Repeated rehydration of lipid films as a method to mix phospholipids without the use of organic solvents.

A technically simple method for mixing phospholipids of different species without using organic solvents or additives has been developed. Based on the reported literature regarding aqueous lamellar systems, phospholipid interaction parameters, and lipid diffusion coefficients, we hypothesized that the repeated drying and rehydration of a multispecies phospholipid sample, using only deionized water, should produce a uniform distribution of phospholipid molecules. Different lipid films of binary mixtures of zwitterionic and anionic glycerophospholipids were prepared using this method. The resulting films were reconstituted in vesicular form and compared to controls prepared with organic solvents by differential scanning calorimetry. The calorimetric scans revealed no significant differences between samples and controls for any of the tested mixtures. This finding suggests that the proposed technique creates a product with equivalent compositional homogeneity than the conventional method. From an environmental, health and safety standpoint, we are confident that this technique can contribute to the implementation of sustainable chemical practices, especially in industrial settings where organic solvents are tightly regulated.