This is feasible for hydrogen-bonded layer-by-layer assemblies, preferably obtained from solutions of low water content (such as 91-96% ethanol), though imprinting from aqueous buffer solutions has also been demonstrated. The track-etched membranes were used as supports, and polyacrylic acid and polyallylamine as polyelectrolytes. Ionic liquid is useful in the deposition of the polymer multilayers, as it increases the ionic strength (impermeable membranes are obtained with from ionic strength solutions). The technique does not require cross-linking, though it might increase the quality of the impints. Polar compounds with ionizable groups (penicillins, Rhodamin B) can form the imprints, while less polar non-ionizable compounds (phytosterols) do not.