Abstract: Disclosed herein are polycationic microfibers comprising a high-aspect-ratio polymeric core, the polymeric core comprising a blend of a first core polymer and a second core polymer, and a polycationic polymer immobilized on the surface of the polymeric core. The polycationic microfibers are capable of sequestering or clearing nucleic acids, proteins, biomolecular complexes, exosomes, or microparticles from solutions and samples and may be formed into filters or integrated into filtration apparatuses. Also disclosed are methods for sequestering or clearing solutes from solutions and fluids, methods for the treatment of diseases or conditions, and methods for the prevention of diseases or conditions.