Tailor-Made Antimicrobial/Antiviral Star Polymer via ATRP of Cyclodextrin and Guanidine-Based Macromonomer

Novel star-like polymers are prepared via atom transfer radical polymerization (ATRP) of polyhexamethylene guanidine hydrochloride (PHMG) macromonomer and acrylamide (AM) using beta-cyclodextrin (CD) with 8-active and 5-active sites as a macroinitiator. The resulting star-like polymers are characterized by gel permeation chromatography (GPC) and H-1 NMR and are used for deactivating bacteria and viruses. It is found that star polymers with comparable amounts of PHMG possess excellent antimicrobial activity, which, however, strongly depends on the topological structure (i.e., the arm number and the monomer ratio) of the composing copolymers. The in vitro antibacterial activities of the synthesized polymers are investigated against Escherichia coli in terms of the minimum inhibitory concentration (MIC), whereas the antiviral activity of star copolymers is assessed via a plaque assay against non-enveloped adenovirus (ADV). The results show that the highest antimicrobial activity is achieved by the star-like copolymer with the monomer ratio of 20:3 (AM:PHGM, mol/mol), while the number of functional arms is fixed at 8. The incorporation of PHMG also renders the star copolymer highly antiviral, thus permitting it to be used as an effective antibacterial/antiviral agent for various applications.