T

Example of a flow cell used in a TIRE system for studies of protein adsorption. An half-cylindrical prism is shown here as an example Fig. 5. Example of a flow cell used in a TIRE system for studies of protein adsorption. An half-cylindrical prism is shown here as an example supported flow control system, either separate from or built into the data-acquisition software of the ellipsometer. Additional stirring in the cell can be achieved with the aid of a magnet rotated by an external...

Results

We begin by discussing certain important optoelectronic properties of the ITO-coated sensor chip. In Fig. 4, we present the effective refractive index, the current, and the ITO and platinum electrode potentials versus applied voltage in the presence of deionized water (of pH 5.5-6 and conductivity 1.30 0.05 S at 25 C) and HEPES buffer 10 mM N-(2-hydroxyethyl) Fig. 4. The asymptotic current, the electric potential of the ITO and Pt electrodes, and the effective refractive index of the ITO-coated...

Kinetic Parameters

Kineticanalysiswascarriedout by recordingthesolution substrateconcen-tration of the at the column exit. According to the investigation reported previously (Wang et al. 1996), the immobilized enzyme reactivity in the carbon felt was estimated by considering the residence time of the substrate solution in the membrane. The mean residence time, tr, of solute in the porous material can be calculated using the following equation Fig. 27. Effect of pH on the enzyme activity of the membrane Fig. 27....

Protein Structure and Metal Ion Interactions Transglutaminases

Transglutaminases are catalysts that are involved in the post-translational modification of proteins, forming isopeptide bonds at glutamine residues (Greenberg et al. 1991 Folk and Finnlayson 1997). The primary function of these enzymes appears to be in the stabilisation of tissues and, as such, their occurrence is widespread, being found in both extracellular and cellular fluids. There is evidence that transglutaminases may be bifunctional, also having capabilities to perform the role of...

Enzymatic Activity Measurements

Urease catalyzes the hydrolysis of urea, producing ammonium and carbonate ions according to the following reaction NH2CONH2 + 2H2O 2NH+ + CO3- (4) Determination of the activities of the free and immobilized urease is carried out by measuring the production of ammonium according to a procedure given by Sigma (Sigma catalog no. 535) with a blood urea nitrogen (BUN) acid reagent and BUN color reagent (Sigma). A calibration curve is established by mixing 3 ml of BUN acid reagent with 2 ml of BUN...

Polypyrrolebiotin Film Characterization

The structure of the film was assessed by scanning electron microscopy. The polymerization of the pyrrole-biotin monomer was carried out on a carbon felt. Figure 25 shows photographs of polymer deposition on the carbon surface. The latter illustrates that the electrochemical addressing of polymer films allows the spatially controlled functionalization of surfaces whatever their shape and size are. We recently demonstrated by gravimetric measurements that the immobilization of avidin on...

Principles of Tofsims

TOF-SIMS is a SIMS technique that utilizes a time-of-flight mass analyzer to enhance its sensitivity and expand its range of application (Vickerman and Briggs 2001). TOF-SIMS provides a characterization of complex sample surfaces such as protein-adsorbed materials, and chemical mapping information, for example, the imaging of the distribution pattern of a particular protein. SIMS refers to the mass spectrometry of ionized particles (secondary ions) emitted by a beam of primary ions bombarding a...

Observation by Streaming Potential

Measurement of streaming current (Daly et al. 2003) and streaming potential (Etheve and Dejardin 2002 Vasina and Dejardin 2004) during adsorption can be useful to obtain information on the orientation of molecules at interfaces. The variation of streaming potential with protein interfacial concentration exhibits a change at some critical concentration for the a-chymotrypsin mica system at pH 8.6 in 10-2M Tris (Fig. 8). The variation in zeta potential was deduced from the streaming potential,...

Advantages

The advantages of this approach are that the condition of surface is very well understood throughout the experimental procedure. This enables sto-ichiometries of interactions to be investigated and rapid optimisation of the protocol to be undertaken where necessary. It also enables variations in the quality of the materials used to be analysed and taken into account when considering the experiment as a whole. Table 1. Example of verification of dual polarisation interferometry (DPI) data with...

