. Colloidal gold has been of great interest due to its chemical inertness and its ability to perform multiple functions, such as drug delivery, localized heating of tissues (hyperthermia), and imaging (as a contrast agent). It is also readily functionalized through the use of thiols, which spontaneously form sulfur to gold bonds with the surface. Polyethylene glycol (PEG) is the most widely used coating material for these particles as it provides both steric stability to the suspension and protein resistance. These properties extend the circulation time of the particles in blood, and consequently the efficacy of the treatment. Despite widespread use of PEG coated gold particles, the coating chemistry and stability of these particles are largely unknown. The goal of this work was to identify the mechanisms leading to degradation and stability of thiol based polyethylene glycol coatings on gold particles and to relate this behavior to protein adsorption and clearance in vivo. The results indicate that the protective PEG coating is susceptible to sources of oxidation (including dissolved oxygen) and competing adsorbates, among other factors. The quality of commercially available thiolated PEG reagents was also found to play a key role in the quality and protein resistance of the final PEG coating. Analysis of the stability of these coatings indicated that they rapidly degrade under physiological conditions, leading to the onset of protein adsorption when exposed to plasma or blood. Paralleling the protein adsorption behavior and onset of coating degradation observed in vitro, blood clearance of parenterally administered PEG coated particles in mice began after approximately 2h of circulation time. Taken

A review on adsorption refrigeration technology and adsorption deterioration in physical adsorption systems

Energy Technology Data Exchange (ETDEWEB)

Wang, D.C.; Li, Y.H. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Li, D.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Y.Z. [Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China)

2010-01-15

As one kind of environmentally friendly refrigeration, the adsorption refrigeration has attracted many attentions in resent decades. This paper introduces the researches of adsorption refrigeration systems with the commonly used working pairs, advanced adsorption cycles, heat and mass transfer enhancement and attempts of adsorption refrigeration applications. Poor heat and mass transfer problem is a bottleneck to prevent the improvements of the adsorption refrigeration technique. Two ways to enhance the heat and mass transfer are discussed in this paper. The adsorption deterioration of adsorbent, another obstacle to physical adsorption refrigeration applications, is also pointed out. And the possible reasons and the possible methods are analyzed. (author)

Controlling adsorption and passivation properties of bovine serum albumin on silica surfaces by ionic strength modulation and cross-linking.

Science.gov (United States)

Park, Jae Hyeon; Sut, Tun Naw; Jackman, Joshua A; Ferhan, Abdul Rahim; Yoon, Bo Kyeong; Cho, Nam-Joon

2017-03-29

Understanding the physicochemical factors that influence protein adsorption onto solid supports holds wide relevance for fundamental insights into protein structure and function as well as for applications such as surface passivation. Ionic strength is a key parameter that influences protein adsorption, although how its modulation might be utilized to prepare well-coated protein adlayers remains to be explored. Herein, we investigated how ionic strength can be utilized to control the adsorption and passivation properties of bovine serum albumin (BSA) on silica surfaces. As protein stability in solution can influence adsorption kinetics, the size distribution and secondary structure of proteins in solution were first characterized by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and circular dichroism (CD) spectroscopy. A non-monotonic correlation between ionic strength and protein aggregation was observed and attributed to colloidal agglomeration, while the primarily α-helical character of the protein in solution was maintained in all cases. Quartz crystal microbalance-dissipation (QCM-D) experiments were then conducted in order to track protein adsorption onto silica surfaces as a function of ionic strength, and the measurement responses indicated that total protein uptake at saturation coverage is lower with increasing ionic strength. In turn, the QCM-D data and the corresponding Voigt-Voinova model analysis support that the surface area per bound protein molecule is greater with increasing ionic strength. While higher protein uptake under lower ionic strengths by itself did not result in greater surface passivation under subsequent physiologically relevant conditions, the treatment of adsorbed protein layers with a gluteraldehyde cross-linking agent stabilized the bound protein in this case and significantly improved surface passivation. Collectively, our findings demonstrate that ionic strength modulation influences BSA adsorption

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Energy Technology Data Exchange (ETDEWEB)

Darwish, Ahmed A. [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Nuclear and Radiation Engineering, Faculty of Engineering, Alexandria University, Alexandria (Egypt); Fadlallah, Mohamed M. [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Physics, Faculty of Science, Benha University, Benha (Egypt); Badawi, Ashraf [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Maarouf, Ahmed A., E-mail: ahmed.maarouf@egnc.gov.eg [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Egypt Nanotechnology Center & Department of Physics, Faculty of Science, Cairo University, Giza 12613 (Egypt)

2016-07-30

Highlights: • Doping boron nitride sheets with aluminum or gallium atoms significantly enhances their molecular adsorption properties. • Adsorption of glucose or glucosamine on Al- and Ga-doped boron nitride sheets changes the band gap. • Doping concentration changes the bad gap, but has a minor effect on the adsorption energy. - Abstract: Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-doped boron nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

Water on TiO2 studied by work function change: adsorption in cycles

International Nuclear Information System (INIS)

Bundaleski, Nenad; Silva, Ana G; Jean-Shaw, Bobbie; Teodoro, Orlando; Moutinho, Augusto

2013-01-01

The nature of water adsorption on TiO 2 (110) rutile surface attracts a lot of attention for quite some time. In spite of the considerable experimental and theoretical efforts a lot of details remain unclear. We have been using work function study to follow the adsorption of water on TiO 2 at room temperature, and interpreted the results in terms of fast dissociative adsorption on bridging oxygen vacancies (BOV) and much slower non-dissociative adsorption on Ti 5f rows. Additionally, we concluded that water from Ti 5f rows efficiently desorbs at room temperature which is not the case for BOV adsorption sites. Here we propose a novel experimental approach which consists of monitoring in real-time the work function change during cycles of water adsorption. Since desorption at BOVs does not take place at room temperature, this method allows us to resolve the adsorption dynamics on the two adsorption sites. The first results changed our understanding of the phenomenon: we show that both, adsorption on BOVs and Ti 5f are both very fast. Additionally, slow exponential decay of the work function is observed, which is not directly related to water adsorption. The possible explanation of the third slow contribution could be related to the migration of hydrogen atoms along the bridging oxygen rows.

KINETIC AND THERMODYNAMIC STUDY OF THE ADSORPTION OF MANGANESE (II ON ACTIVATED CARBON

Directory of Open Access Journals (Sweden)

OUISSAF BENTABET

2012-06-01

Full Text Available Recent studies revealed the Bay of Algiers was being polluted by manganese. Similar pollution was also reported in Azemmour, Morocco alongside the estuary of Oum Er Rbia, but also in the waters of developed countries (i.e. Canada, especially following the replacement of tetraethylplumbane in gasoline by methylcyclopentadienyl manganese. Treatment of polluted waters by manganese is therefore essential prior to their release, which is within the purpose of the present study. Commercial activated carbon (AC was used for treating synthetic aqueous solution containing different concentrations of Mn. Adsorption kinetics was studied under agitation at different temperatures between 295 and 318 K. Results show that there are two areas where adsorption occurs according to a first-class model. In the first one, rate constant is k1 = 0.001610 min-1, meanwhile in the second, it is k2 = 0.000488 min-1. Equilibrium is reached in 7 hours. The obtained adsorption isotherm is a V type and follows Freundlich model for low concentrations and Langmuir model for high concentrations. The isotherm part described by Freundlich model lessens with the rise of temperature, increasing adsorption maximum capacity from 3.49 mg Mn/g AC (at 295 K to 4.78 mg Mn/g AC (at 318 K. Adsorption is endothermic. Standard enthalpy (14.4869 kJ•mol-1 and standard entropy (36.25 J•mol-1•K-1 have been calculated. The free energy was positive in all the studied temperatures range. The values of adsorption heat indicate a physical adsorption.

Adsorption of Nucleic Acid/Protein Supramolecular Complexes on Goethite: The Influence of Solution Interactions on Behavior at the Solution-Mineral Interface

Science.gov (United States)

Schmidt, M.; Martinez, C. E.

