Spacer technology

AIRLOCK Spacer Technology, http //www.gore-workwear.co.uk/remote/ Satelhte/Innovations/AIRLOCK-Insulation. 

Thermal insulation can also be made of spacer technology, which ensures the inclusion of air. The flame-retardant protective effect not only improves comfort but also saves the lives of firefighters in extreme cases. According to statistics of the National Fire Protection Association, more than half of fatal firefighter accidents are a result of heat stress. Warp-knitted spacer fabrics prevent this effect due to their good insulation, compared to existing lining materials, such as foams (Heide, 2001). 

Here we will focus on the biochemical aspects. The techniques of isolating enzymes, the process of enzyme immobilisation and the behaviour of immobilised enzyme reactors are discussed in detail in the BIOTOL text Technological Applications of Biocatalysts", so will not deal with these aspects in detail here. In outline, however, once the desired enzyme is isolated, it is attached to a carrier material. In order to ascertain sufficient accessibility of the enzyme, a bifunctional spacer molecule is attached to the carrier ... 

One of the key technologies used in combinatorial chemistry is solid-phase organic synthesis (SPOS) [2], originally developed by Merrifield in 1963 for the synthesis of peptides [3]. In SPOS, a molecule (scaffold) is attached to a solid support, for example a polymer resin (Fig. 7.1). In general, resins are insoluble base polymers with a linker molecule attached. Often, spacers are included to reduce steric hindrance by the bulk of the resin. Linkers, on the other hand, are functional moieties, which allow the attachment and cleavage of scaffolds under controlled conditions. Subsequent chemistry is then carried out on the molecule attached to the support until, at the end of the often multistep synthesis, the desired molecule is released from the support. 

Guanaranta and Wilson [111] compared the different methods for immobilization of acetylcholinesterase by direct immobilization on the matrix, introduction of 1,6 diaminohexane as a spacer, and two methods of oriented immobilization via antibody and avidin-biotin linkage. They found that the latter gave the best efficiency, i. e., tenfold higher than direct immobilization on the matrix (which was the lowest) followed by immobilization on the antibody and immobilization using a spacer. Details about the biotin-avidin technology were published by Wilchek and Bayer [112]. 

Recently, monoclonal antibodies were attached to gas-filled microbubbles using this spacer coupHng technology. Testing in vitro, in a cell culture system, demonstrated selective accumulation of decafluorobutane-based lipid shell MP1950 microbubbles with covalently attached anti-lCAM-1 antibodies, onto the surface of activated endotheUum [8]. Anti-P-selectin antibodies attached to such microbubbles via an avidin-biotin scheme showed selective accumulation in the areas of inflammation and ischemia/reperfusion injury in an animal model [93]. In the latter example, biotin was also connected to the microbubble surface via a flexible polymer spacer arm. 

Chem. Soc., 126, 14411-14418 Skander, M., Malan, C., Ivanova, A. and Ward, TR. (2005) Chemical optimization of artificial metaUoenzymes based on the biotin-avidin technology (S)-selective and solvent-tolerant hydrogenation catalysts via the introduction of chiral amino acid spacers. Chem. Commun., 4815-4817 Ward, TR. (2005) Artificial metallo-enzymes for enantioselective catalysis based on the noncovalent incorporation of organometallic moieties in a host protein. Chem.-Eur. J., 11, 3798-3804 Letondor, C. and Ward, TR. (2006) Artificial metaUoenzymes for enantioselective catalysis Recent advances. Chem. Bio. Chem., 7, 1845-1852. 

In conclusion, it has to be emphasized, that the l.c. side chain polymers in principle exhibit field effects like l-l.c. s, assuming that the flexible spacer is sufficiently long. The applicability of polymers in high performance display technology seems to be less practicable due to the high viscosity. On the other hand, the polymer specific glass transition enables the realization of storage elements an information, put in by an electric field in the l.c. state, can be durably frozen in. 

Affinity chromatography combines the analytical and chemical capacities of chemically bonded stationary phases and immobilized enzymes. Technology and methodology of both techniques are joined in the development of affinity stationary phases. Since steric requirements are even more determining than in simple immobilized enzyme systems, spacer molecules have great importance in these modifications. Commonly used spacer arms are summarized in figure 8.3. 

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