Binding of metal cations to chemically modified wool and antimicrobial properties of the wool-metal complexes

Wool was modified by treatment with tannic acid (TA) or by acylation with ethylenediaminetetraacetic (EDTA) dianhydride. Kinetics of modification with TA and acylation with EDTA-dianhydride was investigated as a function of the reaction time. Wool displayed a higher breaking load and lower elongation at break as the degree of acylation increased. The absorption of metal cations (Ag+, Cu2+) by untreated and chemically modified wool was studied as a function of the kind of modifying agent, weight gain, and pH of the metal solution. Absorption of Ag+ and Cu2+ at alkaline pH increased with increasing weight gain of both TA and EDTA-dianhydride. The absorption of metal cations by untreated and TA-treated wool below pH 7 was negligible. Acylation with EDTA-dianhydride enabled wool to absorb and bind significant amounts of metal cations at acidic and neutral pHs. The wool-Ag complexes exhibited low levels of metal desorption at acidic pH, irrespective of chemical modification. Higher levels of metal desorption were shown by wool-Cu and wool-EDTA-Cu complexes. Wool-Ag complexes exhibited prominent antimicrobial activity against Corne-bacterium and E. coli. (C) 2001 John Wiley & Sons, Inc.