Low-cost aqueous two-phase system for affinity extraction

A Low-Cost Aqueous Two-Phase System for Affinity Extraction... 

Szlag DC, Giuhano A, and Snyder SM, A low-cost aqueous two phase system for affinity extraction. In Hamel JFP, Hunter JB, and Sikdar SK, eds. Doivnstream Processing and Bioseparation, Recovery and Purification of Biological Products. ACS Symp. Ser. 419, ACS Press, Washington, 1990 pp. 71-86. 

The main drawback to the widespread use of polymer-polymer aqueous two-phase extraction has been the high cost of fractionated dextran. Crude dextran has been used with some success for the purification of enzymes but is much too viscous for many applications. Conversely, polymer-salt systems have relatively low viscosities, separate rapidly, and are inexpensive. Unfortunately, they lack selectivity and cannot be used for affinity partitioning in most cases since the high salt concentrations interfere with the protein-ligand interaction. The starch derivatives are reasonable alternatives for bottom phase polymers but have been hampered by low solubilities and the tendency for gel formation. Tjemeld has reported that chemically modified starches i.e. hydroxypropyl starch... 

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