Tofsims Spectra and Secondary Ion Images Chemical Identification

TOF-SIMS produces mass spectra of positive and negative secondary ions from the outer few nanometers of material surfaces under static conditions. Secondary ions, including molecular ions, suggest the chemical structures and components of sample surfaces with a high mass resolution of over several 1000 atomic mass units (amu). In the case of an analysis of organic materials such as proteins, however, the organic analyte molecule cation yield is low. In order to achieve high yields oflarge...

Characterization of Proteins on Substrates

The characterization of the proteins adsorbed, or immobilized, on substrates by TOF-SIMS has contributed to the development of other analyti- cal techniques. In 1986, the isolation of an apolipoprotein was studied with TOF-SIMS (Jabs et al. 1986), and an accurate evaluation of the molecular weight of peptides was obtained. Moreover, it became evident at that time that it was feasible using this method to monitor on a microscale basis the genetic polymorphisms of proteins and posttranslational...

Surface Modifications for Reducing Nonspecific Protein Adsorption

There have been many interests in membrane processes for last decade because of they are extremely efficient, have a low energy consumption, and are easy to carry out. Nowadays, membranes are used widely, especially in biomedical applications such as dialysis, plasmapheresis, and oxygenation of blood during cardiac surgery. However, it is well known that the major obstacle to the extensive use of membrane processes in therapeutic treatment is protein fouling of polymeric membrane materials....

Conclusion

To some extent, protein resistance is very important for both antifouling of membranes during filtration and improving the hemocompatibility of Fig. 19. BSA adsorption on PAN-based membranes. The HEMA mole fraction in the PANCHEMA membrane is 0 (a), 6.4 (b), 9.3 (c), and 17.8 (d), and the mole fraction of phospholipid moiety on PMANCP membrane surface is 6.09 (e), 9.19 (f), and 17.1 (g) blood-contact membranes. The methods overviewed above, such as copoly-merization, PEG tethering, physical...

FTIR Spectral Analysis

Infrared spectra of proteins in aqueous media exhibit nine characteristic absorption bands, which represent different vibration modes of their peptide moiety. Among all the amide vibrational modes, the most frequently used in studies of protein secondary structure is the amide I band. This vibrational mode, which lies in the 1,600-1,700 cm-1 spectral range, corresponds to the stretching mode of the peptide carbonyls. This broad infrared absorption band, which is sensitive to protein...

Introduction

Protein adsorption is the first phenomenon that occurs when synthetic materials come into contact with a living organism. The uncontrolled protein adsorption functions as a trigger for foreign body reactions to materials from a host. For biomedical applications, control of protein adsorption becomes quite important in the preparation of synthetic materials. Many concepts have been proposed for non-protein-fouling surfaces using physicochemical, biochemical, and biological approaches. One of the...

Fibronectin Exchange at a Constant Surface Concentration

In a first set of experiments, interfacial FN exchange was studied at various compositions of the protein solution applied for the displacement. Homoexchange by FN as well as heteroexchange by human serum albumin (HSA) was measured by fluorescence confocal laser scanning microscopy (LSM), which was supported by high-performance liquid chromatography (HPLC)-based amino acid quantification. Based upon preceding studies (Salchert et al. 2003), the adsorbed amount of FN onto the polymeric surfaces...

Surface Induced Conformational Changes of a Hard Protein Lysozyme

Changes in Solvation due to Adsorption As illustrated in Fig. 3, a first extremely rapid isotopic exchange occurs within the first 10 min of incubation of lysozyme in the deuterated buffer, corresponding to the exchange in COND of 70 of the amino acid residues. The residual NH content of lysozyme after 2 h of incubation reaches 21 in pure phosphate buffer (Figs. 3A,C) and 16 in phosphate-buffered saline (Fig. 3B). The ionic strength is known to influence the NH ND isotope exchange kinetics of...

Imaging of Protein Distribution

TOF-SIMS is the most useful technique for evaluating proteins on surfaces because it provides chemical mapping at a high spatial resolution. The chemical mapping of oligopeptides immobilized on an array of gold mi-croelectrodes was obtained as secondary ion images with the peptide-dried ion C4H8N+ (Mathieu 2001). In this case, the peptide image was obtained by conventional spectrum analysis, because components of the substrate were different from the peptide, and the fragment ions from the...