2017-12-01

Adsorption of biomolecule rich supramolecular complexes onto mineral surfaces plays an important role in the development of organo-mineral associations in soils. In this study, a series of supramolecular complexes of a model nucleic acid (deoxyribonucleic acid (DNA)) and protein (bovine serum albumin (BSA)) are synthesized, characterized and exposed to goethite to probe their adsorption behavior. To synthesize DNA/BSA complexes, a fixed DNA concentration (0.1 mg/mL) was mixed with a range of BSA concentrations (0.025-0.5 mg/mL) in 5 mM KCl at pH=5.0. Circular dichroism spectroscopy demonstrates strong, cooperative, Hill-type binding between DNA and BSA (Ka= 4.74 x 105 M-1) with DNA saturation achieved when BSA concentration reaches 0.4 mg/mL. Dynamic light scattering measurements of DNA/BSA complexes suggest binding accompanies disruption of DNA-DNA intermolecular electrostatic repulsion, resulting in a decrease of the DNA slow relaxation mode with increasing amount of BSA. Zeta potential measurements show increasing amounts of BSA lead to a reduction of negative charge on DNA/BSA complexes, in line with light scattering results. In situ attenuated total reflectance Fourier transform infrared spectroscopic studies of adsorption of DNA/BSA complexes onto goethite show that complexation of BSA with DNA appears to hinder direct coordination of DNA backbone phosphodiester groups with goethite, relative to DNA by itself. Furthermore, increasing amount of BSA (up to 0.4 mg/mL) in DNA/BSA complexes enhances DNA adsorption, possibly as a result of reduced repulsion between adsorbed DNA helices. When BSA concentration exceeds 0.4 mg/mL, a decrease in adsorbed DNA is observed. We hypothesize that this discrepancy in behavior between systems with BSA concentrations below and above saturation of DNA is caused by initial fast adsorption of loosely associated BSA on goethite, restricting access to goethite surface sites. Overall, these results highlight the impact of solution

Adsorption of gas molecules on graphene-like InN monolayer: A first-principle study

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiang; Yang, Qun [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, 400044 Chongqing (China); Meng, Ruishen [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Tan, Chunjian [Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, 400044 Chongqing (China); Liang, Qiuhua [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Jiang, Junke [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, 400044 Chongqing (China); Ye, Huaiyu [Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, 400044 Chongqing (China); Chen, Xianping, E-mail: xianpingchen@cqu.edu.cn [Faculty of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, 541004 Guilin (China); Key Laboratory of Optoelectronic Technology & Systems, Education Ministry of China, Chongqing University and College of Optoelectronic Engineering, Chongqing University, 400044 Chongqing (China)

2017-05-15

Highlights: • A comprehensive adsorption mechanism of InN monolayer is theoretical studied to distinguish the physic/chemi-sorption. • Different adsorption sites for different gases are systematically discussed. • The influence (enhanced or weakened) of external electric field to InN-gas system is well investigated. • The influences of gas adsorption to the optical properties (work function and light adsorption ability) of InN monolayer are also researched. - Abstract: Using first-principles calculation within density functional theory (DFT), we study the gas (CO, NH{sub 3}, H{sub 2}S, NO{sub 2}, NO, SO{sub 2}) adsorption properties on the surface of single-layer indium nitride (InN). Four different adsorption sites (Bridge, In, N, Hollow) are chosen to explore the most sensitive adsorption site. On the basis of the adsorption energy, band gap and charge transfer, we find that the most energetic favourable site is changeable between In site and N site for different gases. Moreover, our results reveal that InN is sensitive to NH{sub 3}, SO{sub 2}, H{sub 2}S and NO{sub 2}, by a physisorption or a chemisorption nature. We also perform a perpendicular electric field to the system and find that the applied electric field has a significant effect for the adsorption process. Besides, we also observed the desorption effects on NH{sub 3} adsorbed at the hollow site of InN when the electric field applied. In addition, the optical properties of InN monolayer affected by different gases are also discussed. Most of the gas adsorptions will cause the inhibition of light adsorption while the others can reduce the work function or enhance the adsorption ability in visible region. Our theoretical results indicate that monolayer InN is a promising candidate for gas sensing applications.

Study of Adsorption Mechanism of Congo Red on Graphene Oxide/PAMAM Nanocomposite

Science.gov (United States)

Rafi, Mohammad; Samiey, Babak; Cheng, Chil-Hung

2018-01-01

Graphene oxide/poly(amidoamine) (GO/PAMAM) nanocomposite adsorbed high quantities of congo red (CR) anionic dye in 0.1 M NaCl solution, with the maximum adsorption capacity of 198 mg·g−1. The kinetics and thermodynamics of adsorption were investigated to elucidate the effects of pH, temperature, shaking rate, ionic strength, and contact time. Kinetic data were analyzed by the KASRA model and the KASRA, ISO, and pore-diffusion equations. Adsorption adsorption isotherms were studied by the ARIAN model and the Henry, Langmuir, and Temkin equations. It was shown that adsorption sites of GO/PAMAM at experimental conditions were phenolic hydroxyl groups of GO sheets and terminal amine groups of PAMAM dendrimer. Analysis of kinetic data indicated that amine sites were located on the surface, and that hydroxyl sites were placed in the pores of adsorbent. CR molecules interacted with the adsorption sites via hydrogen bonds. The molecules were adsorbed firstly on the amine sites, and then on the internal hydroxyl sites. Adsorption kinetic parameters indicated that the interaction of CR to the –NH3+ sites was the rate-controlling step of adsorption of CR on this site and adsorption activation energies calculated for different parts of this step. On the other hand, kinetic parameters showed that the intraparticle diffusion was the rate-controlling step during the interaction of CR molecules to –OH sites and activation energy of this step was not calculable. Finally, the used GO/PAMAM was completely regenerated by using ethylenediamine. PMID:29587463

Study of Adsorption Mechanism of Congo Red on Graphene Oxide/PAMAM Nanocomposite

Directory of Open Access Journals (Sweden)

Mohammad Rafi

2018-03-01

Full Text Available Graphene oxide/poly(amidoamine (GO/PAMAM nanocomposite adsorbed high quantities of congo red (CR anionic dye in 0.1 M NaCl solution, with the maximum adsorption capacity of 198 mg·g−1. The kinetics and thermodynamics of adsorption were investigated to elucidate the effects of pH, temperature, shaking rate, ionic strength, and contact time. Kinetic data were analyzed by the KASRA model and the KASRA, ISO, and pore-diffusion equations. Adsorption adsorption isotherms were studied by the ARIAN model and the Henry, Langmuir, and Temkin equations. It was shown that adsorption sites of GO/PAMAM at experimental conditions were phenolic hydroxyl groups of GO sheets and terminal amine groups of PAMAM dendrimer. Analysis of kinetic data indicated that amine sites were located on the surface, and that hydroxyl sites were placed in the pores of adsorbent. CR molecules interacted with the adsorption sites via hydrogen bonds. The molecules were adsorbed firstly on the amine sites, and then on the internal hydroxyl sites. Adsorption kinetic parameters indicated that the interaction of CR to the –NH3+ sites was the rate-controlling step of adsorption of CR on this site and adsorption activation energies calculated for different parts of this step. On the other hand, kinetic parameters showed that the intraparticle diffusion was the rate-controlling step during the interaction of CR molecules to –OH sites and activation energy of this step was not calculable. Finally, the used GO/PAMAM was completely regenerated by using ethylenediamine.

Rapid adsorption of copper(II) and lead(II) by rice straw/Fe₃O₄ nanocomposite: optimization, equilibrium isotherms, and adsorption kinetics study.

Science.gov (United States)

Khandanlou, Roshanak; Ahmad, Mansor B; Fard Masoumi, Hamid Reza; Shameli, Kamyar; Basri, Mahiran; Kalantari, Katayoon

2015-01-01

Rice straw/magnetic nanocomposites (RS/Fe3O4-NCs) were prepared via co-precipitation method for removal of Pb(II) and Cu(II) from aqueous solutions. Response surface methodology (RSM) was utilized to find the optimum conditions for removal of ions. The effects of three independent variables including initial ion concentration, removal time, and adsorbent dosage were investigated on the maximum adsorption of Pb (II) and Cu (II). The optimum conditions for the adsorption of Pb(II) and Cu(II) were obtained (100 and 60 mg/L) of initial ion concentration, (41.96 and 59.35 s) of removal time and 0.13 g of adsorbent for both ions, respectively. The maximum removal efficiencies of Pb(II) and Cu(II) were obtained 96.25% and 75.54%, respectively. In the equilibrium isotherm study, the adsorption data fitted well with the Langmuir isotherm model. The adsorption kinetics was best depicted by the pseudo-second order model. Desorption experiments showed adsorbent can be reused successfully for three adsorption-desorption cycles.

