LIPID BILAYERS INCLUDING CHOLESTEROL AS VEHICLES FOR ACID DYES IN WOOL DYEING

We describe the use of large unilamellar liposomes of a defined size a nd containing cholesterol as vehicles in commercial dyeing of untreate d wool with a milling acid dye. To this end, we have investigated lipo somes prepared with egg phosphatidylcholine (PC) and cholesterol (CH) at different lipid compositions (from 10:0 to 8:2 molar ratios) contai ning the commercial acid dye Polar blue G, CI acid blue 90. We assesse d the physical stability of these systems by measuring the mean vesicl e size of the suspensions during dyeing. We also investigated kinetic aspects involving dye adsorption and bonding to untreated wool samples at different PC:CH lipid compositions. Increasing amounts of CH in bi layers enhance both the physical stability of complete liposomes and t he inhibition of dye exhaustion on untreated wool. Using only the dye trapped in bilayers, dyeing kinetics follows a different tendency, rea ching the maximum initial inhibition and final exhaustion for the PC:C H 8.5:1.5 molar ratio. Bonding of dye to wool fibers also improves, re aching the optimum value for the PC: CH molar ratio 8.5:1.5 in all cas es. The smoothness of dyed wool samples is also enhanced, the best res ults being reached with the highest proportion of CH.