Local pH Effects

Proteins are amphoteric, that is, they possess a number of acid base sites whose charge is pH dependent. Since a positively (negatively) charged surface will repel solvated protons (hydroxide ions) and thus raise (lower) the pH near to the surface, the sign of a protein's overall change could change upon approach to the surface. In this case, attraction that is indeed electrostatic in origin may follow. Could this effect explain the antielectrostatic behavior reported in the literature Evidence...

Copolymerization Procedures

Acrylonitrile can be easily copolymerized with a variety of comonomers (Krasteva et al. 2002). Copolymerizations of hydrophilic functional monomers such as maleic acid (Nie et al. 2004a,b), N-vinyl-2-pyrrolidone (Groth et al. 2002 Krasteva et al. 2002 Wan et al. 2005), a-allyl glucoside (Xu et al. 2003, 2004), 2-hydroxyethyl methacrylate (HEMA Huang et al. 2005a,b), acrylamides (Musale and Kulkarni 1996,1997), and N-vinylimidazol (God-jevargova et al. 2000) with acrylonitrile have been...

Experimental Setup

The most basic experimental setup for TIRE includes a glass slide with a thin metal film mounted on a prism and an ellipsometer. In addition, depending on the specific application and measurement conditions, components like a flow cell, a flow control system, application-specific data acquisition, and system control software are needed. These components can be universal, or application specific, depending on the user needs. The setup can be simplified to an absolute minimum if a sensor-type...

Protein Orientation and Subsequent Activity Optimised Antibody Immobilisation Protocol

The immobilisation of a mouse IgG3 antibody raised to Cortisol (anticortisol) is summarised in Table 3. The experimental protocol was as follows. A thiol functionalised chip was first calibrated using standard calibrant solutions and then subjected to ester (sulpho-GMBS), which is a thiol amine linker followed by protein G. Once the protein G had been immobilised (via the sulpho-GMBS linker) the surface was ready for the immobilisation of the IgG3 antibody itself. Protein G has the capability...

A12 Surface Plasmon Resonance

In the absence of the availability of structural information at an appropriate temporal resolution, several optical techniques have been utilised to provide information on the function of proteins. The most common optical method deployed has been SPR. The phenomenon of plasmon resonance was first observed in 1968 (Kretschmann and Raether 1968). The first commercial SPR based biosensors were released in 1990 and have proved useful in the study of equilibrium and kinetic aspects of the...

Biomacromolecule Immobilization

Since PAN is one of the most important polymeric materials used in blood-contacting devices, efforts have been taken to build a blood-compatible surface. A well-known anticoagulant, heparin, which can catalytically increase the formation rate of antithrombin III and inhibit thrombin and some other coagulating proteases, is commonly used to treat patients who submit to hemodialysis. Heparin is a mixture of variably sulfated polysaccharide chains composed of repeating units of D-gluosamine and...

Recent Designs of Nonfouling Phosphorylcholine Surfaces with Well Defined Structures

MPC is one of the best monomers with which to produce biomimetic surfaces because it can be applied to a wide variety of surface modifications, as shown in Fig. 12. These methods have been applied to improve the bio blood compatibility of numerous biomedical devices (Iwasaki and Ishihara 2005). To better understand protein-material and cell-material interactions at the submolecular level, well-defined biomimetic surfaces have recently been produced (Fig. 13). Alkanethiols terminating in various...

Long Term Stability

The stabilities of enzymes in solution and immobilized on the cotton fibers were estimated by following their respective activities with time. Figure 10A,B shows a decrease in activity over time in both cases. However, the activities of immobilized enzymes on cotton fibers remained higher Fig. 10. Stability of pepsin (A) and trypsin (B) in solution and immobilized on cotton fibers Fig. 10. Stability of pepsin (A) and trypsin (B) in solution and immobilized on cotton fibers than that in solution...

Secondary Structure of Proteins

The practical limitations encountered with high-resolution structural techniques such as isotope labelling, namely the size of the protein colloid system and the size of the protein itself, mean that methods such as CD and vibrational spectroscopies remain attractive options. These low-resolution techniques provide a global estimation of the secondary structures (a-helix, -sheet or random coil) without specifying the local region involved in the conformational transition. The latter techniques...