Interactions between whey proteins and kaolinite surfaces

Energy Technology Data Exchange (ETDEWEB)

Barral, S. [Department of Chemical Engineering and Environmental Technology, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Villa-Garcia, M.A. [Department of Organic and Inorganic Chemistry, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain)], E-mail: mavg@uniovi.es; Rendueles, M. [Project Management Area, University of Oviedo, Independencia 13, 33004 Oviedo (Spain); Diaz, M. [Department of Chemical Engineering and Environmental Technology, University of Oviedo, Julian Claveria 8, 33006 Oviedo (Spain)

2008-07-15

The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption-desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein-kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered.

Interactions between whey proteins and kaolinite surfaces

International Nuclear Information System (INIS)

Barral, S.; Villa-Garcia, M.A.; Rendueles, M.; Diaz, M.

2008-01-01

The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption-desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein-kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered

Fundamentals of high pressure adsorption

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.P.; Zhou, L. [Tianjin University, Tianjin (China). High Pressure Adsorption Laboratory

2009-12-15

High-pressure adsorption attracts research interests following the world's attention to alternative fuels, and it exerts essential effect on the study of hydrogen/methane storage and the development of novel materials addressing to the storage. However, theoretical puzzles in high-pressure adsorption hindered the progress of application studies. Therefore, the present paper addresses the major theoretical problems that challenged researchers: i.e., how to model the isotherms with maximum observed in high-pressure adsorption; what is the adsorption mechanism at high pressures; how do we determine the quantity of absolute adsorption based on experimental data. Ideology and methods to tackle these problems are elucidated, which lead to new insights into the nature of high-pressure adsorption and progress in application studies, for example, in modeling multicomponent adsorption, hydrogen storage, natural gas storage, and coalbed methane enrichment, was achieved.

Adsorption of IgG onto hydrophobic teflon. Differences between the F(ab) and F(c) domains

NARCIS (Netherlands)

Vermeer, AWP; Giacomelli, CE; Norde, W

2001-01-01

The effect of differences in the degree of hydrophobicity of protein patches/fragments on the adsorption behaviour of the protein is investigated. The adsorption isotherm of a monoclonal mouse anti-human immunoglobulin G (isotype 2b) onto hydrophobic Teflon particles is measured using a depletion

Interfacial behaviour of proteins, with special reference to immunoglobulins. A physicochemical study

NARCIS (Netherlands)

Norde, Willem; Lyklema, Johannes

2012-01-01

Some basic elements of the adsorption of proteins on solid surfaces are briefly reviewed, emphasizing immunoglobulins. The paper focuses on the physicochemical interactions and considers the precautions that have to be taken to let the protein adsorb in a way in which it is biologically active.

Breakthrough Adsorption Study of Crude Oil Removal Using Buffing Dust

Science.gov (United States)

Setyaningsih, L. W. N.; Yuliansyah, A. T.; Prasetyo, A.; Arimanintan, S. K.; Putri, D. R.

2018-05-01

The utilization of leather industry solid waste as adsorbent to separate oil from water emulsions of surfactant flooding process is a solution that is relatively inexpensive. This study was conducted aiming to obtain a mathematical model that is appropriate for the adsorption process of crude oil by buffing dust in emulsion phase with a continuous adsorption method. Variations in the column adsorption experiments were carried out, such as: flow rate of feed of water-crude oil-surfactant, the concentration of crude oil in the feed, and mass of adsorbent used. Data were evaluated using three models: Adams Bohart, Thomas and Yan. Best results are obtained on the following conditions, the feed flow rate of 60 mL/minute, the crude oil concentration in feed is 1.5% volume and the mass of adsorbent used was 10 g. The values of kinetic constant and adsorption capacity obtained from Yan Model was 21.7774 mL/mg/minute and 220.9581 mg/g with the relative error obtained is 5.4424%.

Adsorption of uranium on halloysite

International Nuclear Information System (INIS)

Kilislioglu, A.; Bilgin, B.

2002-01-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Adsorption of uranium on halloysite

Energy Technology Data Exchange (ETDEWEB)

Kilislioglu, A.; Bilgin, B. [Istanbul Univ. (Turkey). Faculty of Engineering

2002-07-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Adsorption of polar organic molecules on sediments: Case-study on Callovian-Oxfordian claystone.

Science.gov (United States)

Rasamimanana, S; Lefèvre, G; Dagnelie, R V H

2017-08-01

The release and transport of anthropogenic organic matter through the geosphere is often an environmental criterion of safety. Sedimentary rocks are widely studied in this context as geological barriers for waste management. It is the case of Callovian-Oxfordian claystone (COx), for which several studies report adsorption of anthropogenic organic molecules. In this study, we evaluated and reviewed adsorption data of polar organic molecules on COx claystone. Experiments were performed on raw claystone, decarbonated and clay fractions. Adsorption isotherms were measured with adsorbates of various polarities: adipate, benzoate, ortho-phthalate, succinate, gluconate, oxalate, EDTA, citrate. A significant adsorption was observed for multidentate polycarboxylic acids as evidenced with phthalate, succinate, oxalate, gluconate, EDTA and citrate (R d  = 1.53, 3.52, 8.4, 8.8, 12.4, 54.7 L kg -1 respectively). Multiple linear regression were performed as a statistical analysis to determine the predictors from these adsorption data. A linear correlation between adsorption data (R d ) and dipole moment (μ) of adsorbates was evidenced (R 2  = 0.91). Molecules with a high dipole moment, μ(D) > 2.5, displayed a significant adsorption, R d ≫1 L kg -1 . A qualitative correlation can be easily estimated using the water/octanol partition coefficient, P ow , of adsorbates (R 2  = 0.77). In this case, two opposite trends were distinguished for polar and apolar molecules. The use of organic carbon content in sediments is relevant for predicting adsorption of apolar compounds, log (P ow )>+1. The oxides/clays contents may be relevant regarding polar molecules, log ( apparent P ow )<-1. The proposed scheme offers a general methodology for investigation of geo-barriers towards heterogeneous organic plumes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Protein adsorption resistant surface on polymer composite based on 2D- and 3D-controlled grafting of phospholipid moieties

International Nuclear Information System (INIS)

Hoshi, Toru; Matsuno, Ryosuke; Sawaguchi, Takashi; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

2008-01-01

To prepare the biocompatible surface, a phosphorylcholine (PC) group was introduced on this hydroxyl group generated by surface hydrolysis on the polymer composite composed of polyethylene (PE) and poly (vinyl acetate) (PVAc) prepared by supercritical carbon dioxide. Two different procedures such as two-dimensional (2D) modification and three-dimensional (3D) modification were applied to obtain the steady biocompatible surface. 2D modification was that PC groups were directly anchored on the surface of the polymer composite. 3D modification was that phospholipid polymer was grafted from the surface of the polymer composite by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC). The surfaces were characterized by X-ray photoelectron spectroscopy, dynamic water contact angle measurements, and atomic force microscope. The effects of the poly(MPC) chain length on the protein adsorption resistivity were investigated. The protein adsorption on the polymer composite surface with PC groups modified by 2D or 3D modification was significantly reduced as compared with that on the unmodified PE. Further, the amount of protein adsorbed on the 3D modified surface that is poly(MPC)-grafted surface decreased with an increase in the chain length of the poly(MPC). The surface with an arbitrary structure and the characteristic can be constructed by using 2D and 3D modification. We conclude that the polymer composites of PE/PVAc with PC groups on the surface are useful for fabricating biomedical devices due to their good mechanical and surface properties

A batch adsorption study on bentonite clay Pertinence to transport modeling?

Science.gov (United States)

BOURG, I.; BOURG, A. C.; SPOSITO, G.

