Cu2O doped gel-type anion exchanger obtained by reduction of brochantite deposit and its antimicrobial activity

Abstract

Abstract A gel-type strongly basic polystyrene/divinylbenzene anion exchanger (An) was used as the support for Cu2O whereby a hybrid ion exchanger (HIX) was obtained. The Cu4(OH)6SO4 deposit was introduced into its skeleton through a reaction with CuSO4 solution, then it was transformed into Cu2O through a wet chemical reduction. Ascorbic acid yielded abundant Cu2O outside of the resin phase. The HIX with the highest Cu2O content (30\u202fmg Cu/g) was obtained with glucose. An SEM/EDS analysis showed that Cu2O microparticles in the HIX occurred in the form of spheres 0.5–2.0\u202fμm in size, with the largest number of them situated close to the surface of the beads and a smaller number inside them. The test performed for the HIX against Enterococcus faecalis and Escherichia coli demonstrated its promising and varied antimicrobial activity. A 100% reduction of viable cells of Enterococcus faecalis from 5 log10 CFU/mL to 0 was observed after 24\u202fh incubation with 128\u202fmg of An/Cu2O. In the case of Escherichia coli the minimum bactericidal concentration of both hybrid polymer or supporting anion exchanger was 64\u202fmg. It was indicated that against Gram-positive bacteria the antibacterial activity was the synergistic effect of presence of Cu2O and the host polymer, while Gram-negative bacteria were highly susceptible to the functional groups of the anion exchanger.