RFF rFce

6 2k z,F' d-F> + Im(nF' ) f' tan 0f' sin 0f' (17) and Im(nF') is the imaginary component of the refractive index. The phase shifts yF> S and yF> F',c are expressed in terms of the associated reflection coefficients by y arcsin Im(r) r . In the absence of an F' layer, the above approach allows for the solution of the refractive index and thickness of the waveguiding film, nF and dF from the effective refractive indices of the transverse electric (NTE) and transverse magnetic (NTM) modes...

Polyethylene glycol Tethering

Surface graft polymerization is one of the most commonly used methods of grafting, including radical, radiation, plasma, and ultraviolet initiated graft polymerization. In general, grafting modification changes the surface properties of a polymer membrane in a defined selective way while preserving its bulk macroporous structure. The physicochemical properties of the membrane surfaces change to a great extent after modifications. Therefore, interactions with solutes such as proteins with a...

Different Models

Figure 9 illustrates the two models ofrearrangements ofthe dipoles roughly normal or parallel to the surface to obtain an attractive component between adsorbed proteins. We proposed the model of the ferroelectric-antiferroelectric arrangement normal to the surface to explain the change in variation of the Z potential (Vasina and Dejardin 2004 Fig. 9, left). Saving almost the same orientation of the proteins with respect to the surface (Robeson and Tilton 1996), cooperative clustering could...

Surface Induced Conformational Changes of a Soft Protein BSA

In general, proteins with low structural stability tend to adsorb on both hydrophobic and hydrophilic supports via a gain in conformational entropy. In the case of hydrophilic support, the soft proteins undergo more severe unfolding of the ordered structure because of a stronger increase in con-formational entropy to compensate for the repulsive coulombic interaction on an electrostatically repelling surface. Changes in Solvation due to Adsorption The NH ND exchange that BSA undergoes in...

Covalent Binding

Covalent binding means that the enzyme is immobilized by a chemical reaction between the enzyme and the support material to form covalent bonds. Although this immobilization generally enhances enzyme stability, one major disadvantage of this method is that the activity of the immobilized enzyme is often significantly decreased because the active site maybe blocked, multiple point-binding may occur, or the enzyme may be denatured (Butterfield et al. 1994 Ganapathi et al. 1998 Zhuang and...

On the Polyacrylonitrilebased Membrane Surface an Overview

Ling-Shu Wan, Zhi-Kang Xu, Xiao-Jun Huang Abstract. Protein adsorption and or deposition at the surface of polymeric membranes play important roles in membrane separation processes. Although polyacrylonitrile-based membranes have been used successfully in many fields, surface modifications to improve the protein resistance and hemocompatibility have received considerable interest. Various methods such as copolymerization, grafting, physical adsorption, biomacro-molecule immobilization, and...

Forces Involved in Protein Adsorption

The interactions that are involved in protein adsorption to solid surfaces (Lee et al. 2001) are known to include van der Waals forces, electrostatic double-layer forces, solvation forces, and entropic forces (Israelachivili and McGuiggan 1988 Oscarsson 1997). The extent of protein adsorption is Electrostatic interaction Hydrophobic interaction Specific interaction Van der Waais force Electrostatic interaction Hydration forces Steric repulsion Fig. 2. Types of attractive and repulsive forces...

Discussion

We observe an applied potential to have a significant effect on adsorption beyond the transport-limited regime. The apparent adsorption rate constant introduced in and around Eq. 11 - a measure of the rate of adsorption to an empty surface and a physical property depending on protein surface solvent characteristics - increases with applied voltage for the negatively charged albumin, decreases somewhat for the positively charged cytochrome c in water, and remains roughly constant for cy-tochrome...

Selective Cell Attachment to a Biomimetic Polymer Surface Through the Recognition of Cell Surface Tags

Synthetic polymers capable of selectively recognizing proteins or cells play important roles in cell separation, biosensors, and the development of biomedical materials (Ratner 1993, 1996). In general, few synthetic poly mers can recognize a specific biomolecule or cell in vivo because of the complexity of the environment. In a living cell, carbohydrates on the cell surface contribute to most of the communications between the cell and its environment (Dwek 1996). Therefore, it might be possible...