2001-12-01

Bentonite clay is often used as a component of engineered barriers for the isolation of high-level toxic wastes. This swelling clay is used for its physical (impermeability, self-healing) but also for its chemical properties, mostly a high cation exchange capacity (CEC). The adsorbed cations being temporarily immobilized, this should slow down the release of cations from the waste to the surrounding environment. In order to assess the performance of the engineered barrier, the partitioning of solutes between the liquid and solid phases needs to be quantified for use in transport models. The usual method for characterizing the adsorption is through batch adsorption experiments on dispersed suspensions of the solid, yielding an adsorption isotherm (adsorbed concentration vs. dissolved concentration). This isotherm however should be a function of various environmental variables (e.g., pH, ionic strength, concentrations of various ligands and competing adsorbents), so that extrapolation of lab data to performance assessment in the field is problematic. We present results from a study of the adsorption of cesium, strontium, cadmium and lead on dispersed suspensions of the standard BX-80 bentonite. Through a wide range of experimental parameters (pH, ionic strength, reaction time, reactor open or closed to the atmosphere, study of a range of cations of differing properties), we seek a mechanistic interpretation of the results instead of an empirical determination of adsorption parameters. Depending on the mechanisms that control the adsorption in different experimental ranges, we discuss the degree to which the partitioning coefficient (Kd) obtained in the lab can be extrapolated to a transport model through compacted bentonite in a natural environment.

Electron stimulated desorption study of oxygen adsorption on tungsten

International Nuclear Information System (INIS)

Prince, R.H.; Floyd, G.R.

1978-01-01

The adsorption of oxygen on a polycrystalline tungsten surface at approximately 800 K has been studied by means of electron stimulated desorption (ESD). Although precision gas dosing was not employed, the initial sticking probability for dissociative adsorption appears to be essentially unity, while the variation with coverage suggests that a high degree of order exists and that precursor state kinetics are significant. A most noticeable and reproducible discontinuity in ESD parameters occurs at a fractional coverage theta approximately 0.8 (exposure approximately 1.4 X 10 15 molecules/cm 2 incident) which is interpreted as an order-disorder transition within a single (β 1 ) chemisorption state, and results in an increase in the ionic desorption cross-section by a factor of approximately 1.26. A discussion of the adsorption kinetics and the disorder transition is given in terms of current models of dissociative adsoption which include the effects of nearest neighbour lateral interactions. (Auth.)

Carbon Nanotubes Facilitate Oxidation of Cysteine Residues of Proteins.

Science.gov (United States)

Hirano, Atsushi; Kameda, Tomoshi; Wada, Momoyo; Tanaka, Takeshi; Kataura, Hiromichi

2017-10-19

The adsorption of proteins onto nanoparticles such as carbon nanotubes (CNTs) governs the early stages of nanoparticle uptake into biological systems. Previous studies regarding these adsorption processes have primarily focused on the physical interactions between proteins and nanoparticles. In this study, using reduced lysozyme and intact human serum albumin in aqueous solutions, we demonstrated that CNTs interact chemically with proteins. The CNTs induce the oxidation of cysteine residues of the proteins, which is accounted for by charge transfer from the sulfhydryl groups of the cysteine residues to the CNTs. The redox reaction simultaneously suppresses the intermolecular association of proteins via disulfide bonds. These results suggest that CNTs can affect the folding and oxidation degree of proteins in biological systems such as blood and cytosol.

A supramolecular strategy for self-mobile adsorption sites in affinity membrane.

Science.gov (United States)

Lin, Ligang; Dong, Meimei; Liu, Chunyu; Wei, Chenjie; Wang, Yuanyuan; Sun, Hui; Ye, Hui

2014-09-01

Disclosed here is the design of a novel supramolecular membrane with self-mobile adsorption sites for biomolecules purification. In the 3D micropore channels of membrane matrix, the ligands are conjugated onto the cyclic compounds in polyrotaxanes for protein adsorption. During membrane filtration, the adsorption sites can rotate and/or slide along the axial chain, which results in the enhanced adsorption capacity. The excellent performance of supra-molecular membrane is related with the dynamic working manner of adsorption sites, which plays a crucial role on avoiding spatial mismatching and short-circuit effect. The supra-molecular strategy described here has general suggestions for the "sites" involved technologies such as catalysis, adsorption, and sensors, which is of broad interest. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein adsorption and biomimetic mineralization behaviors of PLL-DNA multilayered films assembled onto titanium

Energy Technology Data Exchange (ETDEWEB)

Gao Wenli [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Feng Bo, E-mail: fengbo@swjtu.edu.cn [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Ni Yuxiang [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Yang Yongli [College of Material Science and Engineering, Sichuan University, Chengdu 610054 (China); Lu Xiong; Weng Jie [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

2010-11-01

Titanium and its alloys are frequently used as surgical implants in load bearing situations, such as hip prostheses and dental implants, owing to their biocompatibility, mechanical and physical properties. In this paper, a layer-by-layer (LBL) self-assembly technique, based on the polyelectrolyte-mediated electrostatic adsorption of poly-L-lysine (PLL) and DNA, was used to the formation of multilayer on titanium surfaces. Then bovine serum albumin (BSA) adsorption and biomimetic mineralization of modified surfaces were studied. The chemical composition and wettability of assembled substrates were investigated by X-ray photoelectron spectroscopy (XPS), fluorescence microscopy and water contact angle measurement, respectively. The XPS analysis indicated that the layers were assembled successfully through electrostatic attractions. The measurement with ultraviolet (UV) spectrophotometer revealed that the LBL films enhanced ability of BSA adsorption onto titanium. The adsorption quantity of BSA on the surface terminated with PLL was higher than that of the surface terminated with DNA, and the samples of TiOH/P/D/P absorbed BSA most. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that samples of assembled PLL or/and DNA had better bioactivity in inducing HA formation. Thus the assembling of PLL and DNA onto the surface of titanium in turn via a layer-by-layer self-assembly technology can improve the bioactivity of titanium.

Adsorption of Dyes in Studying the Surface Chemistry of Ultradispersed Diamond

Science.gov (United States)

Khokhlova, T. D.; Yunusova, G. R.; Lanin, S. N.

2018-05-01

The effect the surface chemistry of ultradispersed diamond (UDD) has on the adsorption of watersoluble dyes is considered. A comparison is made to adsorption on graphitized thermal carbon black (GTCB), which has a homogeneous and nonporous surface. The adsorption isotherms of dyes and the dependence of the adsorption on the pH of solutions are measured. It is found that UDD adsorbs acid (anionic) dyes—acid orange (AO) and acid anthraquinone blue (AAB)—but barely adsorbs a basic (cationic) dye, methylene blue (MB), because of the predominance of positively charged basic groups on the surface of UDD. The maximum adsorption of AO is much lower on UDD than on GTCB, while the maximum adsorption of AAB is similar for both surfaces. The adsorption of AO on UDD depends strongly on the pH of the solution, while the adsorption of AAB is independent of this parameter. It is suggested that the adsorption of AAB is determined not only by ionic and hydrophobic interactions but also by coordination interactions with impurity metal ions on a UDD surface. It is concluded that the adsorption of dyes characterizes the chemistry of a UDD surface with high sensitivity.

Adsorption of cellulases onto sugar beet shreds and modeling of the experimental data

Directory of Open Access Journals (Sweden)

Ivetić Darjana Ž.

