Ligand functionalized polymers

A method of separating a target biological species from a fluid comprising the target biological species comprising:

• a. contacting the fluid with a suspension or solution of water-soluble or water-dispersible aminopolymer functionalized with pendent or catenary guanidinyl groups represented by the following general formula:
• wherein
• R2 is H, C1-C12 alkyl, C5-C12 (hetero)aryl, or a residue of the polymer chain;
• each R3 is independently H, C1-C12 alkyl, or C5-C12 (hetero)aryl,
• each R4 is H, C1-C12 alkyl or alkylene, C5-C12 (hetero)aryl or (hetero)arylene, cyano, or —C(═NH)—N(R2)-Polymer,
• n is 1 or 2;
• and
• “Polymer-N(R2)—” is the linkage formed between an amine group of the polyamino polymer and guanylating agent;
• b. forming a complex in the fluid that comprises the aminopolymer functionalized with guanidinyl groups and the target biological species;
• and
• c. separating the complex from the fluid;
• wherein the target biological species is selected from biomacromolecules and microbiological species.