References

Dee KC, Puleo DA, Bizios R (2002) An Introduction to Tissue-Biomaterial Interactions. John Wiley & Sons, New York Etheve J, Dejardin P, Boissiere M (2003) Adsorption of lysozyme on a hemodialysis sulfonated polyacrylonitrile membrane, with and without preadsorbed poly(ethylene-imine) on the external faces. Colloids Surf B 28 285-293 Godjevargova T, Konsulov V, Dimov A, Vasileva N (2000) Behavior of glucose oxidase immobilized on ultrafiltration membranes obtained by copolymerizing...

Physical Adsorption

One of the commonest methods of modifying the surface properties of a membrane is to coat that membrane, which has the desired bulk properties, with an agent that has the desired surface properties. Mostly, coating is based on the physical adsorption of an agent on the membrane surface. Hence, the stability and durability of the coating agent is one of the key factors. D jardin et al. (Etheve et al. 2003 Thomas et al. 2000 Valette et al. 1999 Yan et al. 1992) reported a series of studies on...

Protein Orientation

Lysozyme Orientation at the Silica-Water Interface Lysozyme adsorption at the silica-water interface and subsequent layer structures were investigated. The build-up (and removal) of molecular layers adsorbing or reacting on a lightly doped silicon dioxide (silica) surface were measured in terms of thickness and refractive index changes over time. Lysozyme adsorption was monitored at a range of concentrations (from 0.03 g dm-3 to 4.0 g dm-3) and at both pH 4 and pH 7 in a flow-through cell...

Urease Immobilization by Molecular Recognition

The first step for enzyme entrapment is the synthesis of a biotinylated ure-ase. The amount of enzyme immobilized is calculated by kinetic measurements. Assuming that the enzyme keeps its activity after immobilization, the weight of immobilized enzyme is given by Wt Wi - Wim - Wr, where Wt, Wi, Wim, and Wr are the weight of enzyme attached to the textile, the weight of enzyme in the initial solution, the weight of enzyme in the solution after textile immersion, and the weight of enzyme in the...

By Enzyme Immobilization onto Textiles

Advanced biotechnological techniques are now being used in the chemical engineering of membrane processes, notably enzyme immobilization procedures, biosensors, and, more recently, proteomics. The knowledge and increasingly fine control of the production and reactivity of enzymes also profits research whose aim is to use on a large scale the catalytic material properties of biocatalysts (enzymes). These materials with reactive properties could be introduced into membrane technology,...

Mode Equations for OWLS

This assumes that the F,S interface is flat and abrupt. Introducing the normalized propagation constant b (Ghatak and Thya-garajan 1989) and the dimensionless waveguide parameter W where k 2n A is the wavenumber of the light in vacuo with wavelength A, the mode equations for a three layer waveguide (2,F,C) are then tan W(1- W I ( nj 1- b(b + a) nc nF)-2X1-b) (12) with p 0 and 1 for the TE (transverse electric, i. e. s-polarized) and TM (transverse magnetic, i. e. p-polarized) modes,...

Xanthine Oxidase and Uricase Immobilization

Xanthine Absorbance

The efficiency of the immobilization method being demonstrated with urease and in order to prove the potentiality of the molecular recognition Fig. 15. Catalytic chemical reactions achieved by xanthine oxidase and uricase Fig. 15. Catalytic chemical reactions achieved by xanthine oxidase and uricase process, different types of enzyme have been fixed onto textiles xanthine oxidase, which allows the chemical transformation of xanthine into uric acid, and uricase, which transforms uric acid into...

OWLS Experiments

A schematic of our OWLS system (BIOS-1, MicroVacuum, Budapest, Hungary), as modified to allow for detection in the presence of an applied potential difference, appears in Fig. 2. The adsorbing surface is an indium tin oxide (ITO, or In2-2xSnxO3-x with x 0.50 0.02)-coated optical waveguide 2400 sensor chip (MicroVacuum). The ITO layer has a thickness of approximately 10 nm and complex refractive index 1.80-0.03i and rests on a silicon titanium oxide layer (STO, or Si1-xTixO2 with x 0.25 0,05) of...

