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

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 Cu-4(OH)(6)SO4 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 mg 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 mu m 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 h incubation with 128 mg of An/Cu2O. In the case of Escherichia coli the minimum bactericidal concentration of both hybrid polymer or supporting anion exchanger was 64 mg. 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.