Polymer support agarose

Natural supports (agarose, dextran, cellulose, porous glass, silica, the optical fiber itself or alumina) and synthetic resins (acrylamide-based polymers, methacrylic acid-based polymers, maleic anhydride-based polymers, styrene-based polymers or nylon, to name a few) have been applied for covalent attachment of enzymes. These materials must display a high biocatalyst binding capacity (as the linearity and the limit of detection of the sensing layers will be influenced by this value), good mechanical and chemical stability, low cost, and ease of preparation. 

Supports based on synthetic hydrophilic polymers such as polyvinyl alcohol and polyacrylamide or natural polymers like agarose have been developed. 

It is important that the support material be stable under operational conditions with respect to mechanical forces, solvent temperature, pH, etc. A wide variety of different supports have been used for enzyme immobilization including natural polymers (cellulose, agarose diitosan), synthetic polymers (acrylic resins, styrene-divinylbenzene, polypropylene), and inorganic materials (silica, porous glass, Celite). Each offers advantages and disadvantages, and the optimal support for a given enzyme and reaction must be chosen individually. 

Various support media may be employed in electrophoretic techniques. Separation on agarose, acrylamide, and paper is influenced not only by electrophoretic mobiUty, but also by sieving of the samples through the polymer mesh. The finer the weave of selected matrix, the slower a molecule travels. Therefore, molecular weight or molecular length, as well as charge, can influence the rate of migration. 

Because of the limitations of silica, several manufacturers offer SEC columns based on hydrophilic organic polymer. These include polymethacrylate supports, proprietary hydrophilic polymers, and semirigid cross-linked agaroses and dextrans. These materials are more stable under high-pH operation. 

Chromatographic resolution is also dependent on column efficiency (i). Column efficiency is directly dependent on the nature of the support matrix and how well that support is packed in its column. Available chromatographic supports are based on dextran, agarose, polystyrene, acrylic, cellulose, silica gel and a variety of other polymers. Althou cellulosic supports are manufactured in both microcrystalline and leaded forms, most supports are beaded. Newer supports may use hybrid bead construction where the base support is coated with a second materid (e.g., dextran or silica coated with agarose). 

Support materials for low-pressure affinity chromatography include agarose (cross-linked with epichlorohydrin), cellulose, dextran, silica, and polyacrylamide 62 in HPLC a rigid, highly porous, hydrophilic polymer is typically used. Large pore sizes are necessary, as either the analyte or the affinity ligand are macromolecules. To provide unhindered access of... 

The ultimate combination of HPLC and AC is effectuated in High Performance Affinity Chromatography (HPAC).47 The development of this hybrid technique was highly assisted by the use of modified silica. Traditional polysaccharide supports may not be used for HPAC, because they lack mechanical stability to withstand the high pressure drops, inherent to this method. Modified silica beads are well suited. These may be coated with active groups as in normal AC applications. Additionally, if the separation requires the use of an organic stationary phase, the silica beads are modified with a silane or polymer with subsequent deposition of polysaccharides such as dextrans, agarose or cellulose.50... 

Ion-exchange supports based on derivatized cellulose and agarose have been popular since the 1960s, particularly for protein analysis. For high-performance liquid chromatography (HPLC), less compressible supports, such as silica and cross-Unked polymers, are most commonly used. 

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