Plasma treatment

Plasma modification of polymeric materials is an extremely useful way of tailing a polymer into a desired material by utilizing the selective chemistry and molecular structure on the surface (Kiaei et al. 1995 Lee et al. 1991 Oehr et al. 1999). It is an efficient way to produce functional groups such as hydroxyl groups, amino groups, and carboxylic groups. Plasma can also initiate polymerization reactions of monomers on a surface. Graft polymerization can be carried out by plasma treatment...

Tosylation of Cotton and Enzyme Immobilization

The cotton used was obtained locally and had a density of 1.27 g cm3. The value of specific surface for the cotton fibers was about 55 x 103 m2 kg (Kaewprasit et al. 1998). The immobilization procedure comprised four main steps mercerization of the cotton with NaOH, pretreatment with pyridine, tosyl activation of the cotton, and enzyme coupling to the cotton fibers. For mercerization, 0.1 g of cotton was soaked in 10 ml of 3 N NaOH solution for several hours (24 h, but about 4 h can be...

Future Developments

The optical waveguide device can be considered to be an optical bench. As such, a wide variety of optical experiments can, in principle, be carried out either sequentially or, preferentially, simultaneously. Rather than listing the variety of such experiments, for the sake of brevity, just one extension to the DPI technique will be briefly discussed here. Perhaps the most obvious additional experiment is to measure the extinction coefficient (the losses) of the sensing waveguide. These can be...

Biomimetic Modification

A potential technique for reducing protein adsorption on polymeric membranes is to mimic a biologic surface in nature, commonly named bio-mimetic modification. For example, the red blood cell plasma membrane, unlike synthetic polymer membranes, naturally resists protein fouling. This property may be attributed to the unique phospholipid bilayer structure of the biomembrane. Therefore, great efforts have been made to immobilize phospholipid molecules onto the polymer surface to build a...

Cell Manipulation on a Well Defined Phosphorylcholine Polymer Brush

Adsorption of fluorescein-isothiocyanate-labeled BSA was well controlled on a patterned graft polymer surface, as shown in Fig. 15. On an UV-irradiated region with no polymer brush, the fluorescence intensity was significantly high, indicating that a large amount of BSA was adsorbed in this region. Conversely, BSA adsorption was remarkably reduced in the Polymerization time 18 h Polymer thickness 12 nm Fig. 15. Fluorescence micrographs of fluorescein isothiocyanate-labeled albumin adsorption on...

Ozone Method

Wang et al. (2000) performed surface modification of PPMMs by using ozone to introduce peroxide onto the membrane surface. After that, graft polymerization of HEMA was carried out. The polymerization was initiated at a mild temperature by redox decomposition of the peroxide (Fig. 12). Similar to the results of Kang et al. (see previous section), these HEMA-grafted PPMMs also showed great protein resistance (see Figs. 13a,b and 14). The trend of flux decline for the modified (grafted) membrane...

On a Phosphorylcholine Polymer Nonfouling Surface

Cell adhesion on material surfaces depends strongly on the plasma (serum) protein adsorption onto the surface because there are many kinds of cell adhesive proteins in plasma (serum). It has already been reported that an MPC polymer can reduce the adhesion of a variety of cells such as blood cells (Hasegawa et al. 2002 Ishihara et al. 1992, 1993, 2000 Iwasaki et al. 1997, 2001), fibroblasts (Ishihara et al. 1999 Iwasaki et al. 1999), and Fig. 14. a Synthetic route of poly(MPC) brushes on...

Textile Characterization

Cellulose copolymer textiles are modified by plasma irradiation treatment to graft ionic groups onto the fiber. The number of ionic groups are deduced from the ion-exchange capacity of the textile, as measured by determining of the amount of fixed ions on the textile (Yakup Arica 2000). The experimental procedure will now be described. For anion-exchange textiles, the tissues are equilibrated in sodium chloride solution (1 M) for 24 h. Solutions are changed three times (the corresponding total...

Ultraviolet UV modification

Induced Grafting

UV irradiation is an effective technique for membrane surface modification. It maybe the most appropriate of all surface modification techniques because of certain features the low cost of operation, mild reaction conditions, it is highly surface-selective, and because it alters the material surface with facile control of the chemistry (Ma et al. 2000a). Several studies have been carried out using photoinitiators (Kita et al. 1994 Richey et al. 2000 Ulbricht et al. 1998) or specially...

