Synthesis of 1,4-diazabicyclo[2.2.2]octane and pyridinium based cationic polymers via ROMP technique and examination of their antibacterial activity and cytotoxicity

Abstract

This paper focuses on the synthesis of cationic antibacterial polymers that could be a potential source for new-generation antibiotics with well-defined architecture derived from the Ring Opening Metathesis Polymerization (ROMP) technique. Mono- and double-charge bearing quaternary groups have been used to synthesize cationic homopolymers (MWs: 3000 and 10,000 g/mole) and their copolymers (MWs: 5000 g/mole). Hemolytic concentration (HC50, ≥1000 µg/mL) and MTS assay results showed that the polymers are non-toxic. It has been observed that the double-charge bearing polymers have the highest antimicrobial activity (S. aureus= 8 µg/mL) and a high selectivity against S. aureus (>250). Percent killing efficiencies were tested on a glass surface where moderate killing efficiency was observed in the range of 40–80% in 5 min. Cationic charge density and zeta potential studies were used to investigate the mechanisms of antimicrobial efficiency of the polymers in a solution during the action against S. aureus to understand structure-activity relationships. Scanning electron microscopy (SEM) was also conducted for the bacterial morphology assay.