Surface adsorption of proteins

Another attractive application of polymer brushes is directed toward a biointerface to tune the interaction of solid surfaces with biologically important materials such as proteins and biological cells. For example, it is important to prevent surface adsorption of proteins through nonspecific interactions, because the adsorbed protein often triggers a bio-fouling, e.g., the deposition of biological cells, bacteria and so on. In an effort to understand the process of protein adsorption, the interaction between proteins and brush surfaces has been modeled like the interaction with particles, the interaction with proteins is simplified into three generic modes. One is the primary adsorption. 

Seifert et al. (1986) prepared a planar Si02-TiC>2 wave guide with a surface relief by using an embossing technique. The waveguide reacts sensitively to the surface adsorption of proteins. IgG has been adsorbed and the binding of anti-IgG was registered with a difference refracto-meter. 

So far, various surfactants have been used for dynamic PDMS coating, including Briji-35 [9], Tween-20 [10], SDS [11], DOC [11], PVP [12] and Triton X-100 [13], etc. Brij-35 has long been used in microfluidic devices to reduce the surface adsorption of proteins. Though when it is incubated to the surface with aqueous solution flow, Brij-35 is physisorbed onto hydrophobic surface by its hydrophobic alkyl long chain, increasing the hydrophilic property with the polyethylene oxide (PEO) end to the free surface [14]. Seos... 

Formulation strategies for stabilization of proteins commonly include additives such as other proteins (e.g., serum albumin), amino acids, and surfactants to minimize adsorption to surfaces. Modification of protein structure to enhance stability by genetic engineering may also be feasible, as well as chemical modification such as formation of a conjugate with polyethylene glycol. 

Mechanical forces, such as shearing, shaking, and pressure, may also denature proteins [44,45], Shaking proteins may lead to inactivation owing to an increase in the area of the gas/liquid interface. At the interface, the protein unfolds and maximizes exposure of hydrophobic residues to the air. Surface denaturation may also occur at the protein/container interface and has been observed following adsorption of proteins to filter materials [46]. 

Clay minerals or phyllosilicates are lamellar natural and synthetic materials with high surface area, cation exchange and swelling properties, exfoliation ability, variable surface charge density and hydrophobic/hydrophilic character [85], They are good host structures for intercalation or adsorption of organic molecules and macromolecules, particularly proteins. On the basis of the natural adsorption of proteins by clay minerals and various clay complexes that occurs in soils, many authors have investigated the use of clay and clay-derived materials as matrices for the immobilization of enzymes, either for environmental chemistry purpose or in the chemical and material industries. 

The adsorption of proteins onto surfaces is the oldest and easiest immobilization method. Adsorbing forces can be of different types Van der Waals interactions, ionic, hydrophobic or hydrogen bonding. The main advantages of this procedure are the simplicity of preparation and the little... 

To suppress cell adhesion on a material surface, one approach is to inhibit the adsorption of proteins. SAMs of alkanethiols that carry oligo(ethylene glycol) (OEG) [69] and phosphorylcholine [46, 70, 71] have been shown to prevent... 

Sigal GB, Mrksich M, Whitesides GM (1998) Effect of surface wettability on the adsorption of proteins and detergents. J Am Chem Soc 120 3464-3473... 

Ostuni E, Chapman RG, Holmlin RE, Takayama S, Whitesides GM (2001) A survey of structure-property relationships of surfaces that resist the adsorption of protein. Langmuir 17 5605... 

Prime KL, Whitesides GM (1993) Adsorption of proteins onto surfaces containing end-attached oligo(ethylene oxide) A model system using self-assembled monolayers. J Am Chem Soc 115 10714-10721... 

Prime, K.L., and Whitesides, G.M. (1991) Self-assembled organic monolayers model systems for studying adsorption of proteins at surfaces. Science 252, 1164. 

The physical adsorption of protein onto the surface of an electrode is a simple immobilization method. The adsorption is obtained by volatilizing the buffers containing proteins. The physical adsorption needs no chemical reagent, seldom activation and rinse, so that the bioactivities of the immobilized proteins can be retained well. However, the immobilized proteins are easy to break off from the electrode, which restrict broad applications of this method. Below are some examples of the physical adsorption of proteins immobilized on electrodes. 

To give an example both sensitivity coefficients are evaluated for the current sensor (see Sect. 10.3 for details). For the bulk detection of glucose this results in A bulk (rad) = 5.6 x 102 AC (g/ml), whereas for the adsorption of proteins on the sensor surface the overall sensitivity of the sensor is evaluated as A< >layer (rad) = 2.0 x 10 5 Am/A (fg/mm2). Measuring the phase change A< >,-, between any of the two channels i and j can thus give an estimation on the change in analyte concentrations between those two channels. If one channel (e.g., channel N) is used as a reference channel, then ACV = 0 and AmN = 0 and absolute analyte concentrations can be determined. 

TIRF has been used to study equilibrium adsorption of proteins to artificial surfaces both to learn about the surface properties of various biomaterials that have medical applications and also to test the TIRF technique itself. 

Electrochemistry of proteins is another case where electrode size affects the electrochemical results. Direct adsorption of proteins, such as enzymes, onto bulk metal surfaces frequently results in denaturation of the... 

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