Optical Waveguide Lightmode Spectroscopy

In the latter half of the 17th century Newton (1730) demonstrated the existence of an evanescent field when light falls on the interface between dense and rare optical media and is totally reflected back into the dense medium. During the intervening years the phenomenon has been extensively studied, and has given rise to important measurement techniques for investigating interfacial phenomena (cf. Table 1). The overall approach is for the optically dense medium (typically a transparent...

Physical Adsorption Entrapment

Schematic Protein Adsorption

Physical adsorption is the most convenient way to achieve enzyme immobilization, avoiding the tedious and time-consuming multistep procedure of covalent binding (Aleixo et al. 1985 Cleveland et al. 1981). Entrapment immobilizes enzymes by trapping them into porous materials (membranes). Because there is no covalent attachment, the activity of the enzymes immobilized by physical adsorption, and entrapment is easily maintained. However, loss of enzyme in applications is inevitable for the...

Conclusions

The surface of a material is the phase boundary that resides between the bulk material and the outer environment. The performance of materials relies largely upon the properties of the boundaries in many applications. For biological biomedical applications, polypropylene membranes often suffer from grievous problems such as hydrophobicity, being chemical inert, and lacking functional groups. These disadvantages cause nonspecific protein adsorption and make PPMMs incapable ofenzyme...

Total Internal Reflection Ellipsometry

Before discussing TIRE, it is useful to recall two important measurement techniques, one of which is based on the ellipsometric principle and the other on the SPR phenomenon. In brief, ellipsometry can be characterized as a measurement of the change of the state of polarization of light upon reflection on the sample surface Fig. 1 . As the light is not only re- Fig. 1. The principle of ellipsometry see text for details . p Parallel, s perpendicular Fig. 1. The principle of ellipsometry see text...

Application Examples

Protein Adsorption Kinetic

Three examples of possible applications of TIRE in the area of protein adsorption are presented here. The first example shows a potential for microstructural analysis of protein monolayers adsorbed onto metal films. The second example addresses problems with potential industrial rele vance. It also demonstrates one of the TIRE strengths - the possibility of measurement in opaque solutions. The final example illustrates a major TIRE advantage extremely high sensitivity under SPR conditions. The...

Investigation of Conformation and Orientation of Proteins on Substrates

Based on the investigation of fragment ions from proteins, information on the conformation and orientation of the proteins can be evaluated using TOF-SIMS spectra. TOF-SIMS produces important fragment ions with information regarding chemical structures at the uppermost surfaces of the samples. The surface is bombarded with a pulsed primary ion beam, inducing the desorption of particles. Because of the matrix effect, the desorption probability of particles and the formation probability of...

Mechanism of Resistance to Protein Adsorption on the MPC Polymer Surface

To reduce protein adsorption on polymer surfaces, surface modifications that induce repulsive interactions or reduce attractive interactions have been conducted. It has been known for quite some time that in general, as a surface becomes more hydrophobic, the extent of protein adsorption increases Elwing et al. 1987 Golander and Pitt 1990 Golander et al. 1990 Lee and Lee 1993 . The unusually strong attraction between proteins and hydrophobic surfaces in water has been described by a hydrophobic...

Fundamental Interactions Between MPC Polymers and Proteins

Protein adsorption on material surfaces causes serious biological reactions such as, for example, thrombus formation, immune response, and complement activation, capsulation Brash and Horbett 1987 Horbett and Brash 1995 . To understand the blood compatibility of surfaces, it is necessary not only to determine the amount of adsorbed protein but also the species Fig. 10. Amount of protein adsorbed on polymer surfaces from human plasma. Poly BMA poly butyl methacrylate , Poly HEMA poly...

Fukumoto Inglewood Adoption 1962

AbramovitzM, Stegun IA 1972 Handbook of Mathematical Functions. Dover Publications, New York, p 255 Adler PM, Thovert J-F 1998 Real porous media local geometry and macroscopic properties. Appl Mech Rev 51 537-585 Andrade J 1985 Surface and Interfacial Aspects of Biomedical Polymers. Plenum Press, New York Antosiewicz J, Porschke D 1989 The nature of protein dipole moments experimental and calculated permanent dipole of a-chymotrypsin. Biochemistry 28 10072-10078 Bae YM, Oh B-K, Lee W, Lee WH,...