2014-01-01

Full Text Available This study investigated the adsorption of cellulases onto sugar beet shreds. The experiments were carried out using untreated, as well as dried and not dried dilute acid and steam pretreated sugar beet shreds at different initial enzyme loads. Both dilute acid and steam pretreatment were beneficial in respect of cellulases adsorption providing 8 and 9 times higher amounts of adsorbed proteins, respectively, in comparison to the results obtained with the untreated substrate. Although the use of higher solids load enabled by drying of pretreated substrates, could be beneficial for process productivity, at the same time it decreases the adsorption of enzymes. The obtained experimental data were fitted to five adsorption models, and the Langmuir model having the lowest residual sum of squares was used for the determination of adsorption parameters which were used to calculate the strength of cellulases binding to the substrates.[Projekat Ministarstva nauke Republike Srbije, br. TR 31002

Effect of citrate on Aspergillus niger phytase adsorption and catalytic activity in soil

Science.gov (United States)

Mezeli, Malika; Menezes-Blackburn, Daniel; Zhang, Hao; Giles, Courtney; George, Timothy; Shand, Charlie; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Stutter, Marc; Blackwell, Martin; Darch, Tegan; Wearing, Catherine; Haygarth, Philip

2015-04-01

Current developments in cropping systems that promote mobilisation of phytate in agricultural soils, by exploiting plant-root exudation of phytase and organic acids, offer potential for developments in sustainable phosphorus use. However, phytase adsorption to soil particles and phytate complexion has been shown to inhibit phytate dephosphorylation, thereby inhibiting plant P uptake, increasing the risk of this pool contributing to diffuse pollution and reducing the potential benefits of biotechnologies and management strategies aimed to utilise this abundant reserve of 'legacy' phosphorus. Citrate has been seen to increase phytase catalytic efficiency towards complexed forms of phytate, but the mechanisms by which citrate promotes phytase remains poorly understood. In this study, we evaluated phytase (from Aspergillus niger) inactivation, and change in catalytic properties upon addition to soil and the effect citrate had on adsorption of phytase and hydrolysis towards free, precipitated and adsorbed phytate. A Langmuir model was fitted to phytase adsorption isotherms showing a maximum adsorption of 0.23 nKat g-1 (19 mg protein g-1) and affinity constant of 435 nKat gˉ1 (8.5 mg protein g-1 ), demonstrating that phytase from A.niger showed a relatively low affinity for our test soil (Tayport). Phytases were partially inhibited upon adsorption and the specific activity was of 40.44 nKat mgˉ1 protein for the free enzyme and 25.35 nKat mgˉ1 protein when immobilised. The kinetics of adsorption detailed that most of the adsorption occurred within the first 20 min upon addition to soil. Citrate had no effect on the rate or total amount of phytase adsorption or loss of activity, within the studied citrate concentrations (0-4mM). Free phytases in soil solution and phytase immobilised on soil particles showed optimum activity (>80%) at pH 4.5-5.5. Immobilised phytase showed greater loss of activity at pH levels over 5.5 and lower activities at the secondary peak at pH 2

Water adsorption on goethite: Application of multilayer adsorption models

Science.gov (United States)

Hatch, C. D.; Tumminello, R.; Meredith, R.

2016-12-01

Adsorbed water on the surface of atmospheric mineral dust has recently been shown to significantly affect the ability of mineral dust aerosol to act as cloud condensation nuclei. We have studied water adsorption as a function of relative humidity (RH) on goethite (α-FeO(OH)), a common component of atmospheric mineral dust. The goethite surface area and particle size was determined using BET analysis and with N2 as an adsorbate and scanning electron microscopy, respectively. Water adsorption on the sample was monitored using horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy equipped with a flow cell. Water content was determined using Beer's law and the optical constants for bulk water. The results were analyzed using Type II adsorption isotherms to model multilayer adsorption, including BET (Brunauer, Emmet and Teller), FHH (Frenkel, Halsey and Hill) and Freundlich. BET fits to experimental data provide parameters of monolayer coverage, while the FHH and Freundlich isotherms provide insights into multilayer adsorption mechanisms. Results indicate that goethite contains 5% H2O by mass at 50% RH, which increases to 12% by mass at 90% RH. Adsorption parameters and experimental results will be presented.

The studies on gas adsorption properties of MIL-53 series MOFs materials

Directory of Open Access Journals (Sweden)

Yuqiu Jiao

2017-08-01

Full Text Available Molecular dynamics (MD, grand canonical Monte Carlo (GCMC and ideal adsorbed solution theory (IAST were used to study the structures and gas adsorption properties of MIL-53(M[M=Cr, Fe, Sc, Al] metal organic framework (MOF materials. The results show that the volumes of those MOF materials increase significantly at high temperature. By analyzing the adsorption isotherms, we found that the temperature had a paramount effect on the gas adsorption behaviors of these MOF materials. For MIL-53(Cr, the orders of the quantities of adsorbed gases were CH4>N2>CO2>H2S, CH4>H2S>CO2>N2 and CH4>CO2>H2S>N2 at 100K, 293K and 623K, respectively. We also calculated the adsorption of several combinations of two gases by MIL-53(Cr at 293K, the results indicate that the material had selective adsorption of CH4 over CO2, H2S and N2. Our calculations provide microscopic insights into the gas adsorption performances of these MOFs and may further guide the practice of gas separation.

The studies on gas adsorption properties of MIL-53 series MOFs materials

Science.gov (United States)

Jiao, Yuqiu; Li, Zhenyu; Ma, Yue; Zhou, Guanggang; Wang, Shuangxi; Lu, Guiwu

2017-08-01

Molecular dynamics (MD), grand canonical Monte Carlo (GCMC) and ideal adsorbed solution theory (IAST) were used to study the structures and gas adsorption properties of MIL-53(M)[M=Cr, Fe, Sc, Al] metal organic framework (MOF) materials. The results show that the volumes of those MOF materials increase significantly at high temperature. By analyzing the adsorption isotherms, we found that the temperature had a paramount effect on the gas adsorption behaviors of these MOF materials. For MIL-53(Cr), the orders of the quantities of adsorbed gases were CH4>N2>CO2>H2S, CH4>H2S>CO2>N2 and CH4>CO2>H2S>N2 at 100K, 293K and 623K, respectively. We also calculated the adsorption of several combinations of two gases by MIL-53(Cr) at 293K, the results indicate that the material had selective adsorption of CH4 over CO2, H2S and N2. Our calculations provide microscopic insights into the gas adsorption performances of these MOFs and may further guide the practice of gas separation.

First principles study of NH3 molecular adsorption on LiH (100) surfaces

International Nuclear Information System (INIS)

Lu Xiaoxia; Chen Yuhong; Dong Xiao

2012-01-01

The adsorption of NH 3 on LiH (100) crystal surfaces was studied by first principles method. The preferred adsorption sites, adsorption energy, dissociation energy and electronic structure of the LiH (100)/NH 3 systems were calculated separately. It is found that chemical adsorption happened mainly when NH 3 molecules are on the LiH (100) crystal surfaces. When NH 3 is adsorbed on the Li top site, NH 2 is formed on the LiH (100) crystal surfaces after loss of H atom, the calculated adsorption energy, 0.511 eV, belongs to strong chemical adsorption, then the interaction is strongest. The interaction between NH 2 and the neighboring Li, H are ionic. The covalent bonds are formed between N and H atoms in NH 2 . One H 2 molecule is formed by another H atom in NH 3 and H atom from LiH (100) crystal sur- faces. The covalent bonds are formed between H and H atoms in H 2 . (authors)

Comparative study of strontium adsorption on dioctahedral and trioctahedral smectites

International Nuclear Information System (INIS)

Galambos, M.; Rosskopfova, O.; Krajnak, A.; Rajec, P.; Osacky, M.; Comenius University, Bratislava

2012-01-01

Slovak bentonites characterized by good rheological, mineralogical and chemical stability are considered as suitable sealing barriers for construction of Slovak deep geological repository for high-level radioactive waste and spent nuclear fuel. There is several Slovak bentonite deposits, bentonites of which have appropriate adsorption properties meeting the geotechnical requirements for this type of barriers. Study of adsorption properties of bentonites (mainly smectites) is an essential step for developing the migration model long-lived corrosion and activation products, and fission products of uranium. Nuclear wastes contain the most important nuclear fission products, β-emitter 90 Sr with long half-life, biological half-life and high mobility. The present paper investigates and compares the strontium adsorption properties of bentonites of different mineral composition consisted mainly of dioctahedral and trioctahedral smectites. (author)

Adsorption and Desorption of Bioactive Proteins on Hydroxyapatite for Protein Delivery Systems

Directory of Open Access Journals (Sweden)

Chie Kojima

2012-01-01

Full Text Available Hydroxyapatite (HA is a precursor of bone and has been studied as a biomaterial. We attempted HA to apply to protein delivery systems. In this study, the association and dissociation properties of two types of bioactive proteins, cytochrom c and insulin, to HA were investigated. Cytochrom c was less associated with HA than insulin, which was easily released from it. However, the release of insulin from HA was slow. Insulin was released from HA at pH 7.4 more rapidly than at pH 3. The association and dissociation properties might be influenced by the size, solubility and net charge of protein. HA is a potential protein carrier with controlled release.

Adsorption of apo- and holo-tear lipocalin to a bovine Meibomian lipid film.

