The 3M™ Polisher ST is a fully encapsulated single-use anion exchange (AEX) product. It is intended to reduce host cell protein, viruses, and other negatively charged contaminants in a flow-through polishing chromatography mode in biopharmaceutical process streams. The 3M™ Polisher ST is a synthetic, hybrid purifier containing two complementary AEX-functional media: a quaternary ammonium (“Q”) functional nonwoven and a guanidinium-functional membrane. The Q-functional nonwoven provides reduction of turbidity (when present) and DNA. It also provides a portion of the product’s AEX capacity for HCP and virus reduction. Guanidinium functionalized membrane downstream of the functionalized nonwoven provides additional AEX polishing capacity. The novel guanidinium functionality of the downstream AEX polishing membrane mimics the amino acid, arginine, one of the three positively charged naturally occurring standard amino acids that make up proteins and is responsible for viral clearance and high salt tolerance.