The effect of reactive dyes upon the uptake and antibacterial efficacy of poly(hexamethylene biguanide) on cotton. Part 3: Reduction in the antibacterial efficacy of poly(hexamethylene biguanide) on cotton, dyed with bis(monochlorotriazinyl) reactive dyes

The antibacterial efficiency of poly(hexamethylene biguanide), PHMB, on un-dyed cotton has been compared with that of PHMB on cotton coloured with a range of reactive dyes. In each case, the presence of covalently bound dye resulted in a reduction in antibacterial efficiency. In the absence of dye, the cationic PHMB binds to the cotton via weak ion-ion linkages with the carboxylate groups present on cotton; these dissociate readily allowing release of free PHMB, the active antibacterial agent. In the presence of reactive dye, the cationic PHMB forms stronger ion-ion linkages with the strong sulphonic acid groups of the dyes; thus release of free PHMB, the active agent, is less facile and antibacterial efficiency reduced accordingly. © 2006 Elsevier Ltd. All rights reserved.