Science.gov (United States)

Mudgil, Poonam; Millar, Thomas J

2008-04-01

Adsorption of apo- and holo-tear lipocalin (Tlc) to bovine Meibomian lipid film was studied. A Langmuir trough was used for these studies and the adsorption of protein was observed by recording changes in the pressure with time (pi-T profile). The films were photographed at different stages of adsorption by doping Meibomian lipids with a fluorescently tagged lipid. The results indicated that apo-Tlc adsorbed much more quickly than holo-Tlc to the Meibomian lipid film. Contrary to the expectation that holo-Tlc would release lipids to the surface and surface pressure would be higher, it was found that the surface pressure was higher with the adsorption of apo-Tlc to the surface. Photography of the films showed that apo- and holo-Tlc interacted differently with the Meibomian lipid layer. Adsorption of holo-Tlc resulted in big bright patches and adsorption of apo-Tlc resulted in many small patches along with the big patches. Both forms of Tlc produced a more stable film as indicated by decreased movement of the protein adsorbed films, and a higher maximum surface pressure upon compression of these films compared with Meibomian lipid films alone. Isocyles of apo-Tlc adsorbed films gave a higher surface pressure than that of holo-Tlc. From these results, it is concluded that both apo- and holo-Tlc adsorbed to the Meibomian lipid layer and the delivery of the lipids from Tlc to the outer lipid layer could not be detected by our techniques. Its scavenging role to remove lipids from the corneal surface and bind with them might be beneficial for increasing tear viscosity but whether those lipids are delivered to the outermost lipid layer still remains unclear.

Adsorption of rationally designed "surf-tides" to a liquid-crystal interface.

Science.gov (United States)

Badami, Joseph V; Bernstein, Chaim; Maldarelli, Charles; Tu, Raymond S

2015-09-07

The interfacial adsorption of proteins in surfactant laden systems occurs both in nature and industrial processing, yet much of the fundamental behavior behind these systems is still not well understood. We report the development of a system that monitors optical transitions of a liquid-crystalline/aqueous interface to examine the dynamics of adsorption of two rationally designed model peptide molecules. The two molecules synthesized in this study were both designed to become surface-active upon folding and contain the same net charge of +3, but one of the peptides, K-2.5, has its three charges separated by 2.5 amino acids as compared to K-6.0, which has its three charges separated by 6 amino acids. Our study examines the roles that surfactant adsorption, peptide charge distribution and secondary structure have on the relative adsorption dynamics of these two models peptides onto a fluid/fluid interface. Using the optical detection of molecular adsorption and image analysis of these events, we obtain quantitative information about the dynamics as a function of the charge spacing and initial peptide concentration. We show that both peptides initially follow a diffusion-limited adsorption model onto the interface. Additionally, our results suggest that the K-6.0 peptides demonstrate enhanced adsorption kinetics, where the enhanced rates are a consequence of the well-folded adsorbed state and spatial distribution on the surface. These findings provide further insights into the role that charge spacing has on secondary structure and subsequently the dynamics of adsorption, while developing a versatile system capable of extracting quantitative information from a simple inexpensive optical system.

Quantitative surface studies of protein adsorption by infrared spectroscopy. II. Quantification of adsorbed and bulk proteins

International Nuclear Information System (INIS)

Fink, D.J.; Hutson, T.B.; Chittur, K.K.; Gendreau, R.M.

1987-01-01

Attenuated total reflectance Fourier transform infrared spectra of surface-adsorbed proteins are correlated with concentration measurements determined by 125 I-labeled proteins. This paper demonstrates that linear correlations between the intensity of the major bands of proteins and the quantity of proteins can be obtained for human albumin and immunoglobulin G up to surface concentrations of approximately 0.25 microgram/cm2. A poorer correlation was observed for human fibrinogen. A linear correlation was also observed between the concentration in the bulk solution and the major bands of albumin up to a concentration of 60 mg/ml

Platinum adsorption onto graphene and oxidized graphene: A quantum mechanics study

Energy Technology Data Exchange (ETDEWEB)

Jafari, S.A.; Jahanshahi, M. [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of); Ahangari, M. Ghorbanzadeh, E-mail: ghorbanzadeh.morteza@gmail.com [Department of Mechanical Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar (Iran, Islamic Republic of)

2017-04-01

Density functional theory based on first-principle calculations was used to examine platinum-supported oxidized graphene as a beneficial nanomaterial in terms of its catalytic activity and utility for contaminant removal and disinfecting polluted solutions in both domestic and industrial applications. The first step was to select the most appropriate available computing package to apply the supercell technique, which would provide a better representation of a large and real graphene slab. Using OpenMX was less time-consuming after we enforced a basis set for valence electrons to avoid an all-electron calculation, and this had very slight and negligible effect on the accuracy of the calculations. The OpenMX software was selected to perform forward steps of investigating changes in the properties such as adsorption energy and ground state structure of the complexes made by the adsorption of a platinum atom on the surface of pristine graphene (Pt/PG) and oxidized graphene (Pt/OG), which had the lowest adsorption energy of −5.28 eV. Moreover, we examined the effect of Pt atom adsorption on the surface and between two layers of graphene. Our results show that, there was no specific change observed in mentioned properties of Pt atom adsorption on bilayer graphene in comparison with single layer. - Highlights: • Pt adsorption on graphene and oxidized graphene was examined. • We have also considered the effect of the layered graphene on the Pt adsorption. • We first compared two different DFT calculation codes, SIESTA and OpenMX. • We then used ORCA to validate and select a suitable computation package for this study.

Studies on some influential factors of the zinc-activated carbon composite adsorbent on adsorptivity for uranium

International Nuclear Information System (INIS)

Miyai, Yoshitaka; Kitamura, Takao; Takagi, Norio; Katoh, Shunsaku; Miyazaki, Hidetoshi

1978-01-01

Factors, which influence the uranium adsorption of powdery composite adsorbent of basic zinc carbonate and activated carbon were studied. In the range studied, zinc content of the adsorbent was the most influential factor on the uranium adsorption, and the second influential factor was sea water volume and the third factor was adsorption period. Interactive effects were observed between zinc content and sea water volume, and between zinc content and adsorption period, and it was deduced that there existed the optimum value of sea water volume and adsorption period respectively for the zinc content of the adsorbent. Maximum uranium adsorption of adsorbent with 40% zinc content was observed at sea water volume of 15 liters and adsorption period of 25 hrs. As for temperature in the range of 15 - 35 0 C, the lower the temperature, the larger amount of adsorbed uranium was. The powdery adsorbent was made into granule, and its strength and its uranium adsorptivity were studied in relation to the granulating conditions. By use of PVA with degree of polymerization above 1,700 as binder, the granular adsorbent with the same strength as commercial granular activated carbon was obtained. PVA amount and its degree of polymerization gave only small effect on uranium adsorption of the adsorbent. Effect of granule size on the uranium adsorption rate in the range of 1 - 4 mm was that the uranium adsorption rate changed proportionally to surface area of assumed sphere. As a test for practical use, five times repetitions of adsorption and desorption were carried out on the same granular adsorbent. During the repetition the amount of adsorbed uranium rather increased, and desorption ratio of adsorbed uranium was constant at 91 - 93%. The weight loss of the adsorbent in a cycle of adsorption and desorption was about 3%. (author)

Adsorption Studies of Lead by Enteromorpha Algae and Its Silicates Bonded Material

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Hassan H. Hammud

2014-01-01

Full Text Available Lead adsorption by green Enteromorpha algae was studied. Adsorption capacity was 83.8 mg/g at pH 3.0 with algae (E and 1433.5 mg/g for silicates modified algae (EM. FTIR and thermal analysis of algae materials were studied. Thomas and Yoon-Nelson column model were best for adsorbent (E and algae after reflux (ER and Yan model for (EM with capacity 76.2, 71.1, and 982.5 mg/g, respectively. (ER and (EM show less swelling and better flow rate control than (E. Nonlinear methods are more appropriate technique. Error function calculations proved valuable for predicting the best adsorption isotherms, kinetics, and column models.

Recovery of gold from industrial wastewater by extracellular proteins obtained from a thermophilic bacterium Tepidimonas fonticaldi AT-A2.

