Survey of the most common solid supports

Virtually any water-insoluble substance that satisfies the required characteristics discussed in Section 4.7.2.1 can serve as a solid support. However, no ideal matrix has been introduced yet. But an important factor is the rapid development of solid supports. If, at present, some carrier is neglected owing to some undesirable quality, it may be suitable after appropriate modification. It is almost impossible to find a matrix material which does not interact with biological active molecules by hydrogen bonding or ionic or hydrophobic interaction. Occasionally, these interactions fortuitously improve adsorption selectivity, but according to the opinion of Egly and 

Polyacrylamide gels are synthesized by copolymerization of acrylamide and N,N -methylene bisacrylamide. The acrylamide thus formed consists of a hydrocarbon skeleton onto which carboxamide groups are bound  

Polyacrylamide is chemically stable in the pH range of 3-10, and at temperature below 35°C, but cannot withstand some organic solvents [76]. The advantage of this support is the high density of the chemically reactive carboxamide groups. Unfortunately, however, after chemical modification the porosity of the beads is reduced to the detriment of the effectiveness of the gel in the purification of macromolecules. The main producer of polyacrylamide gels is Bio-Rad Labs. (Richmond, CA, U.S.A., under the trademark Bio-Gel P). 

In order to minimize the reduction of porosity of polyacrylamide during activation the copolymers of agarose and polyacrylamide are produced. This support combines the advantages of each individual polymer, whilst extending the potential range of derivatisation procedures by virtue of the availability of both amide and hydroxyl groups of activation [81]. Copolymers are produced by LKB-Produkter AB (Bromma, Sweden). A support of similar properties, dextran crosslinked with iV,fV -methylene-bisacrylamide [82], is produced by Pharmacia (Uppsala, Sweden, under the trademark Sephacryl). 

The silica-based supports are supplied by Bio-Rad Labs (Richmond, CA, U.S.A., under the trademark Bio-Glass) by Electro-Nucleonics, Inc. (Fairfield, NJ, U.S.A.) and Pierce Chem. Co. (Rockford, IL, U.S.A. under the name CPG (controlled-Pore Glass)) by Waters Associates (Milford, MA, U.S.A. under the name Porasil) by E. Merck (Darmstadt, G.F.R., under the names Fractosil or LiChrospher) by DuPont Instrument Products Div. (Wilmington, DE, U.S.A., under the name SE Series or Zorbax), or by Rhone Poulenc (France, under the name Spherosil). The modified silica-based supports are supplied by Electro-Nucleonics, Inc. (Fairfield, NJ, U.S.A.) or Pierce Chem. Comp. (Rockford, IL, U.S.A., under the trademark Glycophase- 

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