The present invention relates to a bimodal polymer such as a soluble polymer capable of irreversibly binding to insoluble particulates and a subset of soluble impurities and also capable of reversibly binding to one or more desired biomolecules in an unclarified biological material containing stream and the methods of using such a material to purify one or more desired biomolecules from such a stream without the need for prior clarification. Such a polymer comprises domains of charged pendant groups such as primary, secondary, tertiary or quaternary amines, (first mode) and is rendered insoluble and precipitates out of solution simply upon complexing with oppositely charged solid particulates and a fraction of the soluble impurities in an amount sufficient to form an aggregate that can no longer be held in solution. The polymer further comprises other domains of pendant groups that are charged or uncharged, hydrophilic or hydrophobic or have a ligand that is selective for the biomolecule of interest depending on the process conditions such as pH, ionic strength, salts, and the like (second mode). When present in one mode, such as the uncharged form, said pendant groups are capable of binding to one or more desired biomolecules within the stream (protein, polypeptide, etc) in an unclarified cell broth. The precipitate can then be removed from the stream, such as by being filtered out from the remainder of the stream and the desired biomolecule is recovered such as by selective elution.