Science.gov (United States)

Han, Yin-Lung; Wu, Jen-Hao; Cheng, Chieh-Lun; Nagarajan, Dillirani; Lee, Ching-Ray; Li, Yi-Heng; Lo, Yung-Chung; Chang, Jo-Shu

2017-09-01

Biosorption has emerged as a promising alternative approach for treating wastewater with dilute metal contents in a green and cost effective way. In this study, extracellular proteins of an isolated thermophilic bacterium (Tepidimonas fonticaldi AT-A2) were used as biosorbent to recover precious metal (i.e., Au) from wastewater. The Au (III) adsorption capacity on the T. fonticaldi AT-A2 proteins was the highest when the pH was set at about 4.0-5.0. The adsorption capacity increased with increasing temperature from 15 to 70°C. Adsorption isotherm studies show that both Langmuir and Freundrich models could describe the adsorption equilibrium. The maximum adsorption capacity of Au (III) at 50°C and pH 5 could reach 9.7mg Au/mg protein. The protein-based biosorbent was also used for the recovery of Au from a wastewater containing 15mg/L of Au, achieving a high adsorption capacity of 1.45mg Au/mg protein and a removal efficiency of 71%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Theoretical study of adsorption of organic phosphines on transition metal surfaces

Science.gov (United States)

Lou, Shujie; Jiang, Hong

2018-04-01

The adsorption properties of organic phosphines on transition metal (TM) surfaces (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) have been studied to explore the possibility of building novel heterogeneous chiral catalytic systems based on organic phosphines. Preferred adsorption sites, adsorption energies and surface electronic structures of a selected set of typical organic phosphines adsorbed on TM surfaces are calculated with density-functional theory to obtain a systematic understanding on the nature of adsorption interactions. All organic phosphines considered are found to chemically adsorb on these TM surfaces with the atop site as the most preferred one, and the TM-P bond is formed via the lone-pair electrons of the P atom and the directly contacted TM atom. These findings imply that it is indeed possible to build heterogeneous chiral catalytic systems based on organic phosphines adsorbed on TM surfaces, which, however, requires a careful design of molecular structure of organic phosphines.

Protein-material interactions: From micro-to-nano scale

International Nuclear Information System (INIS)

Tsapikouni, Theodora S.; Missirlis, Yannis F.

2008-01-01

The article presents a survey on the significance of protein-material interactions, the mechanisms which control them and the techniques used for their study. Protein-surface interactions play a key role in regenerative medicine, drug delivery, biosensor technology and chromatography, while it is related to various undesired effects such as biofouling and bio-prosthetic malfunction. Although the effects of protein-surface interaction concern the micro-scale, being sometimes obvious even with bare eyes, they derive from biophysical events at the nano-scale. The sequential steps for protein adsorption involve events at the single biomolecule level and the forces driving or inhibiting protein adsorption act at the molecular level too. Following the scaling of protein-surface interactions, various techniques have been developed for their study both in the micro- and nano-scale. Protein labelling with radioisotopes or fluorescent probes, colorimetric assays and the quartz crystal microbalance were the first techniques used to monitor protein adsorption isotherms, while the surface force apparatus was used to measure the interaction forces between protein layers at the micro-scale. Recently, more elaborate techniques like total internal reflection fluorescence (TIRF), Fourier transform infrared spectroscopy (FTIR), surface plasmon resonance, Raman spectroscopy, ellipsometry and time of flight secondary ion mass spectrometry (ToF-SIMS) have been applied for the investigation of protein density, structure or orientation at the interfaces. However, a turning point in the study of protein interactions with the surfaces was the invention and the wide-spread use of atomic force microscopy (AFM) which can both image single protein molecules on surfaces and directly measure the interaction force

Adsorption of dyes onto activated carbon cloth: using QSPRs as tools to approach adsorption mechanisms.

Science.gov (United States)

Metivier-Pignon, Hélène; Faur, Catherine; Le Cloirec, Pierre

2007-01-01

The present study aimed to investigate the adsorption of dyes onto activated carbon cloths. Kinetics and isotherms were studied based on results of batch reactors to constitute databases for the adsorption rates and capacities of 22 commercial dyes. Added to a qualitative analysis of experimental results, quantitative structure property relationships (QSPRs) were used to determine the structural features that influence most adsorption processes. QSPRs consisted of multiple linear regressions correlating adsorption parameters with molecular connectivity indices (MCIs) as molecular descriptors. Results related to adsorption kinetics showed that the size of molecules was the significant feature, the high order MCIs involved in QSPRs indicating the influence of a critical size on adsorption rate. Improved statistical fits were obtained when the database was divided according to the chemical classes of dyes. As regards to adsorption isotherms, their particular form led to the use of saturation capacity as the adsorption parameter. By contrast with adsorption kinetics, molecular overcrowding seemed to be of less influence on adsorption equilibrium. In this case, MCIs included in the QSPR were more related to details of the molecular structure. The robustness of the QSPR assessed for azo dyes was studied for the other dyes. Although the small size of the database limited predictive ability, features relevant to the influence of the database composition on QSPRs have been highlighted.

Adsorption of Pb(II) from fish sauce using carboxylated cellulose nanocrystal: Isotherm, kinetics, and thermodynamic studies.

Science.gov (United States)

Wang, Nan; Jin, Ru-Na; Omer, A M; Ouyang, Xiao-Kun

2017-09-01

In the present study, a new adsorbent based on carboxylated cellulose nanocrystal (CCN) was developed for the adsorption of Pb(II) from fish sauce. The prepared adsorbent material was characterized by zeta potential, FT-IR, XRD, and XPS tools. The changes in the morphological structure of the developed CCN surface were evidenced by SEM and TEM. The favorable adsorption conditions were selected by studying the contact time, initial concentration, temperature, and concentration of the used glutamic acid and NaCl. The results indicated that the Langmuir isotherm model agrees very well with experimental adsorption data (R 2 =0.9962) with a maximum adsorption capacity 232.56mg/g of Pb(II) at 293.2K. Additionally, data of the adsorption kinetics follow the pseudo-second-order kinetics (R 2 >0.9990). On the other hand, the thermodynamics studies show that the adsorption process is spontaneous and endothermic. Furthermore, the developed CCN could be regenerated using acid treatment with a good reusability for Pb(II) adsorption. The results clearly indicated that the synthesized CCN could be effectively applied as a new material for Pb(II) adsorption from fish sauce solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterizing and modeling protein-surface interactions in lab-on-chip devices

Science.gov (United States)

Katira, Parag

Protein adsorption on surfaces determines the response of other biological species present in the surrounding solution. This phenomenon plays a major role in the design of biomedical and biotechnological devices. While specific protein adsorption is essential for device function, non-specific protein adsorption leads to the loss of device function. For example, non-specific protein adsorption on bioimplants triggers foreign body response, in biosensors it leads to reduced signal to noise ratios, and in hybrid bionanodevices it results in the loss of confinement and directionality of molecular shuttles. Novel surface coatings are being developed to reduce or completely prevent the non-specific adsorption of proteins to surfaces. A novel quantification technique for extremely low protein coverage on surfaces has been developed. This technique utilizes measurement of the landing rate of microtubule filaments on kinesin proteins adsorbed on a surface to determine the kinesin density. Ultra-low limits of detection, dynamic range, ease of detection and availability of a ready-made kinesin-microtubule kit makes this technique highly suitable for detecting protein adsorption below the detection limits of standard techniques. Secondly, a random sequential adsorption model is presented for protein adsorption to PEO-coated surfaces. The derived analytical expressions accurately predict the observed experimental results from various research groups, suggesting that PEO chains act as almost perfect steric barriers to protein adsorption. These expressions can be used to predict the performance of a variety of systems towards resisting protein adsorption and can help in the design of better non-fouling surface coatings. Finally, in biosensing systems, target analytes are captured and concentrated on specifically adsorbed proteins for detection. Non-specific adsorption of proteins results in the loss of signal, and an increase in the background. The use of nanoscale transducers as

Characterization of DOM adsorption of CNTs by using excitation-emission matrix fluorescence spectroscopy and multiway analysis.

