Patent ID: 6936215

Claim:
A method for controlling the wall thickness of lipid microtubules formed by cooling a heated methanol-water mixture containing the dissolved lipid comprising the steps: (a) selecting a methanol-water system to be used which is characterized by a volume ratio of methanol and water that totals 100 volume percent, wherein the methanol and water are first filtered to remove any particulates and wherein the filter is at least as fine as a 0.22 micron filter; (b) determining the amount of lipid to be used for the solvent system selected in step (a) so as to produce the desired wall thickness of the microtubule; (c) dissolving the determined amount of lipid from step (b) into a portion of the methanol which has been heated to a temperature above the transition temperature for the lipid to form a clear solution; (d) adding the heated methanol lipid solution of step (c) into a mixture of the remaining methanol and water as selected in step (a) which has been heated to a comparable temperature above the transition temperature for the lipid as in step (c) so that the total amount of methanol and water is in the desired amount selected in step (a); and (e) cooling the heated mixture in step (d) slowly to permit the formation of microtubules with a controlled, uniform number of bilayers.