Cationic polymeric N-halamines bind onto biofilms and inactivate adherent bacteria.

Abstract

A series of amine-based cationic polymeric N-halamine precursors, poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-trimethyl-2-methacryloxyethylammonium chloride)(PMPQ), were synthesized by copolymerizing 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TMPM) with trimethyl-2-methacryloxyethylammonium chloride (TMAC) at different molar ratios (TMPM:TMAC = 10:90,30:70,50:50,70:30, and 90:10). After chlorine bleach treatment, the TMPM moieties in the new copolymers were transformed into amine-based N-halamines (Cl-PMPQ). The chemical structures of the samples were characterized with 1H NMR, FT-IR, and UV spectra, and the molecular weights were determined by dynamic light scattering (DLS). With lower than 70 mol% of the original TMPM content, the resulting Cl-PMPQ copolymers were soluble in water, and demonstrated potent antibacterial functions against Escherichia coli (E. coli, a representative Gram-negative bacteria) and Staphylococcus epidermidis (S. epidermidis, a representative Gram-positive bacteria). E. coli and S. epidermidis were allowed to form biofilms on glass slides. Zeta potential analyses demonstrated that the Cl-PMPQ copolymers rapidly adsorbed onto the preexisting biofilms, and bacterial culturing studies confirmed that the bound Cl-PMPQ provided a total kill of the adherent bacteria in the biofilms. The kinetics of the Cl-PMPQ binding onto the preexisting biofilms were studied with UV analyses. The data fitted well to the bimodal model. The binding kinetic parameters of Cl-PMPQ onto the bacterial biofilms were thus determined.