Science.gov (United States)

Peng, Mingguo; Li, Huajie; Li, Dongdong; Du, Erdeng; Li, Zhihong

2017-06-01

Carbon nanotubes (CNTs) were utilized to adsorb DOM in micro-polluted water. The characteristics of DOM adsorption on CNTs were investigated based on UV 254 , TOC, and fluorescence spectrum measurements. Based on PARAFAC (parallel factor) analysis, four fluorescent components were extracted, including one protein-like component (C4) and three humic acid-like components (C1, C2, and C3). The adsorption isotherms, kinetics, and thermodynamics of DOM adsorption on CNTs were further investigated. A Freundlich isotherm model fit the adsorption data well with high values of correlation. As a type of macro-porous and meso-porous adsorbent, CNTs preferably adsorb humic acid-like substances rather than protein-like substances. The increasing temperature will speed up the adsorption process. The self-organizing map (SOM) analysis further explains the fluorescent properties of water samples. The results provide a new insight into the adsorption behaviour of DOM fluorescent components on CNTs.

A first-principles study of gas molecule adsorption on borophene

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Tingting Liu

2017-12-01

Full Text Available Borophene, a new two-dimensional material, was recently synthesized. The unique anisotropic structure and excellent properties of borophene have attracted considerable research interest. This paper presents a first-principles study of the adsorption of gas molecules (CO, CO2, NH3, NO, NO2 and CH4 on borophene. The adsorption configurations, adsorption energies and electronic properties of the gas molecules absorpted on borophene are determined, and the mechanisms of the interactions between the gas molecules and borophene are evaluated. We find that CO, CO2, NH3, NO and NO2 are chemisorbed on borophene, while CH4 is physisorbed on borophene. Furthermore, our calculation also indicate that CO and CO2 are chemisorbed on borophene with moderate adsorption energy and NO, NO2 and NH3 are chemisorbed on borophene via strong covalent bonds. Moreover, CO is found as an electron donor, while CO2 an electron acceptor. The chemisorption of CO and CO2 on borophene increases the electrical conductivity, so It seems that borophene has the potential to be used in high-sensitivity CO and CO2 gas sensors.

Study on uranium adsorption ability of tannix resin from solution

International Nuclear Information System (INIS)

Le Thi Kim Dung; Le Quang Thai; Nguyen Lanh; Le Ngoc Thuy

2004-01-01

During past years, generated liquid waste from uranium ore processing has been treated by co-precipitation method in ITRRE. In this liquid waste treatment process, mixing liquid waste and lime, decantation, filtration of precipitate were implemented. The treated fluid has underlimited toxic concentration and ensures for moving into environment. Residue was dried and packed into drums as low level radioactive waste. Next to the advantages of this method such as simplest technology, cheapest cost, easy operation. Some amount of secondary radioactive waste as noncombustible materials must be stored with complicated technologies a highly cost. We have been researching a new liquid waste treatment system replaceable precipitation system. In the new process, insoluble tannin is utilized as adsorbent of uranium liquid waste. Advantage of insoluble tannin is expected to be possible to reduce its volume incineration as well as its adsorption ability. Those are the reasons why tannix resin is used this research subject. In this subject, we have studied adsorption capacity of uranium in Tannix, relation of adsorption rate and pH, the change of adsorption ability of column system, the pyrolysis curve of dried Tannix (author)

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite.

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Yajun Chen

Full Text Available Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR and ciprofloxacin (CIP, by nano-hydroxyapatite (n-HAP were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g · L(-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

Science.gov (United States)

Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

2015-01-01

Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

Preliminary Study on Benzoic Acid Adsorption from Crude Active Coals and Bentonite

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Abbes Boucheta

2016-04-01

Full Text Available We studied the adsorption of pollutant benzoic acid by the modified bentonite of Maghnia (west of Algeria, and coal (Coal from the mines, southwest of Algeria, Bechar area under three forms, crude and activated. Kinetic data show that the balance of bentonite (as amended adsorbs organic acids better than activated and raw coal. Indeed, the intercalation of bentonite with benzoic acid causes an improvement in the texture of porous material, which allows its use in the adsorption of organic compounds. The adsorption isotherms (Langmuir and Freundlich indicate that the adsorption of benzoic acid by the coal and bentonite yielded results favorably. The results obtained showed the practical value of using the activated coal and bentonite (as amended in the field of remediation of water contaminated with organic pollutants

Conductometric Studies Of Adsorption Of Sulfide On Charcoal From Aqueous Solution

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Md. Rezwan Miah

2017-03-01

Full Text Available Adsorption of sulfide S2- from aqueous solution on commercial charcoal was studied using conductometric technique. A proportionally constant for concentration of S2- and its conductance was obtained by measuring conductance of S2- solution over a concentration range of 0.0005amp614850.02 M. The time-dependent measured conductance of S2- solution was converted to concentration using the obtained constant. The adsorption data were analyzed by both Freundlich and Langmuir isotherms. A surface coverage equal to 2.5 mg per gram of charcoal was obtained. The adsorption was found to follow first-order kinetics having rate constant equal to 2.65 amp61620 10amp614853 s-1.

Batch study, equilibrium and kinetics of adsorption of naphthalene using waste tyre rubber granules

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Felix A. Aisien

2014-04-01

Full Text Available The potential use of waste tyre rubber granules (WTRG for the batch adsorption of naphthalene from aqueous solutions was investigated. The effect of various operational variables such as contact time, initial naphthalene concentration, adsorbent dose, size of adsorbent particles, and temperature of solution on the adsorption capacity of WTRG was evaluated. The adsorption of naphthalene by WTRG was a fast kinetic process with an equilibrium contact time of 60 min. A low temperature (5°C, small adsorbent particle size (0.212 mm and higher adsorbent dosage favored the adsorption process. Results of isotherm studies revealed that adsorption of naphthalene was best described by the Langmuir isotherm equation (R2=0.997 while the kinetics of the process was best described by the Lagergren pseudofirst order kinetic equation (R2=0.998. This study has demonstrated the suitability of WTRG for the removal of naphthalene from aqueous solution.

Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

Science.gov (United States)

Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

2015-12-01

In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

Kinetic studies of uranyl ion adsorption on acrylonitrile (AN) / polyethylene glycol (PEG) interpenetrating networks (IPN)

International Nuclear Information System (INIS)

Aycik, G.A.; Gurellier, R.

2004-01-01

The kinetics of the adsorption of uranyl ions on amidoximated acrylonitrile (AN)/ polyethylene glycol (PEG) interpenetrating network (IPNs) from aqueous solutions was studied as a function of time and temperature. Adsorption analyses were performed for definite uranyl ion concentrations of 1x10 -2 M and at four different temperatures as 290K, 298K, 308K and 318K. Adsorption time was increased from zero to 48 hours. Adsorption capacities of uranyl ions by PEG/AN IPNS were determined by gamma spectrometer. The results indicate that adsorption capacity increases linearly with increasing temperature. The max adsorption capacity was found as 602 mgu/g IPN at 308K. Adsorption rate was evaluated from the curve plotted of adsorption capacity versus time, for each temperature. Rate constants for uranyl ions adsorption on amidoximated ipns were calculated for 290K, 298K, 308K and 318K at the solution concentration of 1x10 -2 M . The results showed that as the temperature increases the rate constant increases exponentially too. The mean activation energy of uranyl ions adsorption was found as 34.6 kJ/mole by using arrhenius equation. (author)

Studies on Thorium Adsorption Characteristics upon Activated Titanium Hydroxide Prepared from Rosetta Ilmenite Concentrate

International Nuclear Information System (INIS)

Gado, M; Zaki, S

2016-01-01

The titanium hydroxide prepared from Rosetta ilmenite concentrate has been applied for Th (IV) adsorption from its acid aqueous solutions. The prepared hydroxide is first characterized by both Fourier transform infrared (FT-IR) spectrum and thermogravimetric analysis. The relevant factors affecting the adsorption process have been studied. The obtained equilibrium data fits well with the Langmuir isotherm rather than Freundlich isotherm, while the adsorption kinetic data follow the pseudo-second order model. The different thermodynamic parameters have also been calculated and indicate that the adsorption process is spontaneous

Kinetics of the Adsorption of Bovine Serum Albumin of White Wine ...

African Journals Online (AJOL)

NJD

2008-11-07

Nov 7, 2008 ... surfaces. The protein adsorption capacity of zirconium oxide was observed to ... cases.7 In some, conformational changes occur in the protein molecule ... specific electrostatic attractive force between the negative charges on ...