Immobilization strategies

Wagner P 1998 Immobilization strategies for biological scanning probe microscopy FEBS Lett. 430 112... 

The choice of immobilization strategy obviously depends on the enzyme, electrode surface, and fuel properties, and on whether a mediator is required, and a wide range of strategies have been employed. Some general examples are represented in Fig. 17.4. Key goals are to stabilize the enzyme under fuel cell operating conditions and to optimize both electron transfer and the efficiency of fuel/oxidant mass transport. Here, we highlight a few approaches that have been particularly useful in electrocatalysis directed towards fuel cell applications. 

Topogildis, E., Cass, C.J., Cass, A.E.G., Gilardi, G., Sadeghi, S., Beaumont, N. and Durrant, J.R. (1998) Protein adsorption on nanocrystalline TiCfi films An immobilization strategy for bioanalytical devices. Analytical Chemistry, 70, 5111—5113. 

Peluso P., Wilson D.S., Do D., Tran H., Venkatasubbaiah M., Quincy D., Heidecker B., Poindexter K., Tolani N., Phelan M., Witte K., Jung L.S., Wagner P., Nock S., Optimizing antibody immobilization strategies for the construction of protein microarrays, Anal Biochem. 2003 312 113-124. 

Lee et al. utilized the self-assembled layer of thiol group-modified protein A for the oriented immobilization of antibodies [64], An increased binding capacity was further observed. As another illustrative instance, a protein A-based orientation-controlled immobilization strategy for antibodies was proposed for the fabrication of a QCM immunosensor using nanometer-sized gold particles and amine-terminated PPF [65], Moreover, in recent years, there has emerged another oriented immobilization... 

H. Wang, Y. Liu, Y. Yang, T. Deng, G.L. Shen, and R.Q. Yu, A protein A-based orientation-control-led immobilization strategy for antibodies using nanometer-sized gold particles and plasma-polymerized film. Anal. Biochem. 324, 219-226 (2004). 

The first report of surface-immobilized dendrimers was in 1994 [54]. Subsequently, our research group showed that the amine-terminated PAMAM and PPl dendrimers could be attached to an activated mercaptoimdecanoic acid (MUA) self-assembled monolayer (SAM) via covalent amide linkages [55, 56]. Others developed alternative surface immobilization strategies involving metal com-plexation [10] and electrostatic binding [57]. These surface-confined dendrimer monolayers and multilayers have found use as chemical sensors, stationary phases in chromatography, and catalytic interfaces [41,56,58,59]. Additional applications for surface-confined dendrimers are inevitable, and are dependent only on the synthesis of new materials and the development of clever, new immobilization strategies. 

Several years after its demonstration as a viable approach to interrogating ligand binding events in mixtures, FAC-MS systems, immobilization strategies and methods have advanced to the degree where FAC assays can be constructed around most molecular interactions relevant to the drug discovery industry. Aside... 

Fig. 12 Schematic illustration of immobilization strategy using affinity reactions via avidin-biotin coupling. Biotinylated mixed monolayers improve the availability of the surface-bound avidin or streptavidin to biotin coupled probe biomolecules...

Fig. 14 A schematic illustration of an orientated immobilization strategy via crystallized S-layer proteins a side view of the crystalline ordered S-layer proteins fused with the recognition center streptavidin for biotinylated biomolecules probes b front view of the orientated and crystalline ordered S-layer proteins...

Immobilization by electrostatic interaction results in a tight association of the NA backbone with the surface that may leave part of the molecule in an unfavorable conformation for its subsequent hybridization with complementary sequences. This could result in a loss of hybridization efficiency and is the primary reason why this method is recommended principally if the arrayed material is available in large quantities and its price is not an issue for consideration. Alternatively, this method can also be used if the NA does not possess specific chemical functionalities which can be used in other more directed immobilization strategies (e.g. covalent bonding). 

Immobilization strategies for electrochemical detection may involve physical adsorption, thiol-finking chemistries to gold electrodes, and organosilane finking chemistries to oxidized silicon or glass substrates. Immobilization... 

To give the reader an idea of the practical effort of the immobilization strategies discussed, applications of these DNA chips are also included, e.g. with one chapter describing the immobilization step included in a short oligonucleotide ligation assay on DNA chip (SOLAC) to identify mutations in a gene of Mycobacterium tuberculosis in chnic isolates indicating rifampin resistance. 

The immobilization strategies are of particular interest. The authors reasoned that the use of aldehydes to tether proteins to the solid phase could be ideal for certain protein-protein interaction studies. Since many protein-lysine residues are available for coupling to aldehydes via Schiff s base, a number of spatial orientations are possible. Such random oriented attachments would permit exposure of various surfaces of a protein to the solution, and new protein-protein interactions would be potentially possible. 

Sikora T, Marcilla R, Mecerreyes D, Rodriguez J, Pomposo JA, Ochoteco E (2009) Enzymatic synthesis of water-soluble conducting poly(3,4-ethylenedioxythiophene) a simple enzyme immobilization strategy for recycling and reusing. J Polym Sci A Polym Chem 47(l) 306-309... 

Peluso P, Wilson DS, Do D, et al. (2003) Optimizing antibody immobilization strategies for the construction of protein microarrays. Anal Biochem 312, 113-24. 

A unique immobilization strategy was developed by Alt, who synthesized metallocenes with alkene functionalities and employed these functionalized metallocene catalysts for polymerization. During the polymerization process, the metallocene catalysts are consumed as a co-monomer, leading to the generation of polymer-supported metallocene catalysts. 

In recent times the incorporation of enzymes into nanostructured materials is commonly referred to as nanobiocatalysis. Nanobiocatalysis has emerged as a rapidly growing research and development area. Lately, nanobiocatalytic approaches have evolved beyond simple enzyme immobilization strategies to include also topics like artificial enzymes and cells, nanofabrication, and nanopatterning [18]. A recent bibliometric analysis [19] of nanobiocatalysis publications shows a strong increase within the last decade (Fig. 14.1). The analysis has been compiled from... 

Some examples for the application of such immobilization strategies and the application of the immobilized complexes to asymmetric hydrogenation and epoxidation as well as to ring-opening reactions of epoxides will be presented in this chapter. 

The same immobilization strategy based on avidin/biotin linkage can be achieved on magnetic beads. After their efficient modification, the magnetic beads can be easily captured on an m-GEC transducer for the electrochemical determination of the hybridization event. 

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