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j. Soc. Cosmet. Chem., 43, 113-118 (March/April 1992) Some properties of N-acyl sarcosinate lipid vesicles DONALD F. H. WALLACH, RAJIV MATHUR, GERARD J. M. REDZINIAK, and JEAN-FRANCOIS TRANCHANT, Micro Vesicular Systems, Inc., 20 Cotton Road, Nashua, NH 03049 (D.F.H.W., R.M.), and Parfums Christian Dior 45804 Saint Jean de Braye, France (G.J.M.R., J.-F.T.). Received August 1 O, 19910 INTRODUCTION In recent years considerable effort has been directed toward the development of lipid bilayer vesicle delivery systems employing lipid amphiphiles other than phospholipids. Amphiphiles have been shown to form lipid vesicles of different types and stabilities and include fatty acids (1,2), dialkyldimethylammonium amphiphiles (3-7), dialkyl amo phiphiles with ionic or zwitterionic head groups (8,9), polyglycerol alkyl ethers and polyethoxylated analogues (10,11), two-tailed sucrose fatty acid esters (12,13), and appropriate mixtures of single-tailed cationic and anionic surfactants (14). Our own efforts have focused on the production of nonophospholipid paucilamellar vesicles that we call "novasomes" (15-20). These vesicles are 0.1-1.0 microns in di- ameter, with 2-5 bilayer shells surrounding an unstructured space that can be occupied by aqueous or water-immiscible materials. These vesicles are formed by injection of a liquid amphiphile mixture into the excess aqueous phase at high velocity, followed by cooling under conditions of turbulent mixing. The injection step causes the lipid to form minute droplets that are quickly converted into micelies. The cooling step causes the micelles to fuse into paucilamellar vesicles within milliseconds. The vesicles can be produced in amounts ranging from milliliter batches to continuous flow at costs equiv- alent to those of making simple emulsions. This paper concerns novasomes made from N-acyl sarcosinates, amphiphiles widely used in shampoos, soaps, skin cleansers, and a variety of other cosmetic and personal care applications. Noacyl sarcosinates have the following general structure: R - C - N - CH2 - COOH (--) R - C - N - CH2 - CH2 - COO - -4- H + O CH 3 O CH 3 where R is a single fatty acyl chain, usually lauroyl or oleoyl or a mixture (e.g., coconut oil fatty acids). 113