The invention relates to an ancient defense polymer having biological activity. The polymer comprises both discrete hydrophilic blocks containing cationic charge(s) and discrete hydrophobic blocks, making it amphipathic and antimicrobial in a manner analogous to natural antimicrobial peptides that form an ancient defense mechanism employed by many organisms. Such a polymer may be formed into devices designed to resist infection or bound to the surface of an apparatus to lend the biological activity to the surface of the apparatus.